UI--多行文本折叠展开效果
1.概述
经常在APP中能看到有引用文章或大段博文的内容，他们的展示样式也有点儿意思，默认是折叠的，当你点击文章之后它会自动展开。再次点击他又会缩回去。
网上有找到部分效果，感觉不是很满意。最后自己尝试用 自定义布局layout 写了个demo。比较简陋，不过可以用了。有这方面需求的朋友可以稍加改造下。如有更好的创意，也不妨分享一下。
效果图：
2.具体实现
但从实现效果方面来看，只用简单定义必要view即可，后变为了方便扩展使用和挪用，又对整个布局进行封装，方便直接使用。
2.1 通过多个布局组合实现
第一想法当然是用多个View组合来实现。那么久定义一个LinearLayout布局分别嵌套TextView和ImageView来做。
大概步骤：
- 定义布局，垂直的线性LinearLayout布局、TextView和ImageView。 在layout中定义基本组件。
- 设置TextView的高度为指定行数*行高。 不使用maxLine的原因是maxLine会控制显示文本的行数，不方便后边使用动画展开全部内容。因此这里TextView的高度也因该为wrap_content。
- 给整个布局添加点击事件，绑定动画。 点击时，若TextView未展开则展开至其实际高度，imageView 旋转；否则回缩至 指定行数*行高 , imageView 旋转缩回。
开始编写代码：
1.在xml中定义布局:
<code class="language-xml hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout
</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/description_layout"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:orientation</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"vertical"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingLeft</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"12dip"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingRight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"12dip"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingTop</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"5dip"</span> ></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">TextView
</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/description_view"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:textColor</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@android:color/black"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:textSize</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"18dip"</span> ></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">TextView</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">ImageView
</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/expand_view"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_gravity</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"right"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingBottom</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"5dip"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingLeft</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"5dip"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingRight</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"5dip"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:paddingTop</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"5dip"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:src</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@drawable/text_ic_expand"</span>
<span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:visibility</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"gone"</span> /></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li></ul>
2.首先在activity中定义并初始化这些view：
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">MainActivity</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Activity</span> {</span>
TextView descriptionView;
View layoutView ,expandView; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//LinearLayout布局和ImageView</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> maxDescripLine = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//TextView默认最大展示行数</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//在OnCreate中初始化</span>
{
layoutView = findViewById(R.id.description_layout);
descriptionView = (TextView)findViewById(R.id.description_view);
expandView = findViewById(R.id.expand_view);
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>
3.然后设置textview显示文本，再根据默认展示行数设置其高度，并根据其是否已完全显示（当前展示行数是否大于等于实际行数）来判断需不需要点击更多按钮。
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//设置文本</span>
descriptionView.setText(getText(R.string.content));
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//descriptionView设置默认显示高度</span>
descriptionView.setHeight(descriptionView.getLineHeight() * maxDescripLine);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//根据高度来判断是否需要再点击展开</span>
descriptionView.post(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Runnable() {
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">run</span>() {
expandView.setVisibility(descriptionView.getLineCount() > maxDescripLine ? View.VISIBLE : View.GONE);
}
}); </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li></ul>
因为textView设置的是wrap_content，所以会显示实际高度和行数，这里根据maxDescripLine来设置其高度。
看了最后一行代码可能有人会问？ImageView （点击展开更多）是否应该显示 的判断逻辑为什么要放在post方法里边呢？ 这是由于在OnCreate方法中定义设置的textView不会马上渲染并显示，所以textview的getLineCount()获取到的值一般都为零，因此使用post会在其绘制完成后来对ImageView进行显示控制。
ps: 感觉我描述不清的朋友可以看下stackoverflow 上的讲解 how to use getlinecount() in textview android.
4.给layoutView设置点击事件。
给ImageView定义一个RotateAnimation的旋转动画，在旋转过程中根据旋转百分比进度控制textView高度，进而达到我们想要的效果。
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> layoutView.setOnClickListener(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> View.OnClickListener() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> isExpand;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//是否已展开的状态</span>
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onClick</span>(View v) {
isExpand = !isExpand;
descriptionView.clearAnimation();<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//清楚动画效果</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> deltaValue;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//默认高度，即前边由maxLine确定的高度</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> startValue = descriptionView.getHeight();<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//起始高度</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> durationMillis = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">350</span>;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//动画持续时间</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (isExpand) {
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 折叠动画
* 从实际高度缩回起始高度
*/</span>
deltaValue = descriptionView.getLineHeight() * descriptionView.getLineCount() - startValue;
RotateAnimation animation = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RotateAnimation(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180</span>, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f);
animation.setDuration(durationMillis);
animation.setFillAfter(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>);
expandView.startAnimation(animation);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 展开动画
* 从起始高度增长至实际高度
*/</span>
deltaValue = descriptionView.getLineHeight() * maxDescripLine - startValue;
RotateAnimation animation = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RotateAnimation(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f);
animation.setDuration(durationMillis);
animation.setFillAfter(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>);
expandView.startAnimation(animation);
}
Animation animation = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Animation() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">applyTransformation</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> interpolatedTime, Transformation t) { <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//根据ImageView旋转动画的百分比来显示textview高度，达到动画效果</span>
descriptionView.setHeight((<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>) (startValue + deltaValue * interpolatedTime));
}
};
animation.setDuration(durationMillis);
descriptionView.startAnimation(animation);
}
});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li></ul>
至此，通过布局已经实现了我们想要的效果。具体代码参见代码示例 的第一部分。
当然，我们可以这样使用，但是每次都这么重写未免显得有些麻烦。因此有必要把他写成一个单独控件，方便我们以后的开袋即食。废话不多说，上菜。
2.2 通过自定义View组合封装
这个view的布局结构并不打算使用xml来定义layout，直接定义一个继承LinearLayout的MoreTextView类.这个类里边添加TextView和ImageView。
1.使用styleable自定义View属性
为了后边能够方便的在xml布局中使用MoreTextView这个自定义View，类似通过
android：text = “XXX”
android：textSize = “XXX”
这样快捷的绑定文本内容和设置字体大小等属性，我们可以通过 declare-styleable在values文件下的xml中自定义我们想要的属性，并在View中获取和使用。详细使用declare-styleable的内容会在后边补充，这里简要说下。
比如，MoreTextView应该有的基本属性,像 文本字体大小(textSize)、颜色(textColor)和文本内容（text），还有默认显示行数(maxLine)等几种属性。我们要想像TextView一样直接在xml中设置绑定，可以这样做。
首先在values目录下新建个attrs.xml(名字随意),并定义MoreTextView这些属性。
<code class="language-xml hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-pi" style="color: rgb(0, 102, 102); box-sizing: border-box;"><?xml version="1.0" encoding="utf-8"?></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">resources</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">declare-styleable</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"MoreTextStyle"</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">attr</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"textSize"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">format</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"dimension"</span>/></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">attr</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"textColor"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">format</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"color"</span>/></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">attr</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"maxLine"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">format</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"integer"</span> /></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">attr</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">name</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"text"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">format</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"string"</span> /></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">declare-styleable</span>></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">resources</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>
2.自定义MoreTextView并获取这些属性的值
上边定义了这些属性，就等于允许我们在xml中使用
more：text = “XXX”
more：textSize = “XXX”
more : textColor = “XXX”
more : maxLine = “XXX”
(注： more这个关键字可以随意)
这样直接设置属性值。那么具体怎么取值，我们稍后来讲。
（1）定义MoreTextView的属性：
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">MoreTextView</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">LinearLayout</span>{</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> TextView contentView; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//文本正文</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> ImageView expandView; <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//展开按钮</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//对应styleable中的属性</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> textColor;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> textSize;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> maxLine;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> String text;
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//默认属性值</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> defaultTextColor = Color.BLACK;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> defaultTextSize = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">12</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> defaultLine = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>;
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//....实现部分略</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul>
（2）MoreTextView的构造方法：
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">MoreTextView</span>(Context context, AttributeSet attrs) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(context, attrs);
initalize();
initWithAttrs(context, attrs);
bindListener();
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>
这三个方法简单说明下：
- initalize() 初始化并添加View。初始化TextView和ImageView,并添加到MoretextView中去。
- initWithAttrs(context, attrs) 取值并设置。利用attrs从xml布局中取我们配置好的text/textSize/textColor/maxLine等属性的属性值，并设置到View上去。
- bindListener() 绑定点击事件并设置动画。 给当前MoreTextView设置点击事件，实现点击折叠和展开。
各个方法的具体实现：
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//初始化并添加View</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">initalize</span>() {
setOrientation(VERTICAL); <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//设置垂直布局</span>
setGravity(Gravity.RIGHT); <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//右对齐</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//初始化textView并添加</span>
contentView = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> TextView(getContext());
addView(contentView, LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//初始化ImageView并添加</span>
expandView = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ImageView(getContext());
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> padding = dip2px(getContext(), <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5</span>);
expandView.setPadding(padding, padding, padding, padding);
expandView.setImageResource(R.drawable.text_ic_expand);
LinearLayout.LayoutParams llp = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
addView(expandView, llp);</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li></ul>
取值并设置这部分有必要将一下。我们利用TypedArray从定义的styleable中取出属性值，赋给我们定义好的类的属性变量。记得取完之后调用recycle()回收释放。
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">initWithAttrs</span>(Context context, AttributeSet attrs) {
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.MoreTextStyle);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> textColor = a.getColor(R.styleable.MoreTextStyle_textColor,
defaultTextColor); <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//取颜色值，默认defaultTextColor</span>
textSize = a.getDimensionPixelSize(R.styleable.MoreTextStyle_textSize, defaultTextSize);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//取颜字体大小，默认defaultTextSize</span>
maxLine = a.getInt(R.styleable.MoreTextStyle_maxLine, defaultLine);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//取颜显示行数，默认defaultLine</span>
text = a.getString(R.styleable.MoreTextStyle_text);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//取文本内容</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//绑定到textView bindTextView(textColor,textSize,maxLine,text);</span>
a.recycle();<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//回收释放</span>
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//绑定到textView </span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">bindTextView</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> color,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> size,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> line,String text){
contentView.setTextColor(color);
contentView.setTextSize(TypedValue.COMPLEX_UNIT_PX,size);
contentView.setText(text);
contentView.setHeight(contentView.getLineHeight() * line);
post(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Runnable() {<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//前面已讲，不再赘述</span>
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">run</span>() {
expandView.setVisibility(contentView.getLineCount() > line ? View.VISIBLE : View.GONE);
}
});
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li></ul>
最后设置点击事件。
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//点击展开与折叠，不再赘述</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">bindListener</span>(){
setOnClickListener(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> View.OnClickListener() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">boolean</span> isExpand;
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onClick</span>(View v) {
isExpand = !isExpand;
contentView.clearAnimation();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> deltaValue;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> startValue = contentView.getHeight();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> durationMillis = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">350</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (isExpand) {
deltaValue = contentView.getLineHeight() * contentView.getLineCount() - startValue;
RotateAnimation animation = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RotateAnimation(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180</span>, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f);
animation.setDuration(durationMillis);
animation.setFillAfter(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>);
expandView.startAnimation(animation);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
deltaValue = contentView.getLineHeight() * maxLine - startValue;
RotateAnimation animation = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> RotateAnimation(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">180</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f, Animation.RELATIVE_TO_SELF, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f);
animation.setDuration(durationMillis);
animation.setFillAfter(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>);
expandView.startAnimation(animation);
}
Animation animation = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Animation() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">applyTransformation</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> interpolatedTime, Transformation t) {
contentView.setHeight((<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>) (startValue + deltaValue * interpolatedTime));
}
};
animation.setDuration(durationMillis);
contentView.startAnimation(animation);
}
});
}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li></ul>
另外，定义几个方法方便外部调用（获取文本TextView，直接设置文本内容），同时还定义了一个dip转像素的静态方法。
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> TextView <span class="hljs-title" style="box-sizing: border-box;">getTextView</span>(){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> contentView;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">setText</span>(CharSequence charSequence){
contentView.setText(charSequence);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> <span class="hljs-title" style="box-sizing: border-box;">dip2px</span>(Context context, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> dipValue){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> scale = context.getResources().getDisplayMetrics().density;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>)(dipValue * scale + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>f);
} </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>
其实到这里，我们的自定义多文本折叠展开MoreTextView已经完成了。如何使用呢？
-
在layout/xx.xml中使用
要想方便的使用我们刚刚的自定义属性来定义值，记得在xml namespace中定义应用：自动引用命名空间res-auto
xmlns:more=”http://schemas.android.com/apk/res-auto”
或者 直接定义包名
xmlns:more=”http://schemas.android.com/apk/res/com.qiao.moretext”命名空间后边跟的 more即下边你要使用自定义属性的开头部分。
比如我们的activity_main.xml
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><LinearLayout xmlns:android=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://schemas.android.com/apk/res/android"</span>
xmlns:more=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://schemas.android.com/apk/res/com.qiao.moretext"</span>
android:id=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"@+id/root"</span>
android:layout_width=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"match_parent"</span>
android:layout_height=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"match_parent"</span>
android:background=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"@android:color/white"</span>
android:orientation=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"vertical"</span> >
<com.qiao.moretext.MoreTextView
android:layout_width=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"match_parent"</span>
android:layout_height=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"wrap_content"</span>
android:layout_margin=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"5dip"</span>
more:textColor=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"@android:color/black"</span>
more:textSize=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"18dip"</span>
more:maxLine=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"3"</span>
more:text=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"@string/content"</span>/>
</LinearLayout></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li></ul>
- 在java中直接定义使用
由于上边定义MoreTextView只定义了一种构造方法 MoreTextView(Context context, AttributeSet attrs) ，所以使用时，也只能：
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> MoreTextView content = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> MoreTextView(MainActivity.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>);
content.setText(getText(R.string.content));
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//然后addview到你要添加的地方</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>
当然，聪明如你，可肯定知道怎么定义另外的构造方法来简单实用啦。
–>
MoreTextView(Context context){
//使用默认值直接初始化
bindTextView()；
}
3.综述
综上呢，我们已经完成了所要实现的功能，作为UI呢，他可能会有些简陋，但作为一个demo起到示范作用已经够了。后边我们可能会考虑把它作为微博的一个listitem做成列表一样，并加入点赞等功能。有兴趣不妨做一下咯。。
源码示例下载地址
转载请保留出处 by Qiao
http://blog.csdn.net/qiaoidea/article/details/45568653