android开发笔记之不同机型的适配的解决方案(完整篇)

      现在,市场上android的机型太多,如何让自己的应用更多的适配不同的机型,这是一个非常现实的并且是要处理解决的问题。android官方给出的解决文档是从三个方向来分析处理的。

(1)支持不同屏幕大小的设备(Supporting Different Screen Sizes)

1.1  合理使用wrap_content,match_parent

1.2 尽可能的使用 RelativeLayout

1.3 针对不同的机型,使用不同的布局文件(Use Size Qualifiers):

     res/layout/main.xml

    res/layout-large/main.xml

1.4 尽量使用点9图片(Use Nine-patch Bitmaps)


(2)支持不同屏幕密度的设备(Supporting Different Screen Densities)

2.1 使用与密度无关的相素单位(Use Density-independent Pixels)-----dp,sp

<Button android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/clickme"
    android:layout_marginTop="20dp" />

<TextView android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:textSize="20sp" />

2.2 对不同的设备提供可选择的图片(Provide Alternative Bitmaps)

不同分辨率之间的比例关系:

xhdpi: 2.0
hdpi: 1.5
mdpi: 1.0 (baseline)
ldpi: 0.75

awesomeimage.png图片位置的放置:

MyProject/
res/
drawable-xhdpi/
awesomeimage.png
drawable-hdpi/
awesomeimage.png
drawable-mdpi/
awesomeimage.png
drawable-ldpi/
awesomeimage.png


(3)实现自适应用户界面流(Implementing Adaptative UI Flows)

3.1 识别当前的布局文件是那个(Determine the Current Layout):这个主要是采用标志位的方式来得到当前使用的布局文件

public class NewsReaderActivity extends FragmentActivity {
    boolean mIsDualPane;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_layout);

        View articleView = findViewById(R.id.article);
        mIsDualPane = articleView != null && 
                        articleView.getVisibility() == View.VISIBLE;
    }
}

针对当前布局文件没有的控件(eg:button),要对其进行判断是否为null:

Button catButton = (Button) findViewById(R.id.categorybutton);
OnClickListener listener = /* create your listener here */;
if (catButton != null) {
    catButton.setOnClickListener(listener);
}

3.2 根据当前布局,使用不同的响应操作(React According to Current Layout)

public void onHeadlineSelected(int index) {
    mArtIndex = index;
    if (mIsDualPane) {
        /* display article on the right pane */
        mArticleFragment.displayArticle(mCurrentCat.getArticle(index));
    } else {
        /* start a separate activity */
        Intent intent = new Intent(this, ArticleActivity.class);
        intent.putExtra("catIndex", mCatIndex);
        intent.putExtra("artIndex", index);
        startActivity(intent);
    }
}

final String CATEGORIES[] = { "Top Stories", "Politics", "Economy", "Technology" };

public void onCreate(Bundle savedInstanceState) {
    ....
    if (mIsDualPane) {
        /* use tabs for navigation */
        actionBar.setNavigationMode(android.app.ActionBar.NAVIGATION_MODE_TABS);
        int i;
        for (i = 0; i < CATEGORIES.length; i++) {
            actionBar.addTab(actionBar.newTab().setText(
                CATEGORIES[i]).setTabListener(handler));
        }
        actionBar.setSelectedNavigationItem(selTab);
    }
    else {
        /* use list navigation (spinner) */
        actionBar.setNavigationMode(android.app.ActionBar.NAVIGATION_MODE_LIST);
        SpinnerAdapter adap = new ArrayAdapter(this, 
                R.layout.headline_item, CATEGORIES);
        actionBar.setListNavigationCallbacks(adap, handler);
    }
}

3.3 在其它的activity中复用Fragments(Reuse Fragments in Other Activities):

在这一部分,android提供了一个解决同一操作,不同响应的解决方案,就是在父类中提供一个interface,在子类中实现interface,以实现不同的操作:

public class HeadlinesFragment extends ListFragment {
    ...
    OnHeadlineSelectedListener mHeadlineSelectedListener = null;

    /* Must be implemented by host activity */
    public interface OnHeadlineSelectedListener {
        public void onHeadlineSelected(int index);
    }
    ...

    public void setOnHeadlineSelectedListener(OnHeadlineSelectedListener listener) {
        mHeadlineSelectedListener = listener;
    }
}

public class HeadlinesFragment extends ListFragment {
    ...
    @Override
    public void onItemClick(AdapterView<?> parent, 
                            View view, int position, long id) {
        if (null != mHeadlineSelectedListener) {
            mHeadlineSelectedListener.onHeadlineSelected(position);
        }
    }
    ...
}



原始资料:

1.Designing for Multiple Screens:

http://developer.android.com/training/multiscreen/index.html

2.Supporting Different Screen Sizes:

http://developer.android.com/training/multiscreen/screensizes.html

3.Supporting Different Screen Densities:

http://developer.android.com/training/multiscreen/screendensities.html

4.Implementing Adaptative UI Flows:

http://developer.android.com/training/multiscreen/adaptui.html


参考资料:

1.

http://blog.csdn.net/hfreeman2008/article/details/9351687


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