Android TextView标点符号换行问题（顺便学习Android自定义View）
Android的TextView在显示文字的时候有个问题就是一行还没显示满就跳到下一行，原因是：
1） TextView在显示中文的时候 标点符号不能显示在一行的行首和行尾，如果一个标点符号刚好在一行的行尾，该标点符号就会连同前一个字符跳到下一行显示；
2）一个英文单词不能被显示在两行中（ TextView在显示英文时，标点符号是可以放在行尾的，但英文单词也不能分开 ）；
如果只是想让标点符号可以显示在行尾，有一个简单的方法就是在标点符号后加一个空格，则该标点符号就可以显示在行尾了；
如果想要两端对齐的显示效果，有两种方法：
1）修改Android源代码；将frameworks/base/core/java/android/text下的StaticLayout.java文件中的如下代码：
if (c == ' ' || c == '/t' ||
((c == '.' || c == ',' || c == ':' || c == ';') &&
(j - 1 < here || !Character.isDigit(chs[j - 1 - start])) &&
(j + 1 >= next || !Character.isDigit(chs[j + 1 - start]))) ||
((c == '/' || c == '-') &&
(j + 1 >= next || !Character.isDigit(chs[j + 1 - start]))) ||
(c >= FIRST_CJK && isIdeographic(c, true) &&
j + 1 < next && isIdeographic(chs[j + 1 - start], false))) {
okwidth = w;
ok = j + 1;
if (fittop < oktop)
oktop = fittop;
if (fitascent < okascent)
okascent = fitascent;
if (fitdescent > okdescent)
okdescent = fitdescent;
if (fitbottom > okbottom)
okbottom = fitbottom;
}
去掉就可以了。去掉后标点符号可以显示在行首和行尾，英文单词也可以被分开在两行中显示。
但是我师傅说修改框架不美气，会影响其它应用程序，最好是能在应用层面解决问题。 所以就有了方法2；
2）自定义View显示文本
网上就有达人采用自定义View来解决这个问题，我做了实验并总结了一下：
原文地址：http://www.eoeandroid.com/thread-64055-1-1.html
自定义View的步骤：
1）继承View类或其子类，例子继承了TextView类；
2）写构造函数，通过XML获取属性（这一步中可以自定义属性，见例程）；
3）重写父类的某些函数，一般都是以on开头的函数，例子中重写了onDraw()和onMeasure()函数；
=========================CYTextView.java=============================
public class CYTextView extends TextView {
public static int m_iTextHeight; //文本的高度
public static int m_iTextWidth;//文本的宽度
private Paint mPaint = null;
private String string="";
private float LineSpace = 0;//行间距
public CYTextView(Context context, AttributeSet set)
{
super(context,set);
TypedArray typedArray = context.obtainStyledAttributes(set, R.styleable.CYTextView);
int width = typedArray.getInt(R.styleable. CY TextView_textwidth, 320);
float textsize = typedArray.getDimension(R.styleable. CY TextView_textSize, 24);
int textcolor = typedArray.getColor(R.styleable. CY TextView_textColor, -1442840576);
float linespace = typedArray.getDimension(R.styleable. CY TextView_lineSpacingExtra, 15);
int typeface = typedArray.getColor(R.styleable. CY TextView_typeface, 0);
typedArray.recycle();
//设置 CY TextView的宽度和行间距
m_iTextWidth=width;
LineSpace=linespace;
// 构建paint对象
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setColor(textcolor);
mPaint.setTextSize(textsize);
switch(typeface){
case 0:
mPaint.setTypeface(Typeface.DEFAULT);
break;
case 1:
mPaint.setTypeface(Typeface.SANS_SERIF);
break;
case 2:
mPaint.setTypeface(Typeface.SERIF);
break;
case 3:
mPaint.setTypeface(Typeface.MONOSPACE);
break;
default:
mPaint.setTypeface(Typeface.DEFAULT);
break;
}
}
@Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
char ch;
int w = 0;
int istart = 0;
int m_iFontHeight;
int m_iRealLine=0;
int x=2;
int y=30;
Vector m_String=new Vector();
FontMetrics fm = mPaint.getFontMetrics();
m_iFontHeight = (int) Math.ceil(fm.descent - fm.top) + (int)LineSpace;//计算字体高度（字体高度＋行间距）
for (int i = 0; i < string.length(); i++)
{
ch = string.charAt(i);
float[] widths = new float[1];
String srt = String.valueOf(ch);
mPaint.getTextWidths(srt, widths);
if (ch == '/n'){
m_iRealLine++;
m_String.addElement(string.substring(istart, i));
istart = i + 1;
w = 0;
}else{
w += (int) (Math.ceil(widths[0]));
if (w > m_iTextWidth){
m_iRealLine++;
m_String.addElement(string.substring(istart, i));
istart = i;
i--;
w = 0;
}else{
if (i == (string.length() - 1)){
m_iRealLine++;
m_String.addElement(string.substring(istart, string.length()));
}
}
}
}
m_iTextHeight=m_iRealLine*m_iFontHeight+2;
canvas.setViewport(m_iTextWidth, m_iTextWidth);
for (int i = 0, j = 0; i < m_iRealLine; i++, j++)
{
canvas.drawText((String)(m_String.elementAt(i)), x, y+m_iFontHeight * j, mPaint);
}
}
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
int measuredHeight = measureHeight(heightMeasureSpec);
int measuredWidth = measureWidth(widthMeasureSpec);
this.setMeasuredDimension(measuredWidth, measuredHeight);
this.setLayoutParams(new LinearLayout.LayoutParams(measuredWidth,measuredHeight));
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
private int measureHeight(int measureSpec)
{
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
// Default size if no limits are specified.
initHeight();
int result = m_iTextHeight;
if (specMode == MeasureSpec.AT_MOST){
// Calculate the ideal size of your
// control within this maximum size.
// If your control fills the available
// space return the outer bound.
result = specSize;
}else if (specMode == MeasureSpec.EXACTLY){
// If your control can fit within these bounds return that value.
result = specSize;
}
return result;
}
private void initHeight()
{
//设置 CY TextView的初始高度为0
m_iTextHeight=0;
//大概计算 CY TextView所需高度
FontMetrics fm = mPaint.getFontMetrics();
int m_iFontHeight = (int) Math.ceil(fm.descent - fm.top) + (int)LineSpace;
int line=0;
int istart=0;
int w=0;
for (int i = 0; i < string.length(); i++)
{
char ch = string.charAt(i);
float[] widths = new float[1];
String srt = String.valueOf(ch);
mPaint.getTextWidths(srt, widths);
if (ch == '/n'){
line++;
istart = i + 1;
w = 0;
}else{
w += (int) (Math.ceil(widths[0]));
if (w > m_iTextWidth){
line++;
istart = i;
i--;
w = 0;
}else{
if (i == (string.length() - 1)){
line++;
}
}
}
}
m_iTextHeight=(line)*m_iFontHeight+2;
}
private int measureWidth(int measureSpec)
{
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
// Default size if no limits are specified.
int result = 500;
if (specMode == MeasureSpec.AT_MOST){
// Calculate the ideal size of your control
// within this maximum size.
// If your control fills the available space
// return the outer bound.
result = specSize;
}else if (specMode == MeasureSpec.EXACTLY){
// If your control can fit within these bounds return that value.
result = specSize;
}
return result;
}
public void SetText(String text)(注：此函数目前只有在UI线程中调用才可以把文本画出来，在其它线程中
无法画文本，找了好久找不到原因，求高手解答)
{
string = text;
// requestLayout();
// invalidate();
}
}
=======================attrs.xml===============================
该文件是自定义的属性，放在工程的res/values下
=======================main.xml==========================
android:layout_width="320px"
android:layout_height="320px"
android:background="#ffffffff"
>
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
android:id="@+id/mv"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
cy :textwidth="320"
cy :textSize="24sp"
cy :textColor="#aa000000"
cy :lineSpacingExtra="15sp"
cy :typeface="serif">
cy .CYTextView.CYTextView>
蓝色代码即为自定义View，其中以cy命名空间开头的属性是自定义属性；
=======================Main.java=============================
public class Main extends Activity {
CYTextView mCYTextView;
String text = "android提供了精巧和有力的组件化模型构建用户的UI部分。主要是基于布局类：View和 ViewGroup。在此基础上，android平台提供了大量的预制的View和xxxViewGroup子 类，即布局（layout）和窗口小部件（widget）。可以用它们构建自己的UI。";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.main);
mCYTextView = (CYTextView)findViewById(R.id.mv);
mCYTextView.SetText(text);
}
}
运行结果如下：