Android转载五：TextView换行问题
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。
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：
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；
=========================StartCustomTextView.java=============================
public class StartCustomTextView 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 private int left_Margin; private int right_Margin; private int bottom_Margin; public StartCustomTextView(Context context, AttributeSet set) { super(context,set); DisplayMetrics displayMetrics = getResources().getDisplayMetrics(); TypedArray typedArray = context.obtainStyledAttributes(set, R.styleable.CYTextView); int width = displayMetrics.widthPixels; left_Margin = 29; right_Margin = 29; bottom_Margin = 29; width = width - left_Margin -right_Margin; float textsize = typedArray.getDimension(R.styleable.CYTextView_textSize, 34); int textcolor = typedArray.getColor(R.styleable.CYTextView_textColor, getResources().getColor(R.color.white)); float linespace = typedArray.getDimension(R.styleable.CYTextView_lineSpacingExtra, 15); int typeface = typedArray.getColor(R.styleable.CYTextView_typeface, 0); typedArray.recycle(); //设置 CY TextView的宽度和行间距www.linuxidc.com 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); LayoutParams layout = new LinearLayout.LayoutParams(measuredWidth,measuredHeight); layout.leftMargin= left_Margin; layout.rightMargin= right_Margin; layout.bottomMargin= bottom_Margin; this.setLayoutParams(layout); 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) { string = text; // requestLayout(); // invalidate(); } }
=======================attrs.xml===============================
该文件是自定义的属性，放在工程的res/values下
<resources> <attr name="textwidth" format="integer"/> <attr name="typeface"> <enum name="normal" value="0"/> <enum name="sans" value="1"/> <enum name="serif" value="2"/> <enum name="monospace" value="3"/> </attr> <declare-styleable name="CYTextView"> <attr name="textwidth" /> <attr name="textSize" format="dimension"/> <attr name="textColor" format="reference|color"/> <attr name="lineSpacingExtra" format="dimension"/> <attr name="typeface" /> </declare-styleable> </resources>
=======================main.xml==========================
<?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:Android="http://schemas.android.com/apk/res/android" Android:layout_width="320px" Android:layout_height="320px" Android:background="#ffffffff" > <LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android" Android:orientation="vertical" Android:layout_width="fill_parent" Android:layout_height="fill_parent"> <com.cy.CYTextView.CYTextView xmlns:cy="http://schemas.Android.com/apk/res/ com.cy.CYTextView " 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"> </com. cy .CYTextView.CYTextView> </LinearLayout> </ScrollView>
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); } }
转自：http://hi.baidu.com/java_rose/blog/item/2940a030d1ec7f3e96ddd847.html
