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 == '
'){
                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 == '
'){
                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