Android TextView 自動換行問題

Android的TextView在顯示文字的時候有個問題就是一行還沒顯示滿就跳到下一行，原因是：

1） TextView在顯示中文的時候標點符號不能顯示在一行的行首和行尾，如果一個標點符號剛好在一行的行尾，該標點符號就會連同前一個字符跳到下一行顯示；

2）一個英文單詞不能被顯示在兩行中（ TextView在顯示英文時，標點符號是可以放在行尾的，但英文單詞也不能分開）；

如果只是想讓標點符號可以顯示在行尾，有一個簡單的方法就是在標點符號後加一個空格，則該標點符號就可以顯示在行尾了；

如果想要兩端對齊的顯示效果，有兩種方法：

1）修改Android源代碼；將frameworks/base/core/java/android/text下的StaticLayout.java文件中的如下代碼：

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。去掉後標點符號可以顯示在行首和行尾，英文單詞也可以被分開在兩行中顯示。

2）自定義View顯示文本

網上就有達人採用自定義View來解決這個問題，我做了實驗並總結了一下：

自定義View的步驟：

1）繼承View類或其子類，例子繼承了TextView類；

2）寫構造函數，通過XML獲取屬性（這一步中可以自定義屬性，見例程）；

3）重寫父類的某些函數，一般都是以on開頭的函數，例子中重寫了onDraw()和onMeasure()函數；

=========================StartCustomTextView.java=============================

public class StartCustomTextView extends TextView {
    public  static  int m_iTextHeight; //文本的高度
    public  static  int m_iTextWidth;//文本的寬度
    
    private Paint mPaint = null;
    private String string="";
    private float LineSpace = 0;//行間距
    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();
        
        //設置 CY TextView的寬度和行間距www.linuxidc.com
        m_iTextWidth=width;
        LineSpace=linespace;
        
        // 構建paint對象      
        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;//計算字體高度（字體高度＋行間距）

        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()
    {
        //設置 CY TextView的初始高度爲0
        m_iTextHeight=0;
        
        //大概計算 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===============================

該文件是自定義的屬性，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>

藍色代碼即爲自定義View，其中以cy命名空間開頭的屬性是自定義屬性；

=======================Main.java=============================

public class Main extends Activity {
CYTextView mCYTextView;
String text = "Android提供了精巧和有力的組件化模型構建用戶的UI部分。主要是基於佈局類：View和 ViewGroup。在此基礎上，android平臺提供了大量的預製的View和xxxViewGroup子 類，即佈局（layout）和窗口小部件（widget）。可以用它們構建自己的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);
}

}

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轉自：http://hi.baidu.com/java_rose/blog/item/2940a030d1ec7f3e96ddd847.html

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