Android LinearLayout实现自动换行

package com.huanglong.mylinearlayout;
 
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
 
/**
 * @author huanglong 2013-5-28 自定义自动换行LinearLayout
 */
public class FixGridLayout extends ViewGroup {
 private int mCellWidth;
 private int mCellHeight;
 
 public FixGridLayout(Context context) {
  super(context);
 }
 
 public FixGridLayout(Context context, AttributeSet attrs) {
  super(context, attrs);
 }
 
 public FixGridLayout(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
 }
 
 public void setmCellWidth(int w) {
  mCellWidth = w;
  requestLayout();
 }
 
 public void setmCellHeight(int h) {
  mCellHeight = h;
  requestLayout();
 }
 
 /**
  * 控制子控件的换行
  */
 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  int cellWidth = mCellWidth;
  int cellHeight = mCellHeight;
  int columns = (r - l) / cellWidth;
  if (columns < 0) {
   columns = 1;
  }
  int x = 0;
  int y = 0;
  int i = 0;
  int count = getChildCount();
  for (int j = 0; j < count; j++) {
   final View childView = getChildAt(j);
   // 获取子控件Child的宽高
   int w = childView.getMeasuredWidth();
   int h = childView.getMeasuredHeight();
   // 计算子控件的顶点坐标
   int left = x + ((cellWidth - w) / 2);
   int top = y + ((cellHeight - h) / 2);
   // int left = x;
   // int top = y;
   // 布局子控件
   childView.layout(left, top, left + w, top + h);
 
   if (i >= (columns - 1)) {
    i = 0;
    x = 0;
    y += cellHeight;
   } else {
    i++;
    x += cellWidth;
 
   }
  }
 }
 
 /**
  * 计算控件及子控件所占区域
  */
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  // 创建测量参数
  int cellWidthSpec = MeasureSpec.makeMeasureSpec(mCellWidth, MeasureSpec.AT_MOST);
  int cellHeightSpec = MeasureSpec.makeMeasureSpec(mCellHeight, MeasureSpec.AT_MOST);
  // 记录ViewGroup中Child的总个数
  int count = getChildCount();
  // 设置子空间Child的宽高
  for (int i = 0; i < count; i++) {
   View childView = getChildAt(i);
   /*
    * 090 This is called to find out how big a view should be. 091 The
    * parent supplies constraint information in the width and height
    * parameters. 092 The actual mesurement work of a view is performed
    * in onMeasure(int, int), 093 called by this method. 094 Therefore,
    * only onMeasure(int, int) can and must be overriden by subclasses.
    * 095
    */
   childView.measure(cellWidthSpec, cellHeightSpec);
  }
  // 设置容器控件所占区域大小
  // 注意setMeasuredDimension和resolveSize的用法
  setMeasuredDimension(resolveSize(mCellWidth * count, widthMeasureSpec),
    resolveSize(mCellHeight * count, heightMeasureSpec));
  // setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
 
  // 不需要调用父类的方法
  // super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 }
 
 /**
  * 为控件添加边框
  */
 @Override
 protected void dispatchDraw(Canvas canvas) {
  // 获取布局控件宽高
  int width = getWidth();
  int height = getHeight();
  // 创建画笔
  Paint mPaint = new Paint();
  // 设置画笔的各个属性
  mPaint.setColor(Color.BLUE);
  mPaint.setStyle(Paint.Style.STROKE);
  mPaint.setStrokeWidth(10);
  mPaint.setAntiAlias(true);
  // 创建矩形框
  Rect mRect = new Rect(0, 0, width, height);
  // 绘制边框
  canvas.drawRect(mRect, mPaint);
  // 最后必须调用父类的方法
  super.dispatchDraw(canvas);
 }
 
}

package com.huanglong.mylinearlayout;
 
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.CheckBox;
import android.widget.SimpleAdapter;
import android.support.v4.app.NavUtils;
 
public class MainActivity extends Activity {
 private SimpleAdapter adapter;
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  FixGridLayout fixGridLayout = (FixGridLayout) findViewById(R.id.ll);
  fixGridLayout.setmCellHeight(30);
  fixGridLayout.setmCellWidth(100);
  for (int i = 0; i < 7; i++) {
   CheckBox box = new CheckBox(MainActivity.this);
   box.setText("第"+i+"个");
   fixGridLayout.addView(box);
  }
 }
 
 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  getMenuInflater().inflate(R.menu.activity_main, menu);
  return true;
 }
 
 
}