android自定义view实现流式布局（FlowLayout）和热门标签

流式布局的效果图如图所示：应用场景诸如在搜索框的关键词显示等等。自定义view的流式布局(这里定义为FlowLayout)其实它就是一个Viewgroup，而后重写了它的几个方法，

代码如下：

package com.imooc.view;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;

/**
 * 流式布局
 * 
 * @author 黄海
 * 
 */
public class FlowLayout extends ViewGroup {

	public FlowLayout(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
	}

	public FlowLayout(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public FlowLayout(Context context) {
		this(context, null);
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
		int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
		int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
		int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

		// wrap_content
		int width = 0;
		int height = 0;

		// 记录每一行的宽度与高度
		int lineWidth = 0;
		int lineHeight = 0;

		// 得到内部元素的个数
		int cCount = getChildCount();

		for (int i = 0; i < cCount; i++) {
			View child = getChildAt(i);
			// 测量子View的宽和高
			measureChild(child, widthMeasureSpec, heightMeasureSpec);
			// 得到LayoutParams
			MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

			// 子View占据的宽度
			int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
			// 子View占据的高度
			int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;

			// 换行
			if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {
				// 对比得到最大的宽度
				width = Math.max(width, lineWidth);
				// 重置lineWidth
				lineWidth = childWidth;
				// 记录行高
				height += lineHeight;
				lineHeight = childHeight;
			} else
			// 未换行
			{
				// 叠加行宽
				lineWidth += childWidth;
				// 得到当前行最大的高度
				lineHeight = Math.max(lineHeight, childHeight);
			}
			// 最后一个控件
			if (i == cCount - 1) {
				width = Math.max(lineWidth, width);
				height += lineHeight;
			}
		}

		Log.e("TAG", "sizeWidth = " + sizeWidth + "|sizeHeight = " + sizeHeight);
		Log.e("TAG", "width = " + width);

		setMeasuredDimension(
		//
				modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width + getPaddingLeft()
						+ getPaddingRight(), modeHeight == MeasureSpec.EXACTLY ? sizeHeight
						: height + getPaddingTop() + getPaddingBottom()//
		);

	}

	/**
	 * 存储所有的View
	 */
	private List> mAllViews = new ArrayList>();
	/**
	 * 每一行的高度
	 */
	private List mLineHeight = new ArrayList();

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		Log.e("TAG", "onLayout");
		mAllViews.clear();
		mLineHeight.clear();

		// 当前ViewGroup的宽度
		int width = getWidth();

		int lineWidth = 0;
		int lineHeight = 0;

		List lineViews = new ArrayList();

		int cCount = getChildCount();

		for (int i = 0; i < cCount; i++) {
			View child = getChildAt(i);
			MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

			int childWidth = child.getMeasuredWidth();
			int childHeight = child.getMeasuredHeight();

			// 如果需要换行
			if (childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width - getPaddingLeft()
					- getPaddingRight()) {
				// 记录LineHeight
				mLineHeight.add(lineHeight);
				// 记录当前行的Views
				mAllViews.add(lineViews);

				// 重置我们的行宽和行高
				lineWidth = 0;
				lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
				// 重置我们的View集合
				lineViews = new ArrayList();
			}
			lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
			lineHeight = Math.max(lineHeight, childHeight + lp.topMargin + lp.bottomMargin);
			lineViews.add(child);

		}// for end
			// 处理最后一行
		mLineHeight.add(lineHeight);
		mAllViews.add(lineViews);

		// 设置子View的位置

		int left = getPaddingLeft();
		int top = getPaddingTop();

		// 行数
		int lineNum = mAllViews.size();

		for (int i = 0; i < lineNum; i++) {
			// 当前行的所有的View
			lineViews = mAllViews.get(i);
			lineHeight = mLineHeight.get(i);

			for (int j = 0; j < lineViews.size(); j++) {
				View child = lineViews.get(j);
				// 判断child的状态
				if (child.getVisibility() == View.GONE) {
					continue;
				}

				MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

				int lc = left + lp.leftMargin;
				int tc = top + lp.topMargin;
				int rc = lc + child.getMeasuredWidth();
				int bc = tc + child.getMeasuredHeight();

				// 为子View进行布局
				child.layout(lc, tc, rc, bc);

				left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
			}
			left = getPaddingLeft();
			top += lineHeight;
		}

	}

	/**
	 * 与当前ViewGroup对应的LayoutParams
	 */
	@Override
	public LayoutParams generateLayoutParams(AttributeSet attrs) {
		return new MarginLayoutParams(getContext(), attrs);
	}

}

activity代码如下

package com.imooc.flowlayout;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Window;
import android.widget.TextView;

import com.imooc.view.FlowLayout;

public class MainActivity extends Activity {
	private String[] mVals = new String[] { "Hello", "Android", "Weclome Hi ", "Button",
			"TextView", "Hello", "Android", "Weclome", "Button ImageView", "TextView",
			"Hello world", "Android", "Weclome Hello", "Button Text", "TextView" };

	private FlowLayout mFlowLayout;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
		mFlowLayout = (FlowLayout) findViewById(R.id.id_flowlayout);

		initData();
	}

	public void initData() {
		// for (int i = 0; i < mVals.length; i++)
		// {
		// Button btn = new Button(this);
		//
		// MarginLayoutParams lp = new MarginLayoutParams(
		// MarginLayoutParams.WRAP_CONTENT,
		// MarginLayoutParams.WRAP_CONTENT);
		//
		// btn.setText(mVals[i]);
		// mFlowLayout.addView(btn, lp);
		// }
		LayoutInflater mInflater = LayoutInflater.from(this);
		for (int i = 0; i < mVals.length; i++) {
			TextView tv = (TextView) mInflater.inflate(R.layout.tv, mFlowLayout, false);
			tv.setText(mVals[i]);
			mFlowLayout.addView(tv);
		}

	}
	@Override
	protected void onResume() {
		Log.e("TAG","onResume");
		super.onResume();
	}

}

布局文件：

tv.xml布局文件

以及布局中使用的tv_bg.xml

这里我打了几个log，发现FlowLayout的 onMeasure方法会执行4次，onLayout方法会执行两次，请问有知道为什么的吗？

说明：此代码是我看到网上的，觉得这东西不错然后自己写下来做个记录，以便以后学习使用。原作者链接http://www.imooc.com/learn/237，大家有兴趣的可以看下。

源码地址：http://download.csdn.net/detail/u014763302/9416943