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<List<View>> mAllViews = new ArrayList<List<View>>();
/**
 * 每一行的高度
 */
private List<Integer> mLineHeight = new ArrayList<Integer>();

@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<View> lineViews = new ArrayList<View>();

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<View>();
}
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：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <com.imooc.view.FlowLayout
        android:id="@+id/id_flowlayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#E5E5F5"
        android:padding="20dp" >

    </com.imooc.view.FlowLayout>

</RelativeLayout>

<span style="background-color: rgb(255, 255, 255);">tv.xml布局文件</span>

<span style="font-family: Arial, Helvetica, sans-serif;"><?xml version="1.0" encoding="utf-8"?></span>

<TextView xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_margin="5dp"    android:background="@drawable/tv_bg"    android:textColor="#5BC4ED"    android:text="Helloworld" ></TextView>

以及布局中使用的tv_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >

    <solid android:color="#ffffff" />

    <corners android:radius="30dp" />

    <padding
        android:bottom="2dp"
        android:left="10dp"
        android:right="10dp"
        android:top="2dp" />

</shape>

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

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