Android实现热门标签的流式布局

一、概述：

在日常的app使用中，我们会在android 的app中看见 热门标签等自动换行的流式布局，今天，我们就来看看如何
自定义一个类似热门标签那样的流式布局吧（源码下载在下面最后给出）
类似的自定义布局。下面我们就来详细介绍流式布局的应用特点以及用的的技术点：

1.流式布局的特点以及应用场景

特点：当上面一行的空间不够容纳新的TextView时候，
才开辟下一行的空间
原理图：

场景：主要用于关键词搜索或者热门标签等场景

2.自定义ViewGroup,重点重写下面两个方法

1）、onMeasure:测量子view的宽高，设置自己的宽和高
2）、onLayout:设置子view的位置
    onMeasure:根据子view的布局文件中属性，来为子view设置测量模式和测量值
    测量=测量模式+测量值；

测量模式有3种：

    EXACTLY：表示设置了精确的值，一般当childView设置其宽、高为精确值、match_parent时，ViewGroup会将其设置为EXACTLY；
    AT_MOST：表示子布局被限制在一个最大值内，一般当childView设置其宽、高为wrap_content时，ViewGroup会将其设置为AT_MOST；
    UNSPECIFIED：表示子布局想要多大就多大，一般出现在AadapterView的item的heightMode中、ScrollView的childView的heightMode中；此种模式比较少见。

3.LayoutParams

ViewGroup LayoutParams :每个 ViewGroup 对应一个 LayoutParams; 即 ViewGroup -> LayoutParams
getLayoutParams 不知道转为哪个对应的LayoutParams ,其实很简单，就是如下：
子View.getLayoutParams 得到的LayoutParams对应的就是 子View所在的父控件的LayoutParams;

例如，LinearLayout 里面的子view.getLayoutParams ->LinearLayout.LayoutParams

所以 咱们的FlowLayout 也需要一个LayoutParams，由于上面的效果图是子View的 margin，

所以应该使用MarginLayoutParams。即FlowLayout->MarginLayoutParams

4.最后来看看实现的最终效果图：

二、热门标签的流式布局的实现：

1. 自定义热门标签的ViewGroup实现

根据上面的技术分析，自定义类继承于ViewGroup，并重写 onMeasure和onLayout等方法。具体实现代码如下：

<font color="#362e2b"><font style="background-color:rgb(255, 255, 255)"><font face="Arial"><font style="font-size:14px">package com.czm.flowlayout;

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

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
/**
*
* @author caizhiming
* @created on 2015-4-13
*/
public class XCFlowLayout extends ViewGroup{

//存储所有子View
private List<List<View>> mAllChildViews = new ArrayList<>();
//每一行的高度
private List<Integer> mLineHeight = new ArrayList<>();

public XCFlowLayout(Context context) {
this(context, null);
// TODO Auto-generated constructor stub
}
public XCFlowLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
// TODO Auto-generated constructor stub
}
public XCFlowLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub

//父控件传进来的宽度和高度以及对应的测量模式
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

//如果当前ViewGroup的宽高为wrap_content的情况
int width = 0;//自己测量的 宽度
int height = 0;//自己测量的高度
//记录每一行的宽度和高度
int lineWidth = 0;
int lineHeight = 0;

//获取子view的个数
int childCount = getChildCount();
for(int i = 0;i < childCount; i ++){
 View child = getChildAt(i);
 //测量子View的宽和高
 measureChild(child, widthMeasureSpec, heightMeasureSpec);
 //得到LayoutParams
 MarginLayoutParams lp = (MarginLayoutParams) 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;
 //换行时候
 if(lineWidth + childWidth > sizeWidth){
 //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{//不换行情况
 //叠加行宽
 lineWidth += childWidth;
 //得到最大行高
 lineHeight = Math.max(lineHeight, childHeight);
 }
 //处理最后一个子View的情况
 if(i == childCount -1){
 width = Math.max(width, lineWidth);
 height += lineHeight;
 }
}
//wrap_content
setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width,
 modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
mAllChildViews.clear();
mLineHeight.clear();
//获取当前ViewGroup的宽度
int width = getWidth();

int lineWidth = 0;
int lineHeight = 0;
//记录当前行的view
List<View> lineViews = new ArrayList<View>();
int childCount = getChildCount();
for(int i = 0;i < childCount; 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){
 //记录LineHeight
 mLineHeight.add(lineHeight);
 //记录当前行的Views
 mAllChildViews.add(lineViews);
 //重置行的宽高
 lineWidth = 0;
 lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
 //重置view的集合
 lineViews = new ArrayList();
 }
 lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
 lineHeight = Math.max(lineHeight, childHeight + lp.topMargin + lp.bottomMargin);
 lineViews.add(child);
}
//处理最后一行
mLineHeight.add(lineHeight);
mAllChildViews.add(lineViews);

//设置子View的位置
int left = 0;
int top = 0;
//获取行数
int lineCount = mAllChildViews.size();
for(int i = 0; i < lineCount; i ++){
 //当前行的views和高度
 lineViews = mAllChildViews.get(i);
 lineHeight = mLineHeight.get(i);
 for(int j = 0; j < lineViews.size(); j ++){
 View child = lineViews.get(j);
 //判断是否显示
 if(child.getVisibility() == View.GONE){
  continue;
 }
 MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
 int cLeft = left + lp.leftMargin;
 int cTop = top + lp.topMargin;
 int cRight = cLeft + child.getMeasuredWidth();
 int cBottom = cTop + child.getMeasuredHeight();
 //进行子View进行布局
 child.layout(cLeft, cTop, cRight, cBottom);
 left += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
 }
 left = 0;
 top += lineHeight;
}

}
/**
* 与当前ViewGroup对应的LayoutParams
*/
@Override
public LayoutParams generateLayoutParams(AttributeSet attrs) {
// TODO Auto-generated method stub

return new MarginLayoutParams(getContext(), attrs);
}
}</font></font></font></font>

2.相关的布局文件：

引用自定义控件：

<font color="#362e2b"><font style="background-color:rgb(255, 255, 255)"><font face="Arial"><font style="font-size:14px"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<com.czm.flowlayout.XCFlowLayout
android:id="@+id/flowlayout"
android:layout_width="match_parent"
android:layout_height="match_parent" >

</com.czm.flowlayout.XCFlowLayout>

</RelativeLayout></font></font></font></font>

TextView的样式文件：

<font color="#362e2b"><font style="background-color:rgb(255, 255, 255)"><font face="Arial"><font style="font-size:14px"><?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
<solid android:color="#666666" />
<corners android:radius="10dp" />
<padding
android:left="5dp"
android:right="5dp"
android:top="5dp"
android:bottom="5dp"
/>

</shape></font></font></font></font>

三、使用该自定义布局控件类

最后，如何使用该自定义的热门标签控件类呢？很简单，请看下面实例代码：

<font color="#362e2b"><font style="background-color:rgb(255, 255, 255)"><font face="Arial"><font style="font-size:14px">package com.czm.flowlayout;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewGroup.MarginLayoutParams;
import android.widget.TextView;
/**
*
* @author caizhiming
* @created on 2015-4-13
*/
public class MainActivity extends Activity {

private String mNames[] = {
 "welcome","android","TextView",
 "apple","jamy","kobe bryant",
 "jordan","layout","viewgroup",
 "margin","padding","text",
 "name","type","search","logcat"
};
private XCFlowLayout mFlowLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

initChildViews();

}
private void initChildViews() {
// TODO Auto-generated method stub
mFlowLayout = (XCFlowLayout) findViewById(R.id.flowlayout);
MarginLayoutParams lp = new MarginLayoutParams(
 LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
lp.leftMargin = 5;
lp.rightMargin = 5;
lp.topMargin = 5;
lp.bottomMargin = 5;
for(int i = 0; i < mNames.length; i ++){
 TextView view = new TextView(this);
 view.setText(mNames[i]);
 view.setTextColor(Color.WHITE);
 view.setBackgroundDrawable(getResources().getDrawable(R.drawable.textview_bg));
 mFlowLayout.addView(view,lp);
}
}

}</font></font></font></font>

// 流式布局 话不多说，比较简单，注释都写的很清楚

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

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

/**
*
* @author Mr.Himan
* @version 1.0<br>
*  2015年11月4日 11:12:06 <br>
*  流式布局 设置MarginTop 和MarginLeft有效 MarginRight 暂未实现
*/
public class FlowLayout extends ViewGroup {

/**
* 存储所有的子View
*/
private List<List<View>> mAllChildViews = new ArrayList<List<View>>();

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

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

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

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

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
mAllChildViews.clear();
mLineHeight.clear();
// 获取当前ViewGroup的宽度
int width = getWidth();

int lineWidth = 0;
int lineHeight = 0;
// 记录当前行的view
List<View> lineViews = new ArrayList<View>();
int childCount = getChildCount();
for (int i = 0; i < childCount; 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) {
// 记录LineHeight
mLineHeight.add(lineHeight);
// 记录当前行的Views
mAllChildViews.add(lineViews);
// 重置行的宽高
lineWidth = 0;
lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
// 重置view的集合
lineViews = new ArrayList();
}
lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
lineHeight = Math.max(lineHeight, childHeight + lp.topMargin
+ lp.bottomMargin);
lineViews.add(child);
}
// 处理最后一行
mLineHeight.add(lineHeight);
mAllChildViews.add(lineViews);

MarginLayoutParams params = (MarginLayoutParams) this.getLayoutParams();

// 设置子View的位置
int left = 0;
// 添加marginTop
int top = 0 + params.topMargin;
// 获取行数
int lineCount = mAllChildViews.size();
for (int i = 0; i < lineCount; i++) {
// 当前行的views和高度
lineViews = mAllChildViews.get(i);
lineHeight = mLineHeight.get(i);
for (int j = 0; j < lineViews.size(); j++) {
// 为每一列设置marginLeft
if (j == 0) {
left = 0 + params.leftMargin;
}
View child = lineViews.get(j);
// 判断是否显示
if (child.getVisibility() == View.GONE) {
continue;
}
MarginLayoutParams lp = (MarginLayoutParams) child
.getLayoutParams();
int cLeft = left + lp.leftMargin;
int cTop = top + lp.topMargin;
int cRight = cLeft + child.getMeasuredWidth();
int cBottom = cTop + child.getMeasuredHeight();
// 进行子View进行布局
child.layout(cLeft, cTop, cRight, cBottom);
left += child.getMeasuredWidth() + lp.leftMargin
+ lp.rightMargin;
}
left = 0;
top += lineHeight;
}
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

// 父控件传进来的宽度和高度以及对应的测量模式
int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

// 如果当前ViewGroup的宽高为wrap_content的情况
int width = 0;// 自己测量的 宽度
int height = 0;// 自己测量的高度
// 记录每一行的宽度和高度
int lineWidth = 0;
int lineHeight = 0;

// 获取子view的个数
int childCount = getChildCount();

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

MarginLayoutParams params = (MarginLayoutParams) child
.getLayoutParams();
// 子View占据的宽度
int childWidth = child.getMeasuredWidth() + params.leftMargin
+ params.rightMargin;
// 子View占据的高度
int childHeight = child.getMeasuredHeight() + params.bottomMargin
+ params.topMargin;
// 换行时候
if (lineWidth + childWidth > sizeWidth) {
// 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 {
// 不换行情况
// 叠加行宽
lineWidth += childWidth;
// 得到最大行高
lineHeight = Math.max(lineHeight, childHeight);
}
// 处理最后一个子View的情况
if (i == childCount - 1) {
width = Math.max(width, lineWidth);
height += lineHeight;
}
}
setMeasuredDimension(modeWidth == MeasureSpec.EXACTLY ? sizeWidth
: width, modeHeight == MeasureSpec.EXACTLY ? sizeHeight
: height);

}

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

希望本文所述对大家学习Android实现热门标签的流式布局有所帮助。