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>

以上就是本文的全部内容，下面在给大家一个小福利：

// 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。