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。