Android中常见的热门标签的流式布局的实现

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哈）

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：

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) 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);            }        @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);    }}

2.相关的布局文件：

引用自定义控件：

<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>

TextView的样式文件：

<?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>

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：

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);        }    }}

四、源码下载

最后给出源码的下载：http://download.csdn.net/detail/jczmdeveloper/8590113

感谢真题园网提供支持：http://www.zhentiyuan.com

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