Android自定义ViewGroup之实现FlowLayout流式布局

整理总结自鸿洋的博客：http://blog.csdn.net/lmj623565791/article/details/38352503/
 一、FlowLayout介绍
 所谓FlowLayout，就是控件根据ViewGroup的宽，自动的往右添加，如果当前行剩余空间不足，则自动添加到下一行。有点像所有的控件都往左飘的感觉，第一行满了，往第二行飘~所以也叫流式布局。Android并没有提供流式布局，但是某些场合中，流式布局还是非常适合使用的，比如关键字标签，搜索热词列表等，比如下图：

github上已有现成的FlowLayout，本文是从无到有去制作。

二、制作分析

1、对于FlowLayout，需要指定的LayoutParams，我们目前只需要能够识别margin即可，即使用MarginLayoutParams.
2、onMeasure中计算所有childView的宽和高，然后根据childView的宽和高，计算自己的宽和高。（当然，如果不是wrap_content，直接使用父ViewGroup传入的计算值即可）
3、onLayout中对所有的childView进行布局。

三、代码 
1、MainActivity.java

public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // setContentView(R.layout.activity_main2); // setContentView(R.layout.activity_main3); } }

2、CustomViewGroup.java

public class CustomViewGroup extends ViewGroup { private final String TAG = getClass().getSimpleName(); public CustomViewGroup(Context context) { super(context); } public CustomViewGroup(Context context, AttributeSet attrs) { super(context, attrs); } public CustomViewGroup(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } /** * 一、重写generateLayoutParams，确定该ViewGroup的LayoutParams * 返回MarginLayoutParams的实例，这样就为我们的ViewGroup指定了其LayoutParams为MarginLayoutParams */ @Override public LayoutParams generateLayoutParams(AttributeSet attrs) { return new MarginLayoutParams(getContext(), attrs); } /** * 二、计算所有ChildView的宽度和高度 然后根据ChildView的计算结果，设置自己的宽和高 */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //1、获得此ViewGroup上级容器为其推荐的宽和高，以及计算模式 int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int sizeWidth = MeasureSpec.getSize(widthMeasureSpec); int sizeHeight = MeasureSpec.getSize(heightMeasureSpec); // 2、如果ViewGroup布局是wrap_content时，根据childView的尺寸，计算容器的宽和高 int width = 0;//ViewGroup的宽度 int height = 0;//ViewGroup的高度 int lineWidth = 0;//childView所占据的当前行总宽度 int lineHeight = 0;//childView所占据的各行总高度 int cCount = getChildCount();////childView的数量 for(int i=0; i<cCount; i++){//遍历每个childView View childView = getChildAt(i); measureChild(childView, widthMeasureSpec, heightMeasureSpec);// 测量当前child的宽和高 MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams(); int cWidth = childView.getMeasuredWidth() + mlp.leftMargin + mlp.rightMargin; int cHeight = childView.getMeasuredHeight() + mlp.topMargin + mlp.bottomMargin; if(lineWidth + cWidth > sizeWidth){//如果加入当前childView后超出最大宽度，width取最大高度，累加lineHeight，然后开启新行 width = Math.max(lineWidth, cWidth); height += lineHeight; lineWidth = cWidth; }else{//如果加入当前childView后小于最大宽度，则累加lineWidthheight lineHeight取最大高度 lineWidth += cWidth; height = Math.max(lineHeight, cHeight); } if(i == cCount-1){// 如果是最后一个childView，则将当前记录的最大宽度和当前lineWidth做比较 width = Math.max(lineWidth, cWidth); height += lineHeight; } } //3、如果是wrap_content设置为我们计算的值;否则直接设置为父容器计算的值 setMeasuredDimension( (widthMode == MeasureSpec.EXACTLY) ? sizeWidth : width, (heightMode == MeasureSpec.EXACTLY) ? sizeHeight : height ); } /** * 三、重写onLayout，对其所有childView进行定位（设置childView的绘制区域） */ private List<List<View>> allChildViews = new ArrayList<List<View>>();//存储所有的childView，按行记录 private List<Integer> maxLineHeight = new ArrayList<Integer>();//存储每行的最大高度值 @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { allChildViews.clear(); maxLineHeight.clear(); int width = getWidth();//每行的最大宽度 int lineWidth = 0;//每行的即时宽度 int lineHeight = 0;//每行的即时高度 List<View> lineChildViews = new ArrayList<View>();//存储每行所有的childView int cCount = getChildCount(); for(int i=0; i<cCount; i++){//遍历所有childView View childView = getChildAt(i); MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams(); int cWidth = childView.getMeasuredWidth(); int cHeight = childView.getMeasuredHeight(); if(lineWidth + cWidth + mlp.leftMargin + mlp.rightMargin > width){//如果需要换行 maxLineHeight.add(lineHeight);// 存储这一行最大高度 allChildViews.add(lineChildViews);// 将当前行的childView保存，然后开启新的ArrayList保存下一行的childView lineChildViews = new ArrayList<View>(); lineWidth = 0;// 重置行宽 }else{//如果不需要换行 lineWidth += cWidth + mlp.leftMargin + mlp.rightMargin;//即时宽度累加 lineHeight = Math.max(lineHeight,cHeight + mlp.topMargin + mlp.bottomMargin );//即时高度取最大值 lineChildViews.add(childView);//把当前childView存入这一行的集合 } } // 记录最后一行 maxLineHeight.add(lineHeight); allChildViews.add(lineChildViews); int left = 0;//左坐标 int top = 0;//上坐标 int lineNums = allChildViews.size();// 得到总行数 for (int i = 0; i < lineNums; i++) { lineChildViews = allChildViews.get(i);// 取得每一行的所有的views lineHeight = maxLineHeight.get(i);// 取得当前行的最大高度 Log.e(TAG, "第" + i + "行 ：" + lineChildViews.size() + " , " + lineChildViews); Log.e(TAG, "第" + i + "行， ：" + lineHeight); // 遍历当前行所有的View for (int j = 0; j < lineChildViews.size(); j++) { View childView = lineChildViews.get(j);//取得childView if (childView.getVisibility() == View.GONE) { continue; } MarginLayoutParams mlp = (MarginLayoutParams) childView.getLayoutParams(); //计算childView的left,top,right,bottom int lc = left + mlp.leftMargin; int tc = top + mlp.topMargin; int rc = lc + childView.getMeasuredWidth(); int bc = tc + childView.getMeasuredHeight(); Log.e(TAG, childView + " , l = " + lc + " , t = " + t + " , r =" + rc + " , b = " + bc); childView.layout(lc, tc, rc, bc);//设置这个childView的位置 left += childView.getMeasuredWidth() + mlp.rightMargin + mlp.leftMargin;//左坐标累加 } left = 0;//开始新的一行，左坐标重置 top += lineHeight;//开始新的一行，上坐标累加 } } }

3、activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#E1E6F6" android:orientation="vertical"> <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content"> <TextView style="@style/text_flag_01" android:text="Welcome" /> <TextView style="@style/text_flag_01" android:text="IT工程师" /> <TextView style="@style/text_flag_01" android:text="学习ing" /> <TextView style="@style/text_flag_01" android:text="恋爱ing" /> <TextView style="@style/text_flag_01" android:text="挣钱ing" /> <TextView style="@style/text_flag_01" android:text="努力ing" /> <TextView style="@style/text_flag_01" android:text="I thick i can" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> </LinearLayout>

4、activity_main2.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#E1E6F6" android:orientation="vertical"> <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content"> <TextView style="@style/text_flag_01" android:text="Welcome" /> <TextView style="@style/text_flag_01" android:text="IT工程师" /> <TextView style="@style/text_flag_01" android:text="学习ing" /> <TextView style="@style/text_flag_01" android:text="恋爱ing" /> <TextView style="@style/text_flag_01" android:text="挣钱ing" /> <TextView style="@style/text_flag_01" android:text="努力ing" /> <TextView style="@style/text_flag_01" android:text="I thick i can" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginTop="20dp"> <TextView style="@style/text_flag_01" android:background="@drawable/flag_02" android:text="Welcome" android:textColor="#888888" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_02" android:text="IT工程师" android:textColor="#888888" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_02" android:text="学习ing" android:textColor="#888888" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_02" android:text="恋爱ing" android:textColor="#888888" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_02" android:text="挣钱ing" android:textColor="#888888" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_02" android:text="努力ing" android:textColor="#888888" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_02" android:text="I thick i can" android:textColor="#888888" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> <com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginTop="20dp"> <TextView style="@style/text_flag_01" android:background="@drawable/flag_03" android:text="Welcome" android:textColor="#43BBE7" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_03" android:text="IT工程师" android:textColor="#43BBE7" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_03" android:text="学习ing" android:textColor="#43BBE7" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_03" android:text="恋爱ing" android:textColor="#43BBE7" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_03" android:text="挣钱ing" android:textColor="#43BBE7" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_03" android:text="努力ing" android:textColor="#43BBE7" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_03" android:text="I thick i can" android:textColor="#43BBE7" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup> </LinearLayout>

5、activity_main3.xml

<com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="200dp" android:layout_height="wrap_content" android:background="#FFFFFF"> <TextView style="@style/text_flag_01" android:background="@drawable/flag_04" android:text="Welcome" android:textColor="#323232" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_04" android:text="IT工程师" android:textColor="#323232" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_04" android:text="学习ing" android:textColor="#323232" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_04" android:text="恋爱ing" android:textColor="#323232" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_04" android:text="挣钱ing" android:textColor="#323232" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_04" android:text="努力ing" android:textColor="#323232" /> <TextView style="@style/text_flag_01" android:background="@drawable/flag_04" android:text="I thick i can" android:textColor="#323232" /> </com.cctvjiatao.customviewgroupflowlayout.view.CustomViewGroup>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。