学步园

1. 概述：

    接收被拖View的View实现有两种方式，第一种：接收View实现onDragEvent()方法，第二种：接收View添加OnDragListener监听器。

    第一种实现方法已经在   HoneyComb3.0技术系列之Drag And Drop（一） 文章中讲过，下面讲第二种实现方法。

2. 效果图：

    与   HoneyComb3.0技术系列之Drag And Drop（一） 文章中的效果相同。

3. 代码实现：

    （1）自定义第一个View，即：被拖View，命名：AreaOne.java，代码：package com.focus;</p> <p>import android.content.Context;<br /> import android.util.AttributeSet;<br /> import android.view.View;</p> <p>public class AreaOne extends View {</p> <p> public AreaOne(Context context) {<br /> super(context);<br /> }</p> <p> public AreaOne(Context context, AttributeSet attrs) {<br /> super(context, attrs);<br /> }</p> <p>}<br />

    （2）自定义第二个View，即：接受被拖View的View，命名：AreaTwo.java，代码：package com.focus;</p> <p>import android.content.Context;<br /> import android.util.AttributeSet;<br /> import android.view.View;</p> <p>public class AreaTwo extends View {</p> <p> public AreaTwo(Context context) {<br /> super(context);<br /> }</p> <p> public AreaTwo(Context context, AttributeSet attrs) {<br /> super(context, attrs);<br /> }</p> <p>}<br />

    （3）主布局（main.xml）实现：<?xml version="1.0" encoding="utf-8"?></p> <p><LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"<br /> android:orientation = "vertical"<br /> android:layout_width = "fill_parent"<br /> android:layout_height = "fill_parent"<br /> ></p> <p> <com.focus.AreaOne<br /> android:id = "@+id/areaOne"<br /> android:layout_width = "100dip"<br /> android:layout_height = "100dip"<br /> android:background = "#FF0000"<br /> /></p> <p> <TextView<br /> android:layout_width = "100dip"<br /> android:layout_height = "100dip"<br /> /></p> <p> <com.focus.AreaTwo<br /> android:id = "@+id/areaTwo"<br /> android:layout_width = "100dip"<br /> android:layout_height = "100dip"<br /> android:background = "#00FF00"<br /> /></p> <p></LinearLayout><br />

    （4）主Activity实现：package com.focus;</p> <p>import android.app.Activity;<br /> import android.graphics.drawable.Drawable;<br /> import android.os.Bundle;<br /> import android.util.Log;<br /> import android.view.DragEvent;<br /> import android.view.View;<br /> import android.view.View.DragShadowBuilder;<br /> import android.view.View.OnDragListener;<br /> import android.view.View.OnLongClickListener;</p> <p>public class DragAndDropActivity extends Activity {</p> <p> @Override<br /> public void onCreate(Bundle savedInstanceState) {<br /> super.onCreate(savedInstanceState);<br /> setContentView(R.layout.main);</p> <p> final View mAreaOne = findViewById(R.id.areaOne);<br /> mAreaOne.setOnLongClickListener(new OnLongClickListener() {<br /> public boolean onLongClick(View view) {<br /> /**<br /> * 长按AreaOne后开始拖动。<br /> */<br /> mAreaOne.startDrag(null, new DragShadowBuilder(view), (Object)view, 0);<br /> return true;<br /> }<br /> });</p> <p> /**<br /> * 结AreaTwo添加Drag监听器。<br /> */<br /> final View mAreaTwo = findViewById(R.id.areaTwo);<br /> mAreaTwo.setOnDragListener(new OnDragListener() {<br /> public boolean onDrag(View mDropView, DragEvent event) {<br /> boolean result = false;</p> <p> switch (event.getAction()) {<br /> case DragEvent.ACTION_DRAG_STARTED: {</p> <p> Log.i("mayingcai", "有View开始被拖动!");</p> <p> /**<br /> * 在拖动开始时，只有返回true，后面的动作（ACTION_DRAG_ENTERED, ACTION_DRAG_LOCATION, ACTION_DROP）<br /> * 才会被执行!<br /> */<br /> result = true;</p> <p> break;<br /> }</p> <p> case DragEvent.ACTION_DRAG_ENTERED: {</p> <p> Log.i("mayingcai", "被拖动的View进入当前View!");</p> <p> break;<br /> }</p> <p> case DragEvent.ACTION_DRAG_LOCATION: {</p> <p> Log.i("mayingcai", "被拖动的View进入当前View后，位置发生改变!");</p> <p> break;<br /> }</p> <p> case DragEvent.ACTION_DROP: {</p> <p> Log.i("mayingcai", "拖动的View被放入当前View!");</p> <p> /**<br /> * 在放时交互两个View的背景。<br /> */<br /> View mDragView = (View) event.getLocalState();<br /> Drawable mDragViewBackgroud = mDragView.getBackground();<br /> mDragView.setBackgroundDrawable(mDropView.getBackground());<br /> mDropView.setBackgroundDrawable(mDragViewBackgroud);</p> <p> break;<br /> }</p> <p> case DragEvent.ACTION_DRAG_ENDED: {</p> <p> Log.i("mayingcai", "拖动结束!");</p> <p> break;<br /> }</p> <p> case DragEvent.ACTION_DRAG_EXITED: {</p> <p> Log.i("mayingcai", "拖动退出!");</p> <p> break;<br /> }</p> <p> default: {</p> <p> break;<br /> }<br /> }</p> <p> return result;<br /> }<br /> });<br /> }</p> <p>}