Android 列表之拖拽ListView

运行结果


main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="horizontal" android:layout_width="fill_parent"
	android:layout_height="fill_parent">
	<com.iaiai.DragListView android:layout_width="fill_parent"
		android:layout_height="wrap_content" android:id="@+id/MyListView" />
</LinearLayout>

list_items.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="vertical" android:layout_width="fill_parent"
	android:layout_height="wrap_content" android:id="@+id/myListItem"
	android:paddingBottom="4dip" android:paddingLeft="12dip"
	android:paddingRight="12dip">
	<TextView android:layout_height="wrap_content"
		android:layout_width="fill_parent" android:id="@+id/itemTitle"
		android:textSize="20dip" android:layout_alignParentLeft="true" />
	<ImageView android:id="@+id/drag_list_item_image"
		android:src="@drawable/list_icon" android:layout_alignParentRight="true"
		android:layout_centerVertical="true" android:layout_width="wrap_content"
		android:layout_height="@dimen/drag_item_normal_height" />
</RelativeLayout>

values/dimens.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <dimen name="drag_item_normal_height">48dip</dimen>
    <dimen name="drag_item_expand_height">96dip</dimen>
</resources>

DragListView.java

package com.iaiai;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Toast;

/**
 * 
 * <p>
 * Title: DragListView.java
 * </p>
 * <p>
 * E-Mail: [e-mail]
 * </p>
 * <p>
 * QQ: 176291935
 * </p>
 * <p>
 * Http: iaiai.iteye.com
 * </p>
 * <p>
 * Create time: 2011-10-10
 * </p>
 * 
 * @author 丸子
 * @version 0.0.1
 */
public class DragListView extends ListView {

	private ImageView dragImageView;// 被拖拽的项，其实就是一个ImageView
	private int dragSrcPosition;// 手指拖动项原始在列表中的位置
	private int dragPosition;// 手指拖动的时候，当前拖动项在列表中的位置

	private int dragPoint;// 在当前数据项中的位置
	private int dragOffset;// 当前视图和屏幕的距离(这里只使用了y方向上)

	private WindowManager windowManager;// windows窗口控制类
	private WindowManager.LayoutParams windowParams;// 用于控制拖拽项的显示的参数

	private int scaledTouchSlop;// 判断滑动的一个距离
	private int upScrollBounce;// 拖动的时候，开始向上滚动的边界
	private int downScrollBounce;// 拖动的时候，开始向下滚动的边界

	public DragListView(Context context, AttributeSet attrs) {
		super(context, attrs);
		scaledTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
	}

	// 拦截touch事件，其实就是加一层控制
	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		if (ev.getAction() == MotionEvent.ACTION_DOWN) {
			int x = (int) ev.getX();
			int y = (int) ev.getY();

			dragSrcPosition = dragPosition = pointToPosition(x, y);
			if (dragPosition == AdapterView.INVALID_POSITION) {
				return super.onInterceptTouchEvent(ev);
			}

			ViewGroup itemView = (ViewGroup) getChildAt(dragPosition
					- getFirstVisiblePosition());
			dragPoint = y - itemView.getTop();
			dragOffset = (int) (ev.getRawY() - y);

			View dragger = itemView.findViewById(R.id.drag_list_item_image);
			if (dragger != null && x > dragger.getLeft() - 20) {
				//
				upScrollBounce = Math.min(y - scaledTouchSlop, getHeight() / 3);
				downScrollBounce = Math.max(y + scaledTouchSlop,
						getHeight() * 2 / 3);

				itemView.setDrawingCacheEnabled(true);
				Bitmap bm = Bitmap.createBitmap(itemView.getDrawingCache());
				startDrag(bm, y);
			}
			return false;
		}
		return super.onInterceptTouchEvent(ev);
	}

	/**
	 * 触摸事件
	 */
	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		if (dragImageView != null && dragPosition != INVALID_POSITION) {
			int action = ev.getAction();
			switch (action) {
			case MotionEvent.ACTION_UP:
				int upY = (int) ev.getY();
				stopDrag();
				onDrop(upY);
				break;
			case MotionEvent.ACTION_MOVE:
				int moveY = (int) ev.getY();
				onDrag(moveY);
				break;
			default:
				break;
			}
			return true;
		}
		// 也决定了选中的效果
		return super.onTouchEvent(ev);
	}

	/**
	 * 准备拖动，初始化拖动项的图像
	 * 
	 * @param bm
	 * @param y
	 */
	public void startDrag(Bitmap bm, int y) {
		stopDrag();

		windowParams = new WindowManager.LayoutParams();
		windowParams.gravity = Gravity.TOP;
		windowParams.x = 0;
		windowParams.y = y - dragPoint + dragOffset;
		windowParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
		windowParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
		windowParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
				| WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
				| WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
				| WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
		windowParams.format = PixelFormat.TRANSLUCENT;
		windowParams.windowAnimations = 0;

		ImageView imageView = new ImageView(getContext());
		imageView.setImageBitmap(bm);
		windowManager = (WindowManager) getContext().getSystemService("window");
		windowManager.addView(imageView, windowParams);
		dragImageView = imageView;
	}

	/**
	 * 停止拖动，去除拖动项的头像
	 */
	public void stopDrag() {
		if (dragImageView != null) {
			windowManager.removeView(dragImageView);
			dragImageView = null;
		}
	}

	/**
	 * 拖动执行，在Move方法中执行
	 * 
	 * @param y
	 */
	public void onDrag(int y) {
		if (dragImageView != null) {
			windowParams.alpha = 0.8f;
			windowParams.y = y - dragPoint + dragOffset;
			windowManager.updateViewLayout(dragImageView, windowParams);
		}
		// 为了避免滑动到分割线的时候，返回-1的问题
		int tempPosition = pointToPosition(0, y);
		if (tempPosition != INVALID_POSITION) {
			dragPosition = tempPosition;
		}

		// 滚动
		int scrollHeight = 0;
		if (y < upScrollBounce) {
			scrollHeight = 8;// 定义向上滚动8个像素，如果可以向上滚动的话
		} else if (y > downScrollBounce) {
			scrollHeight = -8;// 定义向下滚动8个像素，，如果可以向上滚动的话
		}

		if (scrollHeight != 0) {
			// 真正滚动的方法setSelectionFromTop()
			setSelectionFromTop(dragPosition,
					getChildAt(dragPosition - getFirstVisiblePosition())
							.getTop() + scrollHeight);
		}
	}

	/**
	 * 拖动放下的时候
	 * 
	 * @param y
	 */
	public void onDrop(int y) {

		// 为了避免滑动到分割线的时候，返回-1的问题
		int tempPosition = pointToPosition(0, y);
		if (tempPosition != INVALID_POSITION) {
			dragPosition = tempPosition;
		}

		// 超出边界处理
		if (y < getChildAt(1).getTop()) {
			// 超出上边界
			dragPosition = 1;
		} else if (y > getChildAt(getChildCount() - 1).getBottom()) {
			// 超出下边界
			dragPosition = getAdapter().getCount() - 1;
		}

		// 数据交换
		if (dragPosition > 0 && dragPosition < getAdapter().getCount()) {
			@SuppressWarnings("unchecked")
			MyAdapter adapter = (MyAdapter) getAdapter();
			Object dragItem = adapter.getItem(dragSrcPosition);
			adapter.remove(dragItem);
			adapter.insert(dragItem, dragPosition);
			Toast.makeText(getContext(), adapter.getList().toString(),
					Toast.LENGTH_SHORT).show();
		}

	}
}

MyAdapter.java

package com.iaiai;

import java.util.List;
import java.util.Map;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

/**
 * 
 * <p>
 * Title: MyAdapter.java
 * </p>
 * <p>
 * E-Mail: [e-mail]
 * </p>
 * <p>
 * QQ: 176291935
 * </p>
 * <p>
 * Http: iaiai.iteye.com
 * </p>
 * <p>
 * Create time: 2011-10-10
 * </p>
 * 
 * @author 丸子
 * @version 0.0.1
 */
public class MyAdapter extends ArrayAdapter {
	
	private LayoutInflater mInflater;

	private List<Map<String, String>> listData;

	public MyAdapter(Context context, List<Map<String, String>> listData) {
		super(context, 0,listData);
		this.mInflater = LayoutInflater.from(context);
		this.listData = listData;
	}

	@Override
	public int getCount() {
		return listData.size();
	}

	@Override
	public Object getItem(int position) {
		return listData.get(position);
	}

	@Override
	public long getItemId(int position) {
		return position;
	}

	@Override
	public View getView(final int position, View convertView, ViewGroup parent) {
		convertView = mInflater.inflate(R.layout.list_items, null);

		TextView textView = (TextView) convertView.findViewById(R.id.itemTitle);
		textView.setText(listData.get(position).get("itemTitle"));

		return convertView;
	}
	
	public List<Map<String, String>> getList(){
        return listData;
    }

}

MainActivity.java

package com.iaiai;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;

/**
 * 
 * <p>
 * Title: MainActivity.java
 * </p>
 * <p>
 * E-Mail: [e-mail]
 * </p>
 * <p>
 * QQ: 176291935
 * </p>
 * <p>
 * Http: iaiai.iteye.com
 * </p>
 * <p>
 * Create time: 2011-10-10
 * </p>
 * 
 * @author 丸子
 * @version 0.0.1
 */
public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

		ListView list = (ListView) findViewById(R.id.MyListView);

		// 配置适配器
		MyAdapter adapter = new MyAdapter(this, getData()); // 布局里的控件id
		// 添加并且显示
		list.setAdapter(adapter);
	}

	private List<Map<String, String>> getData() {
		List<Map<String, String>> mylist = new ArrayList<Map<String, String>>();

		for (int i = 0; i < 20; i++) {
			Map<String, String> map = new HashMap<String, String>();
			map.put("itemTitle", "文章1-" + i);
			mylist.add(map);
		}
		
		return mylist;
	}

}

用到的图片: