Android加载器LoaderManager.LoaderCallbacks的使用

LoaderManager.LoaderCallbacks是3.0之后出现的新特性，通过LoaderManager.LoaderCallbacks接口可以很轻松的实现异步加载数据到Fragment或Activity 中，Loaders提供了回调机制onLoadFinished()通知最终的运行结果，有点类似AsyncTask类，但由于Loader对于并发可以用过Loader管理器统一管理，所以更适合批量处理多个异步任务的处理(当然内部仍然是多线程)。要使用Loader就要实现LoaderManager.LoaderCallbacks接口，并实现它的抽象方法

下面是我加载通话记录的Demo，实现了过滤拨入、拨出、未接、所有，删除单条记录，拨号功能，实现效果图

目录结构

ListView中每个item的布局listview_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ImageView
        android:id="@+id/bt_icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_marginLeft="10dp"
        android:background="#00000000"
        android:contentDescription="@string/content_description"
        android:src="@drawable/calllog_incoming" />

    <TextView
        android:id="@+id/tv_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="2dp"
        android:layout_toRightOf="@id/bt_icon"
        android:textSize="23sp" />

    <TextView
        android:id="@+id/tv_number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/tv_name"
        android:layout_below="@id/tv_name"
        android:layout_marginBottom="2dp"
        android:textColor="#7f7f7f"
        android:textSize="16sp" />

    <TextView
        android:id="@+id/tv_date"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignTop="@id/tv_number"
        android:layout_marginLeft="10dp"
        android:layout_toRightOf="@id/tv_number"
        android:ellipsize="end"
        android:textColor="#7f7f7f"
        android:textSize="16sp" />

    <ImageButton
        android:id="@+id/btn_delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:layout_marginRight="10dp"
        android:background="#00000000"
        android:contentDescription="@string/content_description"
        android:focusableInTouchMode="false"
        android:src="@drawable/cl_delete_selector" />

    <ImageButton
        android:id="@+id/btn_call"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_marginRight="5dp"
        android:layout_toLeftOf="@id/btn_delete"
        android:background="#00000000"
        android:contentDescription="@string/content_description"
        android:focusableInTouchMode="false"
        android:src="@drawable/cl_call_selector" />

</RelativeLayout>

整个Activity的布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/tv_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button
        android:id="@+id/btn_all"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv_text"
        android:text="@string/all" />

    <Button
        android:id="@+id/btn_incoming"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv_text"
        android:layout_marginLeft="20dp"
        android:layout_toRightOf="@id/btn_all"
        android:text="@string/incoming" />

    <Button
        android:id="@+id/btn_outcoming"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/btn_all"
        android:layout_marginTop="10dp"
        android:text="@string/outcoming" />

    <Button
        android:id="@+id/btn_missed"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/btn_incoming"
        android:layout_below="@id/btn_all"
        android:layout_marginTop="10dp"
        android:layout_toRightOf="@id/btn_outcoming"
        android:text="@string/missed" />

    <View
        android:id="@+id/line_layout"
        android:layout_width="match_parent"
        android:layout_height="2dp"
        android:layout_below="@id/btn_missed"
        android:background="#000000" >
    </View>

    <ListView
        android:id="@+id/lv_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/line_layout"
        android:clipToPadding="false"
        android:divider="#ff553311"
        android:dividerHeight="2dp"
        android:fadingEdge="none"
        android:paddingTop="10dp" />

</RelativeLayout>

ListView对应的适配器MyCursorAdapter.java

package com.dzt.loaderdemo;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.provider.CallLog;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.CursorAdapter;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;

class MyCursorAdapter extends CursorAdapter {

	private static final String TAG = "dzt";
	private final Context mContext;

	public MyCursorAdapter(Context context, Cursor c) {
		this(context, c, true);
		// TODO Auto-generated constructor stub
	}

	public MyCursorAdapter(Context context, Cursor c, boolean autoRequery) {
		super(context, c, autoRequery);
		// TODO Auto-generated constructor stub
		mContext = context;
	}

	public MyCursorAdapter(Context context, Cursor c, int flags) {
		super(context, c, flags);
		// TODO Auto-generated constructor stub
		mContext = context;
	}

	@Override
	public View newView(Context context, Cursor cursor, ViewGroup parent) {
		// TODO Auto-generated method stub
		LayoutInflater inflater = LayoutInflater.from(context);
		return inflater.inflate(R.layout.listview_item, parent, false);
	}

	@Override
	public void bindView(View view, Context context, Cursor cursor) {
		// TODO Auto-generated method stub
		if (cursor == null)
			return;
		final String id = cursor.getString(0);
		String number = cursor.getString(1);
		String name = cursor.getString(2);
		int type = cursor.getInt(3);
		String date = cursor.getString(4);
		ImageView TypeView = (ImageView) view.findViewById(R.id.bt_icon);
		TextView nameCtrl = (TextView) view.findViewById(R.id.tv_name);
		if (name == null) {
			nameCtrl.setText(mContext.getString(R.string.name_unknown));
		} else {
			nameCtrl.setText(name);
		}
		TextView numberCtrl = (TextView) view.findViewById(R.id.tv_number);
		numberCtrl.setText(number);
		String value = ComputeDate(date);
		TextView dateCtrl = (TextView) view.findViewById(R.id.tv_date);
		dateCtrl.setText(value);
		switch (type) {
		case CallLog.Calls.INCOMING_TYPE:
			TypeView.setImageResource(R.drawable.calllog_incoming);
			break;
		case CallLog.Calls.OUTGOING_TYPE:
			TypeView.setImageResource(R.drawable.calllog_outcoming);
			break;
		case CallLog.Calls.MISSED_TYPE:
			TypeView.setImageResource(R.drawable.calllog_missed);
			break;
		case 4: // CallLog.Calls.VOICEMAIL_TYPE

			break;
		default:
			break;
		}

		ImageButton dailBtn = (ImageButton) view.findViewById(R.id.btn_call);
		dailBtn.setTag(number);
		dailBtn.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				// Intent.ACTION_CALL_PRIVILEGED 由于Intent中隐藏了，只能用字符串代替
				Intent intent = new Intent(Intent.ACTION_CALL, Uri.fromParts(
						"tel", (String) v.getTag(), null));
				intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
				mContext.startActivity(intent);
			}
		});

		ImageButton deleteBtn = (ImageButton) view
				.findViewById(R.id.btn_delete);
		deleteBtn.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				// 根据ID进行记录删除
				String where = CallLog.Calls._ID + "=?";
				String[] selectionArgs = new String[] { id };
				int result = mContext.getContentResolver().delete(
						CallLog.Calls.CONTENT_URI, where, selectionArgs);
				Log.d(TAG, "11result = " + result);
			}
		});
	}

	private String ComputeDate(String date) {
		long callTime = Long.parseLong(date);
		long newTime = new Date().getTime();
		long duration = (newTime - callTime) / (1000 * 60);
		String value;
		// SimpleDateFormat sfd = new
		// SimpleDateFormat("yyyy-MM-dd HH:mm:ss",
		// Locale.getDefault());
		// String time = sfd.format(callTime);
		// Log.d(TAG, "[MyCursorAdapter--ComputeDate] time = " + time);
		// 进行判断拨打电话的距离现在的时间，然后进行显示说明
		if (duration < 60) {
			value = duration + "分钟前";
		} else if (duration >= 60 && duration < MainActivity.DAY) {
			SimpleDateFormat sdf = new SimpleDateFormat("HH:mm",
					Locale.getDefault());
			value = sdf.format(new Date(callTime));

			// value = (duration / 60) + "小时前";
		} else if (duration >= MainActivity.DAY
				&& duration < MainActivity.DAY * 2) {
			value = "昨天";
		} else if (duration >= MainActivity.DAY * 2
				&& duration < MainActivity.DAY * 3) {
			value = "前天";
		} else if (duration >= MainActivity.DAY * 7) {
			SimpleDateFormat sdf = new SimpleDateFormat("MM/dd",
					Locale.getDefault());
			value = sdf.format(new Date(callTime));
		} else {
			value = (duration / MainActivity.DAY) + "天前";
		}
		return value;
	}
}

加载器是放在MainActivity.java类当中

package com.dzt.loaderdemo;

import android.app.Activity;
import android.app.LoaderManager;
import android.content.CursorLoader;
import android.content.Loader;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.CallLog;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ListView;

/**
 * 使用加载器加载通话记录
 * 
 * @author Administrator
 * 
 */
public class MainActivity extends Activity {

	private static final String TAG = "dzt";
	// 查询指定的条目
	private static final String[] CALLLOG_PROJECTION = new String[] {
			CallLog.Calls._ID, CallLog.Calls.NUMBER, CallLog.Calls.CACHED_NAME,
			CallLog.Calls.TYPE, CallLog.Calls.DATE };
	static final int DAY = 1440; // 一天的分钟值
	private static final int ALL = 0; // 默认显示所有
	private static final int INCOMING = CallLog.Calls.INCOMING_TYPE; // 来电
	private static final int OUTCOMING = CallLog.Calls.OUTGOING_TYPE; // 拔号
	private static final int MISSED = CallLog.Calls.MISSED_TYPE; // 未接
	private ListView mListView;
	private MyLoaderListener mLoader = new MyLoaderListener();
	private MyCursorAdapter mAdapter;
	private int mCallLogShowType = ALL;
	private boolean m_FinishLoaderFlag = false; // 第一次加载完成

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		initWidgets();
		initMyLoader();
	}

	private void initWidgets() {
		mListView = (ListView) findViewById(R.id.lv_list);
		Button btn = (Button) findViewById(R.id.btn_all);
		btn.setOnClickListener(new buttonListener());
		btn = (Button) findViewById(R.id.btn_incoming);
		btn.setOnClickListener(new buttonListener());
		btn = (Button) findViewById(R.id.btn_outcoming);
		btn.setOnClickListener(new buttonListener());
		btn = (Button) findViewById(R.id.btn_missed);
		btn.setOnClickListener(new buttonListener());
		mAdapter = new MyCursorAdapter(MainActivity.this, null);
		mListView.setAdapter(mAdapter);
	}

	private void initMyLoader() {
		getLoaderManager().initLoader(0, null, mLoader);
	}

	/**
	 * 实现一个加载器
	 * 
	 * @author Administrator
	 * 
	 */
	private class MyLoaderListener implements
			LoaderManager.LoaderCallbacks<Cursor> {

		@Override
		public Loader<Cursor> onCreateLoader(int id, Bundle args) {
			// TODO Auto-generated method stub
			m_FinishLoaderFlag = false;
			CursorLoader cursor = new CursorLoader(MainActivity.this,
					CallLog.Calls.CONTENT_URI, CALLLOG_PROJECTION, null, null,
					CallLog.Calls.DEFAULT_SORT_ORDER);
			Log.d(TAG, "MyLoaderListener---------->onCreateLoader");
			return cursor;
		}

		@Override
		public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
			// TODO Auto-generated method stub
			if (data == null)
				return;
			Cursor tempData = data;
			if (tempData.getCount() == 0) {
				Log.d(TAG,
						"MyLoaderListener---------->onLoadFinished count = 0");
				mAdapter.swapCursor(null);
				return;
			}
			if (m_FinishLoaderFlag) {
				tempData = null;
				String selection = null;
				String[] selectionArgs = null;
				if (mCallLogShowType == INCOMING) {
					selection = CallLog.Calls.TYPE + "=?";
					selectionArgs = new String[] { "1" };
				} else if (mCallLogShowType == OUTCOMING) {
					selection = CallLog.Calls.TYPE + "=?";
					selectionArgs = new String[] { "2" };
				} else if (mCallLogShowType == MISSED) {
					selection = CallLog.Calls.TYPE + "=?";
					selectionArgs = new String[] { "3" };
				}
				tempData = getContentResolver().query(
						CallLog.Calls.CONTENT_URI, CALLLOG_PROJECTION,
						selection, selectionArgs,
						CallLog.Calls.DEFAULT_SORT_ORDER);
			}
			mAdapter.swapCursor(tempData);
			Log.d(TAG,
					"MyLoaderListener---------->onLoadFinished data count = "
							+ data.getCount());
			m_FinishLoaderFlag = true;
		}

		@Override
		public void onLoaderReset(Loader<Cursor> loader) {
			// TODO Auto-generated method stub
			Log.d(TAG, "MyLoaderListener---------->onLoaderReset");
			mAdapter.swapCursor(null);
		}
	}

	private class buttonListener implements OnClickListener {

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			switch (v.getId()) {
			case R.id.btn_all:
				allCalllog();
				break;
			case R.id.btn_incoming:
				incomingCalllog();
				break;
			case R.id.btn_outcoming:
				outcomingCalllog();
				break;
			case R.id.btn_missed:
				missedCalllog();
				break;
			default:
				break;
			}
		}
	}

	private void allCalllog() {
		mCallLogShowType = ALL;
		String selection = null;
		String[] selectionArgs = null;
		Cursor allCursor = getContentResolver().query(
				CallLog.Calls.CONTENT_URI, CALLLOG_PROJECTION, selection,
				selectionArgs, CallLog.Calls.DEFAULT_SORT_ORDER);
		mAdapter.swapCursor(allCursor);
	}

	private void incomingCalllog() {
		mCallLogShowType = INCOMING;
		String selection = CallLog.Calls.TYPE + "=?";
		String[] selectionArgs = new String[] { "1" };
		Cursor incomingCursor = getContentResolver().query(
				CallLog.Calls.CONTENT_URI, CALLLOG_PROJECTION, selection,
				selectionArgs, CallLog.Calls.DEFAULT_SORT_ORDER);
		mAdapter.swapCursor(incomingCursor);
	}

	private void outcomingCalllog() {
		mCallLogShowType = OUTCOMING;
		String selection = CallLog.Calls.TYPE + "=?";
		String[] selectionArgs = new String[] { "2" };
		Cursor outcomingCursor = getContentResolver().query(
				CallLog.Calls.CONTENT_URI, CALLLOG_PROJECTION, selection,
				selectionArgs, CallLog.Calls.DEFAULT_SORT_ORDER);
		mAdapter.swapCursor(outcomingCursor);
	}

	private void missedCalllog() {
		mCallLogShowType = MISSED;
		String selection = CallLog.Calls.TYPE + "=?";
		String[] selectionArgs = new String[] { "3" };
		Cursor missedCursor = getContentResolver().query(
				CallLog.Calls.CONTENT_URI, CALLLOG_PROJECTION, selection,
				selectionArgs, CallLog.Calls.DEFAULT_SORT_ORDER);
		mAdapter.swapCursor(missedCursor);
	}
}

加载器的使用就是重写三个回调函数，并在加载完时设置Adapter的Cursor，使用Loader之后，只要数据源发生变化，就会自动调用onLoadFinished()，此时listview也会自动刷新

完整的Demo

http://download.csdn.net/detail/deng0zhaotai/7116173