Android加载器LoaderManager.LoaderCallbacks的使用

 

Android加载器LoaderManager.LoaderCallbacks的使用

分类： Android进阶 2014-03-29 13:37  114人阅读  评论(0)  收藏  举报

Android LoaderManager.Loader LoadManager 加载器

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 {

         @Override
         public Loader 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 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 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