一、監聽ContentProvider主要步驟1.在ContentProvider類的insert\update\delete方法加入this.getContext().getContentResolver().notifyChange(URI,null);其中URI表示監聽的URInull表示發送訊息給任何人;
2.在訪問者的類中調用如下方法:context.getContentResolver().registerContentObserver(uri,true,new ContentObserver(new Handler()));
3.建立內部類繼承ContentObserver並重寫下面兩個方法:(1)帶有Handler的建構函式;(2)public void onChange(boolean selfChange); 此函數在內容提供者發出改變訊號時就會被調用
參數selfChange為如果是自己改變的原因,則為true;如果不是自己改變的,則為false;
二、執行個體我們在Test1和Test2應用都對ContentProvider的資料改變進行註冊,如果ContentProvider發出通知,則Test1和Test2都會收到通知;
注意:此處有一個很重要的問題,如果Test1和Test2應用的MainActivity為同一個包,則如果先運行Test2,再運行Test1,則Test2會停止運行,因為Test1應用會覆蓋Test2的應用,即接收不到通知;
因此我們要把Test1應用和Test2應用的包名設為不同,此處為org.xiazdong和org.xzdong;
ContentProvider.java
package org.xiazdong.db;import android.content.ContentProvider;import android.content.ContentUris;import android.content.ContentValues;import android.content.UriMatcher;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.net.Uri;public class PersonProvider extends ContentProvider{private DatabaseHelper helper;private SQLiteDatabase db;private UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);@Overridepublic boolean onCreate() {helper = new DatabaseHelper(this.getContext());matcher.addURI("org.xiazdong.provides.personprovider", "person", 1);return true;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection,String[] selectionArgs, String sortOrder) {return null;}/* * 如果操作集合,則必須以vnd.android.cursor.dir開頭 * 如果操作非集合,則必須以vnd.android.cursor.item開頭 * */@Overridepublic String getType(Uri uri) {return "";}@Overridepublic Uri insert(Uri uri, ContentValues values) {db = helper.getWritableDatabase();switch(matcher.match(uri)){case 1:long rowid = db.insert("person", null, values);this.getContext().getContentResolver().notifyChange(uri, null);//如果改變資料,則通知所有人return ContentUris.withAppendedId(uri, rowid);//返回插入的記錄所代表的URIdefault:throw new IllegalArgumentException("wrong uri");}}@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {return 0;}@Overridepublic int update(Uri uri, ContentValues values, String selection,String[] selectionArgs) {return 0;}}
Test1應用
package org.xiazdong;import android.app.Activity;import android.content.ContentResolver;import android.content.ContentValues;import android.database.ContentObserver;import android.net.Uri;import android.os.Bundle;import android.os.Handler;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity {private Button button;private OnClickListener listener = new OnClickListener(){@Overridepublic void onClick(View v) {ContentResolver resolver = MainActivity.this.getContentResolver();Uri uri = Uri.parse("content://org.xiazdong.provider2/person");resolver.registerContentObserver(uri, true, new PersonObserver(new Handler()));ContentValues values = new ContentValues();values.put("name", "zzz");values.put("age", 1);resolver.insert(uri, values);//向ContentProvider插入資料}};@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); button = (Button)this.findViewById(R.id.button); button.setOnClickListener(listener); }private class PersonObserver extends ContentObserver{//監聽public PersonObserver(Handler handler) {super(handler);}//當ContentProvier資料發生改變,則觸發該函數@Overridepublic void onChange(boolean selfChange) {super.onChange(selfChange);Log.i("Test1", "資料改變");} }}
Test2應用
package org.xzdong;import android.app.Activity;import android.database.ContentObserver;import android.net.Uri;import android.os.Bundle;import android.os.Handler;import android.util.Log;public class MainActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Uri uri = Uri.parse("content://org.xiazdong.provider2/person"); this.getContentResolver().registerContentObserver(uri, true, new PersonObserver(new Handler())); } private class PersonObserver extends ContentObserver{public PersonObserver(Handler handler) {super(handler);}//當ContentProvier資料發生改變,則觸發該函數@Overridepublic void onChange(boolean selfChange) {super.onChange(selfChange);Log.v("Test2", "資料改變");} }}
效果: