当程序A在执行insert、update、delete时，通过getContext().getContentResolver().notifyChange(uri, observer)方法来告诉所有注册在该Uri的监听者数据发生改变

参数1uri：注册的uri

参数2observer：注册的监听者

	/**
	 * 插入操作
	 */
	@Override
	public Uri insert(Uri uri, ContentValues values) {
		if (uriMatcher.match(uri) != USERSCODE) {
			throw new IllegalArgumentException("unknow URI" + uri);
		}
		SQLiteDatabase db = dh.getReadableDatabase();
		long rowId = db.insert("users", "username", values);
		//监听数据变化，通知注册在uri上的监听者
		//参数1：注册的uri，参数2：监听者
		getContext().getContentResolver().notifyChange(uri, null);
		return ContentUris.withAppendedId(uri, rowId);
	}

在B程序通过registerContentObserver(Uri uri, boolean notifyForDescendents, ContentObserver observer)方法来监听A程序的数据改变

• 参数1：uri
  • 匹配的uri 
• 参数2：notifyForDescendents
  • content://www.csdn.com.provider.userContentProvider/users
  • true:模糊匹配content://www.csdn.com.provider.userContentProvider
  • false:绝对匹配content://www.csdn.com.provider.userContentProvider/users
• 参数3：observer
  • observer为监听实例 ，需要通过继承ContentObserver类，并重写onChange(booleab selfChange)方法，该方法在监听Uri的ContentProvider的数据发生改变时触发该方法
    

package com.example.android_providers;

import android.app.Activity;
import android.content.ContentResolver;
import android.database.ContentObserver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v4.widget.SimpleCursorAdapter;
import android.view.View;
import android.widget.ListView;
import android.widget.TextView;

public class CopyOfMainActivity extends Activity {
	private ListView lv_users;
	private TextView tv_tip;
	private SimpleCursorAdapter adapter;
	private ContentResolver contentResolver;
	private static final String URL = "content://www.csdn.com.provider.userContentProvider/users";

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		lv_users = (ListView) findViewById(R.id.lv_users);
		tv_tip = (TextView) findViewById(R.id.tv_tip);
		// 获取内容解析器对象
		contentResolver = getContentResolver();
		initDate();

		// 注册监听器
		getContentResolver().registerContentObserver(Uri.parse(URL), true,
				new UserContentObserver(handler));
	}

	/*
	 * 初始化数据
	 */
	private void initDate() {
		// 执行查询
		Cursor c = contentResolver.query(Uri.parse(URL), new String[] {
				"userid as _id", "username", "userphone" }, null, null,
				"userid desc");
		// 控制层
		adapter = new SimpleCursorAdapter(this, R.layout.item_phone, c,
				new String[] { "username", "userphone" }, new int[] {
						R.id.tv_name, R.id.tv_phone },
				SimpleCursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);

		lv_users.setAdapter(adapter);
	}

	class UserContentObserver extends ContentObserver {

		private Handler handler;

		public UserContentObserver(Handler handler) {
			super(handler);
			this.handler = handler;
		}

		@Override
		public void onChange(boolean selfChange) {
			super.onChange(selfChange);
			tv_tip.setVisibility(View.VISIBLE);
			tv_tip.setText("有新的信息，请点击加载");
		}

	}

	private Handler handler = new Handler() {
		@Override
		public void handleMessage(Message msg) {
			super.handleMessage(msg);
		}

	};

}

实例应用：

http://blog.csdn.net/zhaoyazhi2129/article/details/30064965