使用ContentProvider共享数据

使用ContentResolver操作ContentProvider中的数据

package provider;

import com.example.db.MyDBHelper;

import dao.PersonDBDao;
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;
import android.util.Log;

public class PersonProvider extends ContentProvider {
	// 创建了一个路径的识别器 默认的返回值UriMatcher.NO_MATCH
	public static final UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
	public static final int ALL_PERSON = 1;
	public static final int PERSON = 2;
	public static final int HAHA = 3;
	private static final int INSERT = 4;
	private static final int DELETE = 5;
	private static final int UPDATE = 6;
	Uri baseuri = Uri.parse("content://provider.personprovider");
	static {
		matcher.addURI("provider.personprovider", "persons", ALL_PERSON);
		matcher.addURI("provider.personprovider", "persons/#", PERSON);
		matcher.addURI("provider.personprovider", "haha", HAHA);
		matcher.addURI("provider.personprovider", "insert", INSERT);
		matcher.addURI("provider.personprovider", "delete", DELETE);
		matcher.addURI("provider.personprovider", "update", UPDATE);
	}

	private MyDBHelper openhelper;

	/**
	 * 初始化
	 */
	@Override
	public boolean onCreate() {
		// TODO 自动生成的方法存根
		openhelper = new MyDBHelper(getContext());
		return false;
	}

	@Override
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		int result = matcher.match(uri);
		switch (result) {
		case ALL_PERSON:
			PersonDBDao dao = new PersonDBDao(getContext());
			return dao.findAllbyCursor();
		case PERSON:
			long id = ContentUris.parseId(uri);

			SQLiteDatabase db = openhelper.getReadableDatabase();
			if (db.isOpen()) {
				Cursor cursor = db.query("person", null, "id=?",
						new String[] { id + "" }, null, null, null);
				return cursor;
			}
		case HAHA:
			Log.i("haha", "hahaha");
			break;
		default:
			throw new IllegalArgumentException("uri不能被识别");
		}
		return null;
	}

	/**
	 * 有的时候 我们需要知道内容提供者返回的数据类型 知道返回的数据 是一个集合呀 还是一个单独的条目
	 * 
	 * 有的时候 告诉调用者 返回的数据是什么样的类型 mime的数据类型
	 */
	@Override
	public String getType(Uri uri) {
		int result = matcher.match(uri);
		switch (result) {
		// 符合 content://cn.itcast.db.provider/persons 代表的返回所有的数据
		case ALL_PERSON:
			return "vnd.android.cursor.dir/people";
			// content://cn.itcast.db.provider/person/10
		case PERSON:
			return "vnd.android.cursor.item/people";
		default:
			return null;
		}
	}

	@Override
	public Uri insert(Uri uri, ContentValues values) {
		// TODO 自动生成的方法存根
		int result = matcher.match(uri);
		switch (result) {
		case INSERT:
			SQLiteDatabase db = openhelper.getWritableDatabase();
			db.insert("person", "id", values);
			// 当数据发生改变的时候
			getContext().getContentResolver().notifyChange(baseuri, null);
			return uri;

		default:
			throw new IllegalArgumentException("uri不能被识别");
		}
	}

	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		int result = matcher.match(uri);
		switch (result) {
		case DELETE:
			SQLiteDatabase db = openhelper.getWritableDatabase();
			getContext().getContentResolver().notifyChange(baseuri, null);
			return db.delete("person", selection, selectionArgs);

		default:
			throw new IllegalArgumentException("uri不能被识别");
		}
	}

	@Override
	public int update(Uri uri, ContentValues values, String selection,
			String[] selectionArgs) {
		int result = matcher.match(uri);
		switch (result) {
		case UPDATE:
			SQLiteDatabase db = openhelper.getWritableDatabase();
			getContext().getContentResolver().notifyChange(baseuri, null);
			return db.update("person", values, selection, selectionArgs);
		default:
			throw new IllegalArgumentException("uri不能被识别");
		}
	}
}

package com.example.other;

import android.R;
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.util.Log;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// setContentView(R.layout.main);
		ContentResolver resolver = getContentResolver();
		Uri uri = Uri.parse("content://provider.personprovider/");

		Cursor cursor = null;
		cursor = resolver.query(uri, null, null, null, null);
		while (cursor.moveToNext()) {
			String name = cursor.getString(cursor.getColumnIndex("name"));
			String address = cursor.getString(cursor.getColumnIndex("address"));
			System.out.println(name + "   " + address);
			Toast.makeText(getBaseContext(), name + "   " + address,
					Toast.LENGTH_LONG).show();
		}

		getContentResolver().registerContentObserver(uri, true,
	 	 new MyObserver(new Handler()));

	}

	public class MyObserver extends ContentObserver {

		public MyObserver(Handler handler) {
			super(handler);

		}

		/**
		 * 当内容观察者发现了数据发生改变的时候 调用的方法
		 */
		@Override
		public void onChange(boolean selfChange) {
			System.out.println("数据发生改变了 ");
			Log.i("aaaaaaa", "数据发生改变了");
			super.onChange(selfChange);
		}

	}
}