Android 施用ContentProvider对外共享数据与监听ContentProvider数据的变化

Android 使用ContentProvider对外共享数据与监听ContentProvider数据的变化

package cn.itcast.db;

import cn.itcast.service.DBOpenHelper;
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 DBOpenHelper dbOpenHelper;
	private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
	private static final int PERSONS = 1;
	private static final int PERSON = 2;
	static{
		MATCHER.addURI("cn.itcast.providers.personprovider", "person", PERSONS);
		MATCHER.addURI("cn.itcast.providers.personprovider", "person/#", PERSON);
	}	
	//删除person表中的所有记录   /person
	//删除person表中指定id的记录 /person/10
	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		int count = 0;
		switch (MATCHER.match(uri)) {
		case PERSONS:
			count = db.delete("person", selection, selectionArgs);
			return count;
			
		case PERSON:
			long id = ContentUris.parseId(uri);
			String where = "personid="+ id;
			if(selection!=null && !"".equals(selection)){
				where = selection + " and " + where;
			}
			count = db.delete("person", where, selectionArgs);
			return count;
			
		default:
			throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());
		}
	}

	@Override
	public String getType(Uri uri) {//返回当前操作的数据的mimeType
		switch (MATCHER.match(uri)) {
		case PERSONS:			
			return "vnd.android.cursor.dir/person";
			
		case PERSON:			
			return "vnd.android.cursor.item/person";
			
		default:
			throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());
		}
	}

	@Override
	public Uri insert(Uri uri, ContentValues values) {// /person
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		switch (MATCHER.match(uri)) {
		case PERSONS:
			long rowid = db.insert("person", "name", values); 
			Uri insertUri = ContentUris.withAppendedId(uri, rowid);//得到代表新增记录的Uri
			this.getContext().getContentResolver().notifyChange(uri, null);
			return insertUri;

		default:
			throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());
		}
	}

	@Override
	public boolean onCreate() {
		this.dbOpenHelper = new DBOpenHelper(this.getContext());
		return false;
	}
	//查询person表中的所有记录   /person
	//查询person表中指定id的记录 /person/10
	@Override
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
		switch (MATCHER.match(uri)) {
		case PERSONS:
			return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);
			
		case PERSON:
			long id = ContentUris.parseId(uri);
			String where = "personid="+ id;
			if(selection!=null && !"".equals(selection)){
				where = selection + " and " + where;
			}
			return db.query("person", projection, where, selectionArgs, null, null, sortOrder);
			
		default:
			throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());
		}
	}
	
	//更新person表中的所有记录   /person
	//更新person表中指定id的记录 /person/10
	@Override
	public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
		int count = 0;
		switch (MATCHER.match(uri)) {
		case PERSONS:
			count = db.update("person", values, selection, selectionArgs);
			return count;
			
		case PERSON:
			long id = ContentUris.parseId(uri);
			String where = "personid="+ id;
			if(selection!=null && !"".equals(selection)){
				where = selection + " and " + where;
			}
			count = db.update("person", values, where, selectionArgs);
			return count;
			
		default:
			throw new IllegalArgumentException("Unkwon Uri:"+ uri.toString());
		}
	}

}

import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.test.AndroidTestCase;
import android.util.Log;
public class AccessContentProviderTest extends AndroidTestCase {
 private static final String TAG = "AccessContentProviderTest";
 
 /**
  * 往内容提供者添加数据
  * @throws Throwable
  */
 public void testInsert() throws Throwable{
  ContentResolver contentResolver = this.getContext().getContentResolver();
  Uri insertUri = Uri.parse("content://cn.itcast.providers.personprovider/person");
  ContentValues values = new ContentValues();
  values.put("name", "zhangxiaoxiao");
  values.put("amount", 90);
  Uri uri = contentResolver.insert(insertUri, values);
  Log.i(TAG, uri.toString());
 }
 /**
  * 更新内容提供者中的数据
  * @throws Throwable
  */
 public void testUpdate() throws Throwable{
  ContentResolver contentResolver = this.getContext().getContentResolver();
  Uri updateUri = Uri.parse("content://cn.itcast.providers.personprovider/person/1");
  ContentValues values = new ContentValues();
  values.put("name", "lili");
  contentResolver.update(updateUri, values, null, null);
 }
 
 /**
  * 从内容提供者中删除数据
  * @throws Throwable
  */
 public void testDelete() throws Throwable{
  ContentResolver contentResolver = this.getContext().getContentResolver();
  Uri deleteUri = Uri.parse("content://cn.itcast.providers.personprovider/person/1");
  contentResolver.delete(deleteUri, null, null);
 }
 
 /**
  * 获取内容提供者中的数据
  * @throws Throwable
  */
 public void testFind() throws Throwable{
  ContentResolver contentResolver = this.getContext().getContentResolver();
  Uri selectUri = Uri.parse("content://cn.itcast.providers.personprovider/person");
  Cursor cursor = contentResolver.query(selectUri, null, null, null, "personid desc");
  while(cursor.moveToNext()){
   int id = cursor.getInt(cursor.getColumnIndex("personid"));
   String name = cursor.getString(cursor.getColumnIndex("name"));
   int amount = cursor.getInt(cursor.getColumnIndex("amount"));
   Log.i(TAG, "id="+ id + ",name="+ name+ ",amount="+ amount);
  }
 }
}
 

package cn.itcast.other;

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;

public class OtherActivity extends Activity {
    private static final String TAG = "OtherActivity";
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        Uri insertUri = Uri.parse("content://cn.itcast.providers.personprovider/person");
        ContentResolver contentResolver = this.getContentResolver();
        //对指定uri进行监听，如果该uri代表的数据发生变化，就会调用PersonObserver中的onChange()
        contentResolver.registerContentObserver(insertUri, true, new PersonObserver(new Handler()));
    }
    
    private final class PersonObserver extends ContentObserver{
		public PersonObserver(Handler handler) {
			super(handler);
		}

		@Override
		public void onChange(boolean selfChange) {
			ContentResolver contentResolver = getContentResolver();
			Uri selectUri = Uri.parse("content://cn.itcast.providers.personprovider/person");
			Cursor cursor = contentResolver.query(selectUri, null, null, null, "personid desc");
			while(cursor.moveToNext()){
				int id = cursor.getInt(cursor.getColumnIndex("personid"));
				String name = cursor.getString(cursor.getColumnIndex("name"));
				int amount = cursor.getInt(cursor.getColumnIndex("amount"));
				Log.i(TAG, "id="+ id + ",name="+ name+ ",amount="+ amount);
			}
		}
    	
    }

}