andoird---loadermanager和contentprovider结合，加载数据

本人是刚入android的菜鸟，如果下面有写的不对的地方，特别欢迎纠正。

先说说对loadermanager的理解，loadermanager是对loader进行管理，而loader的作用就是“异步”加载数据，也就是说loader相当于有两个功能（这种说法比较牵强），一个是查询功能，另一种是异步，这样做的好处是ui加载与数据加载分离，效率方面的到很大提升。而loadermanager的功能是监听（monitor）loader的数据，同时将数据的变化返回到ui，进行展现，这里用到了一种设计模式----观察者设计模式。

对于contentprovider，就类似于创建一个“服务器”，“服务器”需要地址访问，同时需要对地址进行解析，同时需要对数据（如：数据库等）,进行CRUD操作。总之，contentprovider作用：1.对地址进行解析   2.CRUD 操作  3.添加访问地址  等

好了废话不多说上代码。

AndroidManifest.xml

DBHelper.java

package com.example.android_contentprovdier_loadermanager.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {
	private final static String name = "mydb1.db";
	private final static int version = 1;
	
	public DBHelper(Context context) {
		super(context, name, null, version);
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		String sql = "create table person(_id integer primary key autoincrement, name varchar(64), address varchar(64))";
		db.execSQL(sql);
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		
	}
}

MyProvider.java

package com.example.android_contentprovdier_loadermanager;

import com.example.android_contentprovdier_loadermanager.db.DBHelper;

import android.content.ContentProvider;
import android.content.ContentResolver;
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 MyProvider extends ContentProvider {
	private DBHelper helper;
	private ContentResolver resolver;
	private static UriMatcher matcher = new UriMatcher(UriMatcher.NO_MATCH);
	private final static int PERSON = 1;
	private final static int PERSONS = 2;
	
	static {
		matcher.addURI("com.example.android.MyProvider", "person", PERSON);
		matcher.addURI("com.example.android.MyProvider", "person/*", PERSONS);
	}

	@Override
	public boolean onCreate() {
		helper = new DBHelper(getContext());
		resolver = getContext().getContentResolver();
		return false;
	}

	@Override
	public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
		SQLiteDatabase database  = helper.getReadableDatabase();
		Cursor cursor = database.query("person", projection, selection, selectionArgs, null, null, sortOrder);
		resolver.notifyChange(uri, null);
		return cursor;
	}

	@Override
	public String getType(Uri uri) {
		int match = matcher.match(uri);
		switch(match) {
		case PERSON:
			return "vnd.android.cursor.item/person";
		case PERSONS:
			return "vnd.android.cursor.dir/person";
		}
		
		return null;
	}

	@Override
	public Uri insert(Uri uri, ContentValues values) {
		SQLiteDatabase database = helper.getWritableDatabase();
		
		int match = matcher.match(uri);
		switch (match) {
		case PERSON:
			long key = database.insert("person", null, values);
			Uri uri1 = ContentUris.withAppendedId(uri, key);
			resolver.notifyChange(uri1, null);
			return uri1;
		case PERSONS:
			
			break;
		}
		
		return null;
	}

	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		return 0;
	}

	@Override
	public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
		return 0;
	}

}

MainActivity.java

package com.example.android_contentprovdier_loadermanager;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.LoaderManager;
import android.app.LoaderManager.LoaderCallbacks;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.CursorLoader;
import android.content.Loader;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity implements LoaderCallbacks {
	private Button button1;
	private ListView listView1;
	private LoaderManager manager;
	private MyAdapter adapter;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		button1 = (Button) this.findViewById(R.id.button1);
		listView1 = (ListView) this.findViewById(R.id.listView1);
		button1.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				ContentResolver resolver = MainActivity.this.getContentResolver();
				ContentValues values = new ContentValues();
				values.put("name", "你好");
				values.put("address", "济南");
				Uri uri = Uri.parse("content://com.example.android.MyProvider/person");
			
				resolver.insert(uri, values);
				
				//重启loadermanager，告诉它重新加载数据
				manager.restartLoader(101, null, MainActivity.this);
			}
		});
		
		manager = getLoaderManager();
		//mainactivity实现loadCallback接口，所以这边的callback用this
		manager.initLoader(101, null, this);
	}
	
	public class MyAdapter extends BaseAdapter {
		private List list;
		
		public MyAdapter(List list) {
			this.list = list;
		}

		@Override
		public int getCount() {
			return list.size();
		}

		@Override
		public Object getItem(int position) {
			return list.get(position);
		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			TextView textView1 = null;
			
			if(convertView != null) {
				textView1 = (TextView) convertView;
			} else {
				textView1 = new TextView(MainActivity.this);
			}
			
			textView1.setText(list.get(position));
			
			return textView1;
		}
		
	}

	//异步查询数据
	@Override
	public Loader onCreateLoader(int id, Bundle args) {
		CursorLoader loader = new CursorLoader(this);
		Uri uri = Uri.parse("content://com.example.android.MyProvider/person");
		loader.setUri(uri);
		loader.setProjection(new String[]{"address"});
		
		return loader;
	}

	//查询过后对数据进行遍历
	@Override
	public void onLoadFinished(Loader loader, Cursor data) {
		List list = new ArrayList();
		int count = data.getColumnCount();
		while(data.moveToNext()) {
			for(int i=0; i loader) {
		
	}

	

}

如果有需要可以去csdn现在资料，我的资料完全免费http://download.csdn.net/detail/scqdscy1994/9713133