ContentProvider

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DatabaseHelper.java

package com.baxian.s1_contentprovider.db;

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

//DatabaseHelper作为一个访问SQLite的助手类，提供两个方面的功能，
//第一，getReadableDatabase(),getWritableDatabase()可以获得SQLiteDatabse对象，通过该对象可以对数据库进行操作
//第二，提供了onCreate()和onUpgrade()两个回调函数，允许我们在创建和升级数据库时，进行自己的操作

public class DatabaseHelper extends SQLiteOpenHelper 

	private static final int VERSION = 1;

	// 在SQLiteOepnHelper的子类当中，必须有该构造函数
	public DatabaseHelper(Context context, String name, CursorFactory factory,
			int version) 
		// 必须通过super调用父类当中的构造函数
		super(context, name, factory, version);
		// TODO Auto-generated constructor stub
	

	public DatabaseHelper(Context context, String name) 
		this(context, name, VERSION);
	

	public DatabaseHelper(Context context, String name, int version) 
		this(context, name, null, version);
	

	// 该函数是在第一次创建数据库的时候执行,实际上是在第一次得到SQLiteDatabse对象的时候，才会调用这个方法
	@Override
	public void onCreate(SQLiteDatabase db) 
		// TODO Auto-generated method stub
		System.out.println("create a Database");
		// execSQL函数用于执行SQL语句
		// db.execSQL("create table " + FirstProviderMetaData.USERS_TABLE_NAME
		// + "(" + FirstProviderMetaData.UserTableMetaData._ID
		// + " INTEGER PRIMARY KEY AUTOINCREMENT,"
		// + FirstProviderMetaData.UserTableMetaData.USER_NAME
		// + " varchar(20));");
	

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) 
		// TODO Auto-generated method stub
		System.out.println("update a Database");


FirstProviderMetadata.java

package com.baxian.s1_contentprovider.cp;

import android.net.Uri;
import android.provider.BaseColumns;

public class FirstProviderMetadata 

	public static final String AUTHORIY = "com.baxian.s1_contentprovider.cp.FirstContentProviderMatadata";

	public static final String DATABASE_NAME = "FirstProvider.db";

	public static final int DATABASE_VERSION = 1;

	public static final String USERS_TABLE_NAME = "users";

	public static final class UserTableMetaData implements BaseColumns 

		public static final String TABLE_NAME = "users";
		// 访问该ContentProvider的URI
		public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORIY
				+ "/users");
		// 该ContentProvider所返回的数据类型的定义
		public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.firstprovider.user";
		public static final String CONTENT_TYPE_ITEM = "vnd.android.cursor.item/vnd.firstprovider.user";

		// 列名
		public static final String USER_NAME = "name";
		// 默认的排序方法
		public static final String DEFAULT_SORT_ORDER = "_id desc";

FirstContentProvider.java 

package com.baxian.s1_contentprovider.cp;

import java.util.HashMap;

import com.baxian.s1_contentprovider.cp.FirstProviderMetadata.UserTableMetaData;
import com.baxian.s1_contentprovider.db.DatabaseHelper;

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.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.text.TextUtils;

public class FirstContentProvider extends ContentProvider 

	public static final UriMatcher uriMatcher;
	public static final int INCOMING_USER_COLLECTION = 1;
	public static final int INCOMING_USER_SINGLE = 2;
	private DatabaseHelper dh;

	static 
		uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
		uriMatcher.addURI(FirstProviderMetadata.AUTHORIY, "/users",
				INCOMING_USER_COLLECTION);
		uriMatcher.addURI(FirstProviderMetadata.AUTHORIY, "/users/#",
				INCOMING_USER_SINGLE);
	

	public static HashMap<String, String> userProjectionMap;
	static 
		userProjectionMap = new HashMap<String, String>();
		userProjectionMap.put(UserTableMetaData._ID, UserTableMetaData._ID);
		userProjectionMap.put(UserTableMetaData.USER_NAME,
				UserTableMetaData.USER_NAME);
	

	// 是一个回调方法，所以说在ContentProvider创建的时候执行
	@Override
	public boolean onCreate() 
		// TODO Auto-generated method stub
		// 打开数据库
		dh = new DatabaseHelper(getContext(),
				FirstProviderMetadata.DATABASE_NAME);
		System.out.println("onCreate");
		return false;
	

	@Override
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) 
		// TODO Auto-generated method stub
		SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
		switch (uriMatcher.match(uri)) 
		case INCOMING_USER_COLLECTION:
			qb.setTables(UserTableMetaData.TABLE_NAME);
			qb.setProjectionMap(userProjectionMap);
			break;
		case INCOMING_USER_SINGLE:
			qb.setTables(UserTableMetaData.TABLE_NAME);
			qb.setProjectionMap(userProjectionMap);
			qb.appendWhere(UserTableMetaData._ID + "="
					+ uri.getPathSegments().get(1));
			break;
		

		String orderby;
		if (TextUtils.isEmpty(sortOrder)) 
			orderby = UserTableMetaData.DEFAULT_SORT_ORDER;
		 else 
			orderby = sortOrder;
		

		SQLiteDatabase db = dh.getWritableDatabase();
		// Cursor c = qb.query(db, projectionIn, selection,
		// selectionArgs,groupBy, having, sortOrder);
		Cursor c = qb.query(db, projection, selection, selectionArgs, null,
				null, orderby);
		c.setNotificationUri(getContext().getContentResolver(), uri);
		System.out.println("query");
		return c;
	

	// 根据传入的URI，返回该URI所表示的数据类型
	@Override
	public String getType(Uri uri) 
		// TODO Auto-generated method stub
		System.out.println("getType");
		switch (uriMatcher.match(uri)) 
		case INCOMING_USER_COLLECTION:
			return UserTableMetaData.CONTENT_TYPE;
		case INCOMING_USER_SINGLE:
			return UserTableMetaData.CONTENT_TYPE_ITEM;
		default:
			throw new IllegalArgumentException("Unknown URI" + uri);
		
	

	/**
	 * 该函数的返回值是一个Uri，这个Uri表示的是刚刚使用这个函数所插入的数据
	 * content://com.baxian.s1_contentprovider.cp.FirstContentProvider/users/1
	 */
	@Override
	public Uri insert(Uri uri, ContentValues values) 
		// TODO Auto-generated method stub
		System.out.println("insert");
		SQLiteDatabase db = dh.getWritableDatabase();
		long rowId = db.insert(UserTableMetaData.TABLE_NAME, null, values);
		Uri insertUri = null;
		if (rowId > 0) 
			insertUri = ContentUris.withAppendedId(
					UserTableMetaData.CONTENT_URI, rowId);
			// 通知监听器，数据已经改变
			getContext().getContentResolver().notifyChange(insertUri, null);

			return insertUri;
		
		return insertUri;
	

	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) 
		// TODO Auto-generated method stub
		System.out.println("delete");
		return 0;
	

	@Override
	public int update(Uri uri, ContentValues values, String selection,
			String[] selectionArgs) 
		// TODO Auto-generated method stub
		System.out.println("update");
		return 0;

ContentProviderActivity.java 

package com.baxian.s1_contentprovider;

import com.baxian.s1_contentprovider.cp.FirstProviderMetadata;

import android.support.v7.app.ActionBarActivity;
import android.content.ContentUris;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class ContentProviderActivity extends ActionBarActivity 

	private Button insert;
	private Button query;

	@Override
	protected void onCreate(Bundle savedInstanceState) 
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		insert = (Button) findViewById(R.id.insert);
		query = (Button) findViewById(R.id.query);

		InsertListener il = new InsertListener();
		insert.setOnClickListener(il);
		QureyListener ql = new QureyListener();
		query.setOnClickListener(ql);

	

	class InsertListener implements OnClickListener 

		@Override
		public void onClick(View v) 
			// TODO Auto-generated method stub
			System.out.println("click insert button");
			ContentValues values = new ContentValues();
			values.put(FirstProviderMetadata.UserTableMetaData.USER_NAME,
					"zhangsan");
			Uri uri = getContentResolver()
					.insert(FirstProviderMetadata.UserTableMetaData.CONTENT_URI,
							values);
			System.out.println("Uri:" + uri);

		
	

	class QureyListener implements OnClickListener 

		@Override
		public void onClick(View v) 
			// TODO Auto-generated method stub
			System.out.println("click query button");
			Cursor c = getContentResolver().query(
					FirstProviderMetadata.UserTableMetaData.CONTENT_URI, null,
					null, null, null);
			while (c.moveToNext()) 
				System.out
						.println(c.getString(c
								.getColumnIndex(FirstProviderMetadata.UserTableMetaData.USER_NAME)));
			

		
	

	@Override
	public boolean onCreateOptionsMenu(Menu menu) 
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	

	@Override
	public boolean onOptionsItemSelected(MenuItem item) 
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) 
			return true;
		
		return super.onOptionsItemSelected(item);


notice AndroidManifest.xml -->


<provider
            android:name=""
            android:authorities="" >
        </provider>

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