mars老师[Android开发视频教学]01_19 Content provider初步

Content Provider初步

创建项目：TestCP

项目截图：



==>CPActivity.java

package mars.cp;

import mars.cp.FirstProviderMetaData.UserTableMetaData;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class CPActivity extends Activity {
	/** Called when the activity is first created. */
	private Button insertButton = null;
	private Button queryButton = null;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		queryButton = (Button) findViewById(R.id.query);
		queryButton.setOnClickListener(new QueryListener());
		insertButton = (Button) findViewById(R.id.insert);
		insertButton.setOnClickListener(new InsertListener());
		System.out.println(getContentResolver().getType(FirstProviderMetaData.UserTableMetaData.CONTENT_URI));
	}

	class InsertListener implements OnClickListener {

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			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.toString());
		}

	}

	class QueryListener implements OnClickListener {

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

	}
}

==>FirstContentProvider.java

package mars.cp;

import java.util.HashMap;

import mars.cp.FirstProviderMetaData.UserTableMetaData;
import mars.sqlite3.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.SQLException;
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);
	}
	@Override
	public int delete(Uri arg0, String arg1, String[] arg2) {
		// TODO Auto-generated method stub
		System.out.println("delete");
		return 0;
	}

	//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://mars.cp.FirstContentProvider/users/1
	 */
	@Override
	public Uri insert(Uri uri, ContentValues values) {
		System.out.println("insert");
		SQLiteDatabase db = dh.getWritableDatabase();
		long rowId = db.insert(UserTableMetaData.TABLE_NAME, null, values);
		if(rowId > 0){
			Uri insertedUserUri = ContentUris.withAppendedId(UserTableMetaData.CONTENT_URI, rowId);
			//通知监听器，数据已经改变
			getContext().getContentResolver().notifyChange(insertedUserUri, null);
			return insertedUserUri;
		}
		throw new SQLException("Failed to insert row into" + uri);
	}

	//是一个回调方法，所以说在ContentProvider创建的时候执行 
	@Override
	public boolean onCreate() {
		//打开数据库  
		dh = new DatabaseHelper(getContext(),FirstProviderMetaData.DATABASE_NAME);
		System.out.println("onCreate");
		return true;
	}

	@Override
	public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
			String sortOrder) {
		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, projection, selection, selectionArgs, null, null, orderBy);
		c.setNotificationUri(getContext().getContentResolver(), uri);
		System.out.println("query");
		return c;
	}

	@Override
	public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {
		// TODO Auto-generated method stub
		System.out.println("update");
		return 0;
	}

}

==>FirstContentProviderMatadata.java

package mars.cp;

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

public class FirstProviderMetaData {
	public static final String AUTHORIY = "mars.cp.FirstContentProvider";
	//数据库名称
	public static final String DATABASE_NAME = "FirstProvider.db";
	//数据库的版本
	public static final int DATABASE_VERSION = 1;
	//表名 
	public static final String USERS_TABLE_NAME = "users";
	
	public static final class UserTableMetaData implements BaseColumns{
		//表名
		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";
	}
}

==>DatabaseHelper.java

package mars.sqlite3.db;

import mars.cp.FirstProviderMetaData;
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");
	}

}

==>main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<Button 
	android:id="@+id/insert"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
	android:text="插入数据"
	/>
<Button 
	android:id="@+id/query"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
	android:text="查询数据"
	/>
</LinearLayout>

==>AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="mars.cp"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".CPActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<provider android:name="mars.cp.FirstContentProvider"
android:authorities="mars.cp.FirstContentProvider"/>
</application>
<uses-sdk android:minSdkVersion="4" />

</manifest> [/code]