Android Content Provider(内容提供者)

一、简介

定义内容提供者可以开发自己已用的数据操作给第三方调用，下面的示例中用到了Android test case ，主要是为了给数据库中添加数据方便内容提供者读取。

二、Test case 添加DB数据

1、声明单元测试

 

    <instrumentation        android:name="android.test.InstrumentationTestRunner"        android:targetPackage="com.am.cpv" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <uses-library android:name="android.test.runner" />    </application>

2、创建数据库工具类SQLiteOpenHelper

import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class MyDBOpenHelper extends SQLiteOpenHelper {public MyDBOpenHelper(Context context) {super(context, "person.db", null, 1);}@Overridepublic void onCreate(SQLiteDatabase db) {db.execSQL("create table person (id integer primary key autoincrement,name varchar(20),number varchar(20))");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stub}}

3、创建AndroidTestCase，添加数据到数据库

import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.test.AndroidTestCase;import com.am.cpv.db.MyDBOpenHelper;public class AddDataTestCase extends AndroidTestCase {public void testAdd() {MyDBOpenHelper oh = new MyDBOpenHelper(getContext());SQLiteDatabase wdb = oh.getWritableDatabase();// wdb.execSQL("insert into person(name) values(?)", new Object[]{"张三"});for (int i = 0; i < 30; i++) {ContentValues values = new ContentValues();values.put("name", "name" + i);values.put("number", "110-" + i);wdb.insert("person", null, values);}wdb.close();}public void testQuery() {MyDBOpenHelper oh = new MyDBOpenHelper(getContext());SQLiteDatabase wdb = oh.getWritableDatabase();// Cursor cursor = wdb.rawQuery("select * from person ", new String[] {});Cursor cursor2 = wdb.query("person", null, null, new String[] {}, null, null, null);while (cursor2.moveToNext()) {String[] columnNames = cursor2.getColumnNames();for (String colName : columnNames) {int columnIndex = cursor2.getColumnIndex(colName);String val = cursor2.getString(columnIndex);System.out.print(val + " ");}System.out.println();}}}

三、创建内容提供者

1、创建ContentProvider

import android.content.ContentProvider;import android.content.ContentValues;import android.content.UriMatcher;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.net.Uri;import com.am.cpv.db.MyDBOpenHelper;public class PersonProvider extends ContentProvider {private static UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);private MyDBOpenHelper helper;private static final int QUERY = 1;static {uriMatcher.addURI("com.am.persionProvider", "query", QUERY);}@Overridepublic boolean onCreate() {helper = new MyDBOpenHelper(getContext());return false;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {// 判断uri的请求是否为查询if (uriMatcher.match(uri) == QUERY) {SQLiteDatabase db = helper.getReadableDatabase();Cursor cursor = db.query("person", projection, selection, selectionArgs, null, null, sortOrder);return cursor;} else {return null;}}//下边的代码未作实现@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {// TODO Auto-generated method stubreturn 0;}@Overridepublic String getType(Uri uri) {// TODO Auto-generated method stubreturn null;}@Overridepublic Uri insert(Uri uri, ContentValues values) {// TODO Auto-generated method stubreturn null;}@Overridepublic int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {// TODO Auto-generated method stubreturn 0;}}

2、AndroidManifest.xml中声明内容提供者

        <provider            android:name="com.am.cpv.pv.PersonProvider"            android:authorities="com.am.persionProvider"            android:exported="true" >        </provider>

四、读取内容提供者的数据

public void click(View v) {ContentResolver cr = getContentResolver();Uri uri = Uri.parse("content://com.am.persionProvider/query");Cursor cursor = cr.query(uri, null, "name=?", new String[] { "name1" }, null);while (cursor.moveToNext()) {String[] columnNames = cursor.getColumnNames();for (String colName : columnNames) {int columnIndex = cursor.getColumnIndex(colName);String val = cursor.getString(columnIndex);System.out.print(val + " ");}}}