/**
 * 內(nèi)容提供者
 * 
 * @author ZhaoKaiQiang
 * @time 2014年6月6日
 */
public class StudentProvider extends ContentProvider {
	// 數(shù)據(jù)庫操作類，用于獲取SQLiteDatabase
	private MyDbOpenHelper dbHelper;
	private static final int STUDENT = 1;
	private static final int STUDENTS = 2;
	// UriMatcher類是一個很重要的類，因為我們需要根據(jù)傳入的uri，來判斷執(zhí)行相對應(yīng)的操作
	private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
	// 靜態(tài)代碼塊用于初始化MATCHER需要匹配的uri
	static {
		// MATCHER.addURI(主機名(用于唯一標示一個ContentProvider,這個需要和清單文件中的authorities屬性相同),路徑(可以用來表示我們要操作的數(shù)據(jù)，路徑的構(gòu)建應(yīng)根據(jù)業(yè)務(wù)而定),返回值(用于匹配uri的時候，作為匹配的返回值));
		MATCHER.addURI("com.example.mydbdemo.StudentProvider", "student", STUDENTS);
		MATCHER.addURI("com.example.mydbdemo.StudentProvider", "student/#", STUDENT);
	}
	// 進行數(shù)據(jù)的初始化操作
	@Override
	public boolean onCreate() {
		dbHelper = new MyDbOpenHelper(getContext());
		return false;
	}
	// 查詢
	// 如果uri為		content://com.example.mydbdemo.StudentProvider/student
	// 則代表查詢所有的student表內(nèi)的數(shù)據(jù)
	// 如果uri為		content://com.example.mydbdemo.StudentProvider/student/6
	// 則代表查詢student表內(nèi)id=6的數(shù)據(jù)
	@Override
	public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
		SQLiteDatabase db = dbHelper.getReadableDatabase();
		//判斷傳入的uri到底匹配哪一個，從而實現(xiàn)不同的業(yè)務(wù)需求
		switch (MATCHER.match(uri)) {
		//查詢?nèi)康膶W(xué)生信息
		case STUDENTS:
			//db.query(表明, 要查詢的列(是一個String數(shù)組), where條件, where條件中的參數(shù), groupBy, having, sortOrder);
			return db.query("student", projection, selection, selectionArgs, null, null, sortOrder);
		//查詢某一個id對應(yīng)的學(xué)生的信息
		case STUDENT:
			//取出我們要查詢的數(shù)據(jù)的id
			long id = ContentUris.parseId(uri);
			String where = "id=" + id;
			//將selection查詢信息拼接到我們的where條件中
			if (selection != null && !"".equals(selection)) {
				where = selection + " and " + where;
			}
			return db.query("student", projection, where, selectionArgs, null, null, sortOrder);
		//如uri不匹配，拋出不合法參數(shù)的異常
		default:
			throw new IllegalArgumentException("Unkwon Uri:" + uri.toString());
		}
	}
	// 插入
	@Override
	public Uri insert(Uri uri, ContentValues values) {
		SQLiteDatabase db = dbHelper.getWritableDatabase();
		switch (MATCHER.match(uri)) {
		case STUDENTS:
			long id = db.insert("student", "name", values);
			return ContentUris.withAppendedId(uri, id);
		default:
			throw new IllegalArgumentException("Uri不匹配");
		}
	}
	//刪除數(shù)據(jù)
	@Override
	public int delete(Uri uri, String selection, String[] selectionArgs) {
		SQLiteDatabase db = dbHelper.getWritableDatabase();
		int count = 0;
		switch (MATCHER.match(uri)) {
		case STUDENTS:
			count = db.delete("student", selection, selectionArgs);
			return count;
		case STUDENT:
			long id = ContentUris.parseId(uri);
			String where = "id=" + id;
			if (selection != null && !"".equals(selection)) {
				where = selection + " and " + where;
			}
			count = db.delete("student", where, selectionArgs);
			return count;
		default:
			throw new IllegalArgumentException("Unkwon Uri:" + uri.toString());
		}
	}
	//更新數(shù)據(jù)
	@Override
	public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
		SQLiteDatabase db = dbHelper.getWritableDatabase();
		int count = 0;
		switch (MATCHER.match(uri)) {
		case STUDENTS:
			count = db.update("student", values, selection, selectionArgs);
			return count;
		case STUDENT:
			long id = ContentUris.parseId(uri);
			String where = "id=" + id;
			if (selection != null && !"".equals(selection)) {
				where = selection + " and " + where;
			}
			count = db.update("student", values, where, selectionArgs);
			return count;
		default:
			throw new IllegalArgumentException("Unkwon Uri:" + uri.toString());
		}
	}
	// 用于獲取MIME Type
	@Override
	public String getType(Uri uri) {
		switch (MATCHER.match(uri)) {
		case STUDENT:
			return "vnd.android.cursor.item/student";
		case STUDENTS:
			return "vnd.android.cursor.dir/student";
		default:
			throw new IllegalArgumentException("Unkwon Uri:" + uri.toString());
		}
	}
}

<!-- 不要忘記exported這個屬性，如果不加，可能會導(dǎo)致外部程序訪問失敗，錯誤信息為權(quán)限拒絕 -->
 		<!-- authorities這個屬性就是我們在ContentProvider中使用的addURI方法時的第一個參數(shù)的取值 -->
        <provider
            android:name="com.example.mydbdemo.StudentProvider"
            android:exported="true"
            android:authorities="com.example.mydbdemo.StudentProvider" >
        </provider>

//使用ContentProvider添加數(shù)據(jù)的測試
	public void testadd() throws Throwable {
		//獲取ContentResolver對象，完成對ContentProvider的調(diào)用
		ContentResolver contentResolver = this.getContext().getContentResolver();
		//構(gòu)建我們的uir，這個uri
		Uri insertUri = Uri.parse("content://com.example.mydbdemo.StudentProvider/student");
		ContentValues values = new ContentValues();
		values.put("name", "zhaokaikai");
		values.put("age", 91);
		values.put("school", "bbbb");
		//返回值為我們剛插入進入的數(shù)據(jù)的uri地址
		Uri uri = contentResolver.insert(insertUri, values);
		Log.i(TAG, uri.toString());
	}

//使用ContentProvider刪除數(shù)據(jù)的測試
	public void testDelete() throws Throwable {
		ContentResolver contentResolver = this.getContext().getContentResolver();
		//刪除id為6的學(xué)生信息
		Uri deleteUri = Uri.parse("content://com.example.mydbdemo.StudentProvider/student/6");
		contentResolver.delete(deleteUri, null, null);
	}

//使用ContentProvider更新數(shù)據(jù)的測試
	public void testUpdate() throws Throwable {
		ContentResolver contentResolver = this.getContext().getContentResolver();
		//更新id = 6 的學(xué)生信息
		Uri updateUri = Uri.parse("content://com.example.mydbdemo.StudentProvider/student/6");
		ContentValues values = new ContentValues();
		values.put("name", "testUp");
		values.put("age", "101");
		values.put("school", "ccccc");
		contentResolver.update(updateUri, values, null, null);
	}

//使用ContentProvider查詢數(shù)據(jù)的測試
	public void testFind() throws Throwable {
		ContentResolver contentResolver = this.getContext().getContentResolver();
		//這個uri用于查詢所有的數(shù)據(jù)，若查詢某個id的數(shù)據(jù)，則構(gòu)建下面的uri
		//Uri selectUri = Uri.parse("content://com.example.mydbdemo.StudentProvider/student/要查詢的id");
		Uri selectUri = Uri.parse("content://com.example.mydbdemo.StudentProvider/student");
		Cursor cursor = contentResolver.query(selectUri, null, null, null, "id desc");
		while (cursor.moveToNext()) {
			int id = cursor.getInt(cursor.getColumnIndex("id"));
			String name = cursor.getString(cursor.getColumnIndex("name"));
			int age = cursor.getInt(cursor.getColumnIndex("age"));
			String school = cursor.getString(cursor.getColumnIndex("school"));
			Log.i(TAG, "id=" + id + ",name=" + name + ",age=" + age +",school="+school);
		}
	}