Android的ContentProvider（二）

接下来是getType方法，此方法参数是URI，根据Uri返回不同的MimeType：

@Overridepublic String getType(Uri uri) {switch (uriMatcher.match(uri)) {case COLL_TYPE_URI_MATCHER: {return Book.ContentType.COLL_TYPE;}case ITEM_TYPE_URI_MATCHER: {return Book.ContentType.ITEM_TYPE;}default: {throw new SQLException("Unknown URI:" + uri);}}}

接下来是insert方法，参数是Uri及ContentValues，较为简单：

@Overridepublic Uri insert(Uri uri, ContentValues values) {if (uriMatcher.match(uri) != COLL_TYPE_URI_MATCHER) {throw new SQLException("Unknown URI:" + uri);}Long now = System.currentTimeMillis();if (!values.containsKey(Book.Columns.NAME)) {throw new SQLException(Book.Columns.NAME.concat(" 的值不得为空！"));}if (!values.containsKey(Book.Columns.AUTHOR)) {values.put(Book.Columns.AUTHOR, "Unknown Author");}if (!values.containsKey(Book.Columns.CREATE_TIME)) {values.put(Book.Columns.CREATE_TIME, now);}SQLiteDatabase db = dbHelper.getWritableDatabase();Long rowId = db.insert(Book.TABLE_NAME, Book.Columns.NAME, values);if (rowId > 0) {Uri insertedBookUri = ContentUris.withAppendedId(Book.CONTENT_URI,rowId);getContext().getContentResolver().notifyChange(insertedBookUri,null);return insertedBookUri;}throw new SQLException("添加图书失败，URI：" + uri);}

前文说过，最好都加上notifyChange。

delete和update也没什么特别的：

@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {int count = 0;SQLiteDatabase db = dbHelper.getWritableDatabase();switch (uriMatcher.match(uri)) {case COLL_TYPE_URI_MATCHER: {count = db.delete(Book.TABLE_NAME, selection, selectionArgs);break;}case ITEM_TYPE_URI_MATCHER: {selection = Book.Columns._ID.concat("=").concat(uri.getPathSegments().get(1)).concat(TextUtils.isEmpty(selection) ? "" : " AND (".concat(selection).concat(")"));count = db.delete(Book.TABLE_NAME, selection, selectionArgs);break;}default: {throw new SQLException("Unknown URI:" + uri);}}getContext().getContentResolver().notifyChange(uri, null);return count;}@Overridepublic int update(Uri uri, ContentValues values, String selection,String[] selectionArgs) {int count = 0;SQLiteDatabase db = dbHelper.getWritableDatabase();switch (uriMatcher.match(uri)) {case COLL_TYPE_URI_MATCHER: {count = db.update(Book.TABLE_NAME, values, selection, selectionArgs);break;}case ITEM_TYPE_URI_MATCHER: {selection = Book.Columns._ID.concat("=").concat(uri.getPathSegments().get(1)).concat(TextUtils.isEmpty(selection) ? "" : " AND (".concat(selection).concat(")"));count = db.update(Book.TABLE_NAME, values, selection, selectionArgs);break;}default: {throw new SQLException("Unknown URI:" + uri);}}getContext().getContentResolver().notifyChange(uri, null);return count;}

至此已实现BookProvider，全部代码如下所示：

/** *  * Dec 22, 2014 3:43:47 PM * @Geloin * */package com.geloin.baseopera.provider;import java.util.HashMap;import java.util.Map;import android.content.ContentProvider;import android.content.ContentUris;import android.content.ContentValues;import android.content.Context;import android.content.UriMatcher;import android.database.Cursor;import android.database.SQLException;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.database.sqlite.SQLiteQueryBuilder;import android.net.Uri;import android.text.TextUtils;/** *  * Dec 22, 2014 3:43:47 PM *  * @Geloin *  */public class BookProvider extends ContentProvider {public class DBHelper extends SQLiteOpenHelper {public DBHelper(Context context) {super(context, Book.DB_FILE_NAME, null, Book.DB_VERSION);}@Overridepublic void onCreate(SQLiteDatabase db) {StringBuilder builder = new StringBuilder();builder.append(" CREATE TABLE ");builder.append(Book.TABLE_NAME);builder.append(" ( ");builder.append(Book.Columns._ID);builder.append(" INTEGER PRIMARY KEY, ");builder.append(Book.Columns.NAME);builder.append(" TEXT, ");builder.append(Book.Columns.AUTHOR);builder.append(" TEXT, ");builder.append(Book.Columns.CREATE_TIME);builder.append(" INTEGER ");builder.append(" ); ");db.execSQL(builder.toString());}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {db.execSQL("DROP TABLE IF EXISTS ".concat(Book.TABLE_NAME));onCreate(db);}}private DBHelper dbHelper;private static UriMatcher uriMatcher;private static final int COLL_TYPE_URI_MATCHER = 1;private static final int ITEM_TYPE_URI_MATCHER = 2;private static Map<String, String> columnMap;static {uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);uriMatcher.addURI(Book.AUTHORITY, "books", COLL_TYPE_URI_MATCHER);uriMatcher.addURI(Book.AUTHORITY, "books/#", ITEM_TYPE_URI_MATCHER);columnMap = new HashMap<String, String>();columnMap.put(Book.Columns._ID, Book.Columns._ID);columnMap.put(Book.Columns.NAME, Book.Columns.NAME);columnMap.put(Book.Columns.AUTHOR, Book.Columns.AUTHOR);columnMap.put(Book.Columns.CREATE_TIME, Book.Columns.CREATE_TIME);}@Overridepublic boolean onCreate() {dbHelper = new DBHelper(getContext());return true;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection,String[] selectionArgs, String sortOrder) {SQLiteQueryBuilder qb = new SQLiteQueryBuilder();switch (uriMatcher.match(uri)) {case COLL_TYPE_URI_MATCHER: {qb.setTables(Book.TABLE_NAME);qb.setProjectionMap(columnMap);break;}case ITEM_TYPE_URI_MATCHER: {qb.setTables(Book.TABLE_NAME);qb.setProjectionMap(columnMap);qb.appendWhere(Book.Columns._ID.concat("=").concat(uri.getPathSegments().get(1)));break;}default: {throw new SQLException("Unknown URI:" + uri);}}String orderBy = null;if (TextUtils.isEmpty(sortOrder)) {orderBy = Book.DEFAULT_ORDER;} else {orderBy = sortOrder;}SQLiteDatabase db = dbHelper.getReadableDatabase();Cursor c = db.query(Book.TABLE_NAME, projection, selection,selectionArgs, null, null, orderBy);// 通知数据库变化c.setNotificationUri(getContext().getContentResolver(), uri);return c;}@Overridepublic String getType(Uri uri) {switch (uriMatcher.match(uri)) {case COLL_TYPE_URI_MATCHER: {return Book.ContentType.COLL_TYPE;}case ITEM_TYPE_URI_MATCHER: {return Book.ContentType.ITEM_TYPE;}default: {throw new SQLException("Unknown URI:" + uri);}}}@Overridepublic Uri insert(Uri uri, ContentValues values) {if (uriMatcher.match(uri) != COLL_TYPE_URI_MATCHER) {throw new SQLException("Unknown URI:" + uri);}Long now = System.currentTimeMillis();if (!values.containsKey(Book.Columns.NAME)) {throw new SQLException(Book.Columns.NAME.concat(" 的值不得为空！"));}if (!values.containsKey(Book.Columns.AUTHOR)) {values.put(Book.Columns.AUTHOR, "Unknown Author");}if (!values.containsKey(Book.Columns.CREATE_TIME)) {values.put(Book.Columns.CREATE_TIME, now);}SQLiteDatabase db = dbHelper.getWritableDatabase();Long rowId = db.insert(Book.TABLE_NAME, Book.Columns.NAME, values);if (rowId > 0) {Uri insertedBookUri = ContentUris.withAppendedId(Book.CONTENT_URI,rowId);getContext().getContentResolver().notifyChange(insertedBookUri,null);return insertedBookUri;}throw new SQLException("添加图书失败，URI：" + uri);}@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {int count = 0;SQLiteDatabase db = dbHelper.getWritableDatabase();switch (uriMatcher.match(uri)) {case COLL_TYPE_URI_MATCHER: {count = db.delete(Book.TABLE_NAME, selection, selectionArgs);break;}case ITEM_TYPE_URI_MATCHER: {selection = Book.Columns._ID.concat("=").concat(uri.getPathSegments().get(1)).concat(TextUtils.isEmpty(selection) ? "" : " AND (".concat(selection).concat(")"));count = db.delete(Book.TABLE_NAME, selection, selectionArgs);break;}default: {throw new SQLException("Unknown URI:" + uri);}}getContext().getContentResolver().notifyChange(uri, null);return count;}@Overridepublic int update(Uri uri, ContentValues values, String selection,String[] selectionArgs) {int count = 0;SQLiteDatabase db = dbHelper.getWritableDatabase();switch (uriMatcher.match(uri)) {case COLL_TYPE_URI_MATCHER: {count = db.update(Book.TABLE_NAME, values, selection, selectionArgs);break;}case ITEM_TYPE_URI_MATCHER: {selection = Book.Columns._ID.concat("=").concat(uri.getPathSegments().get(1)).concat(TextUtils.isEmpty(selection) ? "" : " AND (".concat(selection).concat(")"));count = db.update(Book.TABLE_NAME, values, selection, selectionArgs);break;}default: {throw new SQLException("Unknown URI:" + uri);}}getContext().getContentResolver().notifyChange(uri, null);return count;}}

再把Book代码贴出来：

/** *  * Dec 22, 2014 3:42:39 PM * @Geloin * */package com.geloin.baseopera.provider;import android.net.Uri;import android.provider.BaseColumns;/** *  * Dec 22, 2014 3:42:39 PM *  * @Geloin *  */public class Book {public static final String TABLE_NAME = "books";public static final String DB_FILE_NAME = "books.db";public static final Integer DB_VERSION = 1;public static final String AUTHORITY = "com.geloin.baseopera.provider.BookProvider";public static final String DEFAULT_ORDER = "createTime DESC";public static final Uri CONTENT_URI = Uri.parse("content://".concat(AUTHORITY).concat("/books"));/** * 列名 *  * Dec 22, 2014 3:52:25 PM *  * @Geloin *  */public class Columns implements BaseColumns {public static final String NAME = "name";public static final String AUTHOR = "author";public static final String CREATE_TIME = "createTime";}/** * ContentType *  * Dec 22, 2014 3:53:40 PM *  * @Geloin *  */public class ContentType {/** * 集合 */public static final String COLL_TYPE = "vnd.android.cursor.dir/vnd.androidbook.book";/** * 单项 */public static final String ITEM_TYPE = "vnd.android.cursor.item/vnd.androidbook.book";}}

定义ContentProvider后，必须在AndroidManifest.xml中注册：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.geloin.baseopera"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="17"        android:targetSdkVersion="21" />    <permission        android:name="com.geloin.permission.SayHello"        android:protectionLevel="normal" >    </permission>    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name=".activity.BooksActivity"            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=".provider.BookProvider"            android:authorities="com.geloin.baseopera.provider.BookProvider"            android:exported="false" >        </provider>    </application></manifest>

接下来会讲述如何使用自定义的ContentProvider。