IPC机制--使用ContentProvider

来源：互联网发布：淘宝卖家自动核对地址编辑：程序博客网时间：2024/05/01 00:40

ContentProvider 是Android中专门用于不同应用间进行数据共享的方式。

ContentProvider.java

publicclassBookProviderextendsContentProvider{

privatestaticfinalStringTAG="BookProvider";

publicstaticfinalStringAUTHORITY="com.ryg.chapter_2.book.provider";

publicstaticfinalUriBOOK_CONTENT_URI= Uri.parse("content://"

+AUTHORITY+"/book");

publicstaticfinalUriUSER_CONTENT_URI= Uri.parse("content://"

+AUTHORITY+"/user");

publicstaticfinalintBOOK_URI_CODE= 0;

publicstaticfinalintUSER_URI_CODE= 1;

privatestaticfinalUriMatchersUriMatcher=newUriMatcher(

UriMatcher.NO_MATCH);

static{

sUriMatcher.addURI(AUTHORITY,"book",BOOK_URI_CODE);

sUriMatcher.addURI(AUTHORITY,"user",USER_URI_CODE);

}

privateContextmContext;

privateSQLiteDatabasemDb;

@Override

publicbooleanonCreate() {

Log.d(TAG,"onCreate, current thread:"

+ Thread.currentThread().getName());

mContext= getContext();

//ContentProvider创建的时候，初始化数据库。注意这里仅仅是为了演示，实际使用中不推荐在主线程中进行耗时

//的数据库操作。

initProviderData();

returntrue;

}

privatevoidinitProviderData() {

mDb=newDbOpenHelper(mContext).getWritableDatabase();

mDb.execSQL("delete from "+ DbOpenHelper.BOOK_TABLE_NAME);

mDb.execSQL("delete from "+ DbOpenHelper.USER_TALBE_NAME);

mDb.execSQL("insert into book values(3,'Android');");

mDb.execSQL("insert into book values(4,'Ios');");

mDb.execSQL("insert into book values(5,'Html5');");

mDb.execSQL("insert into user values(1,'jake',1);");

mDb.execSQL("insert into user values(2,'jasmine',0);");

}

@Override

publicCursorquery(Uri uri, String[] projection, String selection,

String[] selectionArgs, String sortOrder) {

Log.d(TAG,"query, current thread:"+ Thread.currentThread().getName());

String table = getTableName(uri);

if(table ==null) {

thrownewIllegalArgumentException("Unsupported URI: "+ uri);

}

returnmDb.query(table, projection, selection, selectionArgs,null,

null, sortOrder,null);

}

@Override

publicStringgetType(Uri uri) {

Log.d(TAG,"getType");

returnnull;

}

@Override

publicUriinsert(Uri uri, ContentValues values) {

Log.d(TAG,"insert");

String table = getTableName(uri);

if(table ==null) {

thrownewIllegalArgumentException("Unsupported URI: "+ uri);

}

mDb.insert(table,null, values);

mContext.getContentResolver().notifyChange(uri,null);

returnuri;

}

@Override

publicintdelete(Uri uri, String selection, String[] selectionArgs) {

Log.d(TAG,"delete");

String table = getTableName(uri);

if(table ==null) {

thrownewIllegalArgumentException("Unsupported URI: "+ uri);

}

intcount =mDb.delete(table, selection, selectionArgs);

if(count > 0) {

getContext().getContentResolver().notifyChange(uri,null);

}

returncount;

}

@Override

publicintupdate(Uri uri, ContentValues values, String selection,

String[] selectionArgs) {

Log.d(TAG,"update");

String table = getTableName(uri);

if(table ==null) {

thrownewIllegalArgumentException("Unsupported URI: "+ uri);

}

introw =mDb.update(table, values, selection, selectionArgs);

if(row > 0) {

getContext().getContentResolver().notifyChange(uri,null);

}

returnrow;

}

privateString getTableName(Uri uri) {

String tableName =null;

switch(sUriMatcher.match(uri)) {

caseBOOK_URI_CODE:

tableName = DbOpenHelper.BOOK_TABLE_NAME;

break;

caseUSER_URI_CODE:

tableName = DbOpenHelper.USER_TALBE_NAME;

break;

default:

break;

}

returntableName;

}

其中 android:authorities 是ContentProvider的唯一标识，通过这个属性外部应用就可以访问我们的BookProvider。因此他必须是唯一的。

android:permission="com.ryg.PROVIDER" 为此BookProvider 添加访问权限，如果要想访问，就必须声明此权限。

<provider

android:name=".provider.BookProvider"

android:authorities="com.ryg.chapter_2.book.provider"

android:permission="com.ryg.PROVIDER"

android:process=":provider">

</provider>

ProviderActivity.java

onCreate 运行在main线程中，也就是UI线程，所以我们不能再onCreate中做耗时操作。

增删改查运行在Binder线程中

publicclassProviderActivityextendsActivity {

privatestaticfinalStringTAG="ProviderActivity";

@Override

protectedvoidonCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_provider);

//Uri uri= Uri.parse("content://com.ryg.chapter_2.book.provider");

// getContentResolver().query(uri, null, null, null, null);

Uri bookUri = Uri.parse("content://com.ryg.chapter_2.book.provider/book");

ContentValues values =newContentValues();

values.put("_id", 6);

values.put("name","程序设计的艺术");

getContentResolver().insert(bookUri, values);

Cursor bookCursor = getContentResolver().query(bookUri,newString[]{"_id","name"},null,null,null);

while(bookCursor.moveToNext()) {

Book book =newBook();

book.bookId= bookCursor.getInt(0);

book.bookName= bookCursor.getString(1);

Log.d(TAG,"query book:"+ book.toString());

}

bookCursor.close();

Uri userUri = Uri.parse("content://com.ryg.chapter_2.book.provider/user");

Cursor userCursor = getContentResolver().query(userUri,newString[]{"_id","name","sex"},null,null,null);

while(userCursor.moveToNext()) {

User user =newUser();

user.userId= userCursor.getInt(0);

user.userName= userCursor.getString(1);

user.isMale= userCursor.getInt(2) == 1;

Log.d(TAG,"query user:"+ user.toString());

}

userCursor.close();

}

SQLiteOpenHelper 数据库

publicclassDbOpenHelperextendsSQLiteOpenHelper{

privatestaticfinalStringDB_NAME="book_provider.db";

publicstaticfinalStringBOOK_TABLE_NAME="book";

publicstaticfinalStringUSER_TALBE_NAME="user";

privatestaticfinalintDB_VERSION= 3;

privateStringCREATE_BOOK_TABLE="CREATE TABLE IF NOT EXISTS "

+BOOK_TABLE_NAME+"(_id INTEGER PRIMARY KEY,"+"name TEXT)";

privateStringCREATE_USER_TABLE="CREATE TABLE IF NOT EXISTS "

+USER_TALBE_NAME+"(_id INTEGER PRIMARY KEY,"+"name TEXT,"

+"sex INT)";

publicDbOpenHelper(Context context) {

super(context,DB_NAME,null,DB_VERSION);

}

@Override

publicvoidonCreate(SQLiteDatabase db) {

db.execSQL(CREATE_BOOK_TABLE);

db.execSQL(CREATE_USER_TABLE);

}

@Override

publicvoidonUpgrade(SQLiteDatabase db,intoldVersion,intnewVersion) {

//TODOignored

}

0 0