ContentProvider 進程間通訊實例

清單文件中定義

 <provider
      android:name=".BookProvider"
      android:authorities="com.billionstech.sharebitmap.provider"
      android:permission="com.billionstech.sharebitmap.PROVIDER"
      android:process=":provider"
      />

加一個權限對應android:permission

 <uses-permission android:name="com.billionstech.sharebitmap.PROVIDER"/>

public class BookProvider extends ContentProvider{
    private Context mContext;
    DBHelper mDbHelper = null;
    SQLiteDatabase db = null;
    public static final String AUTOHORITY = "com.billionstech.sharebitmap.provider";
    // 設置ContentProvider的唯一標識

    public static final int User_Code = 1;
    public static final int Job_Code = 2;

    // UriMatcher類使用:在ContentProvider 中註冊URI
    private static final UriMatcher mMatcher;
    static{
        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        // 初始化
        mMatcher.addURI(AUTOHORITY,"user", User_Code);
        mMatcher.addURI(AUTOHORITY, "job", Job_Code);
        // 若URI資源路徑 = content://cn.scu.myprovider/user ，則返回註冊碼User_Code
        // 若URI資源路徑 = content://cn.scu.myprovider/job ，則返回註冊碼Job_Code
    }

    // 以下是ContentProvider的6個方法

    /**
     * 初始化ContentProvider
     */
    @Override
    public boolean onCreate() {

        mContext = getContext();
        // 在ContentProvider創建時對數據庫進行初始化
        // 運行在主線程，故不能做耗時操作,此處僅作展示
        mDbHelper = new DBHelper(getContext());
        db = mDbHelper.getWritableDatabase();

        // 初始化兩個表的數據(先清空兩個表,再各加入一個記錄)
        db.execSQL("delete from user");
        db.execSQL("insert into user values(1,'Carson');");
        db.execSQL("insert into user values(2,'Kobe');");

        db.execSQL("delete from job");
        db.execSQL("insert into job values(1,'Android');");
        db.execSQL("insert into job values(2,'iOS');");

        return true;
    }

    /**
     * 添加數據
     */

    @Override
    public Uri insert(Uri uri, ContentValues values) {

        // 根據URI匹配 URI_CODE，從而匹配ContentProvider中相應的表名
        // 該方法在最下面
        String table = getTableName(uri);

        // 向該表添加數據
        db.insert(table, null, values);

        // 當該URI的ContentProvider數據發生變化時，通知外界（即訪問該ContentProvider數據的訪問者）
        mContext.getContentResolver().notifyChange(uri, null);

//        // 通過ContentUris類從URL中獲取ID
//        long personid = ContentUris.parseId(uri);
//        System.out.println(personid);

        return uri;
    }

    /**
     * 查詢數據
     */
    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
                        String[] selectionArgs, String sortOrder) {
        // 根據URI匹配 URI_CODE，從而匹配ContentProvider中相應的表名
        // 該方法在最下面
        String table = getTableName(uri);

//        // 通過ContentUris類從URL中獲取ID
//        long personid = ContentUris.parseId(uri);
//        System.out.println(personid);

        // 查詢數據
        return db.query(table,projection,selection,selectionArgs,null,null,sortOrder,null);
    }

    /**
     * 更新數據
     */
    @Override
    public int update(Uri uri, ContentValues values, String selection,
                      String[] selectionArgs) {
        // 由於不展示,此處不作展開
        return 0;
    }

    /**
     * 刪除數據
     */
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        // 由於不展示,此處不作展開
        return 0;
    }

    @Override
    public String getType(Uri uri) {

        // 由於不展示,此處不作展開
        return null;
    }

    /**
     * 根據URI匹配 URI_CODE，從而匹配ContentProvider中相應的表名
     */
    private String getTableName(Uri uri){
        String tableName = null;
        switch (mMatcher.match(uri)) {
            case User_Code:
                tableName = DBHelper.USER_TABLE_NAME;
                break;
            case Job_Code:
                tableName = DBHelper.JOB_TABLE_NAME;
                break;
        }
        return tableName;
    }
}

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
      
        getImage();
        Uri uri = Uri.parse("content//com.billionstech.sharebitmap.provider");

        // 設置URI
        Uri uri_user = Uri.parse("content://com.billionstech.sharebitmap.provider/user");

        // 插入表中數據
        ContentValues values = new ContentValues();
        values.put("_id", 3);
        values.put("name", "Iverson");


        // 獲取ContentResolver
        ContentResolver resolver =  getContentResolver();
        // 通過ContentResolver 根據URI 向ContentProvider中插入數據
        resolver.insert(uri_user,values);

        // 通過ContentResolver 向ContentProvider中查詢數據
        Cursor cursor = resolver.query(uri_user, new String[]{"_id","name"}, null, null, null);
        while (cursor.moveToNext()){
            System.out.println("query book:" + cursor.getInt(0) +" "+ cursor.getString(1));
            // 將表中數據全部輸出
        }
        cursor.close();
        // 關閉遊標

        /**
         * 對job表進行操作
         */
        // 和上述類似,只是URI需要更改,從而匹配不同的URI CODE,從而找到不同的數據資源
        Uri uri_job = Uri.parse("content://com.billionstech.sharebitmap.provider/job");

        // 插入表中數據
        ContentValues values2 = new ContentValues();
        values2.put("_id", 3);
        values2.put("job", "NBA Player");

        // 獲取ContentResolver
        ContentResolver resolver2 =  getContentResolver();
        // 通過ContentResolver 根據URI 向ContentProvider中插入數據
        resolver2.insert(uri_job,values2);

        // 通過ContentResolver 向ContentProvider中查詢數據
        Cursor cursor2 = resolver2.query(uri_job, new String[]{"_id","job"}, null, null, null);
        while (cursor2.moveToNext()){
            System.out.println("query job:" + cursor2.getInt(0) +" "+ cursor2.getString(1));
            // 將表中數據全部輸出
        }
        cursor2.close();
        // 關閉遊標
   }
   }

03-07 11:05:39.670 8760-8760/com.billionstech.sharebitmap I/System.out: query book:1 Carson
03-07 11:05:39.670 8760-8760/com.billionstech.sharebitmap I/System.out: query book:2 Kobe
03-07 11:05:39.670 8760-8760/com.billionstech.sharebitmap I/System.out: query book:3 Iverson
03-07 11:05:39.682 8760-8760/com.billionstech.sharebitmap I/System.out: query job:1 Android
03-07 11:05:39.682 8760-8760/com.billionstech.sharebitmap I/System.out: query job:2 iOS
03-07 11:05:39.682 8760-8760/com.billionstech.sharebitmap I/System.out: query job:3 NBA Player