Android Content provider

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Android Content provider

当应用需要通过Content Provider共享数据时，首先需要继承Content Provider类并重写相应方法。第二步需要在AndroidManifest.xml使用<provider>对Content Provider进行配置。

1. 新建内容提供类：

public class PersonProvider extends ContentProvider {    private DBOpenHelper dbHelper;    private static final UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH);    private static final int PERSONS = 1;    private static final int PERSON = 2;    static {        MATCHER.addURI("com.example.providers.personprovider", "person", PERSONS);        MATCHER.addURI("com.example.providers.personprovider", "person/#", PERSON);    }    @Override    public int delete(Uri uri, String selection, String[] selectionArgs) {        SQLiteDatabase db = dbHelper.getWritableDatabase();        int count = 0;        switch (MATCHER.match(uri)) {        case PERSONS:            count = db.delete("person", selection, selectionArgs);            return count;        case PERSON:            long id = ContentUris.parseId(uri);            String where = "personid=" + id;            if(selection!=null && !"".equals(selection)) {                where = selection + " and " + where;            }            count = db.delete("person", where, selectionArgs);            return count;        default:            throw new IllegalArgumentException("Unknown Uri: " + uri.toString());        }    }    @Override    public String getType(Uri uri) { //返回当前操作的数据的内容类型        switch (MATCHER.match(uri)) {        case PERSONS:            return "vnd.android.cursor.dir/person";        case PERSON:            return "vnd.android.cursor.item/person";        default:            throw new IllegalArgumentException("Unknown Uri: " + uri.toString());        }    }    @Override    public Uri insert(Uri uri, ContentValues values) {        // TODO Auto-generated method stub        SQLiteDatabase db = dbHelper.getWritableDatabase();        switch(MATCHER.match(uri)) {            case PERSONS :                long rowid = db.insert("person", "null", values);                Uri insertUri = ContentUris.withAppendedId(uri, rowid);                this.getContext().getContentResolver().notifyChange(uri, null);                return insertUri;            default:                throw new IllegalArgumentException("Unknown Uri: " + uri.toString());        }    }    @Override    public boolean onCreate() {        this.dbHelper = new DBOpenHelper(this.getContext());        return false;    }    @Override    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,            String sortOrder) {        SQLiteDatabase db = dbHelper.getReadableDatabase();        switch (MATCHER.match(uri)) {        case PERSONS:            return db.query("person", projection, selection, selectionArgs, null, null, sortOrder);        case PERSON:            long id = ContentUris.parseId(uri);            String where = "personid=" + id;            if(selection!=null && !"".equals(selection)) {                where = selection + " and " + where;            }            return db.query("person", projection, where, selectionArgs, null, null, sortOrder);        default:            throw new IllegalArgumentException("Unknown Uri: " + uri.toString());        }    }    @Override    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {        SQLiteDatabase db = dbHelper.getWritableDatabase();        int count = 0;        switch (MATCHER.match(uri)) {        case PERSONS:            count = db.update("person", values, selection, selectionArgs);            return count;        case PERSON:            long id = ContentUris.parseId(uri);            String where = "personid=" + id;            if(selection!=null && !"".equals(selection)) {                where = selection + " and " + where;            }            count = db.update("person", values, where, selectionArgs);            return count;        default:            throw new IllegalArgumentException("Unknown Uri: " + uri.toString());        }    }}

2. 配置Content Provider：

<!--name为Content Provider类名，路径authorities为自定义--><provider android:name=".PersonProvider" android:authorities="com.example.providers.personprovider"/>

3. 新建测试类进行测试：

public class AccessContentProvider extends AndroidTestCase {    public void testInsert() throws Exception {        ContentResolver contentResolver = this.getContext().getContentResolver();        Uri insertUri = Uri.parse("content://com.example.providers.personprovider/person");        ContentValues values = new ContentValues();        values.put("name", "Jospehus");        values.put("amount", 1000);        Uri uri = contentResolver.insert(insertUri, values);        Log.i("URI", uri.toString());    }    public void testUpdate() throws Exception {        ContentResolver contentResolver = this.getContext().getContentResolver();        Uri updateUri = Uri.parse("content://com.example.providers.personprovider/person/8");        ContentValues values = new ContentValues();        values.put("name", "monkey");        contentResolver.update(updateUri, values, null, null);    }    public void testQuery() throws Exception {        ContentResolver contentResolver = this.getContext().getContentResolver();        Uri selectUri = Uri.parse("content://com.example.providers.personprovider/person");        Cursor cursor = contentResolver.query(selectUri, null, null, null, "personid desc");        while(cursor.moveToNext()) {            int id = cursor.getInt(cursor.getColumnIndex("personid"));            String name = cursor.getString(cursor.getColumnIndex("name"));            int amount = cursor.getInt(cursor.getColumnIndex("amount"));            Log.i("QUERY", "id=" + id + "name=" + name + "amount=" + amount);        }    }    public void testDelete() throws Exception {        ContentResolver contentResolver = this.getContext().getContentResolver();        Uri deleteUri = Uri.parse("content://com.example.providers.personprovider/person/8");        contentResolver.delete(deleteUri, null, null);    }}

4. 监听Content Provider中数据的变化

public class OtherActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        ContentResolver contentResolver = this.getContentResolver();        Uri insertUri = Uri.parse("content://com.example.providers.personprovider/person");        contentResolver.registerContentObserver(                insertUri, true, new PersonObserver(new Handler()));        /*ContentValues values = new ContentValues();        values.put("name", "Jospehus");        values.put("amount", 1000);        Uri uri = contentResolver.insert(insertUri, values);        Log.i("URI", uri.toString());*/    }    private final class PersonObserver extends ContentObserver {        public PersonObserver(Handler handler) {            super(handler);            // TODO Auto-generated constructor stub        }        @Override        public void onChange(boolean selfChange) {            ContentResolver contentResolver = OtherActivity.this.getContentResolver();            Uri selectUri = Uri.parse("content://com.example.providers.personprovider/person");            Cursor cursor = contentResolver.query(selectUri, null, null, null, "personid desc");            while(cursor.moveToNext()) {                int id = cursor.getInt(cursor.getColumnIndex("personid"));                String name = cursor.getString(cursor.getColumnIndex("name"));                int amount = cursor.getInt(cursor.getColumnIndex("amount"));                Log.i("QUERY", "id=" + id + "name=" + name + "amount=" + amount);            }        }    }}

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