ContentProvider学习

1.创建类继承ContentProvider类，并实现增、删、改、查功能。

 

public static final String AUTHORITY = "com.diysoul.listshowdemo.providers.PersonContentProvider";

    public static final int INSERT_CODE = 0;

    public static final int DELETE_CODE = 1;

    public static final int UPDATE_CODE = 2;

    public static final int QUARY_CODE = 3;

    public static final int QUARY_BY_ID_CODE = 4;

    public static final String INSERT = "insert";

    public static final String UPDATE = "update";

    public static final String DELETE = "delete";

    public static final String QUERY = "query";

    /*
     * 根据_id查询 #为通配符，表示一个数字 *为通配符，表示任意一个字符串
     */
    public static final String QUERY_BY_ID = "query/#";

    private PersonSqliteHelper mySqlHelper;

    static UriMatcher uriMatcher;

    static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(AUTHORITY, INSERT, INSERT_CODE);
        uriMatcher.addURI(AUTHORITY, UPDATE, UPDATE_CODE);
        uriMatcher.addURI(AUTHORITY, DELETE, DELETE_CODE);
        uriMatcher.addURI(AUTHORITY, QUERY, QUARY_CODE);
        uriMatcher.addURI(AUTHORITY, QUERY_BY_ID, QUARY_BY_ID_CODE);
    }

    @Override
    public boolean onCreate() {
        mySqlHelper = new PersonSqliteHelper(this.getContext());
        return false;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
            String[] selectionArgs, String sortOrder) {
        switch (uriMatcher.match(uri)) {
        case QUARY_CODE: {
            SQLiteDatabase db = mySqlHelper.getReadableDatabase();
            if (db.isOpen()) {
                Cursor cursor = db.query("persons", projection, selection,
                        selectionArgs, null, null, sortOrder);
                return cursor;
            }
        }
            break;
        case QUARY_BY_ID_CODE: {
            SQLiteDatabase db = mySqlHelper.getReadableDatabase();
            if (db.isOpen()) {
                long id = ContentUris.parseId(uri);
                Cursor cursor = db.query("persons", projection, "_id = ?",
                        new String[] { String.valueOf(id) }, null, null,
                        sortOrder);
                return cursor;
            }
        }
            break;
        default:
            throw new IllegalArgumentException("cannot match uri:" + uri);
        }
        return null;
    }

    @Override
    public String getType(Uri uri) {
        switch(uriMatcher.match(uri)) {
        case QUARY_BY_ID_CODE: 
            return "vnd.android.cursor.item/persons";
        case QUARY_CODE:
            return "vnd.android.cursor.dir/persons";
        default:
            break;
        }
        return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        switch (uriMatcher.match(uri)) {
        case INSERT_CODE:
            SQLiteDatabase db = mySqlHelper.getReadableDatabase();
            if (db.isOpen()) {
                long id = db.insert(PersonSqliteHelper.PERSON_TABLE, null,
                        values);
                db.close();
                return ContentUris.withAppendedId(uri, id);
            }
            break;
        default:
            throw new IllegalArgumentException("cannot match uri:" + uri);
        }
        return null;
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        switch (uriMatcher.match(uri)) {
        case DELETE_CODE:
            SQLiteDatabase db = mySqlHelper.getReadableDatabase();
            if (db.isOpen()) {
                int count = db.delete(PersonSqliteHelper.PERSON_TABLE,
                        selection, selectionArgs);
                db.close();
                return count;
            }
            break;
        default:
            throw new IllegalArgumentException("cannot match uri:" + uri);
        }
        return 0;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection,
            String[] selectionArgs) {
        switch (uriMatcher.match(uri)) {
        case UPDATE_CODE:
            SQLiteDatabase db = mySqlHelper.getReadableDatabase();
            if (db.isOpen()) {
                int count = db.update(PersonSqliteHelper.PERSON_TABLE, values,
                        selection, selectionArgs);
                db.close();
                return count;
            }
            break;
        default:
            throw new IllegalArgumentException("cannot match uri:" + uri);
        }
        return 0;
    }

 

2.在AndroidManifest.xml中进行配置，在application根节点下增加

        <provider
            android:name="com.diysoul.listshowdemo.providers.PersonContentProvider"
            android:authorities="com.diysoul.listshowdemo.providers.PersonContentProvider"
            android:exported="true" >
        </provider>

3.创建应用程序访问功能

public void runQuery() {
        Log.v(TAG, "[runQuery]in");
        Uri uri = Uri.parse("content://com.diysoul.listshowdemo.providers.PersonContentProvider/query");
        ContentResolver resolver = this.getContext().getContentResolver();
        Log.v(TAG, "[runQuery]call query");
        Cursor cursor = resolver.query(uri, new String[]{"_id", "name", "tel"}, null, null, null);
        Log.v(TAG, "[runQuery]cursor=" + cursor);
        if(cursor != null && cursor.getCount() > 0) {
            while(cursor.moveToNext()) {
                int id = cursor.getInt(0);
                String name = cursor.getString(1);
                String tel = cursor.getString(2);
                Log.v(TAG, "id=" + id + ",name=" + name + ",tel=" + tel);
            }
        }
    }

4.监听数据改变

　　　　　ContentObserver smsObserver = new ContentObserver(msmHandler) {

            @Override
            public void onChange(boolean selfChange) {
                Log.v(TAG, "[onChange]in selfChange=" + selfChange);
            }

            @Override
            public void onChange(boolean selfChange, Uri uri) {
                Log.v(TAG, "[onChange]in selfChange=" + selfChange + ", uri=" + uri);
                //重新从查询等操作，以改变保存的数据
                readSms();
                //通知事件适配器数据改变，此时会自动刷新适配器关联 的ListView
                smsListAdapter.notifyDataSetChanged();
            }
        };
        getContentResolver().registerContentObserver(Uri.parse(SMS_CONTENT), true, smsObserver);