RxAndroid之操作数据库SqlBrite（RXAndroid实现数据库的增、删、改、查）

一、查询

1.创建SqlBrite

SqlBrite sqlBrite = SqlBrite.create();

2.将SQLiteOpenHelper的一个实例和一个Scheduler作为参数创建BriteDatabase,正确地传入Scheduler可以防止线程被阻塞

BriteDatabase db = sqlBrite.wrapDatabaseHelper(openHelper, Schedulers.io());

3.通过BriteDatabase.createQuery方法来进行查询，它需要两个参数，一个是所要查询的表，一个是sql语句，这个方法与SQLiteDatabase.rawQuery类似Observable<Query> users = db.createQuery("users", "SELECT * FROM users");

4.通过返回的Observable来进行订阅，并通过query.run()方法获取数据

users.subscribe(new Action1<Query>() {  @Override public void call(Query query) {    Cursor cursor = query.run();    // TODO parse data...  }});

二、增加、删除、更新表后所有订阅的数据都会马上进行更新

所有的增、删、改、查操作都必须通过对象BriteDatabase来正确地通知订阅者

final AtomicInteger queries = new AtomicInteger();users.subscribe(new Action1<Query>() {  @Override public void call(Query query) {    queries.getAndIncrement();  }});System.out.println("Queries: " + queries.get()); // Prints 1db.insert("users", createUser("jw", "Jake Wharton"));db.insert("users", createUser("mattp", "Matt Precious"));db.insert("users", createUser("strong", "Alec Strong"));System.out.println("Queries: " + queries.get()); // Prints 4

三、Unsubscribe from the returned Subscription to stop getting updates.

Unsubscribe from the returned Subscription to stop getting updates.

final AtomicInteger queries = new AtomicInteger();Subscription s = users.subscribe(new Action1<Query>() {  @Override public void call(Query query) {    queries.getAndIncrement();  }});System.out.println("Queries: " + queries.get()); // Prints 1db.insert("users", createUser("jw", "Jake Wharton"));db.insert("users", createUser("mattp", "Matt Precious"));s.unsubscribe();db.insert("users", createUser("strong", "Alec Strong"));System.out.println("Queries: " + queries.get()); // Prints 3

四、数据改变较大时使用transactions

final AtomicInteger queries = new AtomicInteger();users.subscribe(new Action1<Query>() {  @Override public void call(Query query) {    queries.getAndIncrement();  }});System.out.println("Queries: " + queries.get()); // Prints 1Transaction transaction = db.newTransaction();try {  db.insert("users", createUser("jw", "Jake Wharton"));  db.insert("users", createUser("mattp", "Matt Precious"));  db.insert("users", createUser("strong", "Alec Strong"));  transaction.markSuccessful();} finally {  transaction.end();}System.out.println("Queries: " + queries.get()); // Prints 2

五、使用操作符

queries只是普通的RxJava 的Observable对象，所有的操作符都可以用来控制所要发给订阅者的数据

users.debounce(500, MILLISECONDS).subscribe(new Action1<Query>() {  @Override public void call(Query query) {    // TODO...  }});

六、监测从其它app查询的数据

BriteContentResolver resolver = sqlBrite.wrapContentProvider(contentResolver, Schedulers.io());Observable<Query> query = resolver.createQuery(/*...*/);

创建数据库和表的类：

public class RxDatabaseHelper extends SQLiteOpenHelper{    private String TAG = "RX";    private  Context context;    private static RxDatabaseHelper rxDatabaseHelper = null;    private RxDatabaseHelper(Context context) {        super(context, "rxdb.sqlite", null, 1);                         //创建数据库rxdb.sqlite        this.context = context;    }    public static RxDatabaseHelper getInstance(Context context){        if(rxDatabaseHelper == null){            synchronized (RxDatabaseHelper.class){                if(rxDatabaseHelper == null){                    rxDatabaseHelper = new RxDatabaseHelper(context);                }            }        }        return rxDatabaseHelper;    }    @Override    public void onCreate(SQLiteDatabase db) {        //创建表rx_db_test,表中的字段：_id,name,gender,age        db.execSQL("create table if not exists rx_db_test (_id integer primary key,name text, gender text, age long)");    }    @Override    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {    }

测试增删改查的类：

public class RxDatabaseActivity extends Activity{    private String TAG = "RX";    private RxDatabaseHelper rxDatabaseHelper;    private SQLiteOpenHelper sqLiteOpenHelper;    private SQLiteDatabase sqLiteDatabase;    private BriteDatabase briteDatabase;    private SqlBrite sqlBrite;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.rx_widget_layout);        sqLiteOpenHelper = RxDatabaseHelper.getInstance(getApplicationContext());        sqLiteDatabase = sqLiteOpenHelper.getWritableDatabase();        sqlBrite = SqlBrite.create();        briteDatabase = sqlBrite.wrapDatabaseHelper(sqLiteOpenHelper,Schedulers.io());//        testInser();                      //增//        testDelete();                     //删//        testUpdate();                     //改        testQuery();                       //查    }    //查询数据    private void testQuery() {        Observable<SqlBrite.Query> rxDbTest = briteDatabase.createQuery("rx_db_test", "SELECT * FROM rx_db_test");        rxDbTest.subscribe(new Action1<SqlBrite.Query>() {            @Override            public void call(SqlBrite.Query query) {                Cursor cursor = query.run();                while (cursor.moveToNext()){                    Log.e(TAG,"["+cursor.getString(cursor.getColumnIndex("name"))+","+cursor.getString(cursor.getColumnIndex("gender"))+","                    +cursor.getLong(cursor.getColumnIndex("age"))+"]");                }            }        });    }    //修改数据    private void testUpdate() {        ContentValues contentValues = new ContentValues();        contentValues.put("age",10);        //将姓名为zhangsan19的人的年龄改为10        briteDatabase.update("rx_db_test",contentValues,"name=?","zhangsan19");    }    //删除数据    private void testDelete() {        //删除age=10的那条数据        //第一个参数是表名，第二个参数是所要匹配的字段的名字，第三个参数是所要匹配的字段值        briteDatabase.delete("rx_db_test","age=?","10");    }    //添加数据    private void testInser() {        ContentValues contentValues = new ContentValues();        //第一个参数是表名，第二个参数是所要添加的数据的键值对//        db.execSQL("create table if not exists rx_db_test (_id integer primary key,name text, gender text, age long)");       for(int i=1;i<20;i++){           contentValues.put("name","zhangsan"+i);           if(i%2 == 0) {               contentValues.put("gender", "女");           }else{               contentValues.put("gender", "男");           }           contentValues.put("age", i);           briteDatabase.insert("rx_db_test", contentValues);       }    }}

增加数据运行结果：

删除数据运行结果（将age=10的那条数据删除了）：

修改数据后运行的结果（将姓名为zhangsan19的人的年龄改为10):

查询运行的结果：

注：1.需要在build.gradle中添加compile 'com.squareup.sqlbrite:sqlbrite:0.7.0'

2.参考资料：https://github.com/ReactiveX/RxAndroid/wiki#removed

     https://github.com/square/sqlbrite