Android 架構 -- Room

摘要： room // add for room implementation "android.arch.persistence.room:runtime:1.1.1" // room 配合 RxJava implementation "android.arch.pers...

room

// add for room
implementation "android.arch.persistence.room:runtime:1.1.1"
// room 配合 RxJava
implementation "android.arch.persistence.room:rxjava2:1.1.1"
annotationProcessor 'android.arch.persistence.room:compiler:1.1.1'

// RxJava
implementation 'io.reactivex.rxjava2:rxandroid:2.0.1'
implementation 'io.reactivex.rxjava2:rxjava:2.1.3'

model物件：

import android.arch.persistence.room.Entity;
import android.arch.persistence.room.PrimaryKey;

@Entity
public class User {
// 用 @ColumnInfo 來標明資料庫表的列名， 用 @PrimaryKey 來標示 主鍵
@PrimaryKey(autoGenerate = true)
private longuid;
private Stringname;
private Stringaddress;
private Stringphone;
private Integer age;

public long getUid() {
return uid;
}

public void setUid(long uid) {
this.uid = uid;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getAddress() {
return address;
}

public void setAddress(String address) {
this.address = address;
}

public String getPhone() {
return phone;
}

public void setPhone(String phone) {
this.phone = phone;
}

public Integer getAge() {
return age;
}

public void setAge(Integer age) {
this.age = age;
}

@Override
public String toString() {
return "User{" + "uid=" + uid + ", name='" + name + '\'' + ", address='" + address + '\'' + ", phone='" + phone + '\'' + ", age=" +
age + '}';
}
}

相對應的DAO類：

import android.arch.persistence.room.Dao;
import android.arch.persistence.room.Insert;
import android.arch.persistence.room.OnConflictStrategy;
import android.arch.persistence.room.Query;
import java.util.List;

import io.reactivex.Flowable;

@Dao
public interface UserDao {

@Insert(onConflict = OnConflictStrategy.REPLACE)
List<Long> insert(User... users);

@Query("SELECT * from user")
Flowable<List<User>> loadUser();

@Delete
void delete(User user);
}

當準備好所有的 Model 和 DAO 後，我們就需要把它放入 DataBase 的管理中:

package com.soyoungboy.room.database;

import android.arch.persistence.room.Database;
import android.arch.persistence.room.RoomDatabase;
import android.arch.persistence.room.TypeConverters;

import com.soyoungboy.room.database.daos.BookDao;
import com.soyoungboy.room.database.daos.UserDao;
import com.soyoungboy.room.database.entities.Book;
import com.soyoungboy.room.database.entities.User;


@Database(entities = {User.class, Book.class}, version = 3)
@TypeConverters({Converters.class})
public abstract class AppDatabase extends RoomDatabase {

public abstract UserDao userDao();

public abstract BookDao bookDao();

}

Converters.java為時間轉換的類：

public class Converters {

@TypeConverter
public static Date fromTimestamp(Long value) {
return value == null ? null : new Date(value);
}

@TypeConverter
public static Long dateToTimestamp(Date date) {
return date == null ? null : date.getTime();
}
}

Room資料庫資料庫升級：

import android.app.Application;
import android.arch.persistence.db.SupportSQLiteDatabase;
import android.arch.persistence.room.Room;
import android.arch.persistence.room.migration.Migration;

public class AppApplication extends Application {

private AppDatabase mAppDatabase;

@Override
public void onCreate() {
super.onCreate();
mAppDatabase = Room.databaseBuilder(getApplicationContext(), AppDatabase.class, "android_room_dev.db")
.allowMainThreadQueries()
.addMigrations(MIGRATION_1_2, MIGRATION_2_3)
.build();
}

public AppDatabase getAppDatabase() {
return mAppDatabase;
}

/**
* 資料庫版本 1->2 user表格新增了age列
*/
static final Migration MIGRATION_1_2 = new Migration(1, 2) {
@Override
public void migrate(SupportSQLiteDatabase database) {
database.execSQL("ALTER TABLE User ADD COLUMN age integer");
}
};

/**
* 資料庫版本 2->3 新增book表格
*/
static final Migration MIGRATION_2_3 = new Migration(2, 3) {
@Override
public void migrate(SupportSQLiteDatabase database) {
database.execSQL(
"CREATE TABLE IF NOT EXISTS `book` (`uid` INTEGER PRIMARY KEY autoincrement, `name` TEXT , `userId` INTEGER, 'time' INTEGER)");
}
};
}

操作資料庫：

1,首先獲取AppDatabase物件：

AppDatabase mAppDatabase = ((AppApplication)getApplication()).getAppDatabase();

2,新增操作：

User user = new User();
user.setPhone("18320770932");
user.setAddress("深圳");
user.setName("soyoungboy");
//user.setAge("28");
List<Long> ids = mAppDatabase.userDao().insert(user);

3,查詢操作：

mAppDatabase.userDao()
.loadUser()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<List<User>>() {
@Override
public void accept(List<User> entities) {
if (entities != null) {
for (User user : entities) {
Log.d("soyoungboy", user.toString());
}
}

}
});

4,刪除操作：

findViewById(R.id.button_delete_user).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
User user = new User();
user.setPhone("18320770932");
user.setAddress("深圳");
user.setName("soyoungboy");
user.setUid(5);
UserDao userDao = mAppDatabase.userDao();
userDao.delete(user);
}
});