Room数据库

Room数据库

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1.Room使用

Step1：Gradle文件的dependencies中添加以下代码

//room数据库
compile "android.arch.persistence.room:runtime:1.1.0-beta2"                     
annotationProcessor "android.arch.persistence.room:compiler:1.1.0-beta2"
//rxjava2对room支持
compile "android.arch.persistence.room:rxjava2:1.1.0-beta2"                     

Step2：创建实体类文件,比如UserModel.java

import android.arch.persistence.room.ColumnInfo;
import android.arch.persistence.room.Entity;
import android.arch.persistence.room.Ignore;
import android.arch.persistence.room.PrimaryKey;
import android.support.annotation.NonNull;

@Entity(tableName = "user_table")       //数据表名字user_table
public class UserModel {

    @PrimaryKey(autoGenerate = false)   //主键，自动增长=false
    @ColumnInfo(name = "user_id")       //userId数据表字段为user_id
    @NonNull                            //主键设置为非空
    private String userId;              //用户id

    @ColumnInfo(name = "user_name")     //userName数据表字段为user_name，默认允许空值
    private String userName;            //用户名(公司或个人姓名)

    @ColumnInfo(name = "user_pet_name")
    private String userPetName;         //用户呢称(系统生成，之后可以修改)

    @ColumnInfo(name = "user_phone")
    private String userPhone;           //用户电话

    @ColumnInfo(name = "user_icon")
    private String userIcon;            //用户头像

    @ColumnInfo(name = "vip_type")
    private int vipType;                //用户vip类型

    @ColumnInfo(name = "create_time")
    private long createTime;            //用户注册时间

    @ColumnInfo(name = "sex")
    private int sex;                    //用户性别 1-->男 2-->女

    @ColumnInfo(name = "integral")
    private double integral;            //积分

    @ColumnInfo(name = "id_card_number")
    private String idCardNumber;        //身份证号

    @ColumnInfo(name = "email")
    private String email;               //用户邮箱

    @ColumnInfo(name = "status")
    private int status;                 //用户状态 0-->禁用  1-->正常

    public UserModel() {                //Room调用的构造函数

    }

    @Ignore                             //有2个构造函数，让Room忽略掉这个，使用上面一个构造函数
    public UserModel(String userIcon, String userName) {
        this.userIcon = userIcon;
        this.userName = userName;
    }

    @Override
    public String toString() {
        return "UserModel{" +
                "userId='" + userId + '\'' +
                ", userName='" + userName + '\'' +
                ", userPetName='" + userPetName + '\'' +
                ", userPhone='" + userPhone + '\'' +
                ", userIcon='" + userIcon + '\'' +
                ", vipType=" + vipType +
                ", createTime=" + createTime +
                ", sex=" + sex +
                ", integral=" + integral +
                ", idCardNumber='" + idCardNumber + '\'' +
                ", email='" + email + '\'' +
                ", status=" + status +
                '}';
    }

    //=================================================================
    //  以为字段设置成private，提供get\set方法给room使用
    //=================================================================
    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserPetName() {
        return userPetName;
    }

    public void setUserPetName(String userPetName) {
        this.userPetName = userPetName;
    }

    public String getUserPhone() {
        return userPhone;
    }

    public void setUserPhone(String userPhone) {
        this.userPhone = userPhone;
    }

    public String getUserIcon() {
        return userIcon;
    }

    public void setUserIcon(String userIcon) {
        this.userIcon = userIcon;
    }

    public int getVipType() {
        return vipType;
    }

    public void setVipType(int vipType) {
        this.vipType = vipType;
    }

    public long getCreateTime() {
        return createTime;
    }

    public void setCreateTime(long createTime) {
        this.createTime = createTime;
    }

    public int getSex() {
        return sex;
    }

    public String getSexString() {
        return getSex() == 1 ? Util.getString(R.string.man) : Util.getString(R.string.woman);
    }

    public void setSex(int sex) {
        this.sex = sex;
    }

    public double getIntegral() {
        return integral;
    }

    public void setIntegral(double integral) {
        this.integral = integral;
    }

    public String getIdCardNumber() {
        return idCardNumber;
    }

    public void setIdCardNumber(String idCardNumber) {
        this.idCardNumber = idCardNumber;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }
}

Step3：创建Dao层

import android.arch.persistence.room.Dao;
import android.arch.persistence.room.Delete;
import android.arch.persistence.room.Insert;
import android.arch.persistence.room.OnConflictStrategy;
import android.arch.persistence.room.Query;

import io.reactivex.Flowable;

//Dao层用@Dao标识
@Dao    
public interface UserModelDao {

    //查询语句
    @Query("SELECT * FROM user_table WHERE user_id = :id")
    Flowable<UserModel> getUserModel(String id);

    //插入，onConflict = OnConflictStrategy.REPLACE表示插入有冲突时候替代
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    void insert(UserModel userModel);

    @Delete
    void delete(UserModel userModel);
}

Step4：创建提供Dao层的抽象类，继承RoomDatabase

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

//创建一个抽象类。用@Database标识，表示是RoomDatabase
//entities = {UserModel.class}，表示数据库存储的实体类有UserModel
//version = 1，表示数据库版本号为1
@Database(entities = {UserModel.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {

    //抽象方法，提供UserModelDao
    public abstract UserModelDao getUserModelDao();

    //单例
    private static volatile AppDatabase instance;

    //获取单例
    public static AppDatabase getInstance() {
        if (instance == null) {
            synchronized (AppDatabase.class) {
                if (instance == null) {
                    //Room为我们实现抽象类
                    instance = Room.databaseBuilder(Util.getApplication(),
                            AppDatabase.class,
                            Constant.DATABASE_NAME).build();
                }
            }
        }
        return instance;
    }
}

Step5：使用

AppDatabase.getInstance()
                .getUserModelDao()
                .insert(userModel);

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常见问题

• 无法import RoomDatabase
  • 因为RoomDatabase需要com.android.support在26.0.1之后
  • 项目中com.android.support修改为26.0.1之后就可以了