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文章目录

• 一、配置依赖

  plugins {
      id 'kotlin-kapt'
  }
  
  android {
      compileOptions {
          sourceCompatibility JavaVersion.VERSION_17
          targetCompatibility JavaVersion.VERSION_17
      }
      kotlinOptions {
          jvmTarget = '17'
      }
  }
  
  dependencies {
      implementation("androidx.room:room-runtime:2.4.2")
      kapt("androidx.room:room-compiler:2.4.2")
  }

• 二、标记实体类

  @Entity(tableName = "banner")
  data class Banner(
      val desc: String,
      @PrimaryKey
      val id: Int,
      val imagePath: String,
      val isVisible: Int,
      val order: Int,
      val title: String,
      val type: Int,
      val url: String
  )

• 三、封装工具类

  object RoomUtil {
      @Volatile
      private var mDataBase: MyDataBase? = null
  
      fun getInstance(context: Context): MyDataBase {
          if (mDataBase == null) {
              synchronized(this) {
                  if (mDataBase == null) {
                      mDataBase = Room.databaseBuilder(context, MyDataBase::class.java, "my_database")
                          .allowMainThreadQueries()
                          .build()
                  }
              }
          }
          return mDataBase!!
      }
  
      @Database(entities = [Banner::class], version = 1)
      abstract class MyDataBase : RoomDatabase() {
          abstract fun bannerDao(): BannerDao
      }
  
      @Dao
      interface BannerDao {
          @Query("SELECT * FROM banner")
          fun getBanners(): List<Banner>
  
          @Query("SELECT * FROM banner WHERE id = :userId")
          fun getBannerById(userId: Int): Banner?
  
          @Insert(onConflict = OnConflictStrategy.REPLACE) //重复时则会替换
          fun insert(user: Banner)
  
          @Delete
          fun delete(user: Banner)
  
          @Update
          fun update(user: Banner)
      }
  }

• 四、使用

  data.forEach {
       RoomUtil.getInstance(this@WelcomeActivity).bannerDao().insert(it)
   }
  
  val banner = RoomUtil.getInstance(this@WelcomeActivity).bannerDao().getBanners()[0]
  
  RoomUtil.getInstance(this@WelcomeActivity).bannerDao().delete(banner)
  RoomUtil.getInstance(this@WelcomeActivity).bannerDao().getBanners()
  RoomUtil.getInstance(this@WelcomeActivity).bannerDao().getBannerById(banner.id)