从普通函数异步返回值

编程问答 2022-11-13

问题描述

我正在使用Bukkit API开发minecraft插件。我使用的侦听器要求从数据库中（异步）检索数据，然后检查该数据并执行其他操作。

异步访问任何Bukkit API方法不是一个好主意。

我的活动看起来像这样

class ClickSignEvent(private val plugin: ExpBankPlugin,private val connection: Connection): Listener {
    @EventHandler(ignoreCancelled = true)
    fun onClickSign(event: PlayerInteractEvent) {
        // get a few things sync like their UUID
        val results = getAmount(uuid,world,clickedBlock) // this needs to be accessed async
        // do a few things sync based on the results val
    }

    private suspend fun getAmount(uuid: UUID,world: String,clickedBlock: Block): ResultSet? {
        return withContext(dispatchers.IO) {
            return@withContext try {
                val query = "SELECT amount,rowid FROM expbank_expbanks WHERE uuid=? and world=? and x=? and y=? and z=?"
                val preparedStatement = connection.prepareStatement(query)
                preparedStatement.setString(1,uuid.toString())
                preparedStatement.setString(2,world)
                preparedStatement.setInt(3,clickedBlock.x)
                preparedStatement.setInt(4,clickedBlock.y)
                preparedStatement.setInt(5,clickedBlock.z)
                preparedStatement.executeQuery()
            } catch (e: sqlException) {
                e.printstacktrace()
                null
            }
        }

    }

这是我的数据库类：

class ExpDataSource {
    private var ds: HikariDataSource
    val connection: Connection
        get() = ds.connection
    init {
        Class.forName("com.MysqL.cj.jdbc.Driver").getDeclaredConstructor().newInstance()
        val config = HikariConfig()
        config.jdbcUrl = "jdbc:MysqL://ip:3306/u1770_db?useJDBCCompliantTimezoneshift=true&useLegacyDatetimeCode=false&serverTimezone=UTC"
        config.username = "u1770"
        config.password = "password"
        config.driverClassName = "com.drugpvp.expbank.shadow.MysqL.cj.jdbc.Driver"
        config.addDataSourceProperty("cachePrepStmts","true")
        config.addDataSourceProperty("prepStmtCacheSize","256")
        config.addDataSourceProperty("prepStmtCachesqlLimit","2048")
        config.addDataSourceProperty("maximumPoolSize","10")
        config.addDataSourceProperty("minimumIdle","2")
        ds = HikariDataSource(config)
    }

    fun createTable() {
        val statement = connection.createStatement()
        val query = "CREATE TABLE IF NOT EXISTS expbank_expbanks (rowid INTEGER AUTO_INCREMENT PRIMARY KEY,uuid VARCHAR(36),world TEXT,amount INTEGER,X INTEGER,Y INTEGER,Z INTEGER)"
        statement.executeUpdate(query)
    }
}

我想不出要做什么以使某些事情同步，等待结果异步，然后基于此做一些同步事情-而不会阻塞主线程。在getAmount()上说“仅应从协程或其他暂停函数调用暂停函数'getAmount'”

解决方法

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bukkitkotlinkotlinkotlin-coroutinesminecraft