Druid+Sqlite-JDBC+Kotlin,封装的一个都是毛病的工具类，奆佬们，评论区教一下我怎么封装

Druid+JDBC工具类
我只是一个新手，也不怎么会kotlin但是我看教程都很少，讲SQLite-JDBC结合Druid或者说怎么写Durid的配置文件，

我先放工具类

import com.alibaba.druid.pool.DruidDataSourceFactory
import java.io.FileInputStream
import java.io.InputStream
import java.lang.reflect.Constructor
import java.lang.reflect.Field
import java.sql.*
import java.util.*
import javax.sql.DataSourceclass JdbcUtil {//数据源连接池对象private var dataSource: DataSource? = null//ThreadLocal 对象private var threadLocal: ThreadLocal<Connection>? = nullprivate constructor() {try {val inputStream: InputStream = FileInputStream("db.properties")val prop: Properties = Properties()prop.load(inputStream)//使用Druid连接池方式dataSource = DruidDataSourceFactory.createDataSource(prop)threadLocal = ThreadLocal()} catch (e: Exception) {throw RuntimeException("加载配置文件出错！${e.message}")}}@Throws(SQLException::class)fun getConnection(): Connection? {//从当前线程获取Connectionvar connection: Connection? = this.threadLocal!!.get()if (connection == null) {//如果没有就从连接池获取connection = dataSource?.connection//添加到ThreadLocalthis.threadLocal?.set(connection)}return connection}companion object {@Volatileprivate var instance: JdbcUtil? = nullfun getInstance() = instance ?: synchronized(this) {instance ?: JdbcUtil().also { instance = it }}}/*** 封装的通用增删改方法* @param sql 需要操作的SQL语句* @param params 执行SQL语句时需要的参数*/private fun update(sql: String, vararg params: Any = emptyArray()): Int {var connection: Connection? = nullvar statement: PreparedStatement? = nulltry {connection = getConnection()statement = connection?.prepareStatement(sql)if (params.isNotEmpty()) {for (i in params.indices) {statement?.setObject(i + 1, params[i])}}return statement!!.executeUpdate()} catch (e: Exception) {e.printStackTrace()} finally {destroy(connection, statement, null)}return 0}fun executeUpdate(sql: String): Int {return update(sql)}fun executeUpdateBoolean(sql: String): Boolean {val result: Int = update(sql)if (result > 0) {return true}return false}fun executeUpdate(sql: String, vararg params: Any): Int {return update(sql, params)}fun getPreparedStatement(sql: String): PreparedStatement {return getConnection()!!.prepareStatement(sql)}fun executeUpdateBoolean(sql: String, vararg params: Any): Boolean {val result: Int = update(sql, params)if (result > 0) {return true}return false}/*** 查询多条数据的封装方法* @param clazz 结果的封装对象* @param sql 要执行的SQL语句* @param params 执行SQL语句时需要的参数* @param <T> 消费金融泛型类型* @return 返回查询的结果集*/fun <T> query(sql: String, clazz: Class<T>, vararg params: Any): List<T> {var connection: Connection? = nullvar statement: PreparedStatement? = nullvar rs: ResultSet? = nullvar entities: List<T>?try {connection = getConnection()statement = connection!!.prepareStatement(sql)for (i in params.indices) {statement?.setObject(i + 1, params[i])}rs = statement.executeQuery()entities = mutableListOf()//获取ResultSet对象来获取元数据信息val meteData: ResultSetMetaData = rs.metaDataval columnCount: Int = meteData.columnCountwhile (rs.next()) {val entity: T = clazz.getDeclaredConstructor().newInstance()for (i in 1..columnCount) {val columnLabel: String = meteData.getColumnLabel(i)val field: Field = clazz.getDeclaredField(columnLabel)field.isAccessible = truefield.set(entity, rs.getObject(columnLabel))}entities.add(entity)}return entities} catch (e: Exception) {e.printStackTrace()throw RuntimeException("查询多条数据时出错，错误信息为:${e.message}")} finally {destroy(connection, statement, rs)}}//                entity = if (clazz == Int::class.java) {//                    val constructor: Constructor<T> = clazz.getDeclaredConstructor(Int::class.javaPrimitiveType)
//                    constructor.newInstance(rs.getInt(1))
//                } else if (clazz == Long::class.java) {//                    val constructor: Constructor<T> = clazz.getDeclaredConstructor(Long::class.javaPrimitiveType)
//                    constructor.newInstance(rs.getLong(1))
//                } else {//                    throw RuntimeException("参数中能传 int 类型或 long 类型。")
//                }/*** 查询多条数据的封装方法* @param clazz 结果的封装对象* @param sql 要执行的SQL语句* @param params 执行SQL语句时需要的参数* @param <T> 消费金融泛型类型* @return 返回查询的结果</T> */fun <T> queryForObject(clazz: Class<T>, sql: String?, vararg params: Any?): T? {var conn: Connection? = nullvar pstm: PreparedStatement? = nullvar rs: ResultSet? = nullvar entity: T? = nulltry {conn = getConnection()pstm = conn!!.prepareStatement(sql)for (i in params.indices) {pstm.setObject(i + 1, params[i])}rs = pstm.executeQuery()val metaData: ResultSetMetaData = rs.metaDatawhile (rs.next()) {entity = when (clazz) {Int::class -> {val constructor: Constructor<T> = clazz.getDeclaredConstructor(Int::class.java)constructor.newInstance(rs.getInt(1))}Long::class -> {val constructor: Constructor<T> = clazz.getDeclaredConstructor(Long::class.java)constructor.newInstance(rs.getLong(1))}else -> {throw RuntimeException("参数可以转换int或者long")}}}return entity} catch (e: Exception) {e.printStackTrace()throw RuntimeException("统计查询时出错，错误信息为：" + e.message)} finally {destroy(conn, pstm, rs)}}private fun destroy(connection: Connection?, statement: PreparedStatement?, rs: ResultSet?) {connection?.close()statement?.close()rs?.close()}}

这两个随便借鉴，我都感觉有问题，我太菜了

import java.io.File
import java.io.FileInputStream
import java.lang.reflect.Field
import java.net.URL
import java.sql.*
import java.util.*
import kotlin.collections.ArrayListclass SQLiteUtils {//磁盘文件路劲名 dbprivate var path: String? = null// 操作链接private var connection: Connection? = null//语法执行层private var statement: Statement? = null//连接数据库的信息private var user = ""private var password = ""private var url = ""private var driver = ""private constructor(path: String) {this.path = pathconnection = getConnection(path)}/*** 把JDBC返回的结果集封装成特定类型* @Author: fangju* @Date: 2019/6/15*/interface IResultSetHandler<T> {@Throws(Exception::class)fun handle(rs: ResultSet): T?}//Kotlin 可带参数的检测锁模式companion object {@Volatileprivate var instance: SQLiteUtils? = nullfun getInstance(path: String) = instance ?: synchronized(this) {instance ?: SQLiteUtils(path).also { instance = it }}}@Throws(SQLException::class)fun getStatement(): Statement? {if (this.statement == null) {this.statement = this.connection!!.createStatement()}return this.statement}/*** 获取Sqlite操作链接** @param path sqlite数据表，为磁盘文件名* @return*/@Throws(SQLException::class, ClassNotFoundException::class)private fun getConnection(path: String?): Connection? {var connection: Connection? = nullClass.forName("org.sqlite.JDBC")if (path!!.endsWith(".db")) {connection = DriverManager.getConnection("jdbc:sqlite:$path")}return connection}/*** 增删改操作* @param sql 传入的SQL语句* @param params 可变参数* @return 操作结果*//* 在kotlin变长参数中 * 叫 spread操作，可以理解为“打散”，“分散”*/fun executeUpdate(sql: String, vararg params: Any): Int {var preparedStatement: PreparedStatement? = nullvar result: Int = 0try {preparedStatement = connection?.prepareStatement(sql)//给预编译语句赋值for (i in params.indices) {preparedStatement?.setObject(i + 1, params[i])}//执行SQL语句，获取执行结果result = preparedStatement!!.executeUpdate()} catch (e: SQLException) {e.printStackTrace()} finally {preparedStatement?.close()}return result}fun <T> executeQuery(sql: String, handler: IResultSetHandler<T>, vararg params: Any): T? {var preparedStatement: PreparedStatement? = nullvar rs: ResultSet? = nullvar connection: Connection? = nulltry {connection = this.connectionpreparedStatement = connection?.prepareStatement(sql)for (i in params.indices) {preparedStatement!!.setObject(i + 1, params[i])}rs = preparedStatement!!.executeQuery()return handler.handle(rs)} catch (e: Exception) {e.printStackTrace()} finally {preparedStatement?.close()rs?.close()connection?.close()}return null}fun executeDML(sql: String, vararg params: Any): Boolean {var connection: Connection? = nullvar statement: PreparedStatement? = nulltry {connection = getConnection(path)statement = connection?.prepareStatement(sql)for (i in params.indices) {statement?.setObject(i + 1, params[i])}val resultCode: Int = statement!!.executeUpdate()if (resultCode > 0) {return true}} catch (e: Exception) {e.printStackTrace()} finally {connection?.close()statement?.close()}return false}//获取连接的方法private fun getConnection(): Connection? {var connection: Connection? = nulltry {//通过反射获取配置文件位置val resource: URL? = SQLiteUtils::class.java.getResource("/")val filePath = File(resource!!.file)val files: Array<File> = filePath.listFiles()var configFile: File? = null //配置文件路径for (file in files) {if (!file.isDirectory) //不是文件夹{if (file.name.equals("mysql.properties")) //文件名为mysql.properties{configFile = File(file.path) //确定配置文件}}}if (configFile == null) { //如果没有mysql.properties配置文件就抛出异常throw java.lang.Exception("小老弟,检查检查配置文件mysql.properties有没有")}//        通过Properties读取配置文件val properties = Properties()properties.load(FileInputStream(configFile))//        获取连接数据库的信息user = properties.getProperty("user")password = properties.getProperty("password")url = properties.getProperty("url")driver = properties.getProperty("driver")// 获取数据库连接Class.forName(driver) //加载驱动connection = DriverManager.getConnection(url, user, password)} catch (e: java.lang.Exception) {e.printStackTrace()}return connection}/*** 通用的查询方法** @param sql    要执行的sql语句* @param clazz  对应的实体类* @param params 条件参数(?对应的值)* @param <T>    对应的实体类型* @return</T> *///    T表示集合中使用的泛型,Class<T> clazz就是对应的实体类fun <T> executeDQL(sql: String?, clazz: Class<T>, vararg params: Any?): List<T>? {var connection: Connection? = null//PreparedStatement 是 Statement 的子类，它的一大好处是可以防止 SQL 注入var statement: PreparedStatement? = nullvar resultSet: ResultSet? = nullvar list: List<T>? = null //存放实体类的集合try {connection = getConnection() //获取连接statement = connection!!.prepareStatement(sql) //执行sql语句//            设置参数,如果params不为空说明要设置参数for (i in params.indices) {//从第一位开始对应赋值statement.setObject(i + 1, params[i])}resultSet = statement.executeQuery() //获取结果集//        可以通过ResultSet获取当前有那些列val metaData = resultSet.metaData //元数据,可以通过它获取表中的列//        获取表中列的总数val columnCount = metaData.columnCount//            用来存放我们查询的信息对应的实体类list = ArrayList()//判断是否有记录,然后再根据列名获取每列的信息while (resultSet.next()) { //每次循环获取的是一列数据//我们现在不能确定传入的实体类,这里用泛型替代,当你传入实体类型时确定val t = clazz.getDeclaredConstructor().newInstance()for (i in 1..columnCount)  //循环要从1开始{ //遍历列数,获取每一列的名字val columnLabel = metaData.getColumnLabel(i) //列名//                通过列名获取对应列的数据val `object` = resultSet.getObject(columnLabel)//                    通过列名获取实体类中的属性名val field: Field = clazz.getDeclaredField(columnLabel)//                    给获取的实体类的属性赋值field.isAccessible = true //取消安全检查field.set(t, `object`) //给t对象设置从数据库中查询出来的object值field.isAccessible = false //开启安全检查}list.add(t) //把得到的实体类存入集合}} catch (e: java.lang.Exception) {e.printStackTrace()} finally {//关闭连接close(connection, statement, resultSet)}return list //返回实体类集合}private fun close(connection: Connection?, statement: Statement?, resultSet: ResultSet?) {try {connection?.close()statement?.close()resultSet?.close()} catch (e: Exception) {e.printStackTrace()}}@Throws(SQLException::class)fun executeUpdate(sql: String) {getStatement()?.executeUpdate(sql)}@Throws(SQLException::class)private fun releaseConnection() {if (this.connection != null || this.connection!!.isClosed) {this.connection!!.close()this.connection = null}if (this.statement != null) {this.statement!!.close()this.statement = null}}}

我是在网上找大佬写的，我只是把代码转成kotlin并改成了单例模式，我也很少写文章，懒。不能保证这个工具类有没有问题，我对kotlin的反射还不是很了解，希望大家可以评论区留言，

db.properties


druid.driverClassName=org.sqlite.JDBC
druid.url=jdbc:sqlite:test.db
druid.validationQuery=SELECT 1
druid.testWhileIdle=true
druid.testOnBorrow=false
druid.testOnReturn=false

如上配置之后，运行项目idea终端会抛出

5月 10, 2022 6:43:09 下午 com.alibaba.druid.pool.DruidDataSource info
信息: {dataSource-1} inited

百度了一圈，没什么解决办法，
反正项目运行之后会在C:\Users\WuXiangGuJun\IdeaProjects\SQLite-JDBC\test.db

在idea中双击test.db可以打开数据库文件

这是刚刚创建的数据库，当然这些列是我自己搞的

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Druid+Sqlite-JDBC+Kotlin,封装的一个都是毛病的工具类，奆佬们，评论区教一下我怎么封装

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