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Java Scala实现数据库增删查改操作详解

作者：你∈我　　发布时间：2022-02-03 05:09:22　

标签：Java,Scala,增删查改,数据库

添加jar包

这里的Scala不是maven工程所以要找到项目结构（快捷键：同时按住Ctrl+shift+Alt+s）在模块里面添加添加MySQL的jar包，如果是Maven工程可以直接在pom里面直接加即可

实现操作数据库需要两个类，一个用于测试的Demo，一个用于实现增删查改的Util方法

在MysqlDemo在这里需要用到伴生类和伴生对象，伴生类主要是实现连接数据库

class MysqlDemo {
// 连接数据库底层原理还是jdbc
//驱动名称
var driver = "com.mysql.cj.jdbc.Driver"
// 访问MySQL服务器，通过3306端口访问mysql数据库
var url = "jdbc:mysql://192.168.152.184:3306/exam"
//用户名
var user = "root"
//密码
var password = "123456"
//辅助构造器
def this(driver: String, url: String, user: String, pwd: String) {
this()
this.driver = driver
this.url = url
this.user = user
this.password = pwd
}
}

伴生对象则主要是实现操作数据库，需要先实现apply方法，主函数里面创建对象调用apply方法，调用连接方法和释放资源

object MysqlDemo {
// 实现apply方法
def apply(): MysqlDemo = new MysqlDemo()
def apply(driver: String, url: String, user: String, pwd: String): MysqlDemo = new MysqlDemo(driver, url, user, pwd)
def main(args: Array[String]): Unit = {
//创建对象，调用apply方法
val demo = MysqlDemo()
//导入MySQLUtil包
import MysqlUtil._
//调用创建连接的方法
demo.conn()
// 调用释放资源方法
demo.close(connection)
/**操作数据库代码*/
}

Util则需要先初始化数据库连接，注册驱动，得到数据库连接，释放资源

import java.sql.{Connection, DriverManager, PreparedStatement, ResultSet}
object MysqlUtil {
implicit class MysqlOp(obj: MysqlDemo) {
//初始化数据连接
private var connection: Connection = _
def conn(): Connection = {
//注册driver
Class.forName(obj.driver)
//得到数据库连接
val connection: Connection = DriverManager.getConnection(obj.url, obj.user, obj.password)
connection
}
//释放资源
def close(conn: Connection): Unit = {
if (conn != null) {
conn.close()
}
}
}

准备工作已做完下面要实现对数据库的增删查改

添加数据

方法一

//Util代码
//添加数据方法一
def insertStudent: Int = {
val insertSqlStr = "insert into student(name, age, gender, telephone, email, classid)" +
"values ('周七', 6, '男', '13888888888', '346497@qq.com', 2)"
val i: Int = conn().createStatement.executeUpdate(insertSqlStr)
i
}
//Demo测试代码
//添加数据方法一
val i: Int = demo.insertStudent
if (i == 1) {
println("添加成功")
} else if (i == 0) {
println("添加失败")
}

方法二

//Util代码
//添加数据方法二
def insertStudent(name: String, age: Int, gender: String, telephone: String, email: String, classid: Int): Int = {
val insertSqlStr = "insert into student(id,name, age, gender, telephone, email, classid)" +
"values (null,?,?,?,?,?,?)"
val preStmt: PreparedStatement = conn().prepareStatement(insertSqlStr)
preStmt.setString(1, name)
preStmt.setInt(2, age)
preStmt.setString(3, gender)
preStmt.setString(4, telephone)
preStmt.setString(5, email)
preStmt.setInt(6, classid)
val i: Int = preStmt.executeUpdate()
i
}
//Demo测试代码
//添加数据方法二
val i: Int = demo.insertStudent("aaa", 18, "男", "12345678910", "34649756@qq.com", 1)
if (i == 1) {
println("添加成功")
} else if (i == 0) {
println("添加失败")
}

删除数据

//Util代码
def deleteStudent(id: Int): Int = {
val deleteSql = "delete from student where id= ?"
val preStmt: PreparedStatement = conn().prepareStatement(deleteSql)
preStmt.setInt(1, id)
val i: Int = preStmt.executeUpdate()
i
}
//Demo测试代码
val i: Int = demo.deleteStudent(21)
if (i == 1) {
println("删除成功")
} else if (i == 0) {
println("删除失败")
}

查询数据

//Util代码
def selectStudent: Unit = {
val selectSql = "select id,name, age, gender, telephone, email, classid from student"
val rs: ResultSet = conn().createStatement().executeQuery(selectSql)
println("学号\t姓名\t年龄\t性别\t手机号\t邮箱\t班级编号")
while (rs.next()) {
val id: Int = rs.getInt("id")
val name: String = rs.getString("name")
val age: Int = rs.getInt("age")
val gender: String = rs.getString("gender")
val telephone: String = rs.getString("telephone")
val email: String = rs.getString("email")
val classid: String = rs.getString("classid")
println(id + "\t" + name + "\t" + age + "\t" + gender + "\t" + telephone + "\t" + email + "\t" + classid)
}
}
//Demo测试代码
demo.selectStudent

修改数据

//Util代码
def updateStudent(id: Int, name: String, age: Int, gender: String, telephone: String, email: String, classid: Int): Int = {
val updateSql = "update student set name=?," + "age=?, " + "gender=?," +
"telephone=?," + "email=?, " + "classid=? where id=?"
val preStmt: PreparedStatement = conn().prepareStatement(updateSql)
preStmt.setString(1, name)
preStmt.setInt(2, age)
preStmt.setString(3, gender)
preStmt.setString(4, telephone)
preStmt.setString(5, email)
preStmt.setInt(6, classid)
preStmt.setInt(7, id)
val i: Int = preStmt.executeUpdate()
i
}
//Demo测试代码
val i: Int = demo.updateStudent(22, "test", 25, "女", "123456789", "369852@qq.com", 2)
if (i == 1) {
println("修改成功")
} else if (i == 0) {
println("修改失败")
}

完整代码

MysqlUtil代码

import java.sql.{Connection, DriverManager, PreparedStatement, ResultSet}
object MysqlUtil {
implicit class MysqlOp(obj: MysqlDemo) {
//初始化数据连接
private var connection: Connection = _
def conn(): Connection = {
//注册driver
Class.forName(obj.driver)
//得到数据库连接
val connection: Connection = DriverManager.getConnection(obj.url, obj.user, obj.password)
connection
}
//释放资源
def close(conn: Connection): Unit = {
if (conn != null) {
conn.close()
}
}
//添加数据方法一
def insertStudent: Int = {
val insertSqlStr = "insert into student(name, age, gender, telephone, email, classid)" +
"values ('bbb', 6, '男', '13852277346', '3464975236@qq.com', 2)"
val i: Int = conn().createStatement.executeUpdate(insertSqlStr)
i
}
//添加数据方法二
def insertStudent(name: String, age: Int, gender: String, telephone: String, email: String, classid: Int): Int = {
val insertSqlStr = "insert into student(id,name, age, gender, telephone, email, classid)" +
"values (null,?,?,?,?,?,?)"
val preStmt: PreparedStatement = conn().prepareStatement(insertSqlStr)
preStmt.setString(1, name)
preStmt.setInt(2, age)
preStmt.setString(3, gender)
preStmt.setString(4, telephone)
preStmt.setString(5, email)
preStmt.setInt(6, classid)
val i: Int = preStmt.executeUpdate()
i
}
//删除数据
def deleteStudent(id: Int): Int = {
val deleteSql = "delete from student where id= ?"
val preStmt: PreparedStatement = conn().prepareStatement(deleteSql)
preStmt.setInt(1, id)
val i: Int = preStmt.executeUpdate()
i
}
//修改数据
def updateStudent(id: Int, name: String, age: Int, gender: String, telephone: String, email: String, classid: Int): Int = {
val updateSql = "update student set name=?," + "age=?, " + "gender=?," +
"telephone=?," + "email=?, " + "classid=? where id=?"
val preStmt: PreparedStatement = conn().prepareStatement(updateSql)
preStmt.setString(1, name)
preStmt.setInt(2, age)
preStmt.setString(3, gender)
preStmt.setString(4, telephone)
preStmt.setString(5, email)
preStmt.setInt(6, classid)
preStmt.setInt(7, id)
val i: Int = preStmt.executeUpdate()
i
}
//查询数据
def selectStudent: Unit = {
val selectSql = "select id,name, age, gender, telephone, email, classid from student"
val rs: ResultSet = conn().createStatement().executeQuery(selectSql)
println("学号\t姓名\t年龄\t性别\t手机号\t邮箱\t班级编号")
while (rs.next()) {
val id: Int = rs.getInt("id")
val name: String = rs.getString("name")
val age: Int = rs.getInt("age")
val gender: String = rs.getString("gender")
val telephone: String = rs.getString("telephone")
val email: String = rs.getString("email")
val classid: String = rs.getString("classid")
println(id + "\t" + name + "\t" + age + "\t" + gender + "\t" + telephone + "\t" + email + "\t" + classid)
}
}
}
}

MysqlDemo代码

import java.sql.Connection
class MysqlDemo {
// 连接数据库底层原理还是jdbc
//驱动名称
var driver = "com.mysql.cj.jdbc.Driver"
// 访问MySQL服务器，通过3306端口访问mysql数据库
var url = "jdbc:mysql://192.168.152.184:3306/exam"
//用户名
var user = "root"
//密码
var password = "123456"
//辅助构造器
def this(driver: String, url: String, user: String, pwd: String) {
this()
this.driver = driver
this.url = url
this.user = user
this.password = pwd
}
}
object MysqlDemo {
// 实现apply方法
def apply(): MysqlDemo = new MysqlDemo()
def apply(driver: String, url: String, user: String, pwd: String): MysqlDemo = new MysqlDemo(driver, url, user, pwd)
def main(args: Array[String]): Unit = {
//创建对象，调用apply方法
val demo = MysqlDemo()
//导入MySQLUtil包
import MysqlUtil._
//调用创建连接的方法
val connection: Connection = demo.conn()
// 调用释放资源方法
demo.close(connection)
//添加数据方法一
val i: Int = demo.insertStudent
if (i == 1) {
println("添加成功")
} else if (i == 0) {
println("添加失败")
}
//添加数据方法二
val i: Int = demo.insertStudent("aaa", 18, "男", "12345678910", "34649756@qq.com", 1)
if (i == 1) {
println("添加成功")
} else if (i == 0) {
println("添加失败")
}
//查询数据
demo.selectStudent
// 修改数据
val i: Int = demo.updateStudent(22, "test", 25, "女", "123456789", "369852@qq.com", 2)
if (i == 1) {
println("修改成功")
} else if (i == 0) {
println("修改失败")
}
//删除数据
val i: Int = demo.deleteStudent(21)
if (i == 1) {
println("删除成功")
} else if (i == 0) {
println("删除失败")
}
}
}

来源：https://blog.csdn.net/qq_57151931/article/details/129802346

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