JavaEE企业级开发技术-利用Mybatis完成CRUD

参考书籍《JavaEE企业级开发技术》-黑马程序员

利用Mybatis框架实现客户（银行账户）信息（tb_cust:id\cname\csex\cbirth\cfavs\ctel\caddr）的查询，新增，更新及删除的功能。

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.itheima</groupId><artifactId>mybatistest</artifactId><version>1.0-SNAPSHOT</version><dependencies><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.2</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.11</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><!--   	        <scope>test</scope>--><scope>compile</scope></dependency></dependencies><build><resources><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources></build></project>

db.properties

mysql.driver=com.mysql.cj.jdbc.Driver
mysql.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false
mysql.username=root
mysql.password=root

User.java

package com.itheima.pojo;public class User {private int uid;             //用户idprivate String uname;       //用户姓名private int uage;            //用户年龄public int getUid() {return uid;}public void setUid(int uid) {this.uid = uid;}public String getUname() {return uname;}public void setUname(String uname) {this.uname = uname;}public int getUage() {return uage;}public void setUage(int uage) {this.uage = uage;}
}

UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- mapper为映射的根节点-->
<!-- mapper为映射的根节点，namespace指定Dao接口的完整类名
mybatis会依据这个接口动态创建一个实现类去实现这个接口，
而这个实现类是一个Mapper对象-->
<mapper namespace="com.itheima.pojo.User"><!--id ="接口中的方法名"parameterType="传入的参数类型"resultType = "返回实体类对象，使用包.类名"--><select id="findById" parameterType="int"resultType="com.itheima.pojo.User">select * from users where uid = #{id}</select>
</mapper>

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><!-- 环境配置 --><!-- 加载类路径下的属性文件 --><properties resource="db.properties"/><environments default="development"><environment id="development"><transactionManager type="JDBC"/><!-- 数据库连接相关配置 ,db.properties文件中的内容--><dataSource type="POOLED"><property name="driver" value="${mysql.driver}"/><property name="url" value="${mysql.url}"/><property name="username" value="${mysql.username}"/><property name="password" value="${mysql.password}"/></dataSource></environment></environments><!-- mapping文件路径配置 --><mappers><mapper resource="mapper/UserMapper.xml"/></mappers></configuration>

UserTest.java

package Test;import com.itheima.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;import java.io.IOException;
import java.io.Reader;public class UserTest {@Testpublic void userFindByIdTest() {//读取文件名String resources = "mybatis-config.xml";//创建流Reader reader = null;try {//读取mybatis-config.xml文件内容到reader对象中reader = Resources.getResourceAsReader(resources);} catch (IOException e) {e.printStackTrace();}//初始化mybatis数据库,创建SqlSessionFactory类的实例SqlSessionFactory sqlMapper = newSqlSessionFactoryBuilder().build(reader);//创建SqlSession实例SqlSession session = sqlMapper.openSession();//传入参数查询，返回结果User user = session.selectOne("findById", 1);//输出结果System.out.println(user.getUname());//关闭sessionsession.close();}
}

现在已经有了一个基本的MyBatis配置，包括一个用户实体类User，一个映射文件UserMapper.xml，以及一个测试类UserTest用于测试查询功能。现在，增加更新、插入和删除的功能。以下是如何实现这些功能的步骤：

更新功能

在UserMapper.xml中添加一个update标签来定义更新操作：

<update id="updateUser" parameterType="com.itheima.pojo.User">update usersset uname = #{uname}, uage = #{uage}where uid = #{uid}
</update>

插入功能

在UserMapper.xml中添加一个insert标签来定义插入操作：

<insert id="insertUser" parameterType="com.itheima.pojo.User">insert into users (uid, uname, uage) values (#{uid}, #{uname}, #{uage})
</insert>

删除功能

在UserMapper.xml中添加一个delete标签来定义删除操作：

<delete id="deleteUser" parameterType="int">delete from users where uid = #{uid}
</delete>

更新测试类

在UserTest类中添加测试方法来测试更新、插入和删除功能：

package Test;import com.itheima.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;import java.io.IOException;
import java.io.Reader;public class UserTest {@Testpublic void userFindByIdTest() {// 已有的查询测试代码}@Testpublic void userUpdateTest() {String resources = "mybatis-config.xml";Reader reader = null;try {reader = Resources.getResourceAsReader(resources);SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);SqlSession session = sqlMapper.openSession();User user = new User();user.setUid(1);user.setUname("Updated Name");user.setUage(30);session.update("updateUser", user);session.commit();System.out.println("User updated successfully");session.close();} catch (IOException e) {e.printStackTrace();}}@Testpublic void userInsertTest() {String resources = "mybatis-config.xml";Reader reader = null;try {reader = Resources.getResourceAsReader(resources);SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);SqlSession session = sqlMapper.openSession();User user = new User();user.setUid(3);user.setUname("New User");user.setUage(25);session.insert("insertUser", user);session.commit();System.out.println("User inserted successfully");session.close();} catch (IOException e) {e.printStackTrace();}}@Testpublic void userDeleteTest() {String resources = "mybatis-config.xml";Reader reader = null;try {reader = Resources.getResourceAsReader(resources);SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);SqlSession session = sqlMapper.openSession();session.delete("deleteUser", 3);session.commit();System.out.println("User deleted successfully");session.close();} catch (IOException e) {e.printStackTrace();}}
}

确保您的数据库连接配置正确，并且数据库中有一个名为users的表，其结构与您的User实体类相匹配。

use mybatis;
create table users(uid int primary key auto_increment,uname varchar(20) not null,uage int not null
);
insert into users(uid,uname,uage) values(null,'张三',20),(null,'李四',18);

为了利用Mybatis框架实现实现客户（银行账户）信息（tb_cust:id\cname\csex\cbirth\cfavs\ctel\caddr）的查询，新增，更新及删除的功能。我们需要做以下几个步骤：