生产环境： eclipse + navicat + mysql
Snipaste_2020-10-10_11-22-20.png
pom.xml设置
- 这里需要注意的点是mysql-connector-java的版本号和mysql本身的版本要保持一致（也可以是在同一个大版本号下如mysql版本为4.5.1，mysql-connector-java版本就为4.5.X）
<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.example</groupId>
<artifactId>department</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>department</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.6</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
</dependency>
</dependencies>
</project>
myabits-config.xml配置
- 这里需要注意的问题是driver的版本，低版本的不需要cj，高版本的需要cj
//低版本
<property name="driver" value="com.mysql.jdbc.Driver"/>
//高版本（如如如8.0.00），高版本需要加时区
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://127.0.0.1:3306/department?serverTimezone=UTC"/>
<property name="username" value="root"/>
<property name="password" value="12345"/>
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://127.0.0.1:3306/department?serverTimezone=UTC"/>
<property name="username" value="root"/>
<property name="password" value="12345"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/example/department/UserMapper.xml"/>
</mappers>
</configuration>
xxxMapper.xml（我理解为xml的数据库语句）
需要注意的点：
- mapper的命名空间尽量和Mapper所在的架包下
- parameterType：参数类型，可以是java普通数据类型，也可以是自定义的实体类
- resultType：返回值，如果bean与数据库一一对应，则会自动映射
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.department.UserMapper">
<!-- 通过ID查询一个用户
id名字，namespace+id用来定位具体的sql parameterType：参数类型 resultType：返回值，如果bean与数据库一一对应，则会自动映射 where id=#{v}，#{} 占位符，里面要写一个任意字符
-->
<select id="selectDepartment" resultType="com.example.department.Bean.Department" parameterType="com.example.department.Bean.Department">
select * from department where id=#{id}
</select>
<insert id="addDepartment" parameterType="com.example.department.Bean.Department">
insert into department (id,info,leader,u) values (#{id},#{info},#{leader},#{u});
</insert>
<update id="updateDepartment" parameterType="com.example.department.Bean.Department">
update department set info =#{info},leader=#{leader},u=#{u} where id = #{id}
</update>
<delete id="deleteDepartment" parameterType="com.example.department.Bean.Department">
delete from department where id = #{id}
</delete>
</mapper>
java代码
package com.example.department;
import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.annotations.Param;
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 com.example.department.Bean.Department;
import com.example.department.Bean.Student;
public class UserTest {
//resource为文件路径
private static String resource="com/example/department/myabits-config.xml";
//xml为java . 路径
private static String xml = "com.example.department.UserMapper.";
//select,selet方法可以不用commit
public static void selectDepartment(@Param("department")Department department) {
try {
InputStream inputStream = Resources.getResourceAsStream(UserTest.resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession session = sqlSessionFactory.openSession();
//搜索一个数据库对象
Department user = session.selectOne(UserTest.xml+"selectDepartment",department);
System.out.println(user);
session.close();
inputStream.close();
}catch(IOException e) {
e.printStackTrace();
}
}
//update
public static void updateDepartment(Department department) {
try {
InputStream inputStream = Resources.getResourceAsStream(UserTest.resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession session = sqlSessionFactory.openSession();
session.update(UserTest.xml+"updateDepartment",department);
session.commit();
session.close();
inputStream.close();
}catch(IOException e) {
e.printStackTrace();
}
}
//delete
public static void deleteDepartment(Department department) {
try {
InputStream inputStream = Resources.getResourceAsStream(UserTest.resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession session = sqlSessionFactory.openSession();
session.delete(UserTest.xml+"deleteDepartment",department);
session.commit();
session.close();
inputStream.close();
}catch(IOException e) {
e.printStackTrace();
}
}
//add
public static void addDepartment(@Param("department")Department department) {
try {
InputStream inputStream = Resources.getResourceAsStream(UserTest.resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession session = sqlSessionFactory.openSession();
session.insert(UserTest.xml+"addDepartment",department);
session.commit();
session.close();
inputStream.close();
}catch(IOException e) {
e.printStackTrace();
}
}
}
记一个究极傻逼的错误，我在用写sql语句作为了key，花了我一晚上来解决，命名不规范，两行泪呀！
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