Mybatis步骤分解实现一个增删改查程序（springboot整合mybatis实现增删改查）

目录

1.idea新建Maven项目Mybatis-study 将项目里的src文件夹删掉 依次将此项目作为父项目

2.在Mybatis-study中新建模块mybatis-01

在mybatis的pom文件中可以看到其父项目为ybatis-study

    MyBatis-study    org.example    1.0-SNAPSHOT

3. 在Mybatis-study的pom.xml中引入如下jar包

junit

junit

4.11

test

org.mybatis

mybatis

3.5.9

mysql

mysql-connector-java

8.0.29

4.将IDEA和MySQL数据库建立连接：

根据实际情况填写user和password 填写之后点击Test Connection

测试成功之后点击Schemas选择你要链接的数据库

5.新建mybatis-config.xml配置文件 引入数据库资源

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

</environments>

6.创建实体类User 注意:实体类中成员变量名要和数据库表中字段名完全一致

package com.kero.pojo;

public class User {

private int id;

private String name;

private String password;

public User() {

}

public User(int id, String name, String password) {

this.id = id;

this.name = name;

this.password = password;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getpassword() {

return password;

}

public void setpassword(String pwd) {

this.password = pwd;

}

@Override

public String toString() {

return "User{" +

"id=" + id +

", name='" + name + '\'' +

", pwd='" + password + '\'' +

'}';

}

}

7.编写工具类Utils

package com.kero.utils;

import org.apache.ibatis.io.Rehttp://sources;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;

import java.io.InputStream;

//sqlSessionFactory

public class MyBatisUtils {

private static SqlSessionFactory sqlSessionFactory;

static {

try {

//使用Mybatis第一步 获取sqlSessionFactory对象

String resource = "mybatis-config.xml";

InputStream inputStream = Resources.getResourceAsStream(resource);

sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

} catch (IOException e) {

throw new RuntimeException(e);

}

}

/*

既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。SqlSession

提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句。例如：

*/

public static SqlSession getSqlSession(){

return sqlSessionFactory.openSession();

}

}

8.定义接口

package com.kero.dao;

import com.kero.pojo.User;

import java.util.List;

public interface UserMapper {

//查询全部用户

List getUserList();

//根据ID查询用户

User getUserByID(int id);

//insert一个用户

int addUser(User user);

//修改一个用户

int updateUser(User user);

//删除一个用户

int deleteUser(int id);

}

9.定义Mapper文件 这里的Mapper文件相当于原来传统方式中接口的实现类

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

select * from smbms.user

select * from smbms.user where id = #{id}

insert into smbms.user (id, name, password) VALUES (#{id},#{name},#{password})

update smbms.user set name=#{name},password=#{password} where id = #{id}

delete from smbms.user where id = #{id}

10.编写测试类

import com.kero.dao.UserMapper;

import com.kero.pojo.User;

import com.kero.utils.MyBatisUtils;

import org.apache.ibatis.session.SqlSession;

import org.junit.Test;

import java.util.List;

public class test {

@Test

public void test(){

SqlSession session = MyBatisUtils.getSqlSession();

UserMapper mapper = session.getMapper(UserMapper.class);

List userList = mapper.getUserList();

for (User l:userList) {

System.out.println(l.toString());

}

session.close();

}

@Test

public void testgetUserByID(){

SqlSession session = MyBatisUtils.getSqlSession();

UserMapper mapper = session.getMapper(UserMapper.class);

User userByID = mapper.getUserByID(1);

System.out.println(userByID);

session.close();

}

//增删改需要提交事务

@Test

public void testaddUser(){

SqlSession session = MyBatisUtils.getSqlSession();

UserMapper mapper = session.getMapper(UserMapper.class);

int zhhgf = mapper.addUser(new User(10, "zhhgf", "1k23jbjk"));

System.out.println(zhhgf);

session.pmUVPmPicjcommit();

//提交事务

session.close();

}

@Test

public void testupdateUser(){

SqlSession session = MyBatisUtils.getSqlSession();

UserMapper mapper = session.getMapper(UserMapper.class);

int i = mapper.updateUser(new User(8,"asdfsdf","234sdfs"));

session.commit();

//提交事务

session.close();

}

@Test

public void testdeleteUser(){

SqlSession session = MyBatisUtils.getSqlSession();

UserMapper mapper = session.getMapper(UserMapper.class);

int i = mapper.deleteUser(8);

session.commit();

//提交事务

session.close();

}

}

11.测试查询功能 : 输出结果与数据库表中数据

User{id=1, name='Sugawara Ryota', pwd='8X8Jq7HVNs'}

User{id=2, name='Shawn Mills', pwd='R78IHGDSXr'}

User{id=3, name='Matsuda Hina', pwd='mUi3CVA7mc'}

User{id=4, name='Cynthia Hawkins', pwd='NO1EwWbOs9'}

User{id=5, name='Rachel Bennett', pwd='YefuPVxzb9'}

tips:

如果一切配置正常但出现java.lang.ExceptionInInitializerError

Caused by org.apache.ibatis.execeptions.PersistenceExecepyion错误

是因为:maven由于它的约定大于配置 我们写的配置文件可能会出现无法被导出或者生效的问题解决方案 在pom.xml文件中添加如下代码

src/main/resources

**/*.properties

**/*.xml

true

src/main/java

**/*.properties

**/*.xml

true

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