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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
<parent>
<artifactId>MyBatis-study</artifactId>
<groupId>org.example</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
3. 在Mybatis-study的pom.xml中引入如下jar包
<dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.11</version> <scope>test</scope> </dependency> <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.9</version> </dependency> <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.29</version> </dependency> </dependencies>
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
<?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://localhost:3306/smbms?useSSL=true&characterEncoding=UTF-8"/> <property name="username" value="root"/> <property name="password" value="root"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/kero/dao/UserMapper.xml" /> </mappers> </configuration>
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.Resources;
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<User> 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
<?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">
<!--namespace会绑定一个对应的Mapper接口-->
<mapper namespace="com.kero.dao.UserMapper">
<select id="getUserList" resultType="com.kero.pojo.User">
select * from smbms.user
</select>
<select id="getUserByID" parameterType="int" resultType="com.kero.pojo.User">
select * from smbms.user where id = #{id}
</select>
<insert id="addUser" parameterType="com.kero.pojo.User">
insert into smbms.user (id, name, password) VALUES (#{id},#{name},#{password})
</insert>
<update id="updateUser" parameterType="com.kero.pojo.User">
update smbms.user set name=#{name},password=#{password} where id = #{id}
</update>
<delete id="deleteUser" parameterType="int">
delete from smbms.user where id = #{id}
</delete>
</mapper>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<User> 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.commit();
//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
<build> <resources> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> <resource> <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> </resources> </build>
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