你的UserMapper.xml有多个sql(比如有增删改)语句,但是你对应的接口写不全(只写了对应xml的增方法)这些sql的方法时也不会报错啊。
重点:接口的参数名无论parameterType是对象还是基本都是随便写。xml才要求对象要写属性名,基本才随便写(接口不管参数名的,只管参数的类型要跟xml的parameterType一样就行):
下面的mapper就是之前的dao,只不过叫法不一样而已
Sys_user:
package com.itheima.domain;
/**
* @author QLBF
* @version 1.0
* @date 2021/1/28 12:18
*/
public class Sys_user {
private int id;
private String username;
private String email;
private String password;
private String phoneNum;
@Override
public String toString() {
return "Sys_user{" +
"id=" + id +
", username='" + username + '\'' +
", email='" + email + '\'' +
", password='" + password + '\'' +
", phoneNum='" + phoneNum + '\'' +
'}';
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getPhoneNum() {
return phoneNum;
}
public void setPhoneNum(String phoneNum) {
this.phoneNum = phoneNum;
}
}
UserMapper:
package com.itheima.mapper;
import com.itheima.domain.Sys_user;
import java.util.List;
/**
* @author QLBF
* @version 1.0
* @date 2021/1/30 11:06
*/
public interface UserMapper {
public List<Sys_user> findAll();
public Sys_user findone(int id2); //由于parameterType是基本类型,那么参数名在接口和.xml都是随便写
public int save(Sys_user user1);
}
ServiceDemo:
package com.itheima.service;
import com.itheima.domain.Sys_user;
import com.itheima.mapper.UserMapper;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import org.apache.ibatis.io.Resources;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
/**
* @author QLBF
* @version 1.0
* @date 2021/1/30 11:07
*/
public class ServiceDemo {
@Test
//查全部
public void test1() throws IOException {
InputStream resourceAsStream= Resources.getResourceAsStream("sqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(resourceAsStream);
SqlSession sqlSession=sqlSessionFactory.openSession(true);
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
List<Sys_user> sys_userList = mapper.findAll();
System.out.println(sys_userList);
}
@Test
//测试查一条
public void test2() throws IOException {
InputStream resourceAsStream= Resources.getResourceAsStream("sqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(resourceAsStream);
SqlSession sqlSession=sqlSessionFactory.openSession(true);
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
Sys_user sys_use = mapper.findone(7);
System.out.println(sys_use);
}
@Test
//增
public void test3() throws IOException {
Sys_user sys_user=new Sys_user();
sys_user.setUsername("喜洋洋");
sys_user.setPhoneNum("555522");
InputStream resourceAsStream= Resources.getResourceAsStream("sqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(resourceAsStream);
SqlSession sqlSession=sqlSessionFactory.openSession(true);
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
int count = mapper.save(sys_user);
System.out.println(count);
}
}
测试成功,演示test3:
UserMapper.xml:
<?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.itheima.mapper.UserMapper">
<!--查询数据表封装成集合输出-->
<select id="findAll" resultType="com.itheima.domain.Sys_user"> /*Sys_user是数据库对应的实体类*/
SELECT * FROM sys_user /*这里是sys_user是数据库真实的表*/
</select>
<!--查询一个对象数据-->
<select id="findone" resultType="com.itheima.domain.Sys_user" parameterType="int"> /*Sys_user是数据库对应的实体类*/
SELECT * FROM sys_user WHERE id=#{id1}/*这里是sys_user是数据库真实的表*/
</select>
<!--插入操作,save是随便起的,parameterType后面都是写对象类型进行传递的哦,这里的user是对应sqlMapConfig的别名-->
<insert id="save" parameterType="user">
/*这里#后的{}写的是对应上面parameterType对象里面的属性,而不是对应数据库表的哦
(虽然一般数据库表跟实体类设置成一样,但有时不一样,这里要写的是实体类的哦)*/
INSERT INTO sys_user VALUES(#{id},#{username},#{email},#{password},#{phoneNum})
</insert>
</mapper>
jdbc.properties:
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root
sqlMapConfig.xml:
<?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>
<!--通过properties标签加载外部properties文件-->
<properties resource="jdbc.properties"></properties>
<!--自定义别名-->
<typeAliases>
<typeAlias type="com.itheima.domain.Sys_user" alias="user"></typeAlias>
<!--这里还可以配多个-->
</typeAliases>
<!--数据源环境-->
<environments default="developement">
<environment id="developement">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"></property>
<property name="url" value="${jdbc.url}"></property>
<property name="username" value="${jdbc.username}"></property>
<property name="password" value="${jdbc.password}"></property>
</dataSource>
</environment>
</environments>
<!--加载映射文件-->
<mappers>
<mapper resource="com.itheima.mapper/UserMapper.xml"></mapper>
</mappers>
</configuration>
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>cn.itcast</groupId>
<artifactId>Mybatis_day2_dao</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>war</packaging>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.32</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.5</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>
</project>