整合mybatis实现简单的增删改查

mybatis配置相关代码

配置

<?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>
    <properties resource="mysql.properties"/>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${user}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="dao/UserMapper.xml"/>
    </mappers>
</configuration>

工具类

package utilts;

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.springframework.core.io.Resource;

import java.io.IOException;
import java.io.InputStream;

import static org.apache.ibatis.io.Resources.getResourceAsStream;

public class MybatisUtils {
    private static SqlSessionFactory sqlSessionFactory;
   static {
       try {
           String resource="mybatis-config.xml";
           InputStream in= Resources.getResourceAsStream(resource);
           sqlSessionFactory=new SqlSessionFactoryBuilder().build(in);
       } catch (IOException e) {
           e.printStackTrace();
       }
   }
   public static SqlSession getSqlsession(){
       return sqlSessionFactory.openSession(true);
   }

}

映射实现

<?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="dao.UserMapper">
<insert id="add" parameterType="pojo.User">
    insert into home.user values (#{id},#{name},#{age})
</insert>
<delete id="delete" parameterType="String">
    delete from home.user where id=#{id}
</delete>
    <update id="update" parameterType="pojo.User">
        update user
<set>
    <if test="id!=null and id!=''">id=#{id},</if>
        <if test="name!=null and name!=''" >name=#{name},</if>
    <if test="age!=null and age!=''" >age=#{age}</if>
</set>
where id=#{id}
    </update>
    <select id="select" resultType="pojo.User">
        select * from user
    </select>
</mapper>

此次遇到的问题

servlet映射路径未找到报404

这个问题实属无语

问题的关键在于应用上下文，程序执行之后页面实际地址为http://localhost:8081/add,但是因为tomcat里面的上下文为/MavenSon3_war_exploded，所以事实上得跳转到

http://localhost:8081/MavenSon3_war_exploded/add才可以找到

解决方案将应用程序上下文改为空

其次就是tomcat10和tomcat9的问题了，本人装了两个tomcat，端口分别为8080和8081，本次如果是tomcat9则会报一个异常，而tomcat10则不会

网上查找资料说是jar包和tomcat版本不匹配的问题，由于本人最近才开始使用idea，之前用eclipse并未碰到如此问题，发现idea的版本匹配机制挺迷糊的

之前jdk和maven版本也出现了不匹配问题

另外切记程序在运行之前一定要注册mapper