mybatis

Posted 2021-03-18 大赵传奇

1.新建个maven,注意一开始只勾一个，不选下面的starter什么的，进来就有maven的目录结构

 

-- Create table
create table USERS
(
id NUMBER(10),
username VARCHAR2(20),
age NUMBER(3)
)

 

 

 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>org.example</groupId>
    <artifactId>test5</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <java.version>1.8</java.version>
    </properties>


    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.2.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.oracle.ojdbc</groupId>
            <artifactId>ojdbc8</artifactId>
            <scope>runtime</scope>
            <version>19.3.0.0</version>
        </dependency>
<!--      去除异常  java.sql.SQLException: 不支持的字符集 (在类路径中添加 orai18n.jar): ZHS16GBK-->
        <dependency>
            <groupId>cn.easyproject</groupId>
            <artifactId>orai18n</artifactId>
            <version>12.1.0.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
            <version>2.2.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <defaultGoal>compile</defaultGoal>

        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.2.2.RELEASE</version>
            </plugin>
        </plugins>
    </build>


</project>

View Code

IUserDao.java

package dao;


import domain.User;

public interface IUserDao {
    User GetUserByID(Integer id) throws Exception;
}

User.java

package domain;

import org.apache.ibatis.type.Alias;

@Alias(value="user1") //测试指定别名
public class User {

    private int id;
    private String user_Name; //这里测试别名
    private int age;



    //为了测试，console.writeln能显示值 toString方法
    //getter seter方法也可以不要
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name=\'" + user_Name + \'\\\'\' +
                ", dept=\'" + age + \'\\\'\' +
                \'}\';
    }

}

userMap.xml

<?xml version="1.0" encoding="UTF-8" ?>

<!-- mapper 约束-->
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<!--namespace 写的是 dao权限类名-->
<mapper namespace="dao.IUserDao" >

    <!--查询用户-->
    <select id="GetUserByID" resultType="domain.User">
        select id, username as user_Name, age from users where id=#{id}
    </select>


</mapper>

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>

<!-- configuration 约束-->
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<!--mybatis的主配置文件-->
<configuration>
    <!--  配置环境  -->
    <environments default="oracle">
        <!--配置mysql环境-->
        <environment id="oracle">
            <!--   配置事务类型  -->
            <transactionManager type="JDBC"/>
            <!--  配置数据源（连接池）  -->
            <dataSource type="POOLED">
                <property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
                <property name="url" value="jdbc:oracle:thin:@localhost:1521:ORCL"/>
                <property name="username" value="test1"/>
                <property name="password" value="123"/>
            </dataSource>
        </environment>
    </environments>

    <!--指定映射配置文件的位置，映射配置文件指的是每个dao配置的文件-->
    <mappers>
        <!--使用的是xml-->
        <mapper resource="mapper/userMap.xml"/>
        <!--<mapper class="com..dao.IUserMapper"/> ;使用的是注解 -->

    </mappers>

</configuration>

MyBatisTest.java

import dao.IUserDao;
import domain.User;
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.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.List;

public class MybatisTest {

    InputStream in;
    SqlSession sqlSession;
    IUserDao userDao;

    @Before//初始化
    public void init()throws Exception{
        //1.读取配置文件
        in = Resources.getResourceAsStream("mybatis/mybatis-config.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂创建SqlSession
        sqlSession =factory.openSession();
        //4.使用SqlSession创建dao接口的代理对象
        userDao =sqlSession.getMapper(IUserDao.class);
    }
    @After//测试结束之后执行
    public void destory() throws Exception{
        //6.释放资源
        sqlSession.close();
        in.close();
    }

    @Test//查询
    public void test_getUserById() throws Exception {
        //5.使用代理对象的方法
        User users = userDao.GetUserByID(5);
        System.out.println(users);
    }
}

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