【Mybatis】入门程序

忘是亡心i 2022-06-13 01:20 232阅读 0赞

一、需求：根据用户id查询用户信息

二、环境

java环境：JDK1.7.0  
mysql:5.6.24  
mybatis运行环境（jar包）：3.2.7  
加入mysql驱动包，免费下载：[mysql-connector-java-5.1.7-bin.jar][]

三、log4j.properties

# Global logging configuration
    # 在开发环境下日志级别设置成DEBUG，生产环境设置成info或error
    log4j.rootLogger=DEBUG, stdout
    # Console output...
    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
    log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

四、工程结构

![这里写图片描述][SouthEast]

五、SqlMapConfig.xml编写

<?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="db.properties">
            
            
        </properties>
        
        <typeAliases>
    
            
            
            
            <package name="cn.itcast.mybatis.po"/>
    
        </typeAliases>
    
        
        <environments default="development">
            <environment id="development">
            
                <transactionManager type="JDBC" />
            
                <dataSource type="POOLED">
                    <property name="driver" value="${jdbc.driver}" />
                    <property name="url" value="${jdbc.url}" />
                    <property name="username" value="${jdbc.username}" />
                    <property name="password" value="${jdbc.password}" />
                </dataSource>
            </environment>
        </environments>
    
    </configuration>

六、查询用户

1、创建po类  
![这里写图片描述][SouthEast 1]

2、映射文件User.xml

<select id="findUserById" parameterType="int" resultType="cn.itcast.mybatis.po.User">
        SELECT * FROM USER WHERE id=#{value}
    </select>

3、SqlMapConfig.xml中加载User.xml

4、程序编写

private SqlSessionFactory sqlSessionFactory;
    
        // 此方法是在执行testFindUserById之前执行
        @Before
        public void setUp() throws Exception {
            // 创建sqlSessionFactory
    
            // mybatis配置文件
            String resource = "SqlMapConfig.xml";
            // 得到配置文件流
            InputStream inputStream = Resources.getResourceAsStream(resource);
    
            // 创建会话工厂，传入mybatis的配置文件信息
            sqlSessionFactory = new SqlSessionFactoryBuilder()
                    .build(inputStream);
        }
        @Test
        public void testFindUserById() throws Exception {
    
            SqlSession sqlSession = sqlSessionFactory.openSession();
    
            //创建UserMapper对象，mybatis自动生成mapper代理对象
            UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    
            //调用userMapper的方法
    
            User user = userMapper.findUserById(1);
    
            System.out.println(user);
    
        }

总结  
实践，加深理解。

[mysql-connector-java-5.1.7-bin.jar]: http://download.csdn.net/detail/yangs_1235/5049404
[SouthEast]: /images/20220613/7374d2d6522a41e28fa87ef1a3df723c.png
[SouthEast 1]: /images/20220613/df9f9c2e9bbe4acc920fa92fdb1a2d7d.png