mybatis中Sql映射器Mapper的使用-mybatis学习笔记02

以你之姓@ 2022-04-08 12:17 252阅读 0赞

**mybatis中Sql映射器Mapper的使用**

*  第一步：导入jar包  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70]
 *  第二步：配置resources文件  
    ![在这里插入图片描述][20181213213648612.png]  
    db.properties是数据库的配置文件

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql:///数据库名称
    jdbc.username=登陆数据库的用户名
    jdbc.password=登陆数据库的密码

log4j.properties是日志文件配置

#trace:详细级别
    #debug:调试级别
    #info: 提示级别
    #warnnig: 警告级别
    #error：错误级别
    
    #error的级别最高，但是显示的信息最少
    
    log4j.rootLogger=ERROR, stdout
    #log4j.rootLogger=NONE
    log4j.logger.包名=TRACE
    
    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
    log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

mybatis-config.xml是mybatis的主要配置文件

<?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>
    
        
        <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>
        <mappers>
            
            
              <mapper resource="cn/itsource/mybatis/mapper/UserMapper.xml"/>
        </mappers>
    </configuration>

![在这里插入图片描述][2018121321413655.png]

*  新建domain类和domainMapper接口  
    这里测试用的domain类为：

package cn.itsource.mybatis.mapper;
    public class User {
    
        private Long id;
        private String username;
        private String password;
    
        public Long getId() {
            return id;
        }
    
        public void setId(Long id) {
            this.id = id;
        }
    
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        public String getPassword() {
            return password;
        }
    
        public void setPassword(String password) {
            this.password = password;
        }
    
    }

domainMaper接口为：  
package cn.itsource.mybatis.mapper;

public interface UserMapper \{  
/\*\*  
\* 根据id查找用户  
\* @param id  
\* @return  
\*/  
User findOne(Long id);  
\}

*  写domainMaper.xml配置，主要用于写sql

<?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="cn.itsource.mybatis.mapper.UserMapper">
        
        <select id="findOne" parameterType="java.lang.Long"
                resultType="cn.itsource.mybatis.mapper.User">
            select * from user where id = #{id}
        </select>
    </mapper>

*  新建工具类，用于获得SqlSession  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 1]
 *  测试查询：  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 2]  
    结果为：  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 3]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70]: /images/20220405/c8f10d1197a04e838708f7b1d000cc4d.png
[20181213213648612.png]: /images/20220405/61d63af4ea984bd7ba1498c4f715a83d.png
[2018121321413655.png]: /images/20220405/29cf1d42b5164dc6bce3cad717df0e94.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 1]: /images/20220405/3e5286e43a8c4df5aa3630dceb347c63.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 2]: /images/20220405/2e30068541ed4539b845ef3e77936af7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 3]: /images/20220405/512a6c6ff28144119243422d52853ce8.png