mybatis的第一个程序

Bertha 。 2022-06-08 03:11 253阅读 0赞

程序结构图：

![Center][]

表结构；

![Center 1][]

创表sql：

CREATE TABLE \`users\` (  
  \`id\` int(11) NOT NULL AUTO\_INCREMENT,  
  \`username\` varchar(200) DEFAULT NULL,  
  \`password\` varchar(32) DEFAULT NULL,  
  \`sex\` char(1) DEFAULT NULL,  
  \`birthday\` date DEFAULT NULL,  
  PRIMARY KEY (\`id\`)  
) ENGINE=InnoDB AUTO\_INCREMENT=17 DEFAULT CHARSET=utf8

User.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="test">  
  
  
<select id="findUserById" parameterType="int" resultType="com.itheima.mybatis.po.User">  
SELECT \* FROM users WHERE id = \#\{id\}  
</select>  
  
  
<select id="findUserList" parameterType="String" resultType="com.itheima.mybatis.po.User">  
SELECT \* FROM users WHERE username LIKE '%$\{value\}%'  
</select>  
  
</mapper>

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>  
  
<environments default="development">  
<environment id="development">  
<transactionManager type="JDBC" />  
<dataSource type="POOLED">  
<property name="driver" value="com.mysql.jdbc.Driver" />  
<property name="url" value="jdbc:mysql://localhost:3306/mybatisdb?characterEncoding=utf-8" />  
<property name="username" value="root" />  
<property name="password" value="123" />  
</dataSource>  
</environment>  
</environments>  
  
  
<mappers>  
<mapper resource="sqlmap/User.xml"/>  
</mappers>  
</configuration>

log4j.properties：

\# Global logging configuration  
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

代码：

public class TestMybatis \{  
  
  
@Test  
public void testFindUserById() throws Exception \{  
// 加载配置文件  
String resource = "SqlMapConfig.xml";  
InputStream inputStream = Resources.getResourceAsStream(resource);  
// 通过配置文件获取到sqlSessionFactory  
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);  
// 通过sessionFactory对象获取到sqlSession对象  
SqlSession sqlSession = sessionFactory.openSession();  
// 向数据库发起查询（查询单条记录），并接收返回结果  
User user = sqlSession.selectOne("test.findUserById", 3);  
// 打印结果  
System.out.println(user);  
  
// 向数据库发起查询（查询多条记录），并接收返回结果  
List<User> list = sqlSession.selectList("test.findUserList", "小");  
System.out.println(list.size());  
for (User user2 : list) \{  
System.out.println(user2);  
\}  
\}  
\}

执行结果：

![Center 2][]

[Center]: /images/20220608/acafeb7a4cbb4cfc98628d2412947411.png
[Center 1]: /images/20220608/895f66c4f5474a139e45f1aca0c73d24.png
[Center 2]: /images/20220608/4ae40515f37440b08aeda909eae25f0d.png