本文主要和大家分享mysql连接数据库并测试实例，希望能帮助到大家。
1.通过maven导入关于mybatis的jar包
可以通过阿里云的maven库直接下载相关jar包
<dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.5</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-Java</artifactId> <version>5.1.38</version> </dependency> </dependencies>
2.编写mybatis的配置文件
nbsp;
PUBLIC “-//mybatis.org//DTD Config 3.0//EN”
“http://mybatis.org/dtd/mybatis-3-config.dtd”>
<environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <!-- 配置数据库 --> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/my_schema?useSSL=true" /> <property name="username" value="root" /> <property name="password" value="" /> </dataSource> </environment> </environments> <!-- 映射文件 --> <mappers> <mapper resource="UserMapper.xml" /> </mappers> </configuration>
3.编写映射文件UserMapper.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="userMapper"> <select id="selectUser" resultType="entity.User"> select * from user </select> </mapper>
4.写出实体类User,很平常的类,就不在过多解释.
public class User { private String username; private String email; private String password; private String create_time; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getCreate_time() { return create_time; } public void setCreate_time(String create_time) { this.create_time = create_time; } @Override public String toString() { return "User [username=" + username + ", email=" + email + ", password=" + password + ", create_time=" + create_time + "]"; } public User(String username, String email, String password, String create_time) { super(); this.username = username; this.email = email; this.password = password; this.create_time = create_time; } public User() { super(); }
}
5.在写一个类MybatisSamples,里面包含main方法,进行测试.
具体代码如下
public static void main(String[] args) { String resource = "mybatis-config.xml"; SqlSession session = null; try { InputStream is = Resources.getResourceAsStream(resource); //获取一个session工厂 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is); //通过工厂获取session session = sqlSessionFactory.openSession(); //根据映射文件中select标签的id获取集合 List<User> list = session.selectList("userMapper.selectUser"); for(User user: list) { System.out.println(user); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { //注意关闭session!!! session.close(); } }
执行结果如下:
附:
包结构
数据库结构
总结:想入门mybatis最重要的两步,第一是写配置文件,配置数据库和mapper,第二步是写好mapper和实体类,mapper中写sql语句,然后可以就可以通过mybatis把表中的数据映射成为一个对象了。
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