MyBatis学习总结(一)——MyBatis快速入门详解编程语言

1 create database mybatis; 
2 use mybatis; 
3 CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20), age INT); 
4 INSERT INTO users(NAME, age) VALUES('孤傲苍狼', 27); 
5 INSERT INTO users(NAME, age) VALUES('白虎神皇', 27);

 1 <?xml version="1.0" encoding="UTF-8"?> 
 2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> 
 3 <configuration> 
 4     <environments default="development"> 
 5         <environment id="development"> 
 6             <transactionManager type="JDBC" /> 
 7             <!-- 配置数据库连接信息 --> 
 8             <dataSource type="POOLED"> 
 9                 <property name="driver" value="com.mysql.jdbc.Driver" /> 
10                 <property name="url" value="jdbc:mysql://localhost:3306/mybatis" /> 
11                 <property name="username" value="root" /> 
12                 <property name="password" value="XDP" /> 
13             </dataSource> 
14         </environment> 
15     </environments> 
16      
17 </configuration>

 1 package me.gacl.domain; 
 2  
 3 /** 
 4  * @author gacl 
 5  * users表所对应的实体类 
 6  */ 
 7 public class User { 
 8  
 9     //实体类的属性和表的字段名称一一对应 
10     private int id; 
11     private String name; 
12     private int age; 
13  
14     public int getId() { 
15         return id; 
16     } 
17  
18     public void setId(int id) { 
19         this.id = id; 
20     } 
21  
22     public String getName() { 
23         return name; 
24     } 
25  
26     public void setName(String name) { 
27         this.name = name; 
28     } 
29  
30     public int getAge() { 
31         return age; 
32     } 
33  
34     public void setAge(int age) { 
35         this.age = age; 
36     } 
37  
38     @Override 
39     public String toString() { 
40         return "User [id=" + id + ", name=" + name + ", age=" + age + "]"; 
41     } 
42 }

 1 <?xml version="1.0" encoding="UTF-8" ?> 
 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 
 3 <!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的 
 4 例如namespace="me.gacl.mapping.userMapper"就是me.gacl.mapping(包名)+userMapper(userMapper.xml文件去除后缀) 
 5  --> 
 6 <mapper namespace="me.gacl.mapping.userMapper"> 
 7     <!-- 在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，id属性值必须是唯一的，不能够重复 
 8     使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型 
 9     resultType="me.gacl.domain.User"就表示将查询结果封装成一个User类的对象返回 
10     User类就是users表所对应的实体类 
11     --> 
12     <!--  
13         根据id查询得到一个user对象 
14      --> 
15     <select id="getUser" parameterType="int"  
16         resultType="me.gacl.domain.User"> 
17         select * from users where id=#{id} 
18     </select> 
19 </mapper>

 1 <?xml version="1.0" encoding="UTF-8"?> 
 2 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> 
 3 <configuration> 
 4     <environments default="development"> 
 5         <environment id="development"> 
 6             <transactionManager type="JDBC" /> 
 7             <!-- 配置数据库连接信息 --> 
 8             <dataSource type="POOLED"> 
 9                 <property name="driver" value="com.mysql.jdbc.Driver" /> 
10                 <property name="url" value="jdbc:mysql://localhost:3306/mybatis" /> 
11                 <property name="username" value="root" /> 
12                 <property name="password" value="XDP" /> 
13             </dataSource> 
14         </environment> 
15     </environments> 
16      
17     <mappers> 
18         <!-- 注册userMapper.xml文件，  
19         userMapper.xml位于me.gacl.mapping这个包下，所以resource写成me/gacl/mapping/userMapper.xml--> 
20         <mapper resource="me/gacl/mapping/userMapper.xml"/> 
21     </mappers> 
22      
23 </configuration>

package me.gacl.test; 
 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.Reader; 
import me.gacl.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; 
 
public class Test1 { 
 
    public static void main(String[] args) throws IOException { 
        //mybatis的配置文件 
        String resource = "conf.xml"; 
        //使用类加载器加载mybatis的配置文件（它也加载关联的映射文件） 
        InputStream is = Test1.class.getClassLoader().getResourceAsStream(resource); 
        //构建sqlSession的工厂 
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is); 
        //使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件） 
        //Reader reader = Resources.getResourceAsReader(resource);  
        //构建sqlSession的工厂 
        //SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader); 
        //创建能执行映射文件中sql的sqlSession 
        SqlSession session = sessionFactory.openSession(); 
        /** 
         * 映射sql的标识字符串， 
         * me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值， 
         * getUser是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL 
         */ 
        String statement = "me.gacl.mapping.userMapper.getUser";//映射sql的标识字符串 
        //执行查询返回一个唯一user对象的sql 
        User user = session.selectOne(statement, 1); 
        System.out.println(user); 
    } 
}