MyBatis入门（一）SqlSessionFactory

（1）新建数据库

1 CREATE TABLE emp (
2     id INT ( 10 ) PRIMARY KEY auto_increment,
3     last_name VARCHAR(255),
4     gender CHAR(1),
5     email VARCHAR(255)    
6 )

（2）输入数据

INSERT INTO emp VALUES(1,"张三","男","we.com");

（3）新建项目

（4）导入Jar包

（5）编写log4j

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
 3  
 4 <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
 5  
 6  <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
 7    <param name="Encoding" value="UTF-8" />
 8    <layout class="org.apache.log4j.PatternLayout">
 9     <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m  (%F:%L) 
" />
10    </layout>
11  </appender>
12  <logger name="java.sql">
13    <level value="debug" />
14  </logger>
15  <logger name="org.apache.ibatis">
16    <level value="info" />
17  </logger>
18  <root>
19    <level value="debug" />
20    <appender-ref ref="STDOUT" />
21  </root>
22 </log4j:configuration>

（6）编写实体类

 1 public class Emp {
 2 
 3     private Integer id;
 4     private String lastName;
 5     private String geder;
 6     private String email;
 7     public Emp() {
 8         super();
 9     }
10     public Emp(Integer id, String lastName, String geder, String email) {
11         super();
12         this.id = id;
13         this.lastName = lastName;
14         this.geder = geder;
15         this.email = email;
16     }
17     public Integer getId() {
18         return id;
19     }
20     public void setId(Integer id) {
21         this.id = id;
22     }
23     public String getLastName() {
24         return lastName;
25     }
26     public void setLastName(String lastName) {
27         this.lastName = lastName;
28     }
29     public String getGeder() {
30         return geder;
31     }
32     public void setGeder(String geder) {
33         this.geder = geder;
34     }
35     public String getEmail() {
36         return email;
37     }
38     public void setEmail(String email) {
39         this.email = email;
40     }
41     @Override
42     public String toString() {
43         return "Emp [id=" + id + ", lastName=" + lastName + ", geder=" + geder + ", email=" + email + "]";
44     }

（7）编写MyBatis的配置文件

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3   PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4   "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 6   <environments default="development">
 7     <environment id="development">
 8       <transactionManager type="JDBC"/>
 9       <dataSource type="POOLED">
10         <property name="driver" value="com.mysql.jdbc.Driver"/>
11         <property name="url" value="jdbc:mysql://localhost:3306/MyBatis"/>
12         <property name="username" value="root"/>
13         <property name="password" value="root"/>
14       </dataSource>
15     </environment>
16   </environments>
17   <mappers>
18     <mapper resource="conf/EmpMapper.xml"/>
19   </mappers>
20 </configuration>

（8）编写Mapper文件EmpMapper.xml

1 <?xml version="1.0" encoding="UTF-8" ?>
2 <!DOCTYPE mapper
3   PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
4   "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
5 <mapper namespace="conf.EmpMapper">
6   <select id="selectEmp" resultType="com.eu.pojo.Emp">
7     select id,last_name lastName,gender,email from Emp where id = #{id}
8   </select>
9 </mapper>

（9）编写测试类

 1 　　@Test
 2     public  void testMapper() throws IOException {
 3         String resource = "conf/mybatis-config.xml";
 4         InputStream inputStream = Resources.getResourceAsStream(resource);
 5         SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
 6         
 7         SqlSession session = sqlSessionFactory.openSession();
 8         try {
 9           Emp emp = (Emp) session.selectOne("conf.EmpMapper.selectEmp", 1);
10           System.out.println(emp);
11         } finally {
12           session.close();
13         }
14     }

（10）测试结果

1 DEBUG 04-14 19:20:32,007 ==>  Preparing: select id,last_name lastName,gender,email from Emp where id = ?   (BaseJdbcLogger.java:145) 
2 DEBUG 04-14 19:20:32,073 ==> Parameters: 1(Integer)  (BaseJdbcLogger.java:145) 
3 DEBUG 04-14 19:20:32,107 <==      Total: 1  (BaseJdbcLogger.java:145) 
4 Emp [id=1, lastName=张三, geder=null, email=we.com]

这种方式还存在缺陷，

 Emp emp = (Emp) session.selectOne("conf.EmpMapper.selectEmp", 1);

如果传入一个字符呢？如何查？所以必须限制传入的是合法的数字。针对这种方式进行了修改，见下一篇  MyBatis入门（二）接口式编程