Java培训课程之MyBatis HelloWorld

1 开发环境的准备

  • 导入MyBatis框架的jar包、Mysql驱动包、log4j的jar包

myBatis-3.4.1.jar

mysql-connector-java-5.1.37-bin.jar

log4j.jar
  • 导入log4j 的配置文件

<?xml version=”1.0″ encoding=”UTF-8″ ?>

<!DOCTYPE log4j:configuration SYSTEM “log4j.dtd”>

 

<log4j:configuration xmlns:log4j=”http://jakarta.apache.org/log4j/”>

 

 <appender name=”STDOUT” class=”org.apache.log4j.ConsoleAppender”>

   <param name=”Encoding” value=”UTF-8″ />

   <layout class=”org.apache.log4j.PatternLayout”>

    <param name=”ConversionPattern” value=”%-5p %d{MM-dd HH:mm:ss,SSS} %m  (%F:%L) \n” />

   </layout>

 </appender>

 <logger name=”java.sql”>

   <level value=”debug” />

 </logger>

 <logger name=”org.apache.ibatis”>

   <level value=”info” />

 </logger>

 <root>

   <level value=”debug” />

   <appender-ref ref=”STDOUT” />

 </root>

</log4j:configuration>

2 创建测试表

— 创建库

CREATE DATABASE test_mybatis;

— 使用库

USE test_mybatis;

— 创建表

CREATE TABLE tbl_employee(

   id INT(11) PRIMARY KEY AUTO_INCREMENT,

   last_name VARCHAR(50),

   email VARCHAR(50),

   gender CHAR(1)

);

3 创建javaBean

public class Employee {

 

         private Integer id ;

         private String lastName;

         private String email ;

         private String gender ;

         public Integer getId() {

                  return id;

         }

         public void setId(Integer id) {

                  this.id = id;

         }

         public String getLastName() {

                  return lastName;

         }

         public void setLastName(String lastName) {

                  this.lastName = lastName;

         }

         public String getEmail() {

                  return email;

         }

         public void setEmail(String email) {

                  this.email = email;

         }

         public String getGender() {

                  return gender;

         }

         public void setGender(String gender) {

                  this.gender = gender;

         }

         @Override

         public String toString() {

                  return “Employee [id=” + id + “, lastName=” + lastName + “, email=” + email + “, gender=” + gender + “]”;

         }

4创建MyBatis的全局配置文件

  • 参考MyBatis的官网手册

<?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>

         <!– 数据库连接环境的配置 –>

         <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/mybatis_1129” />

                                   <property name=“username” value=“root” />

                                   <property name=“password” value=“1234” />

                          </dataSource>

                  </environment>

         </environments>

         <!– 引入SQL映射文件,Mapper映射文件 –>

         <mappers>

                  <mapper resource=“EmployeeMapper.xml” />

         </mappers>

</configuration>

5 创建Mybatis的sql映射文件

  • 参考MyBatis的官方手册

<?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=“suibian”>

         <select id=“selectEmployee” resultType=“com.atguigu.myabtis.helloWorld.Employee”>

                  select id ,last_name lastName ,email ,gender from tbl_employee where id = #{id}

                  <!– select * from tbl_employee  where id = #{id} –>

         </select>

</mapper>

6 测试

  • 参考MyBatis的官方手册

@Test

         public void test() throws Exception {

                  String resource = “mybatis-config.xml”;

                  InputStream inputStream = Resources.getResourceAsStream(resource);

                  SqlSessionFactory sqlSessionFactory =

                                            new SqlSessionFactoryBuilder().build(inputStream);

                  System.out.println(sqlSessionFactory);

 

                  SqlSession session  = sqlSessionFactory.openSession();

                  try {

                          Employee employee =

                                            session.selectOne(“suibian.selectEmployee”, 1001);

                          System.out.println(employee);

                  } finally {

                          session.close();

                  }

         }

7 Mapper接口开发MyBatis HelloWorld

  • 编写Mapper接口

public interface EmployeeMapper {

 

         public Employee getEmployeeById(Integer id );     

 

}

 

 

  • 完成两个绑定
  • Mapper接口与Mapper映射文件的绑定

在Mppper映射文件中的<mapper>标签中的namespace中必须指定Mapper接口

的全类名

  • Mapper映射文件中的增删改查标签的id必须指定成Mapper接口中的方法名.
  • 获取Mapper接口的代理实现类对象

         @Test

         public void test()  throws Exception{

                  String resource = “mybatis-config.xml”;

                  InputStream inputStream =

                 Resources.getResourceAsStream(resource);

                  SqlSessionFactory sqlSessionFactory =

                                   new SqlSessionFactoryBuilder()

              .build(inputStream);        

                  SqlSession session =

                         sqlSessionFactory.openSession();

 

                  try {

                          //Mapper接口:获取Mapper接口的 代理实现类对象

                          EmployeeMapper mapper =

                 session.getMapper(EmployeeMapper.class);         

                          Employee employee =

                  mapper.getEmployeeById(1006);

                          System.out.println(employee);

                  } finally {

                          session.close();

                  }

         }

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