快速学习-MyBatis入门

第2章 MyBatis HelloWorld

2.1 开发环境的准备

1. 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

2. 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>

2.2 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)
);

2.3 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 + "]";
  }

2.3 创建MyBatis的全局配置文件

1. 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>

2.4 创建Mybatis的sql映射文件

1. 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>

2.5 测试

1. 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();
    }
  }

2.6 Mapper接口开发MyBatis HelloWorld

1. 编写Mapper接口

public interface EmployeeMapper {

  public Employee getEmployeeById(Integer id ); 

}

2. 完成两个绑定

• • 
    
• ①Mapper接口与Mapper映射文件的绑定在Mppper映射文件中的标签中的namespace中必须指定Mapper接口的全类名
• ②Mapper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.
  • 
    

3. 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();
    }
  }