study Mybatis step by step

史蒂夫和斯凯

• 
  简单查询
  一、首先创建下载mybatis的相关jar包和数据库的相关jar包，mybatis的jar包的官方下载地址http://mybatis.github.io/
  
  二、建立一个java项目并且将刚才下在的jar包放在相应的文件下面，然后参照到项目中
  
  三、建立mybatis-config.xml 配置文件如下：<?xml version="1.0" encoding="UTF-8"?>
  <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.2//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
  <configuration>
  <!-- properties for the mybatis configuration -->
  <properties>
  <property name="driver" value="com.mysql.jdbc.Driver"/>
  <property name="url" value="jdbc:mysql://localhost:3306/test"/>
  <property name="username" value="root"/>
  <property name="password" value=""/>
  </properties>
  <!-- java type mapping -->
  <typeAliases>
  <typeAlias alias="Course"  type="com.mybatis.in.Course"/>
  </typeAliases>
  <!-- environment configuration -->
  <environments default="development">
  <environment id="development">
  <transactionManager type="JDBC">
  </transactionManager>
  <!-- database connection configuration -->
  <dataSource type="POOLED">
  <property name="driver" value="${driver}"/>
  <property name="url" value="${url}"/>
  <property name="username" value="${username}"/>
  <property name="password" value="${password}"/>
  </dataSource>
  </environment>
  </environments>
  <!-- mapper configuration file -->
  <mappers>
  <mapper resource="com/test/mybatis/CourseMapper.xml"/>
  </mappers>
  </configuration>
  
  四、在com.test.mybatis下面建立一个CourseMapper.xml作为course的映射配置文件
  <?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">
  <!-- configuration for course mapper -->
  <mapper namespace="com.mybatis.in.CourseMapper">
  <!-- mapping the course table and java course type-->
  <resultMap id="courseMap" type="Course">
  <id property="courseId" column="courseId"/>
  <result property="courseType" column="courseType"/>
  <result property="courseName" column="courseName"/>
  </resultMap>
  <!-- configuration for the SQL -->
  <select id="getCourses" resultMap="courseMap">
  <![CDATA[select courseId,courseType,courseName from course]]>
  </select>
  </mapper>
  五、建立CourseMapper接口和Course类
  
  CourseMapper
  
  package com.mybatis.in;
  import java.util.List;
  public interface CourseMapper {
  public List<Course> getCourses();
  }
  
  
  Course
  package com.mybatis.in;
  public class Course {
  private String courseId;
  private String courseName;
  private String courseType;
  public String getCourseId() {
  return courseId;
  }
  public void setCourseId(String courseId) {
  this.courseId = courseId;
  }
  public String getCourseName() {
  return courseName;
  }
  public void setCourseName(String courseName) {
  this.courseName = courseName;
  }
  public String getCourseType() {
  return courseType;
  }
  public void setCourseType(String courseType) {
  this.courseType = courseType;
  }
  }
  
  
  
  完成以上五个步骤，一个简单的Mybatis查询就建立好了，下面我们可以写一段程序测试一下我们上面的配置是否正确
  package com.tests;
  import java.io.IOException;
  import java.util.List;
  import org.apache.ibatis.io.Resources;
  import org.apache.ibatis.session.SqlSession;
  import org.apache.ibatis.session.SqlSessionFactory;
  import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  import com.mybatis.in.Course;
  import com.mybatis.in.CourseMapper;
  public class Main {
  /**
  * @param args
  * @throws IOException
  */
  public static void main(String[] args) throws IOException {
  SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
  SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourceAsStream("mybatis-config.xml"));
  SqlSession session = sqlSessionFactory.openSession();
  CourseMapper courseMapper =session.getMapper(CourseMapper.class);
  List<Course> courses = courseMapper.getCourses();
  System.out.println(courses.size());
  session.close();
  }
  }