学步园

使用Mybatis把握四个要点：

1.Mybatis配置文件mybatis-config.xml

2.Mybatis映射文件MyMapper.xml

3.对应映射文件的接口MyMapper.java

4.实体类My.java

1.mybatis-config.xml

<?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>

    <properties resource="properties/mybatis-config.properties">
        <property name="username" value="test"/>
        <property name="password" value="test123"/>
    </properties>

    <settings>
        <!--配置默认的执行器:重用预处理语句-->
        <setting name="defaultExecutorType" value="REUSE"/>
    </settings>

    <typeAliases>
        <typeAlias alias="Student" type="com.agcro.myapp.model.Student"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <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>
    <mappers>
        <mapper resource="com/agcro/myapp/data/StudentMapper.xml"/>
    </mappers>
</configuration>

2.MyMapper.xml

<?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="com.agcro.myapp.data.StudentMapper">
    <resultMap id="studentResultMap" type="Student">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="gender" column="gender"/>
        <result property="major" column="major"/>
        <result property="grade" column="grade"/>
    </resultMap>

    <select id="getById" parameterType="int" resultMap="studentResultMap">
        select * from student where id=#{id}
    </select>
</mapper>

3.映射接口文件MyMapper.java

package com.agcro.myapp.data;

import com.agcro.myapp.model.Student;

/**
 * Created by x on 13-6-23.
 */
public interface StudentMapper {
    public Student getById(int id);
}

4.实体类My.java

public class Student {
    private int id;
    private String name;
    private String gender;
    private String major;
    private String grade;


    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }

    public String getGrade() {
        return grade;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }

}

最后是业务测试

import com.agcro.myapp.data.StudentMapper;
import com.agcro.myapp.model.Student;
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 java.io.IOException;
import java.io.Reader;

/**
 * Created by x on 13-6-23.
 */
public class test {
    public static void main(String[] args)
    {
        //mybatis-config.xml中的mapper配置类似，告诉MyBatis
        //应读取的核心配置文件
        String resource = "com/agcro/myapp/data/mybatis-config.xml";
        Reader reader = null;
        try{
            reader = Resources.getResourceAsReader(resource);
        }catch(IOException e)
        {
            e.printStackTrace();
        }
        //创建SqlSessionFactory实例。没有指定要用到的
        //environment，则使用默认的environment
        SqlSessionFactory sqlSessionFactory
                = new SqlSessionFactoryBuilder().build(reader);

        SqlSession sqlSession = sqlSessionFactory.openSession();

        try{
            StudentMapper mapper =
                    sqlSession.getMapper(StudentMapper.class);
            Student student = mapper.getById(1);

            if(student != null)
            {
                System.out.println("姓名： "+student.getName()
                        +"\n专业： "+student.getMajor());
            }
            else
            {
                System.out.println("没有找到。");
            }
        }
        finally
        {
            sqlSession.close();
        }
    }
}

最后补充上面.properties配置文件mybatis-config.properfies

#数据库
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/test
username=test
password=test123