MyBatis3（一）

第二章 MyBatis 项目配置

第一节：environments
MyBatis 支持多个环境，可以任意配置（开发环境，测试环境...）；

第二节：transactionManager
MyBatis 支持两种类型的事务管理器：JDBC 和 MANAGED(托管)；
JDBC：应用程序负责管理数据库连接的生命周期，Tomcat 就选JDBC ；
MANAGED：由应用服务器负责管理数据库连接的生命周期；(一般商业服务器才有此功能，如
JBOSS,WebLogic)

第三节：dataSource
用来配置数据源；类型有：UNPOOLED，POOLED，JNDI；
UNPOOLED，没有连接池，每次数据库操作，MyBatis 都会创建一个新的连接，用完后，关闭；适合小并发
项目；
POOLED，用上了连接池；
JNDI，使用应用服务器配置 JNDI 数据源获取数据库连接；

第四节：properties
配置属性 <properties resource="jdbc.properties"/>

第五节：typeAliases
给类的完成限定名取别名，方便使用；<typeAliases><package name="com.java1234.model"/></typeAliases>, 这样mappers映射文件可以写别名。

第六节：mappers
引入映射文件　　<mappers><package name="com.java1234.mappers"/></mappers>

第七节：配置 Log4j日志

<?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="jdbc.properties"/> -->
    <properties>                <!-- 2种都可以，上面的简洁点 -->
        <property name="jdbc.driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="jdbc.url" value="jdbc:mysql://localhost:3306/db_mybatis"/>
        <property name="jdbc.username" value="root"/>
        <property name="jdbc.password" value="123456"/>
    </properties>
    
    <!-- <typeAliases>
        <typeAlias alias="Student" type="com.java1234.model.Student"/>
    </typeAliases> -->
    <typeAliases>
        <package name="com.java1234.model"/>    <!-- 把包下所有类自动取别名 -->    
    </typeAliases>
    
    <environments default="development">        <!-- MyBatis 支持多个环境 -->
        <environment id="development">
            <transactionManager type="JDBC" />        <!-- 应用程序负责管理数据库连接的生命周期,Tomcat 就选JDBC -->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driverClassName}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <!-- <mapper resource="com/java1234/mappers/StudentMapper.xml" /> -->
        <!-- <mapper class="com.java1234.mappers.StudentMapper"/> -->
        <package name="com.java1234.mappers"/>
    </mappers>
</configuration>

mybatis-config.xml

public class SqlSessionFactoryUtil {

    private static SqlSessionFactory sqlSessionFactory;
    
    public static SqlSessionFactory getSqlSessionFactory(){
        if(sqlSessionFactory==null){
            InputStream inputStream=null;
            try{
                inputStream=Resources.getResourceAsStream("mybatis-config.xml");
                sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
            }catch(Exception e){
                e.printStackTrace();
            }
        }
        return sqlSessionFactory;
    }
    
    public static SqlSession openSession(){
        return getSqlSessionFactory().openSession();
    }
}

SqlSessionFactory

public class StudentTest {

    private static Logger logger=Logger.getLogger(StudentTest.class);
    
    public static void main(String[] args) {
        SqlSession sqlSession=SqlSessionFactoryUtil.openSession();
        StudentMapper studentMapper=sqlSession.getMapper(StudentMapper.class);
        Student student=new Student("李四",11);
        int result=studentMapper.add(student);
        sqlSession.commit();
        if(result>0){
            logger.info("添加成功！");
        }
    }
}

StudentTest

<?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.java1234.mappers.StudentMapper">

    <insert id="add" parameterType="Student"  >
        insert into t_student values(null,#{name},#{age})
    </insert>

</mapper>

StudentMapper.xml

log4j.rootLogger=info,appender1,appender2

log4j.appender.appender1=org.apache.log4j.ConsoleAppender 

log4j.appender.appender2=org.apache.log4j.FileAppender 
log4j.appender.appender2.File=C:/logFile.txt
 
log4j.appender.appender1.layout=org.apache.log4j.TTCCLayout
log4j.appender.appender2.layout=org.apache.log4j.TTCCLayout

log4j.properties

第三章使用 XML配置SQL映射器

第一节：INSERT映射语句
第二节：UPDATE 映射语句
第三节：DELETE 映射语句
第四节：SELECT 映射语句

<?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.java1234.mappers.StudentMapper">

    <resultMap type="Student" id="StudentResult">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
    </resultMap>

    <insert id="add" parameterType="Student"  >
        insert into t_student values(null,#{name},#{age})
    </insert>

    <update id="update" parameterType="Student">
        update t_student set name=#{name},age=#{age} where id=#{id}
    </update>
    
    <delete id="delete" parameterType="Integer">
        delete from t_student where id=#{id}
    </delete>
    
    <select id="findById" parameterType="Integer" resultType="Student">
        select * from t_student where id=#{id}
    </select>
    
    <select id="find" resultMap="StudentResult">
        select * from t_student
    </select>
</mapper>

StudentMapper.xml

public interface StudentMapper {

    public int add(Student student);
    
    public int update(Student student);
    
    public int delete(Integer id);
    
    public Student findById(Integer id);
    
    public List<Student> find();
}




public class StudentTest2 {

    private static Logger logger=Logger.getLogger(StudentTest.class);
    private SqlSession sqlSession=null;
    private StudentMapper studentMapper=null;
    
    /**
     * 测试方法前调用
     * @throws Exception
     */
    @Before
    public void setUp() throws Exception {
        sqlSession=SqlSessionFactoryUtil.openSession();
        studentMapper=sqlSession.getMapper(StudentMapper.class);
    }

    /**
     * 测试方法后调用
     * @throws Exception
     */
    @After
    public void tearDown() throws Exception {
        sqlSession.close();
    }

    @Test
    public void testAdd() {
        logger.info("添加学生");
        Student student=new Student("王五",12);
        studentMapper.add(student);
        sqlSession.commit();
    }
    
    @Test
    public void testUpdate(){
        logger.info("修改学生");
        Student student=new Student(8,"王五2",13);
        studentMapper.update(student);
        sqlSession.commit();
    }
    
    @Test
    public void testDelete(){
        logger.info("删除学生");
        studentMapper.delete(8);
        sqlSession.commit();
    }
    
    @Test
    public void testFindById(){
        logger.info("通过ID查找学生");
        Student student=studentMapper.findById(1);
        System.out.println(student);
    }

    @Test
    public void testFind(){
        logger.info("查找所有学生");
        List<Student> studentList=studentMapper.find();
        for(Student s:studentList){
            System.out.println(s);
        }
    }
}

StudentMapper.java

第四章 MyBatis 关系映射

第一节：一对一关系实现

<!-- 对象级联方式，重用性不好，column 是数据库的字段，property是类的属性 -->
    <!-- <resultMap type="Student" id="StudentResult">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
        
        <result property="address.id" column="addressId"/>
        <result property="address.sheng" column="sheng"/>
        <result property="address.shi" column="shi"/>
        <result property="address.qu" column="qu"/>
    </resultMap> -->
    
    <!-- 方式二： -->
    <!-- <resultMap type="Address" id="AddressResult">
        <result property="id" column="id"/>
        <result property="sheng" column="sheng"/>
        <result property="shi" column="shi"/>
        <result property="qu" column="qu"/>
    </resultMap>
    
    <resultMap type="Student" id="StudentResult">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
        <association property="address" resultMap="AddressResult"/>
    </resultMap> -->
    
    <!-- 方式三：同上，只是把属性写在里面 -->
    <!-- <resultMap type="Student" id="StudentResult">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
        <association property="address" javaType="Address">
            <result property="id" column="id"/>
            <result property="sheng" column="sheng"/>
            <result property="shi" column="shi"/>
            <result property="qu" column="qu"/>
        </association>
    </resultMap> -->
    
    <!-- 推荐使用，关联对象的属性address， 对应student表的外键addressId,select是根据id的查询方法 -->
    <resultMap type="Student" id="StudentResult">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
        <association property="address" column="addressId" select="com.java1234.mappers.AddressMapper.findById"></association>
    </resultMap>

<select id="findStudentWithAddress" resultMap="StudentResult" parameterType="Integer">
        select * from t_student t1,t_address t2 where t1.addressId=t2.id and t1.id=#{id}
    </select>

StudentMapper.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.java1234.mappers.AddressMapper">

    <resultMap type="Address" id="AddressResult">
        <result property="id" column="id"/>
        <result property="sheng" column="sheng"/>
        <result property="shi" column="shi"/>
        <result property="qu" column="qu"/>
    </resultMap>
    
    <select id="findById" parameterType="Integer" resultType="Address">
        select * from t_address where id=#{id}
    </select>

</mapper>

AddressMapper.xml

package com.java1234.model;

public class Address {

    private Integer id;
    private String sheng;
    private String shi;
    private String qu;
    
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getSheng() {
        return sheng;
    }
    public void setSheng(String sheng) {
        this.sheng = sheng;
    }
    public String getShi() {
        return shi;
    }
    public void setShi(String shi) {
        this.shi = shi;
    }
    public String getQu() {
        return qu;
    }
    public void setQu(String qu) {
        this.qu = qu;
    }
    @Override
    public String toString() {
        return "Address [id=" + id + ", sheng=" + sheng + ", shi=" + shi
                + ", qu=" + qu + "]";
    }
    
    
}


package com.java1234.model;

public class Student {

    private Integer id;
    private String name;
    private Integer age;
    private Address address;
    
    
    public Student() {
        super();
        // TODO Auto-generated constructor stub
    }
    
    
    public Student(Integer id, String name, Integer age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }


    public Student(String name, Integer age) {
        super();
        this.name = name;
        this.age = age;
    }



    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public Address getAddress() {
        return address;
    }


    public void setAddress(Address address) {
        this.address = address;
    }




    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", age=" + age
                + ", address=" + address + "]";
    }
    
}

=============StudentTest3=======================

    @Test
    public void testFindStudentWithAddress() {
        logger.info("查询学生(带地址)");
        Student student=studentMapper.findStudentWithAddress(2);
        System.out.println(student);
    }

View Code

第二节：一对多关系实现

注意student 和 grade 的toString方法，只能有一边打印对方，如果双向打印对方，就会内存溢出，陷入死循环。

resultMap 中有些常用参数id,result,association,collection. GradeMapper中关联查询学生，是通过主键id，而StudentMapper中关联查询年级，是通过外键gradeId。

<resultMap type="Student" id="StudentResult">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
        <association property="address" column="addressId" select="com.java1234.mappers.AddressMapper.findById"></association>
        <association property="grade" column="gradeId" select="com.java1234.mappers.GradeMapper.findById"></association>
    </resultMap>
    
    <select id="findStudentWithAddress" resultMap="StudentResult" parameterType="Integer">
        select * from t_student t1,t_address t2 where t1.addressId=t2.id and t1.id=#{id}
    </select>
    
    <select id="findByGradeId" resultMap="StudentResult" parameterType="Integer">
        select * from t_student where gradeId=#{gradeId}
    </select>


==========================================


<mapper namespace="com.java1234.mappers.GradeMapper">

    <resultMap type="Grade" id="GradeResult">
        <result property="id" column="id"/>
        <result property="gradeName" column="gradeName"/>
        <collection property="students" column="id" select="com.java1234.mappers.StudentMapper.findByGradeId"></collection>
    </resultMap>
    
    <select id="findById" parameterType="Integer" resultMap="GradeResult">
        select * from t_grade where id=#{id}
    </select>

</mapper>

mapper.xml

package com.java1234.model;

public class Student {

    private Integer id;
    private String name;
    private Integer age;
    private Address address;
    private Grade grade;
    
    
    public Student() {
        super();
        // TODO Auto-generated constructor stub
    }
    
    
    public Student(Integer id, String name, Integer age) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
    }




    public Student(String name, Integer age) {
        super();
        this.name = name;
        this.age = age;
    }



    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public Address getAddress() {
        return address;
    }


    public void setAddress(Address address) {
        this.address = address;
    }

    
    public Grade getGrade() {
        return grade;
    }

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


    @Override
    public String toString() {
        return "Student [id=" + id + ", name=" + name + ", age=" + age
                + ", address=" + address + ", grade=" + grade + "]";
    }

}


package com.java1234.model;

import java.util.List;

public class Grade {

    private Integer id;
    private String gradeName;
    private List<Student> students;
    
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getGradeName() {
        return gradeName;
    }
    public void setGradeName(String gradeName) {
        this.gradeName = gradeName;
    }
    public List<Student> getStudents() {
        return students;
    }
    public void setStudents(List<Student> students) {
        this.students = students;
    }
    @Override
    public String toString() {
        return "Grade [id=" + id + ", gradeName=" + gradeName +"]";
    }
    
    
}

model

package com.java1234.service;


import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import com.java1234.mappers.GradeMapper;
import com.java1234.model.Grade;
import com.java1234.util.SqlSessionFactoryUtil;

public class GradeTest {

    private static Logger logger=Logger.getLogger(StudentTest.class);
    private SqlSession sqlSession=null;
    private GradeMapper gradeMapper=null;
    
    /**
     * 测试方法前调用
     * @throws Exception
     */
    @Before
    public void setUp() throws Exception {
        sqlSession=SqlSessionFactoryUtil.openSession();
        gradeMapper=sqlSession.getMapper(GradeMapper.class);
    }

    /**
     * 测试方法后调用
     * @throws Exception
     */
    @After
    public void tearDown() throws Exception {
        sqlSession.close();
    }

    @Test
    public void testFindGradeWithStudents() {
        logger.info("查询年级(带学生)");
        Grade grade=gradeMapper.findById(1);
        System.out.println(grade);
    }
    
}


/*要注意更改tostring方法，开始测试了查询年级带出所以学生，要把打印学生的信息删除，否则这次查询学生(带年级)会导致死循环。*/
    @Test
    public void testFindStudentWithGrade(){
        logger.info("查询学生(带年级)");
        Student student=studentMapper.findStudentWithAddress(1);
        System.out.println(student);
    }

View Code

CREATE TABLE `t_student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `addressId` int(11) DEFAULT NULL,
  `gradeId` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `FK_t_student` (`gradeId`),
  KEY `FK_t_student2` (`addressId`),
  CONSTRAINT `FK_t_student2` FOREIGN KEY (`addressId`) REFERENCES `t_address` (`id`),
  CONSTRAINT `FK_t_student` FOREIGN KEY (`gradeId`) REFERENCES `t_grade` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;

CREATE TABLE `t_grade` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `gradeName` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;


CREATE TABLE `t_address` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `sheng` varchar(20) DEFAULT NULL,
  `shi` varchar(20) DEFAULT NULL,
  `qu` varchar(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

View Code

posted @ 2017-04-05 10:14 SKYisLimit 阅读(131) 评论(0) 收藏举报

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MyBatis3（一）

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