MyBatis_Study_002(进阶,增删改查)

源码:https://github.com/carryLess/mbtsstd-002.git

1.主配置文件

<?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">
<!-- (以上)文件头在解压的文件夹中mybatis-3.4.4.pdf文件中搜索mybatis-3-config.dtd即可得到 -->
<configuration>

    <!-- 指定属性配置文件 -->
    <properties resource="jdbc.properties" />
    <!--
        配置类的别名,我建议使用package这种写法
        这样写会将该包中所有类的简单类名配置为别名,简单方便
        ,还有别的写法,自行google
     -->
    <typeAliases>
        <package name="model" />
    </typeAliases>
    <!-- 配置MyBatis运行环境 -->
    <environments default="development">
        <environment id="development">
            <!-- 使用JDBC事务管理 -->
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <!-- 注册映射文件 -->
    <mappers>
        <mapper resource="dao/mapper.xml"/>
        <!--
            实际开发中可能有多个映射文件,而其中sql标签的id相同时候,执行过程就会报错
            我们可以根据mapper映射文件中的namespace属性来区分,调用时候用如下方式
            namespace.id
        -->
        <!--
            <mapper resource="dao/mapper2.xml"/>
        -->
    </mappers>

</configuration>

2.jdbc.properties配置文件

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=root

3.sql映射文件

<?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">
<!-- 文件头在解压的文件夹中mybatis-3.4.4.pdf文件中搜索mybatis-3-mapper.dtd即可得到 -->
<mapper namespace="model.Student">
    <!-- parameterType属性,框架会根据SQLSession中传递的参数检测到,所以我们一般不用指定 -->
    <insert id="insertStudent" parameterType="model.Student">
        insert into student(name,age,score)
        values(#{name},#{age},#{score})
    </insert>

    <!--
        resultType:获取的主键的类型
        keyProperty:指出主键在java实体类中的属性名称
     -->
    <insert id="insertStudentCatchId">
        insert into student(name,age,score)
        values(#{name},#{age},#{score})
        <selectKey resultType="int" keyProperty="id" order="AFTER">
            select @@IDENTITY
            <!-- select last_insert_id(); -->
        </selectKey>
    </insert>

    <delete id="deletById">
        <!-- 这个#{xxx}是占位符,为delete方法的第二个参数,xxx随意填写 -->
        delete from student where id = #{xxx}
    </delete>

    <update id="updateStudent">
        <!-- #{}占位符,里面字符串与实体类的属性名称一致 -->
        update student set name = #{name},age=#{age},score=#{score} where id = #{id}
    </update>

    <!--
        resultType指定返回的结果集中每一条记录封装的对象的类型
        这里的Student是配置的别名(主配置文件中配置),如果没有配置别名,可以写全限定类名
     -->
    <select id="selectAll" resultType="Student">
        select * from student
    </select>

    <select id="selectOne" resultType="Student">
        <!-- 这个#{xxx}是占位符,xxx随意填写 -->
        select * from student where id = #{xxx}
    </select>

    <select id="selectByName" resultType="Student">
        <!-- 模糊查询 -->
        select * from student
        where name like concat('%',#{xxx},'%')
        <!--
            或者写成如下形式
            where name like '%' #{xxx} '%'
        -->
        <!--
            上两种拼接参数会动态的传入sql中,还有以下写法是纯sql拼接,可能引起sql注入
            必须写成如下形式  '%${value}%'
            where name like '%${value}%'
        -->
    </select>

    <select id="selectByMap1" resultType="Student">
        select * from student where age &gt; #{age}
    </select>

    <!-- 查询返回简单类型 -->
    <select id="selectRowCount" resultType="Integer">
        select count(1) from student
    </select>
</mapper>

4.dao接口

package dao;

import model.Student;

import java.util.List;
import java.util.Map;

/**
 * Created by carryLess on 2017/11/29.
 */
public interface IStudentDao {
    /**
     * 插入数据
     * @param student
     */
    void insertStudent(Student student);

    /**
     * 插入数据 获取id
     * @param student
     */
    void insertStudentCatchId(Student student);

    /**
     * 根据id 删除数据
     * @param id
     */
    int deletById(int id);

    /**
     * 修改数据 传入model
     * @param student
     */
    void updateStudent(Student student);

    /**
     * 查询返回所有数据的集合
     * @return
     */
    List<Student> selectAll();

    /**
     * 查询返回map
     * @return
     */
    Map<String,Student> selectMap();

    /**
     * 根据id查询实体类
     * @param id
     * @return
     */
    Student selectById(Integer id);

    /**
     * 根据姓名查询
     * @param name
     * @return
     */
    List<Student> selectByName(String name);

    /**
     * 传递map为参数进行查询
     * @param map
     * @return
     */
    List<Student> selectByMap(Map<String,Object> map);

    /**
     * 返回简单类型 Integer
     * @return
     */
    Integer selectRowCount();
}

5.dao实现类

package dao;

import model.Student;
import org.apache.ibatis.session.SqlSession;
import utils.MyBatisUtils;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * Created by carryLess on 2017/11/29.
 */
public class StudentDaoImpl implements IStudentDao {
    private SqlSession sqlSession;
    @Override
    public void insertStudent(Student student) {
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            sqlSession.insert("insertStudent",student);
            sqlSession.commit();
        }finally {
            //关闭sqlSession
            if(sqlSession != null){
                sqlSession.close();
            }
        }
    }

    @Override
    public void insertStudentCatchId(Student student) {
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            sqlSession.insert("insertStudentCatchId",student);
            sqlSession.commit();
        }finally {
            //关闭sqlSession
            if(sqlSession != null){
                sqlSession.close();
            }
        }
    }

    @Override
    public int deletById(int id) {
        int opCount;
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            opCount = sqlSession.delete("deletById",id);
            sqlSession.commit();
        }finally {
            //关闭sqlSession
            if(sqlSession != null){
                sqlSession.close();
            }
        }
        return opCount;
    }

    @Override
    public void updateStudent(Student student) {
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            sqlSession.update("updateStudent",student);
            sqlSession.commit();
        }finally {
            if(sqlSession != null){
                sqlSession.close();
            }
        }
    }

    @Override
    public List<Student> selectAll() {
        List<Student> selectAll = new ArrayList<>();
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            selectAll = sqlSession.selectList("selectAll");
        }finally {
            if(sqlSession != null){
                sqlSession.close();
            }
        }
        return selectAll;
    }

    @Override
    public Map<String, Student> selectMap() {
        Map<String,Student> sMap;
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            /*第一个参数时映射文件中sql标签的id,第二个参数指定字段名称,以此为map的key*/
            sMap = sqlSession.selectMap("selectAll", "id");
        }finally {
            if(sqlSession != null){
                sqlSession.close();
            }
        }
        return sMap;
    }

    @Override
    public Student selectById(Integer id) {
        Student student;
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            student = sqlSession.selectOne("selectOne",id);
        }finally {
            if(sqlSession != null){
                sqlSession.close();
            }
        }
        return student;
    }

    @Override
    public List<Student> selectByName(String name) {
        List<Student> students;
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            students = sqlSession.selectList("selectByName",name);
        }finally {
            if(sqlSession != null){
                sqlSession.close();
            }
        }
        return students;
    }

    @Override
    public List<Student> selectByMap(Map<String, Object> map) {
        List<Student> students;
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            students = sqlSession.selectList("selectByMap1",map);
        }finally {
            if(sqlSession != null){
                sqlSession.close();
            }
        }
        return students;
    }

    @Override
    public Integer selectRowCount() {
        Integer rowCount;
        try {
            sqlSession = MyBatisUtils.getSqlSession();
            rowCount = sqlSession.selectOne("selectRowCount");
        }finally {
            if(sqlSession != null){
                sqlSession.close();
            }
        }
        return rowCount;
    }

}

6.实体类

package model;

/**
 * Created by carryLess on 2017/11/29.
 */
public class Student {
    private Integer id;
    private String name;
    private Integer age;
    private double score;

    public Student() {
    }

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

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", score=" + score +
                '}';
    }

    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 double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }
}

7.工具类

package utils;

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.InputStream;

/**
 * Created by carryLess on 2017/11/30.
 */
public class MyBatisUtils {

    /*
    * SqlSession 由SqlSessionFactory对象创建,
    * 而SqlSessionFactory对象为重量级对象
    * 并且是线程安全的,所以我们将其设为单例
    * */
    private static SqlSessionFactory factory;

    /**
     * 私有化构造方法,避免该工具类在外部被实例化
     */
    private MyBatisUtils(){}

    /**
     * 获取 SqlSession
     * @return
     */
    public static SqlSession getSqlSession(){
        try {
            if(factory == null){
                //读取配置文件
                InputStream inputStream = Resources.getResourceAsStream("mybatis.xml");
                //创建工厂类
                factory = new SqlSessionFactoryBuilder().build(inputStream);
            }
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        /*
        * factory.openSession(true);     创建一个有自动提交功能的SqlSession
        * factory.openSession(false);    创建一个没有自动提交功能的SqlSession,需要手动提交
        * factory.openSession();         同factory.openSession(false);
        */
        return factory.openSession();
    }
}

8.测试类

package test;

import dao.IStudentDao;
import dao.StudentDaoImpl;
import model.Student;
import org.junit.Before;
import org.junit.Test;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by carryLess on 2017/11/29.
 */
public class MyTest {

    private IStudentDao dao;

    @Before
    public void initDao(){
        dao = new StudentDaoImpl();
    }

    @Test
    public void insertTest(){
        Student student = new Student("张三",18,60.0);
        IStudentDao dao = new StudentDaoImpl();
        dao.insertStudent(student);
    }

    @Test
    public void insertCatchIdTest(){
        Student student = new Student("李四",14,34.3);
        System.out.println(student);
        dao.insertStudentCatchId(student);
        System.out.println(student);
    }

    @Test
    public void testDeletById(){
       dao.deletById(8);
    }

    @Test
    public void testUpdate(){
        Student student = new Student("wangmazi",24,54);
        student.setId(2);
        dao.updateStudent(student);
    }

    @Test
    public void testSelectAll(){
        List<Student> students = dao.selectAll();
        System.out.println(students);
    }

    @Test
    public void testSelectMap(){
        Map<String, Student> selectMap = dao.selectMap();
        System.out.println(selectMap);
    }

    @Test
    public void testSelectOne(){
        Student student = dao.selectById(3);
        System.out.println(student);
    }

    @Test
    public void testSelectByNames(){
        List<Student> students = dao.selectByName("w");
        System.out.println(students);
    }

    @Test
    public void testSelectByMap(){
        Map<String,Object> map = new HashMap<String,Object>();
        map.put("age",10);
        List<Student> students = dao.selectByMap(map);
        System.out.println(students);
    }

    @Test
    public void testSelectRowCount(){
        System.out.println(dao.selectRowCount());
    }
}

9.建表sql

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL,
  `age` int(3) DEFAULT NULL,
  `score` double DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;