MyBatis的单表CRUD操作

1、创建maven工程，导入坐标

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.itcast</groupId>
    <artifactId>mybatis_crud</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>jar</packaging>

    <dependencies>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.26</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>

    </dependencies>

</project>

2、工程目录

3、数据库表字段

CREATE DATABASE mybatis;
USE DATABASE;

DROP TABLE IF EXISTS student;

CREATE TABLE `student` (
  studentNo INT(8) NOT NULL AUTO_INCREMENT COMMENT '学生学号',
  studentName VARCHAR(32) NOT NULL COMMENT '学生姓名',
  sex CHAR(1) DEFAULT NULL COMMENT '学生性别',
  birthday DATETIME DEFAULT NULL COMMENT '学生生日',
  PRIMARY KEY(studentNo)
) ENGINE=INNODB DEFAULT CHARSET = utf8;

INSERT  INTO student(studentNo,studentName,sex,birthday) VALUES(100,'张三同学','男','2018-02-27 17:47:08');
INSERT  INTO student(studentNo,studentName,sex,birthday) VALUES(101,'李四同学','男','2018-02-27 17:47:08');
INSERT  INTO student(studentNo,studentName,sex,birthday) VALUES(102,'王五同学','男','2018-02-27 17:47:08');
INSERT  INTO student(studentNo,studentName,sex,birthday) VALUES(103,'赵六同学','男','2018-02-27 17:47:08');

4、表对应的实体类

package domain;

import java.io.Serializable;
import java.util.Date;

public class Student implements Serializable {
    private Integer studentNo;
    private String studentName;
    private String sex;
    private Date birthday;

    public Student() {
    }

    public Student(Integer studentNo, String studentName, String sex, Date birthday) {
        this.studentNo = studentNo;
        this.studentName = studentName;
        this.sex = sex;
        this.birthday = birthday;
    }

    public Integer getStudentNo() {
        return studentNo;
    }

    public void setStudentNo(Integer studentNo) {
        this.studentNo = studentNo;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "Student{" +
                "studentNo=" + studentNo +
                ", studentName='" + studentName + '\'' +
                ", sex='" + sex + '\'' +
                ", birthday=" + birthday +
                '}';
    }
}

5、实体类对应的DAO接口

package dao;

import domain.Student;

import java.util.List;

public interface StudentDao {

    /**
     * 全表查询
     * @return
     */
    List<Student> findAll();

    /**
     * 根据条件查询
     * @return
     */
    List<Student> findByCondition(Student student);

    /**
     * 插入
     * @param student
     */
    void save(Student student);

    /**
     * 更新（根据ID）
     * @param student
     */
    void update(Student student);

    /**
     * 根据条件删除
     * @param student
     */
    void deleteByCondition(Student student);
}

6、DAO对应的Mapper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">

<mapper namespace="dao.StudentDao">
    <!-- 全表查询 -->
    <select id="findAll" resultType="domain.Student">
        SELECT * FROM student;
    </select>

    <!-- 根据条件查询 -->
    <select id="findByCondition" parameterType="Student" resultType="Student">
        SELECT *
        FROM student
        <where>
            <if test="studentNo != null">
                studentNo = #{studentNo}
            </if>
            <if test="studentName != null">
                AND studentName = #{studentName}
            </if>
            <if test="sex != null">
                AND sex = #{sex}
            </if>
            <if test="birthday != null">
                AND birthday = #{birthday}
            </if>
        </where>

    </select>

    <!-- 插入 -->
    <insert id="save" parameterType="Student">
        INSERT INTO student
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="studentNo != null">
                studentNo,
            </if>
            <if test="studentName != null">
                studentName,
            </if>
            <if test="sex != null">
                sex,
            </if>
            <if test="birthday != null">
                birthday
            </if>
        </trim>

        <trim prefix="VALUES(" suffix=")" suffixOverrides=",">
            <if test="studentNo != null">
                #{studentNo},
            </if>
            <if test="studentName != null">
                #{studentName},
            </if>
            <if test="sex != null">
                #{sex},
            </if>
            <if test="birthday != null">
                #{birthday}
            </if>
        </trim>
    </insert>

    <!-- 更新（根据ID） -->
    <update id="update" parameterType="Student">
        UPDATE student
        <!-- 一般使用set标签 -->
        <trim prefix="SET" suffixOverrides=",">
            <if test="studentName != null">
                studentName = #{studentName},
            </if>
            <if test="sex != null">
                sex = #{sex},
            </if>
            <if test="birthday != null">
                birthday = #{birthday}
            </if>
        </trim>
        WHERE studentNo = #{studentNo}
    </update>

    <!-- 删除 -->
    <delete id="deleteByCondition" parameterType="Student">
        DELETE FROM student
        <trim prefix="WHERE" prefixOverrides="AND">
            <if test="studentNo != null">
                studentNo = #{studentNo}
            </if>
            <if test="studentName != null">
                AND studentName = #{studentName}
            </if>
            <if test="sex != null">
                AND sex = #{sex}
            </if>
            <if test="birthday != null">
                AND birthday = #{birthday}
            </if>
        </trim>
    </delete>
</mapper>

7、全局配置文件

<?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">

<!-- mybatis环境配置 -->
<configuration>
    <!--
        properties：引入配置文件
        resource：用于指定配置配置文件的classPath与fileName
    -->
    <properties resource="./db.properties"></properties>

    <!-- 使用别名 -->
    <typeAliases>
        <!-- 给domain.Student类起一个名为Student类的别名，这样做的好处是在使用该类的时候不需要写包名 -->
        <!-- <typeAlias type="domain.Student" alias="Student"></typeAlias> -->
        <!-- 整个包下的所有类都起别名，别名为类名，不区分大小写 -->
        <package name="domain"/>
    </typeAliases>
    <!--
        environments：环境，可以配置多个
        default：用于指定采用哪个环境
    -->
    <environments default="development">
        <!-- id：唯一标识 -->
        <environment id="development">
            <!-- transactionManager：事务管理器，此处采用jdbc类型的事务管理器 -->
            <transactionManager type="jdbc"></transactionManager>
            <!--
                dataSource：用于指定连接池的类型
                property：配置连接池的数据源
            -->
            <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>

        <environment id="production">
            <transactionManager type="jdbc"></transactionManager>
            <dataSource type="pooled">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!-- <mapper resource="dao/StudentDao.xml"></mapper> -->
        <package name="dao"/>
    </mappers>
    
</configuration>

8、Junit测试类

import dao.StudentDao;
import domain.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 org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class TestMybatis {
    private InputStream inputStream;
    private SqlSessionFactory sqlSessionFactory;
    private SqlSession sqlSession;

    @Before
    public void init() {
        try {
            inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        } catch (IOException e) {
            e.printStackTrace();
        }
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        sqlSession = sqlSessionFactory.openSession();
    }

    @After
    public void destroy() {
        //1. 提交事务
        sqlSession.commit();
        //2. 关闭资源
        if (sqlSession != null) {
            sqlSession.close();
        }
        if (inputStream != null) {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 全表查询
     */
    @Test
    public void test_findAll() {
        //1. 获取接口的代理对象
        StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
        //2. 使用接口的代理对象调用接口中的方法
        List<Student> students = studentDao.findAll();
        //3. 遍历输出
        for (Student student : students) {
            System.out.println(student);
        }
    }

    /**
     * 根据条件查询
     */
    @Test
    public void test_findByCondition() {
        Student student = new Student();
        student.setStudentName("张三同学");
        //1. 获取接口的代理对象
        StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
        //2. 使用接口的代理对象调用接口中的方法
        List<Student> students = studentDao.findByCondition(student);
        //3. 遍历输出
        for (Student stu : students) {
            System.out.println(stu);
        }
    }

    /**
     * 插入
     */
    @Test
    public void test_save() {
        Student student = new Student();
        student.setStudentName("田七同学");
        student.setSex("男");
        //1. 获取接口的代理对象
        StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
        //2. 使用接口的代理对象调用接口中的方法
        studentDao.save(student);
    }

    /**
     * 更新（根据ID）
     */
    @Test
    public void test_update() {
        Student student = new Student();
        student.setStudentNo(107);
        student.setStudentName("露西同学");
        student.setSex("女");
        //1. 获取接口的代理对象
        StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
        //2. 使用接口的代理对象调用接口中的方法
        studentDao.update(student);
    }

    /**
     * 根据条件删除
     */
    @Test
    public void test_deleteByCondition() {
        Student student = new Student();
        //student.setStudentNo(108);
        student.setStudentName("田七同学");
        //1. 获取接口的代理对象
        StudentDao studentDao = sqlSession.getMapper(StudentDao.class);
        //2. 使用接口的代理对象调用接口中的方法
        studentDao.deleteByCondition(student);
    }
}