Mybatis示例講解注解開發(fā)中的單表操作

更新時(shí)間：2022年07月06日 09:17:00 作者：流楚丶格念

這篇文章主要介紹了使用Mybatis對(duì)數(shù)據(jù)庫進(jìn)行單表操作的實(shí)現(xiàn)示例，文中通過示例代碼介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值，需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

Mybatis注解開發(fā)單表操作

MyBatis的常用注解

Mybatis也可以使用注解開發(fā)方式，這樣我們就可以減少編寫Mapper映射文件了。我們先圍繞一些基本的CRUD來學(xué)習(xí)，再學(xué)習(xí)復(fù)雜映射多表操作。

注解	說明
@Insert	實(shí)現(xiàn)新增
@Update	實(shí)現(xiàn)更新
@Delete	實(shí)現(xiàn)刪除
@Select	實(shí)現(xiàn)查詢
@Result	實(shí)現(xiàn)結(jié)果集封裝
@Results	可以與@Result 一起使用，封裝多個(gè)結(jié)果集
@One	實(shí)現(xiàn)一對(duì)一結(jié)果集封裝
@Many	實(shí)現(xiàn)一對(duì)多結(jié)果集封

MyBatis的增刪改查

我們完成簡單的student表的增刪改查的操作

步驟一:創(chuàng)建mapper接口

public interface StudentMapper {
    //查詢?nèi)?
    @Select("SELECT * FROM student")
    public abstract List<Student> selectAll();
    //新增操作
    @Insert("INSERT INTO student VALUES (#{id},#{name},#{age})")
    public abstract Integer insert(Student stu);
    //修改操作
    @Update("UPDATE student SET name=#{name},age=#{age} WHERE id=#{id}")
    public abstract Integer update(Student stu);
    //刪除操作
    @Delete("DELETE FROM student WHERE id=#{id}")
    public abstract Integer delete(Integer id);
}

步驟二：測試類

public class Test01 {
    @Test
    public void selectAll() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        List<Student> list = mapper.selectAll();
        //6.處理結(jié)果
        for (Student student : list) {
            System.out.println(student);
        }
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
    @Test
    public void insert() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        Student stu = new Student(4,"趙六",26);
        Integer result = mapper.insert(stu);
        //6.處理結(jié)果
        System.out.println(result);
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
    @Test
    public void update() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        Student stu = new Student(4,"趙六",36);
        Integer result = mapper.update(stu);
        //6.處理結(jié)果
        System.out.println(result);
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
    @Test
    public void delete() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        Integer result = mapper.delete(4);
        //6.處理結(jié)果
        System.out.println(result);
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
}

例如運(yùn)行test1結(jié)果如下：

注意：

修改MyBatis的核心配置文件，我們使用了注解替代的映射文件，所以我們只需要加載使用了注解的Mapper接口即可

<mappers>
    <!--掃描使用注解的類-->
    <mapper class="com.yyl.mapper.UserMapper"></mapper>
</mappers>

? 或者指定掃描包含映射關(guān)系的接口所在的包也可以

<mappers>
    <!--掃描使用注解的類所在的包-->
    <package name="com.yyl.mapper"></package>
</mappers>

注解開發(fā)總結(jié)

注解可以簡化開發(fā)操作，省略映射配置文件的編寫。

常用注解

@Select(“查詢的 SQL 語句”)：執(zhí)行查詢操作注解
@Insert(“查詢的 SQL 語句”)：執(zhí)行新增操作注解
@Update(“查詢的 SQL 語句”)：執(zhí)行修改操作注解
@Delete(“查詢的 SQL 語句”)：執(zhí)行刪除操作注解

配置映射關(guān)系

<mappers> 
    <package name="接口所在包"/> 
</mappers>

練習(xí)項(xiàng)目代碼

bean

package com.yyl.bean;
public class Student {
    private Integer id;
    private String name;
    private Integer age;
    public Student() {
    }
    public Student(Integer id, String name, Integer age) {
        this.id = id;
        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;
    }
    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

mapper.class

package com.yyl.mapper;
import com.yyl.bean.Student;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import java.util.List;
public interface StudentMapper {
    //查詢?nèi)?
    @Select("SELECT * FROM student")
    public abstract List<Student> selectAll();
    //新增操作
    @Insert("INSERT INTO student VALUES (#{id},#{name},#{age})")
    public abstract Integer insert(Student stu);
    //修改操作
    @Update("UPDATE student SET name=#{name},age=#{age} WHERE id=#{id}")
    public abstract Integer update(Student stu);
    //刪除操作
    @Delete("DELETE FROM student WHERE id=#{id}")
    public abstract Integer delete(Integer id);
}

test

package com.yyl.test;
import com.yyl.bean.Student;
import com.yyl.mapper.StudentMapper;
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.Test;
import java.io.InputStream;
import java.util.List;
public class Test01 {
    @Test
    public void selectAll() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        List<Student> list = mapper.selectAll();
        //6.處理結(jié)果
        for (Student student : list) {
            System.out.println(student);
        }
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
    @Test
    public void insert() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        Student stu = new Student(4,"趙六",26);
        Integer result = mapper.insert(stu);
        //6.處理結(jié)果
        System.out.println(result);
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
    @Test
    public void update() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        Student stu = new Student(4,"趙六",36);
        Integer result = mapper.update(stu);
        //6.處理結(jié)果
        System.out.println(result);
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
    @Test
    public void delete() throws Exception{
        //1.加載核心配置文件
        InputStream is = Resources.getResourceAsStream("MyBatisConfig.xml");
        //2.獲取SqlSession工廠對(duì)象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //3.通過工廠對(duì)象獲取SqlSession對(duì)象
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //4.獲取StudentMapper接口的實(shí)現(xiàn)類對(duì)象
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        //5.調(diào)用實(shí)現(xiàn)類對(duì)象中的方法，接收結(jié)果
        Integer result = mapper.delete(4);
        //6.處理結(jié)果
        System.out.println(result);
        //7.釋放資源
        sqlSession.close();
        is.close();
    }
}

xml

<?xml version="1.0" encoding="UTF-8" ?>
<!--MyBatis的DTD約束-->
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--configuration 核心根標(biāo)簽-->
<configuration>
    <!--引入數(shù)據(jù)庫連接的配置文件-->
    <properties resource="jdbc.properties"/>
    <!--配置LOG4J-->
    <settings>
        <setting name="logImpl" value="log4j"/>
    </settings>
    <!--起別名-->
    <typeAliases>
        <package name="com.yyl.bean"/>
    </typeAliases>
    <!--environments配置數(shù)據(jù)庫環(huán)境，環(huán)境可以有多個(gè)。default屬性指定使用的是哪個(gè)-->
    <environments default="mysql">
        <!--environment配置數(shù)據(jù)庫環(huán)境  id屬性唯一標(biāo)識(shí)-->
        <environment id="mysql">
            <!-- transactionManager事務(wù)管理。  type屬性，采用JDBC默認(rèn)的事務(wù)-->
            <transactionManager type="JDBC"></transactionManager>
            <!-- dataSource數(shù)據(jù)源信息   type屬性 連接池-->
            <dataSource type="POOLED">
                <!-- property獲取數(shù)據(jù)庫連接的配置信息 -->
                <property name="driver" value="${driver}" />
                <property name="url" value="${url}" />
                <property name="username" value="${username}" />
                <property name="password" value="${password}" />
            </dataSource>
        </environment>
    </environments>
    <!--配置映射關(guān)系-->
    <mappers>
        <package name="com.yyl.mapper"/>
    </mappers>
</configuration>

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