3.参数传递

zhanglei 2022年06月01日 487次浏览

总配置文件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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <!--配置数据源：创建Connection对象-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url"
                          value="jdbc:mysql://localhost:3306/bjpowernode?useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="admin"/>
            </dataSource>
        </environment>
    </environments>
    <!--指定其他mapper文件的位置
    找到其他mapper文件的目的是找到sql语句

    使用注意：
        resource="mapper.文件的路径，用/分割"-->

    <mappers>
        <mapper resource="Dao/StudentMapper.xml"/>
    </mappers>
</configuration>

3.1 使用Dao代理

运用dao代理的条件：
mapper文件中的namespace必须是dao接口的全限定名称
并且子标签中id属性必须要是dao接口里的方法名称
dao代理的含义：创建dao接口的一个实现类，重写dao接口方法，创建实现类对象
dao代理的实现：利用sqlSession的getMapper(返回类型的全限定名称)

3.2 参数传递的3个情况

package Dao;
import Para.ParaQuery;
import domain.Student;
import org.apache.ibatis.annotations.Param;
import java.util.List;



public interface StudentDao {
    /*
    单个简单类型(基本类型+String)的参数传递：
    */
    Student SelectById(Integer id);

    /*
    多个简单类型(基本类型+String)的参数传递：
    */
    List<Student> SelectByIdOrName(@Param("StudentId") Integer id,@Param("StudentName") String name);

    /*
    实体类类型对象(基本类型+String)的参数传递：
    */
    int InsertStudent(Student student);

    List<Student> SelectByParaQuery(ParaQuery paraQuery);
}

3.3 StudentMapper.xml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">

<!--绑定接口-->
<mapper namespace="Dao.StudentDao">

    <!--
        mapper是根标签
        mapper里面可以写<insert>,<update>,<select>等标签
            标签的id属性：正常是需要重写的方法名
            标签的resultType属性：将数据赋值给哪个类型的Java对象
        标签内部都有同名的sql语句
    -->

    <!--
    单个简单类型(基本类型+String)的参数传递：
    -->
    <select id="SelectById" parameterType="Integer" resultType="domain.Student">
        select id,name,email,age from student where id=#{RandomName}
    </select>
    <!--
     多个简单类型(基本类型+String)的参数传递：
    -->
    <select id="SelectByIdOrName" resultType="domain.Student">
        select id,name,email,age from student where id=#{StudentId} or name=#{StudentName}
    </select>


    <!--
    实体类类型对象的参数传递：
   -->
    <insert id="InsertStudent" parameterType="domain.Student">
        insert into student values(#{id},#{name},#{email},#{age})
    </insert>

    <select id="SelectByParaQuery" resultType="domain.Student">
        select id,name,email,age from student where id=#{p1} or name=#{p2 }
    </select>
</mapper>

3.4 实体类Student

package domain;

public class Student {
    private Integer id;
    private String name;
    private String email;
    private Integer 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 String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "学生实体{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", age=" + age +
                '}';
    }
}

封装类ParaQuery

package Para;

public class ParaQuery {
    private Object p1;
    private Object p2;

    public Object getP1() {
        return p1;
    }

    public void setP1(Object p1) {
        this.p1 = p1;
    }

    public Object getP2() {
        return p2;
    }

    public void setP2(Object p2) {
        this.p2 = p2;
    }
}

3.5 工具类MyBatisUtil

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;
//工具类：先创建方法创建SqlSessionFactory
public class MyBatisUtil {
    private static SqlSessionFactory sqlSessionFactory;
    static {
        String config="mybatis-config.xml";
        try{
            InputStream inputStream = Resources.getResourceAsStream(config);
            sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);

        }catch(IOException e){
            e.printStackTrace();
        }
    }

    //创建方法，返回值是SqlSession对象sqlSession
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

3.6 Test测试类

package Dao;

import Para.ParaQuery;
import domain.Student;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import utils.MyBatisUtil;

import java.util.List;


//运用dao代理进行单参数传递
public class MyTest {
    @Test
    public void testSelectById() {
        //1.获取SqlSession对象
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        //2.获得dao的实现类对象
        StudentDao mapper = sqlSession.getMapper(StudentDao.class);
        //3.调用方法
        Student student = mapper.SelectById(1);
        System.out.println("查询的结果===" + student);
        //4.关闭sqlSession对象
        sqlSession.close();
    }

//运用dao代理进行多参数传递
    @Test
    public void testSelectByIdOrName(){
        //1.获取sqlSession对象
        SqlSession sqlSession=MyBatisUtil.getSqlSession();
        //2.获取dao的实现类对象
        StudentDao mapper=sqlSession.getMapper(StudentDao.class);
        //3.调用方法，实现SQL语句
        List<Student> list = mapper.SelectByIdOrName(1, "陆婷婷");
        for(Student student:list){
            System.out.println(student);
        }
        sqlSession.close();
    }

//运用dao代理进行实体类对象传递：实质是将传递多个参数封装成对象传递
    @Test
    public void testInsertStudent(){
        //1.获取sqlSession对象
        SqlSession sqlSession=MyBatisUtil.getSqlSession();
        //2.获取dao的实现类对象
        StudentDao mapper=sqlSession.getMapper(StudentDao.class);
        //3.调用方法，实现SQL语句
        Student student=new Student();
        student.setId(4);
        student.setName("周莫");
        student.setEmail("zm@qq.com");
        student.setAge(17);
        int rows = mapper.InsertStudent(student);
        //DML语句要手动提交
        sqlSession.commit();
        System.out.println("影响的行数："+rows);
        sqlSession.close();
    }

//运用dao代理进行自定义类的对象传递：实质是将传递多个参数封装成对象传递
    @Test
    public void testSelectByParaQuery(){
        //1.获取sqlSession对象
        SqlSession sqlSession=MyBatisUtil.getSqlSession();
        //2.获取dao的实现类对象
        StudentDao mapper=sqlSession.getMapper(StudentDao.class);
        //3.调用方法，实现SQL语句
        ParaQuery p=new ParaQuery();
        p.setP1(2);
        p.setP2("张磊");
        List<Student> list = mapper.SelectByParaQuery(p);
        for(Student student:list){
            System.out.println(student);
        }
        sqlSession.close();
    }
}

3.7 测试结果

//testSelectById
查询的结果===学生实体{id=1, name='张磊', email='zl@163.com', age=23}

//testSelectByIdOrName
学生实体{id=1, name='张磊', email='zl@163.com', age=23}
学生实体{id=2, name='陆婷婷', email='luu@163.com', age=22}

//testInsertStudent
navicate查看，已经添加了相关信息

//testSelectByParaQuery
学生实体{id=1, name='张磊', email='zl@163.com', age=23}
学生实体{id=2, name='陆婷婷', email='luu@163.com', age=22}
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