6、SpringBoot+Mybatis整合------参数传递

开发工具：STS

代码下载链接：https://github.com/theIndoorTrain/SpringBoot_Mybatis/tree/7892801d804d2060774f3720f82e776ff318e3ba

前言：

在调用mybatis的查询条件时，之前，遇到需要验证多个参数的查询时，往往需要把所有参数都绑定到一个实体中去，然后调用获取。

现在，我们来详细描述mybatis传递参数的细节。

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一、单个参数：

1.定义mapper接口：

 package com.xm.mapper;

 import java.util.List;

 import com.xm.pojo.Student;

 public interface StudentMapper {

     /**
      * 根据name查询
      * @param name
      * @return
      */
     public Student getByName(String name);

 }

StudentMapper.java

2.实现mapper映射：

 <?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.xm.mapper.StudentMapper">

     <!-- 根据name查询 -->
     <select id="getByName" resultType="student">
     select * from student where name=#{name}
     </select>
 </mapper>

StudentMapper.xml

3.定义测试用例：

 package com.xm;

 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.test.context.junit4.SpringRunner;

 import com.xm.mapper.StudentMapper;
 import com.xm.pojo.Student;

 @RunWith(SpringRunner.class)
 @SpringBootTest
 public class StudentTest {
     @Autowired
     private StudentMapper studentMapper;

     @Test
     public void selectStudent() {

         Student student = studentMapper.getByName("郭小明");
         System.out.println(student);

     }

 }

StudentTest.java

4.测试结果：

(1)数据库查询结果：

（2）测试结果输出：

注意在mapper映射中，单个参数类型，也可以不写 parameterType=""，参数名可以随意写，比如#{names}

实现mapper映射：

 <?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.xm.mapper.StudentMapper">

     <!-- 根据name查询 -->
     <select id="getByName" resultType="student">
     <!-- select * from student where name=#{name} -->
     select * from student where name=#{names}
     </select>
 </mapper>

StudentMapper.xml

二、多个参数

1.根据参数名查询

（1）定义mapper接口：

 package com.xm.mapper;

 import java.util.List;

 import com.xm.pojo.Student;

 public interface StudentMapper {

     /**
      * 根据用户名和id同时查询
      * @param id
      * @param name
      * @return
      */
     public Student getStudentByIdAndName(Integer id,String name);

 }

StudentMapper.java

（2）实现mapper映射：

 <?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.xm.mapper.StudentMapper">

     <!-- 根据用户名和id同时查询 -->
     <select id="getStudentByIdAndName" resultType="student">
     select * from student where name=#{name} and id=#{id}
     </select>
 </mapper>

StudentMapper.xml

（3）定义测试用例：

 package com.xm;

 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.test.context.junit4.SpringRunner;

 import com.xm.mapper.StudentMapper;
 import com.xm.pojo.Student;

 @RunWith(SpringRunner.class)
 @SpringBootTest
 public class StudentTest {
     @Autowired
     private StudentMapper studentMapper;

     @Test
     public void selectStudent() {

         /*Student student = studentMapper.getByName("郭小明");*/
         Student student = studentMapper.getStudentByIdAndName(1, "郭小明");
         System.out.println(student);

     }

 }

StudentTest.java

（4）测试结果：

说明：这种简单的根据参数名传参是失败的

2.根据参数key值获取，获取规则为param1，param2，param3.........：

（1）实现mapper映射：

 <?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.xm.mapper.StudentMapper">

     <!-- 根据用户名和id同时查询 -->
     <select id="getStudentByIdAndName" resultType="student">
     <!-- select * from student where name=#{name} and id=#{id}  -->
     select * from student where name=#{param2} and id=#{param1}
     </select>
 </mapper>

StudentMapper.xml

（2）测试结果：

说明：针对这种情况，如果参数较多的情况下，获取准确的参数名更好一些

3.绑定参数名

（1）定义mapper接口：

 package com.xm.mapper;

 import java.util.List;

 import org.apache.ibatis.annotations.Param;

 import com.xm.pojo.Student;

 public interface StudentMapper {

     /**
      * 根据用户名和id同时查询
      * @param id
      * @param name
      * @return
      */
     public Student getStudentByIdAndName(@Param("id")Integer id,@Param("name")String name);

 }

StudentMapper.java

（2）实现mapper映射：

 <?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.xm.mapper.StudentMapper">

     <!-- 根据用户名和id同时查询 -->
     <select id="getStudentByIdAndName" resultType="student">
     select * from student where name=#{name} and id=#{id}
     <!-- select * from student where name=#{param2} and id=#{param1}  -->
     </select>
 </mapper>

StudentMapper.xml

（3）测试结果：

说明：针对参数较多，且参数都属于同一个pojo类的时候，可以把参数先封装入实体，再获取

4.封装实体参数：

（1）定义mapper接口：

 package com.xm.mapper;

 import java.util.List;

 import org.apache.ibatis.annotations.Param;

 import com.xm.pojo.Student;

 public interface StudentMapper {

     /**
      * 根据用户名和id同时查询
      * @param id
      * @param name
      * @return
      */
     public Student getStudentByIdAndName(Student student);

 }

StudentMapper.java

（2）定义测试用例：

 package com.xm;

 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.test.context.junit4.SpringRunner;

 import com.xm.mapper.StudentMapper;
 import com.xm.pojo.Student;

 @RunWith(SpringRunner.class)
 @SpringBootTest
 public class StudentTest {
     @Autowired
     private StudentMapper studentMapper;

     @Test
     public void selectStudent() {

         /*Student student = studentMapper.getByName("郭小明");*/
         /*Student student = studentMapper.getStudentByIdAndName(1, "郭小明");*/
         Student student = new Student();
         student.setName("郭小明");
         student.setId(1);
         Student student2 = studentMapper.getStudentByIdAndName(student);
         System.out.println(student2);

     }

 }

StudentMapper.java

（3）测试结果：

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