异常代码：
Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'stu_name' in 'class java.lang.String'
### Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'stu_name' in 'class java.lang.String'
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:137)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:75)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)
at com.sun.proxy.$Proxy0.findStudentList4(Unknown Source)
at demo.cyj.Test.main(Test.java:69)
接口StudentDao.java的代码：
此处的异常用到的方法是第五个方法：
public List<Student> findStudentList4(String stu_name);
package demo.cyj.dao;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Param;
import demo.cyj.pojo.Student;
public interface StudentDao {
public List<Student> findStudentList1(Student student);
public List<Student> findStudentList2(Student student);
public int editStudent1(Student student);
public List<Student> findStudentList3(Map<String,Object> map);
public List<Student> findStudentList4(String stu_name);
}
mapperStudentMapper.xml中用到的部分代码：
<!-- 用bind实现模糊查询 -->
<select id="findStudentList4" resultType="Student">
<bind name="stu_name" value="'%'+stu_name+'%'" />
select * from student where stu_name like #{stu_name}
</select>
原因：
根据报错内容，也能看出String类型的参数中没有getter方法，按自己的理解就是这个参数传过来没有用键值对的方式来传递，即这个值没有相应的键来表示它，所以要给值设定一个键。
解决：
解决方案也不少，下面说两个吧，一个是自己写的，不过违背了最初想要传递String的初衷；一个是网上搜的，通过注解，推荐第二种。
-
将要传递的String值封装到一个map中，传递map
具体代码实现如下：
接口StudentDao.java的代码：
可以看到，代码改动在第五个方法那里，将传递的参数改为了map。
package demo.cyj.dao;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Param;
import demo.cyj.pojo.Student;
public interface StudentDao {
public List<Student> findStudentList1(Student student);
public List<Student> findStudentList2(Student student);
public int editStudent1(Student student);
public List<Student> findStudentList3(Map<String,Object> map);
public List<Student> findStudentList4(Map<String,String> map);
}
mapperStudentMapper.xml的部分代码：
<!-- 用bind实现模糊查询 -->
<select id="findStudentList4" parameterType="map" resultType="Student">
<bind name="stu_name" value="'%'+stu_name+'%'" />
select * from student where stu_name like #{stu_name}
</select>
测试方法：
package demo.cyj;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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 demo.cyj.dao.StudentDao;
import demo.cyj.dao.TeacherDao;
import demo.cyj.pojo.Student;
import demo.cyj.pojo.Teacher;
public class Test {
public static void main(String[] args) throws IOException {
String src = "config.xml";
InputStream inputStream = Resources.getResourceAsStream(src);
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sessionFactory.openSession(true);
//绑定
StudentDao sd = sqlSession.getMapper(StudentDao.class);
Map<String,String> map = new HashMap<>();
map.put("stu_name", "拐");
List<Student> list = sd.findStudentList4(map);
System.out.println(list);
}
}
运行结果：
运行结果
-
通过注解，将接口中传递的String类型前加一个@Param("stu_name")
具体代码实现如下：
接口StudentDao.java的代码：
可以看到，代码改动在第五个方法那里，配置了一个注解，相当于给String的参数加了一个键。
package demo.cyj.dao;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Param;
import demo.cyj.pojo.Student;
public interface StudentDao {
public List<Student> findStudentList1(Student student);
public List<Student> findStudentList2(Student student);
public int editStudent1(Student student);
public List<Student> findStudentList3(Map<String,Object> map);
public List<Student> findStudentList4(@Param("stu_name")String stu_name);
}
mapperStudentMapper.xml的部分代码：
<!-- 用bind实现模糊查询 -->
<select id="findStudentList4" resultType="Student">
<bind name="stu_name" value="'%'+stu_name+'%'" />
select * from student where stu_name like #{stu_name}
</select>
测试方法：
public class Test {
public static void main(String[] args) throws IOException {
String src = "config.xml";
InputStream inputStream = Resources.getResourceAsStream(src);
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sessionFactory.openSession(true);
//绑定
StudentDao sd = sqlSession.getMapper(StudentDao.class);
//使用bind进行模糊查询
List<Student> list = sd.findStudentList4("拐");
System.out.println(list);
}
}
运行结果：
运行结果
总结一下：
当在mybatis中遇到诸如此类传递参数出现问题的情况，多想想这里是否设置了键值对。
