需求: 根据传入的参数批量 删除数据:
DAO:
List ll = new ArrayList<Integer>(); for(int i=10;i<25;i++){ ll.add(i); } int res = userMapper.delUser(li); System.out.println(res);
xml:
<delete id="delUser" parameterType="list" > delete from users where id in <foreach collection="li" index="index" open="(" close=")" separator="," item="itm"> #{itm} </foreach> </delete>
这样处理会报错
com.chenzhou.base.mybatis.IbatisSystemException: SqlSession operation; nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: org.apache.ibatis.binding.BindingException: Parameter 'li' not found. Available parameters are [list] ### Cause: org.apache.ibatis.binding.BindingException: Parameter 'studentNameList' not found. Available parameters are [list] at com.chenzhou.base.mybatis.SqlSessionTemplate.wrapException(SqlSessionTemplate.java:341) at com.chenzhou.base.mybatis.SqlSessionTemplate.execute(SqlSessionTemplate.java:127) at com.chenzhou.base.mybatis.SqlSessionTemplate.execute(SqlSessionTemplate.java:106) at com.chenzhou.base.mybatis.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:138) at com.chenzhou.dao.GenericMybatisDao.count(GenericMybatisDao.java:306) at com.chenzhou.cds.ps.dao.impl.StudentDao.getStudentCount(StudentDao.java:42) at com.chenzhou.cds.ps.dao.impl.StudentDao FastClassByCGLIB 8819e766.invoke(<generated>) at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191) at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:689) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150) at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80) at com.chenzhou.util.LogUtil.doMethodInfo(LogUtil.java:85) at com.chenzhou.util.LogUtil.doDebugMethodLog(LogUtil.java:36) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621) at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610) at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:55) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622) at com.chenzhou.cds.ps.dao.impl.StudentDao EnhancerByCGLIB d4fcf513.getStudentCount(<generated>) at com.chenzhou.ps.dao.StudentDaoTest.testgetStudentCount(StudentDaoTest.java:44) ……
根据报错日志分析,是MyBatis在解析xml时找不到其中声明的li,但是在Dao中明明传的参数就是li,怎么会报错呢?
查询了一下MyBatis官方的说明文档,终于找到了原因,在http://mybatis.github.io/mybatis-3/zh/dynamic-sql.html#foreach里有一段说明:
写道
注意 你可以传递一个 List 实例或者数组作为参数对象传给 MyBatis。当你这么做的时 候,MyBatis 会自动将它包装在一个 Map 中,用名称在作为键。List 实例将会以“list” 作为键,而数组实例将会以“array”作为键。
因为我传的参数只有一个,而且传入的是一个List集合,所以mybatis会自动封装成Map<"list",li>。在解析的时候会通过“list”作为Map的key值去寻找。但是我在xml中却声明成li了,所以自然会报错找不到。
更改:
<delete id="delUser" parameterType="map" >
delete from users where id in
<foreach collection="li" index="index" open="(" close=")" separator="," item="itm">
#{itm}
</foreach>
</delete>
List ll = new ArrayList<Integer>(); for(int i=10;i<25;i++){ ll.add(i); } HashMap li =new HashMap(); li.put("li", ll); int res = userMapper.delUser(li); System.out.println(res);
修改dao中的参数传入方式,手动封装成map,然后把map当参数传进去,这样mybatis会跟据参数map的key去匹配value,由于dao的key和xml中的key一样可以匹配上,所以OK,如果
HashMap li =new HashMap(); li.put("li", ll);
和xml中
<foreach collection= "li"........
不一样仍然会报错。
另一种修改的方式是直接修改成
<foreach collection="list" xml中的接受的参数仍然是list即可。
来源:oschina
链接:https://my.oschina.net/u/2308739/blog/496632