mybatis mapper namespace-白红宇

http://www.mybatis.org/mybatis-3/zh/sqlmap-xml.html#insert_update_and_delete

org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: org.apache.ibatis.executor.ExecutorException: No constructor found in tk.mybatis.springboot.model.Course matching [java.lang.Integer, java.lang.String]### The error may exist in mapper/CourseMapper.xml### The error may involve tk.mybatis.springboot.mapper.CourseMapper.selectAll### The error occurred while handling results### SQL: select * from course### Cause: org.apache.ibatis.executor.ExecutorException: No constructor found in tk.mybatis.springboot.model.Course matching [java.lang.Integer, java.lang.String]    at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:122)    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113)    at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:122)    at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:64)    at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)    at com.sun.proxy.$Proxy6.selectAll(Unknown Source)

org.apache.ibatis.jdbc.RuntimeSqlException: Error executing: create TABLE course (id INTEGER ,NAME VARCHAR(20)).  Cause: org.apache.ibatis.jdbc.RuntimeSqlException: Line missing end-of-line terminator (;) => create TABLE course (id INTEGER ,NAME VARCHAR(20))    at org.apache.ibatis.jdbc.ScriptRunner.executeLineByLine(ScriptRunner.java:141)    at org.apache.ibatis.jdbc.ScriptRunner.runScript(ScriptRunner.java:101)

org.apache.ibatis.binding.BindingException: Type interface tk.mybatis.springboot.mapper.CourseMapper is not known to the MapperRegistry.    at org.apache.ibatis.binding.MapperRegistry.getMapper(MapperRegistry.java:47)    at org.apache.ibatis.session.Configuration.getMapper(Configuration.java:689)    at org.apache.ibatis.session.defaults.DefaultSqlSession.getMapper(DefaultSqlSession.java:250)

mybatis中定义行为的接口，需要在xml文件中注册：

问题背景：

在Dao中使用MyBatis进行查询操作，参数是传的一个List：studentNameList，但是在执行查询的时候报错，具体日志如下：

Shell代码

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 'studentNameList' 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)

……

单元测试用例代码如下：

Java代码

@Test

public void testgetStudentCount(){

List<String> studentNameList = new ArrayList<String>();

studentNameList.add("chenzhou");

studentNameList.add("zhangsan");

studentNameList.add("lisi");

int count = studentDao.getStudentCount(studentNameList);

System.out.println(count);

}

studentDao中的getStudentCount方法代码如下：

Java代码

public int getStudentCount(List<String> studentNameList){

return super.count("getStudentCount", studentNameList);

}

MyBatis mapper.xml定义如下：

根据报错日志分析，是MyBatis在解析xml时找不到其中声明的studentNameList，但是在Dao中明明传的参数就是studentNameList，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",studentNameList>。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studentNameList了，所以自然会报错找不到。

解决办法：

第一种就是修改mapper.xml中foreach标签内容，把studentNameList修改为list


     
            AND student_name in      
      
                 #{item}

不过这种方式我个人不太建议，因为以后如果要扩展该方法，增加集合参数的时候，还得修改xml中的内容。

第二种方式，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

Dao方法修改为：

public int getStudentCount(List
     
       studentNameList){       //把参数手动封装在Map中       Map
      
        map = new HashMap
       
        ();       map.put("studentNameList", studentNameList);       return super.count("getStudentCount", map);   }

然后修改mapper.xml中的parameterType类型为Map

修改完后，重新执行了一下测试用例，测试通过。

http://www.cnblogs.com/winkey4986/p/3480328.html