报错原因，及解决办法：

 实体类id属性上少加了@Id 然后mybatis不知道哪个是主键了

 

我写了个demopublic interface UserMapper extends Mapper
     
      注意是继承了Mapper，它里面已经有一个selectByPrimaryKey方法然后我这么调用User u = userMapper.selectByPrimaryKey(1);给我报错  哭了报错信息如下DEBUG - Fetching JDBC Connection from DataSourceDEBUG - JDBC Connection [jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8, UserName=root@localhost , MySQL Connector Java] will not be managed by SpringDEBUG - ==>  Preparing: SELECT id,name,age FROM User WHERE (id = ? AND name = ? AND age = ? ) DEBUG - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3b71d667]DEBUG - Returning JDBC Connection to DataSourceDEBUG - Resolving exception from handler [public java.lang.String com.zqws.app.trade.controller.TestController.test(org.springframework.ui.Model,com.github.pagehelper.PageInfo)]: org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String### The error may exist in com/zqws/app/trade/mapper/UserMapper.java (best guess)### The error may involve com.zqws.app.trade.mapper.UserMapper.selectByPrimaryKey-Inline### The error occurred while setting parameters### SQL: SELECT id,name,age FROM User WHERE (id = ? AND name = ? AND age = ? )### Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.StringDEBUG - Resolving exception from handler [public java.lang.String com.zqws.app.trade.controller.TestController.test(org.springframework.ui.Model,com.github.pagehelper.PageInfo)]: org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String### The error may exist in com/zqws/app/trade/mapper/UserMapper.java (best guess)### The error may involve com.zqws.app.trade.mapper.UserMapper.selectByPrimaryKey-Inline### The error occurred while setting parameters### SQL: SELECT id,name,age FROM User WHERE (id = ? AND name = ? AND age = ? )### Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.StringDEBUG - Resolving exception from handler [public java.lang.String com.zqws.app.trade.controller.TestController.test(org.springframework.ui.Model,com.github.pagehelper.PageInfo)]: org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String### The error may exist in com/zqws/app/trade/mapper/UserMapper.java (best guess)### The error may involve com.zqws.app.trade.mapper.UserMapper.selectByPrimaryKey-Inline### The error occurred while setting parameters### SQL: SELECT id,name,age FROM User WHERE (id = ? AND name = ? AND age = ? )### Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.StringDEBUG - Could not complete requestorg.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String### The error may exist in com/zqws/app/trade/mapper/UserMapper.java (best guess)### The error may involve com.zqws.app.trade.mapper.UserMapper.selectByPrimaryKey-Inline### The error occurred while setting parameters### SQL: SELECT id,name,age FROM User WHERE (id = ? AND name = ? AND age = ? )### Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Stringat org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:75)at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:371)at com.sun.proxy.$Proxy86.selectOne(Unknown Source)at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:163)at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:68)at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52)at com.sun.proxy.$Proxy92.selectByPrimaryKey(Unknown Source)at com.zqws.app.trade.controller.TestController.test(TestController.java:25)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:777)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:706)at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87)at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1736)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1695)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)at java.lang.Thread.run(Thread.java:745)Caused by: org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String### The error may exist in com/zqws/app/trade/mapper/UserMapper.java (best guess)### The error may involve com.zqws.app.trade.mapper.UserMapper.selectByPrimaryKey-Inline### The error occurred while setting parameters### SQL: SELECT id,name,age FROM User WHERE (id = ? AND name = ? AND age = ? )### Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Stringat org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:26)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:111)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:66)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358)... 52 moreCaused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Stringat org.apache.ibatis.type.StringTypeHandler.setNonNullParameter(StringTypeHandler.java:26)at org.apache.ibatis.type.BaseTypeHandler.setParameter(BaseTypeHandler.java:50)at org.apache.ibatis.scripting.defaults.DefaultParameterHandler.setParameters(DefaultParameterHandler.java:81)at org.apache.ibatis.executor.statement.PreparedStatementHandler.parameterize(PreparedStatementHandler.java:80)at org.apache.ibatis.executor.statement.RoutingStatementHandler.parameterize(RoutingStatementHandler.java:61)at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:74)at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:59)at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267)at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49)at com.github.pagehelper.SqlUtil._processPage(SqlUtil.java:351)at com.github.pagehelper.SqlUtil.processPage(SqlUtil.java:329)at com.github.pagehelper.PageHelper.intercept(PageHelper.java:150)at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:60)at com.sun.proxy.$Proxy93.query(Unknown Source)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49)at tk.mybatis.mapper.mapperhelper.MapperOnceInterceptor.intercept(MapperOnceInterceptor.java:81)at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:60)at com.sun.proxy.$Proxy93.query(Unknown Source)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108)... 59 moreDEBUG - Returning cached instance of singleton bean 'sqlSessionFactory'八月 01, 2015 5:02:43 下午 org.apache.catalina.core.StandardWrapperValve invoke严重: Servlet.service() for servlet [springmvc] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String### The error may exist in com/zqws/app/trade/mapper/UserMapper.java (best guess)### The error may involve com.zqws.app.trade.mapper.UserMapper.selectByPrimaryKey-Inline### The error occurred while setting parameters### SQL: SELECT id,name,age FROM User WHERE (id = ? AND name = ? AND age = ? )### Cause: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String] with root causejava.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Stringat org.apache.ibatis.type.StringTypeHandler.setNonNullParameter(StringTypeHandler.java:26)at org.apache.ibatis.type.BaseTypeHandler.setParameter(BaseTypeHandler.java:50)at org.apache.ibatis.scripting.defaults.DefaultParameterHandler.setParameters(DefaultParameterHandler.java:81)at org.apache.ibatis.executor.statement.PreparedStatementHandler.parameterize(PreparedStatementHandler.java:80)at org.apache.ibatis.executor.statement.RoutingStatementHandler.parameterize(RoutingStatementHandler.java:61)at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:74)at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:59)at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267)at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49)at com.github.pagehelper.SqlUtil._processPage(SqlUtil.java:351)at com.github.pagehelper.SqlUtil.processPage(SqlUtil.java:329)at com.github.pagehelper.PageHelper.intercept(PageHelper.java:150)at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:60)at com.sun.proxy.$Proxy93.query(Unknown Source)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49)at tk.mybatis.mapper.mapperhelper.MapperOnceInterceptor.intercept(MapperOnceInterceptor.java:81)at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:60)at com.sun.proxy.$Proxy93.query(Unknown Source)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:66)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358)at com.sun.proxy.$Proxy86.selectOne(Unknown Source)at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:163)at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:68)at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52)at com.sun.proxy.$Proxy92.selectByPrimaryKey(Unknown Source)at com.zqws.app.trade.controller.TestController.test(TestController.java:25)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:483)at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:777)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:706)at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87)at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1736)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1695)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)at java.lang.Thread.run(Thread.java:745)
     

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