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demo public interface UserMapper extends Mapper<User> 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 DataSource DEBUG - JDBC Connection [jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8, UserName=root@localhost , MySQL Connector Java] will not be managed by Spring DEBUG - ==> 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 DataSource DEBUG - 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.String DEBUG - 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.String DEBUG - 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.String DEBUG - Could not complete request 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 at 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.String at 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$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358) ... 52 more Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String at org.apache.ibatis.type.StringTypeHandler.setNonNullParameter(StringTypeHandler.java:26) at org.apache.ibatis.type.BaseTypeHandler.setParameter(BaseTypeHandler.java:50) at org.apache.ibatis.scripting.defaults.DefaultParameterHandler.setParameters(DefaultParameterHandler.java:81) at org.apache.ibatis.executor.statement.PreparedStatementHandler.parameterize(PreparedStatementHandler.java:80) at org.apache.ibatis.executor.statement.RoutingStatementHandler.parameterize(RoutingStatementHandler.java:61) at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:74) at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:59) at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267) at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137) at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96) at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:483) at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49) at com.github.pagehelper.SqlUtil._processPage(SqlUtil.java:351) at com.github.pagehelper.SqlUtil.processPage(SqlUtil.java:329) at com.github.pagehelper.PageHelper.intercept(PageHelper.java:150) at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:60) at com.sun.proxy.$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 more DEBUG - 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 cause java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String at 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$SocketProcessor.r un(NioEndpoint.java:1695) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$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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