SSM 注解式开发if标签使用bug

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在用mybatis开发，在sql中使用<if text=''></if>标签是，出现如下错误，原因是if标签中的变量使用错误，直接使用变量名字就可以，不用加#{}, 代码如下所示：

<if test=' code!= \"\" '>AND LEFT(S.var_name, 1) = #{code}
</if>

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: java.lang.IllegalArgumentException: invalid comparison: java.util.LinkedHashMap and java.lang.String
### Cause: java.lang.IllegalArgumentException: invalid comparison: java.util.LinkedHashMap and java.lang.String
   at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:77)
   at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)
   at com.sun.proxy.$Proxy15.selectList(Unknown Source)
   at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:230)
   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:59)
   at com.sun.proxy.$Proxy18.getVarEquipmentCode(Unknown Source)
   at com.serviceImpl.DyeServiceImpl.getVarEquipmentCode(DyeServiceImpl.java:38)
   at com.controller.DyeController.getCurdayChemicats(DyeController.java:210)
   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:497)
   at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
   at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
   at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:849)
   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:760)
   at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
   at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
   at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
   at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
   at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
   at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109)
   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93)
   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
   at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
   at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
   at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
   at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493)
   at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
   at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
   at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
   at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
   at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
   at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800)
   at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
   at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806)
   at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498)
   at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
   at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
   at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: java.lang.IllegalArgumentException: invalid comparison: java.util.LinkedHashMap and java.lang.String
### Cause: java.lang.IllegalArgumentException: invalid comparison: java.util.LinkedHashMap and java.lang.String
   at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:497)
   at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
   ... 59 more
Caused by: java.lang.IllegalArgumentException: invalid comparison: java.util.LinkedHashMap and java.lang.String
   at org.apache.ibatis.ognl.OgnlOps.compareWithConversion(OgnlOps.java:93)
   at org.apache.ibatis.ognl.OgnlOps.isEqual(OgnlOps.java:143)
   at org.apache.ibatis.ognl.OgnlOps.equal(OgnlOps.java:802)
   at org.apache.ibatis.ognl.ASTNotEq.getValueBody(ASTNotEq.java:53)
   at org.apache.ibatis.ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
   at org.apache.ibatis.ognl.SimpleNode.getValue(SimpleNode.java:258)
   at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:467)
   at org.apache.ibatis.ognl.Ognl.getValue(Ognl.java:431)
   at org.apache.ibatis.scripting.xmltags.OgnlCache.getValue(OgnlCache.java:44)
   at org.apache.ibatis.scripting.xmltags.ExpressionEvaluator.evaluateBoolean(ExpressionEvaluator.java:32)
   at org.apache.ibatis.scripting.xmltags.IfSqlNode.apply(IfSqlNode.java:34)
   at org.apache.ibatis.scripting.xmltags.MixedSqlNode.apply(MixedSqlNode.java:33)
   at org.apache.ibatis.scripting.xmltags.DynamicSqlSource.getBoundSql(DynamicSqlSource.java:41)
   at org.apache.ibatis.mapping.MappedStatement.getBoundSql(MappedStatement.java:292)
   at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:81)
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
   ... 65 more