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1.使用SLF4J打印日志，它有一个占位符“{}”一般不是异常这样打印

logger.info("InvestmentFacadeImpl queryInvestmentInfo: investmentListResponse is {}", investmentListResponse);

{}就是一个占位符打印信息就为：

InvestmentFacadeImpl queryInvestmentInfo: investmentListResponse is********

2.对于异常错误的打印日志

一个错误的示范：

logger.error("CrowdFundingAssetServiceImpl insert throws exception is {}", e.getMessage());

看一下error的源码

 /**
   * Log an exception (throwable) at the ERROR level with an
   * accompanying message.
   *
   * @param msg the message accompanying the exception
   * @param t   the exception (throwable) to log
   */
  public void error(String msg, Throwable t);

所以对于异常，是不需要占位符的，而且也不需要e.getMessage()，直接打印出来即可

logger.error("FinancingManualFacadeImpl.addFinancingProduct failed! ", e);

一.logger.error逗号和加号的区别

catch(Exception e){
	logger.error("[逗号] 测试错误堆栈到日志文件"，e);
	logger.error("[加号] 这里是测试错误信息列表"+e);
	logger.error("错误异常"+e.getmessage);
}

这里实际记录到日志文件里的日志信息是不同的，前者为

逗号在日志文件中的体现

2017-06-05 10:33:56 [ERROR] [com.cooya.health.controller.category.CategoryController.updateStatus:159] |[逗号]测试错误堆栈到日志文件
java.lang.NullPointerException: null
	at com.cooya.health.controller.common.BaseController.getUserName(BaseController.java:48)
	at com.cooya.health.controller.category.CategoryController.updateStatus(CategoryController.java:155)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:869)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)
	at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
	at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
	at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
	at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.jasig.cas.client.session.SingleSignOutFilter.doFilter(SingleSignOutFilter.java:76)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:185)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:151)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:269)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:722)

原因为：

void error(String var1, Throwable var2);

第二个参数为Throwable，为Exception的超类。

2.加号形式：

2017-06-05 10:33:56 [ERROR] [com.cooya.health.controller.category.CategoryController.updateStatus:160] |【加号】这里是测试错误信息列表java.lang.NullPointerException

原因：

void error(String var1)

相当于拼接字符串了

二. e.getmessage和e.tostring 区别

错误异常null ——e.getMessage

错误异常java.lang.NullpoiterException