I have a question about open file at same directory.I have some files,like follows: D:\Apache Tomcat 4.0\webapps\login\WEB-INF\classes\GetUserIdentity.class D:\Apache Tomcat 4.0\webapps\login\WEB-INF\classes\error.txt The role of GetUserIdentity.class is read data from the file "error.txt",The file "GetUserIdentity.java" like: ... try { input=new BufferedReader(new FileReader("error.txt")); ... } catch(IOException e) { e.printStackTrace(); } But when I start Apache Tomcat 4.0,and I visit index.html which locate http://localhost:8080/login/servlets/index.html Then I click OK button,I got errors: Starting service Tomcat-Standalone Apache Tomcat/4.0.1 Starting service Tomcat-Apache Apache Tomcat/4.0.1 java.io.FileNotFoundException: error.txt at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.<init>(Unknown Source) at java.io.FileReader.<init>(Unknown Source) at PreReadError.<init>(PreReadError.java:22) at GetUserIdentity.<init>(GetUserIdentity.java:20) at java.lang.Class.newInstance0(Native Method) at java.lang.Class.newInstance(Unknown Source) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:82 0) at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.jav a:615) at org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServl et.java:396) at org.apache.catalina.servlets.InvokerServlet.doPost(InvokerServlet.jav a:216) at javax.servlet.http.HttpServlet.service(HttpServlet.java:760) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl icationFilterChain.java:247) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF ilterChain.java:193) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV alve.java:243) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline .java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav a:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV alve.java:201) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline .java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav a:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java: 2344) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j ava:164) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline .java:566) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatche rValve.java:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline .java:564) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j ava:170) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline .java:564) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java: 462) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline .java:564) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav a:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal ve.java:163) at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline .java:566) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav a:472) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943) at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcesso r.java:1011) at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.ja va:1106) at java.lang.Thread.run(Unknown Source) I have put GetUserIdentity.class and error.txt in same dictionary,but why can't find it? Any idea will be appreciated!
The problem is in the directory that it is looking for the file. To see the difference you can add code like:
and see the difference in each situation. Web Applications have some strage ClassLoader effects (and I'm ceratinly not covering them here), but the following code will find the file for you:
The first line uses the current class's ClassLoader to find a resource in the same 'area' called 'error.txt', then we convert it to a File. hope this helps. Dave
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