我一直在本地测试一个javaservlet，但我不知道这里发生了什么。文件在目的地正确上传，但在文件正确写入后，我收到一个"访问被拒绝"错误：
Apr 08, 2016 10:12:39 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [FileUploadServlet] in context with path [/FileUpload] threw exception
java.io.IOException: java.io.FileNotFoundException: C:temp (Access is denied)
at org.apache.catalina.core.ApplicationPart.write(ApplicationPart.java:121)
at FileUploadServlet.doPost(FileUploadServlet.java:63)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
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:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.FileNotFoundException: C:temp (Access is denied)
at java.io.FileOutputStream.open(Native Method)
at java.io.FileOutputStream.<init>(FileOutputStream.java:221)
at java.io.FileOutputStream.<init>(FileOutputStream.java:171)
at org.apache.tomcat.util.http.fileupload.disk.DiskFileItem.write(DiskFileItem.java:402)
at org.apache.catalina.core.ApplicationPart.write(ApplicationPart.java:119)
... 22 more
servlet代码：
/**
* Servlet implementation class FileUploadServlet
*/
@WebServlet(asyncSupported = true, urlPatterns = { "/FileUploadServlet" })
@MultipartConfig(location="c:/temp/temp")
public class FileUploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public FileUploadServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response. getWriter();
out.print("<!DOCTYPE html>");
out.println("<head><title>File Upload</title><meta http-equiv='Content-Type' content='text/html charset=UTF-8'>");
out.println("</head><body><form method='POST' action='./FileUploadServlet' enctype='multipart/form-data' >");
out.println("File:<input type='file' name='file' id='file' /> <br/>");
out.println("Destination:<input type='text' value='/tmp' name='destination'/>");
out.println("</br><input type='submit' value='Upload' name='upload' id='upload' />");
out.println("</form></body></html>");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
for (Part part : request.getParts()) {
String fileName = extractFileName(part);
File f = new File(fileName);
part.write("C:" + File.separator + "temp" + File.separator + f.getName());
}
}
/**
* Extracts file name from HTTP header content-disposition
*/
private String extractFileName(Part part) {
String contentDisp = part.getHeader("content-disposition");
String[] items = contentDisp.split(";");
for (String s : items) {
if (s.trim().startsWith("filename")) {
return s.substring(s.indexOf("=") + 2, s.length()-1);
}
}
return "";
}
}
编辑：跟踪中出现问题的行是
part.write("C:" + File.separator + "temp" + File.separator + f.getName());
第2版：终于开始工作了（看起来文件只在发送文件的一部分中）。代码：
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
File uploads = new File("C:/temp");
Part filePart = request.getPart("file");
String fileName = extractFileName(filePart);
File f = new File(fileName);
File file = new File(uploads, f.getName());
try (InputStream input = filePart.getInputStream()) {
Files.copy(input, file.toPath());
} catch (Exception e){
response.setContentType("text/html");
PrintWriter out = response. getWriter();
out.print("<body>Failed to upload file <br>" + e.getMessage());
}
}
SEVERE:Servlet.service（）在路径为[/FileUpload]的上下文中引发异常java.io.IOException:java.io.FileNotFoundException:C:\temp（访问被拒绝）
这意味着执行此java部署的用户（在本例中为运行应用程序服务器的用户）没有访问文件夹的权限。解决方法是，将文件放在运行该文件的用户创建的文件夹中，或者授予该文件夹相应的权限。
终于让它工作起来了（看起来文件是在发送的文件的一部分中）。代码：
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
File uploads = new File("C:/temp");
Part filePart = request.getPart("file");
String fileName = extractFileName(filePart);
File f = new File(fileName);
File file = new File(uploads, f.getName());
try (InputStream input = filePart.getInputStream()) {
Files.copy(input, file.toPath());
} catch (Exception e){
response.setContentType("text/html");
PrintWriter out = response. getWriter();
out.print("<body>Failed to upload file <br>" + e.getMessage());
}
}