当使用Part.getPart()方法时，Servlet抛出一个ServletException

Question

我已经编写了servlet代码来将照片上传到我的数据库，当我运行页面并尝试上传照片时，在这一点上我得到了异常

Part filePart = request.getPart("photo");

其中照片是我表单中输入字段的名称，它的代码是

<input type="file" id="photo" name="photo">

Apache tomcat在浏览器中显示的异常报告是

type: Exception report

message: Servlet execution threw an exception

description: The server encountered an internal error that prevented it from fulfilling this request.

exception:

javax.servlet.ServletException: Servlet execution threw an exception

root cause:

java.lang.AbstractMethodError:org.apache.catalina.connector.RequestFacade.getPart(Ljava/lang/String;)Ljavax/servlet/http/Part;

      Uploaddp.doPost(Uploaddp.java:57)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:847)

全栈跟踪

Sep 29, 2016 3:44:52 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet Uploaddp threw exception
java.lang.AbstractMethodError: org.apache.catalina.connector.RequestFacade.getPart(Ljava/lang/String;)Ljavax/servlet/http/Part;
    at Uploaddp.doPost(Uploaddp.java:57)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Unknown Source)

Answer 1

没有"file“类型。您需要使用multpart/form-data。更多的参考这篇文章What does enctype='multipart/form-data' mean?也，为了在服务器端获取这个文件，你需要使用一些库，这里解释Convenient way to parse incoming multipart/form-data parameters in a Servlet也，考虑像你在处理后将这些文件存储在服务器上的什么地方。用户可能想要下载上传的图像。此外，围绕这些文件的可访问性的安全性。