老师我这个代码第一遍跟着老师敲是没有问题的，我在另一个项目里面又试了一遍老是说我的post方法的enctype有问题，可是我设置了呀，老师我该怎么解决
Type 异常报告
消息 org.apache.tomcat.util.http.fileupload.impl.InvalidContentTypeException: the request doesn't contain a multipart/form-data or multipart/mixed stream, content type header is null
描述 服务器遇到一个意外的情况，阻止它完成请求。
Exception
javax.servlet.ServletException: org.apache.tomcat.util.http.fileupload.impl.InvalidContentTypeException: the request doesn't contain a multipart/form-data or multipart/mixed stream, content type header is null
org.apache.catalina.connector.Request.parseParts(Request.java:2913)
org.apache.catalina.connector.Request.getParts(Request.java:2775)
org.apache.catalina.connector.Request.getPart(Request.java:2944)
org.apache.catalina.connector.RequestFacade.getPart(RequestFacade.java:1105)
com.bjsxt.servlet.FileUpLoadServlet.doPost(FileUpLoadServlet.java:32)
com.bjsxt.servlet.FileUpLoadServlet.doGet(FileUpLoadServlet.java:20)
javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Root Cause
org.apache.tomcat.util.http.fileupload.impl.InvalidContentTypeException: the request doesn't contain a multipart/form-data or multipart/mixed stream, content type header is null
org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.init(FileItemIteratorImpl.java:140)
org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.getMultiPartStream(FileItemIteratorImpl.java:194)
org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.findNextItem(FileItemIteratorImpl.java:213)
org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.<init>(FileItemIteratorImpl.java:131)
org.apache.tomcat.util.http.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:255)
org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:279)
org.apache.catalina.connector.Request.parseParts(Request.java:2873)
org.apache.catalina.connector.Request.getParts(Request.java:2775)
org.apache.catalina.connector.Request.getPart(Request.java:2944)
org.apache.catalina.connector.RequestFacade.getPart(RequestFacade.java:1105)
com.bjsxt.servlet.FileUpLoadServlet.doPost(FileUpLoadServlet.java:32)
com.bjsxt.servlet.FileUpLoadServlet.doGet(FileUpLoadServlet.java:20)
javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
):注意 主要问题的全部 stack 信息可以在 server logs 里查看
JAVA：
package com.bjsxt.servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.UUID;
@WebServlet("/fileupload.do")
@MultipartConfig//基于注解开发的文件上传
public class FileUpLoadServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//设置请求编码
req.setCharacterEncoding("utf-8");
//设置响应编码
resp.setContentType("text/html;charset=utf-8");
//获取文件描述
String desc = req.getParameter("desc");
//获取part对象 参数给form表单中上传文件的name
Part part = req.getPart("file");
/*//设置唯一的文件名，避免因为文件名重复而造成文件覆盖，
* 先截取文件的后缀（扩展名），然后与随机生成唯一的字符串拼接
* UUID.randowUUID()随机生成一个唯一的字符串，返回UUID类型，需要调用toString()返回字符串类型*/
String name = UUID.randomUUID().toString() + part.getSubmittedFileName().substring(part.getSubmittedFileName().lastIndexOf("."));
//将相对路径转换为绝对路径
ServletContext servletContext = this.getServletContext();
String realPath = servletContext.getRealPath("images/" + name);
System.out.println(realPath);
//将上传的对象做IO流chuli,并通过字符输出流写入到路径中
part.write(realPath);
PrintWriter out = resp.getWriter();
/*拼接HTML页面*/
out.println("<!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.0 Transitional//EN'>");
out.println("<HTML>");
out.println("<HEAD><TITLE>临江仙.文件上传</TITLE></HEAD>");
out.println("<BODY>");
out.println("文件上传成功！"+desc);
out.println("<BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
HTML：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body><!--
get：以字符型方式提交，
post：既可以以字节方式提交也可以字符方式提交
-->
<form action="fileupload.do" method="post" enctype="multipart/form-data">
文件描述：<input type="text" name="desc"/>
文件上传：<input type="file" name="file"/>
<input type="submit" value="OK"/>
</form>
</body>
</html>
、
里面那种id：name：这种不是json格式吗为什么啊
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