如何在多部分发布请求中传递参数答案

【问题标题】：How to pass parameter in multipart post request如何在多部分发布请求中传递参数
【发布时间】：2013-12-22 01:21:37
【问题描述】：

Servlet 代码

request.getparameter("fname") //I can't able to get value.

HTML 代码

 <html>
    <head>
    <title>File Uploading Form</title>
    </head>
    <body>
    <h3>File Upload:</h3>
    Select a file to upload: <br />
    <form action="UploadServlet" method="post"
                            enctype="multipart/form-data">
    <input type="text" name="fname" size="50" />   
 <input type="file" name="file" size="50" />
 <input type="submit" value="Upload File" />
    </form>
    </body>
    </html>

我的问题是：如何在多部分发布请求中传递fname 参数？

【问题讨论】：

然后使用类型“fname”不存在。有关可用类型，请参阅w3schools.com/tags/att_input_type.asp。服务器端的“名称”也不存在。您应该使用 request.getparameter("fname")。
我已更正。仍然无法正常工作
也许动作是 UploadServlet.jsp？
See this post

标签： jsp servlets file-upload multipartform-data

【解决方案1】：

简答：您会在请求的Parts 中找到fname。

长答案： 对于多部分类型的请求，即使是简单的 <input type="text"> 字段值也会放在部分中。您将不得不遍历 HttpServletRequest.getParts() 返回的 Part 对象并根据它们的 name 属性处理它们：

for( Part p : request.getParts() ) {
    if( "fname".equals(p.getName()) ) {
        ...
    }
    else if( "file".equals(p.getName()) ) {
        ...
    }
}

为了使事情进一步复杂化，该部分的内容以InputStream - Part.getInputStream() 的形式提供 - 所以你必须做一些转换流 → byte[] → String 来获得值。

【讨论】：

request.getParts()... 不存在....好吧，Javadocs 说它在他们的网站上可用，但它在我的 HttpServletRequest 中不存在
我找到了解决方案。如果您也遇到此问题，请将您的 javax.servlet.api 升级到 3.0.1

【解决方案2】：

Link Each Programms
------------------------------------------------------

import java.sql.*;
import java.io.*;

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 javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import java.util.Hashtable;
import java.util.List;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.ParameterParser;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


/**
 * Servlet implementation class Recent
 */
@WebServlet("/Recent")
@MultipartConfig
public class Recent extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Recent() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // TODO Auto-generated method stub
         Sample  s1=new Sample();
         final String UPLOAD_DIRECTORY = "/home/pradeep/Documents/pradeep/WebContent/Images";
         if(ServletFileUpload.isMultipartContent(request)){
                try {
         List<FileItem> multiparts = new 
                            ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);

                    for(FileItem item : multiparts){
                        if(!item.isFormField())
                        {
                            String name = new File(item.getName()).getName();
                            item.write( new File(UPLOAD_DIRECTORY + File.separator + name));
                            String Path= "/home/pradeep/Documents/pradeep/WebContent/Images/" +name;


                          s1.connecting(Path);


                        }
                    }

                        request.setAttribute("message", "File Uploaded Successfully");
                } catch (Exception ex) {
                   request.setAttribute("message", "File Upload Failed due to " + ex);
                }          

            }else{
                request.setAttribute("message",
                                     "Sorry this Servlet only handles file upload request");
            }



                request.getRequestDispatcher("/Result.jsp").forward(request, response);




    }

}
-------------------------------------------------------------------------------------------
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import dbconnections.Connections;



public class Sample {
    Connections con=new Connections();

    public void connecting(String Path)
    {
        Connection conn=con.Connect();

        PreparedStatement pst;
        String query="INSERT INTO Student1 (Path) values (?)";
       try {

            pst=conn.prepareStatement(query);
            pst.setString(1,Path);
            pst.executeUpdate();

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        // TODO Auto-generated method stub
    }


}
-------------------------------------------------------------------------------------
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<div>
            <h3> Choose File to Upload in Server </h3>          
           <form action="Recent" method="post" enctype="multipart/form-data">

            <input type="file" name="file" />
            <input type="submit" value="upload" />
            </form>          
        </div>


</body>
</html>

【讨论】：