web 项目中的文件上传服务器的代码实现_web上传文件给服务器源码-优快云博客

本文介绍了一种在JavaWeb环境中实现文件上传的方法。通过具体的代码示例，展示了如何配置前端表单以支持文件上传，并详细解释了后端处理流程，包括文件解析、临时文件存储及最终保存到指定路径的过程。

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java web 中文件上传的实现

1，view层
<%@ page language="java" import="java.util.*"
      contentType="text/html;charset=utf-8" pageEncoding="utf-8"%>
<html>
      <body>
            <form action="servlet/UpDownLoadFile" enctype="multipart/form-data"
                     method="post">
                     <input type="text" name="username" />
                     <br />
                     <input type="file" name="myfile" />
                     <br />
                     <input type="file" name="myfile" />
                     <br />
                     <input type="submit" />
            </form>
            <br />
      </body>
</html>
2，文件上传类File_upload
package file_upload;

import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUpload;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.RequestContext;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.fileupload.servlet.ServletRequestContext;

public class File_upload {

      private String dir_name = "BooksImage";

      public HashMap begin_upload(HttpServletRequest request,
                     HttpServletResponse response) {
            HashMap param_hm = new HashMap();
            try {
                     // jsp file encode utf-8 must
                     request.setCharacterEncoding("utf-8");
                     RequestContext requestContext = new ServletRequestContext(request);
                     if (FileUpload.isMultipartContent(requestContext)) {
                              DiskFileItemFactory factory = new DiskFileItemFactory();
                              File temp_file = new File(request.getRealPath("") + "//"
                                             + getDir_name() + "//");
                              temp_file.mkdir();
                              factory.setRepository(temp_file);
                              ServletFileUpload upload = new ServletFileUpload(factory);
                              upload.setHeaderEncoding("utf-8");
                              upload.setSizeMax(-1);
                              List items = new ArrayList();
                              items = upload.parseRequest(request);
                              Iterator it = items.iterator();
                              while (it.hasNext()) {
                                    FileItem fileItem = (FileItem) it.next();
                                    if (fileItem.isFormField()) {
                                             param_hm.put(fileItem.getFieldName(), new String(
                                                            fileItem.getString().getBytes("iso8859-1"),
                                                            "utf-8"));
                                    } else {
                                             if (fileItem.getName() != null
                                                            && fileItem.getSize() != 0) {
                                                      File fullFile = new File(fileItem.getName());
                                                      File newFile = new File(request.getRealPath("")
                                                                     + "//" + getDir_name() + "//"
                                                                     + fullFile.getName());
                                                      fileItem.write(newFile);
                                             } else {
                                                      System.out.println("文件没有选择或文件内容为空");
                                             }
                                    }
                              }
                     }
            } catch (UnsupportedEncodingException e2) {
                     // TODO Auto-generated catch block
                     e2.printStackTrace();
            } catch (FileUploadException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
            } catch (Exception e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
            }

            return param_hm;
      }

      public void setDir_name(String dir_name) {
            this.dir_name = dir_name;
      }

      public String getDir_name() {
            return dir_name;
      }
}
备注：private String dir_name = "BooksImage";此处成员变量，代表你上传时将在服务器你的项目目录：WEB-INF吓创建一个以此变量名称一样的文件夹作为用户上传目录，如果此目录存在，不会创建，直接将文件写入！是不是使用啊！
使用这个类需要file_upload.jar包：下载地址：http://download.youkuaiyun.com/source/337184