Java：Servlet使用AJAX异步上传文件

Java：Servlet使用AJAX异步上传文件

没有中文乱码问题。
1. 客户端使用HTML + JavaScript(AJAX)

< html >
< head >
     < meta  http-equiv ="Content-type"  content ="text/html; charset=utf-8" >
     < title > Upload Demo </ title >

     < style  type ="text/css" ></ style >

     < script  src ="js/jquery.js" ></ script >
     < script  src ="js/ajaxupload.js" ></ script >
     < script  type ="text/javascript" >
    $( function () {
         //  创建AJAX方式上传文件
         var  $uploadBtn  =  $( " #uploadBtn " );
         new  AjaxUpload($uploadBtn, {
            action: 'upload.action',
            name: 'uploadfile',
            onSubmit:  function (file, ext){
                $( " #info " ).html( " start upload file " );
            },
            onComplete:  function (file, response){
                $( " #info " ).html(response);
            }
        });
    });
     </ script >
</ head >

< body >
     < div  id ="info" > Choose file to upload </ div >
     < input  type ="button"  width ="200px"  id ="uploadBtn"  value ="Upload Demo" >
</ body >
</ html >

2. 服务器端使用Servlet：Apache commons-fileupload-1.2.1.jar和commons-io-1.3.2.jar

import  java.io.File;
import  java.io.IOException;
import  java.util.Iterator;
import  java.util.List;

import  javax.servlet.ServletConfig;
import  javax.servlet.ServletContext;
import  javax.servlet.ServletException;
import  javax.servlet.http.HttpServlet;
import  javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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

@SuppressWarnings( " serial " )
public   class  Uploader  extends  HttpServlet {
     private  ServletContext sc;
     private  String uploadDir  =   " downloads " ;

    @Override
     public   void  init(ServletConfig config) {
        sc  =  config.getServletContext();
    }

    @Override
     public   void  doGet(HttpServletRequest request, HttpServletResponse response)  throws  IOException, ServletException {
        doPost(request, response);
    }

    @Override
     public   void  doPost(HttpServletRequest request, HttpServletResponse response)  throws  IOException, ServletException {
        request.setCharacterEncoding( " UTF-8 " );  //  防止中文乱码
        DiskFileItemFactory factory  =   new  DiskFileItemFactory();
        ServletFileUpload upload  =   new  ServletFileUpload(factory);

         try  {
            List items  =  upload.parseRequest(request);
            Iterator itr  =  items.iterator();
             while  (itr.hasNext()) {
                FileItem item  =  (FileItem) itr.next();
                 if  (item.isFormField()) {
                    System.out.println( " 表单参数名： "   +  item.getFieldName()  +   " ,表单参数值： "   +  item.getString( " UTF-8 " ));
                }  else  {
                     if  (item.getName()  !=   null   &&   ! item.getName().equals( "" )) {
                        System.out.println( " 上传文件的大小： "   +  item.getSize());
                        System.out.println( " 文件的类型： "   +  item.getContentType());
                        System.out.println( " 上传文件的名称： "   +  item.getName()); //  返回上传文件在客户端的完整路径名称

                        File file  =   new  File(sc.getRealPath( " / " )  +  File.separatorChar  +  uploadDir  +  File.separatorChar
                                 +  item.getName());
                        item.write(file);
                    }  else  {
                        response.getWriter().println( " 没有选择文件 " );
                    }
                }
            }
        }  catch  (Exception e) {
            e.printStackTrace();
            response.getWriter().println( " 上传文件失败 " );
        }

        response.getWriter().println( " Ok " );
    }
}

From: http://hi.baidu.com/sophyishere/blog/item/b7b186131096511cb9127b5f.html