文件上传与下载

文件上传与下载

a.使用 ajaxfileupload.js 完成文件上传

 http://www.phpletter.com/Our-Projects/AjaxFileUpload/

  js 方法

function ajaxFileUpload()
{
     $("#loading_img").ajaxStart(function(){
         $(this).show();  //开始上传文件时显示一个图片
     }).ajaxComplete(function(){
         $(this).hide();  //文件上传完成将图片隐藏起来
     });
    
      $.ajaxFileUpload
      (
          {
              url:'FileUpLoadServlet',//用于文件上传的服务器端请求地址
              secureuri:false,//一般设置为false
              fileElementId:'file_ajax',//文件上传空间的id属性  <input type="file" id="file" name="file" />
              dataType: 'json',//返回值类型 一般设置为json
              success: function (data, status)  //服务器成功响应处理函数
              {
                  //从服务器返回的json中取出message中的数据,其中message为在struts2中action中定义的成员变量
                  alert(data.message);
                  
                  if(typeof(data.error) != 'undefined')
                  {
                      if(data.error != '')
                      {
                          alert(data.error);
                      }else
                      {
                          alert(data.message);
                      }
                  }
              },
              error: function (data, status, e)//服务器响应失败处理函数
              {
                  alert(e);
              }
          }
      )
      
      return false;

}    

  HTML代码

<img src="images/indicator.gif" id="loading_img" style="display: none;">
<input type="file" id="file_ajax" name="file_ajax">
<input type="button" value="文件上传" onclick="ajaxFileUpload()"/>

  java 部分的代码   （来源于网络，仅作参考）

  http://www.cnblogs.com/hongten/archive/2011/07/26/2117340.html

 

package ajax.fileupload;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
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.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class FileUpLoadServlet extends HttpServlet {
    
     private static final long serialVersionUID = -7744625344830285257L;
     private ServletContext sc;
     private String savePath;

    
    public FileUpLoadServlet() {
        super();
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        doPost(request, response);
    }

    public void init(ServletConfig config) throws ServletException 
    {
          // 在web.xml中设置的一个初始化参数
          savePath = config.getInitParameter("savePath");
          sc = config.getServletContext();
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

          request.setCharacterEncoding("UTF-8");
          response.setCharacterEncoding("UTF-8");
          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("上传文件的类型:" + item.getContentType());
                         
                          // item.getName()返回上传文件在客户端的完整路径名称
                          System.out.println("上传文件的名称:" + item.getName());

                          File tempFile = new File(item.getName());

                          //上传文件的保存路径
                          File file = new File(sc.getRealPath("/") + savePath, tempFile.getName());
                          item.write(file);
                          
                          PrintWriter out = response.getWriter();
                          out.println("{'message':'上传文件成功！'}");
                    }
                    else
                    {
                          request.setAttribute("message", "没有选择上传文件！");
                    }
               }
           }
          }
          catch(FileUploadException e)
          {
              e.printStackTrace();
          }
          catch (Exception e) 
          {
              e.printStackTrace();
              request.setAttribute("message", "上传文件失败！");
          }
          
          //request.getRequestDispatcher("/uploadResult.jsp").forward(request, response);
    }
    
}

 需要引入的jar
 

    FileUpload下载地址：

　　http://commons.apache.org/fileupload/

　　下载：commons-fileupload-1.2.2-bin.zip    得到：commons-fileupload-1.2.2.jar

　　http://commons.apache.org/io/

　　下载：commons-io-1.4-bin.zip       得到：commons-io-1.4.jar

   web.xml文件中需要配置

 <servlet>
  .....
  
    <!--设置初始化参数-->
    <init-param>
     <param-name>savePath</param-name>
     <param-value>uploads</param-value>
    </init-param>
</servlet>

  在tomcat的webapps目录下建 文件夹  uploads
  ......webappsUploadFileuploads

  有进度条的文件上传

  http://plkong.iteye.com/blog/238159