java文件上传--基于ajaxFileUpload+struts2

jQuery插件ajaxFileUpload可以实现ajax文件上传，使用非常简单。

下面做一个简单的demo(以上传图片为例)，实现图片上传，图片显示，图片下载

注：以下的代码是在项目的基础上进行开发。css样式文件、包路径等未做修改。

1、 ajaxFileUpload文件下载地址http://www.phpletter.com/Demo/AjaxFileUpload-Demo/

2、自行引入jquery.js、ajaxFileUpload.js文件

jsp核心代码：

 <script type="text/javascript">
   function fileUpload() {
     $.ajaxFileUpload( {
         url : 'admin/fileAction.do',//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',     //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) {
             $("#downImg").show();   //待上传成功后 显示下载按钮
             $("#downImg").attr("href","admin/downloadImage.do?filePath="+data.filePath);
             $("#showImg").attr("src","admin/redImage.do?path=" + data.filePath);
         }
     })
   }
 </script>
 <table class="editTable">
    <tr>
     <td colspan="4">
         <img id="showImg" alt="" src="">
         <a id="downImg" style="display: none" href="">下载</a>
     </td>
    </tr>
    <tr>
     <td class="title">
         上传图片:
     </td>
     <td colspan="3">
         <input type="file" id="file" name="file" onchange="fileUpload();">
     </td>
    </tr>
 </table>

3、AjaxFileUploadAction

 public class AjaxFileUploadAction extends WebSupport {

     private File file;            //文件
     private String fileFileName;  //文件名
     private String filePath;      //文件路径
     private InputStream inputStream;

     /**
      * 图片上传
      *
      * @return
      */
     public String fileUpload() {
         String path = ServletActionContext.getServletContext().getRealPath("/upload");
         File file = new File(path); // 判断文件夹是否存在,如果不存在则创建文件夹
         if (!file.exists()) {
             file.mkdir();
         }
         try {
           if (this.file != null) {
             File f = this.getFile();
             String fileName = java.util.UUID.randomUUID().toString(); // 采用时间+UUID的方式随即命名
             String name = fileName+ fileFileName.substring(fileFileName.lastIndexOf(".")); // 保存在硬盘中的文件名

             FileInputStream inputStream = new FileInputStream(f);
             FileOutputStream outputStream = new FileOutputStream(path+ "\\" + name);
             byte[] buf = new byte[1024];
             int length = 0;
             while ((length = inputStream.read(buf)) != -1) {
                 outputStream.write(buf, 0, length);
             }
             inputStream.close();
             outputStream.flush();
             //文件保存的完整路径  比如：D:\tomcat6\webapps\eserver\\upload\a0be14a1-f99e-4239-b54c-b37c3083134a.png
             filePath = path+"\\"+name;

           }
         } catch (Exception e) {
             e.printStackTrace();
         }
         return SUCCESS;
     }

     /**
      * 用于图片页面显示
      *
      * @return
      */
     public String readImg() {
         try {
             inputStream = new FileInputStream(new File(getRequest().getParameter("path")));
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         }
         return SUCCESS;
     }
     /**
      * 图片下载
      * @return
      */
     public String download() {
         String path = filePath;
         HttpServletResponse response = ServletActionContext.getResponse();
         try {
             // path是指欲下载的文件的路径。
             File file = new File(path);
             // 取得文件名。
             String filename = file.getName();
             // 取得文件的后缀名。
             String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();
             // 以流的形式下载文件。
             InputStream fis = new BufferedInputStream(new FileInputStream(path));
             byte[] buffer = new byte[fis.available()];
             fis.read(buffer);
             fis.close();
             //清空response
             response.reset();
             //设置response的Header
             String filenameString = new String(filename.getBytes("gbk"),"iso-8859-1");
             response.addHeader("Content-Disposition", "attachment;filename=" + filenameString);
             response.addHeader("Content-Length", "" + file.length());
             OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
             response.setContentType("application/octet-stream");
             toClient.write(buffer);
             toClient.flush();
             toClient.close();
         } catch (IOException ex) {
             ex.printStackTrace();
         }
         return null;
     }

     public File getFile() {
         return file;
     }

     public void setFile(File file) {
         this.file = file;
     }

     public String getFileFileName() {
         return fileFileName;
     }

     public void setFileFileName(String fileFileName) {
         this.fileFileName = fileFileName;
     }

     public String getFilePath() {
         return filePath;
     }

     public void setFilePath(String filePath) {
         this.filePath = filePath;
     }

     public InputStream getInputStream() {
         return inputStream;
     }

     public void setInputStream(InputStream inputStream) {
         this.inputStream = inputStream;
     }

     private static final Logger log = Logger
             .getLogger(AjaxFileUploadAction.class);
     private static final long serialVersionUID = 1L;
 }

4、struts配置

 <struts>
    <package name="struts_Ajax_code" extends="json-default">
        <!-- 文件上传 -->
        <action name="fileAction" class="com.bk.eserver.web.action.AjaxFileUploadAction" method="fileUpload">
             <result type="json" name="success">
                  <param name="contentType">text/html</param>
             </result>
        </action>
    </package>
    <package name="struts_Jsp_code" extends="struts-default">
        <!-- 图片读取 -->
        <action name="redImage" class="com.bk.eserver.web.action.AjaxFileUploadAction" method="readImg">
             <result type="stream">
                  <param name="contentType">application/octet-stream</param>
                  <param name="inputName">inputStream</param>
                  <param name="contentDisposition">attachment;filename=${fileName}</param>
                  <param name="bufferSize">4096</param>
             </result>
        </action>
        <!-- 文件下载 -->
        <action name="downloadImage" class="com.bk.eserver.web.action.AjaxFileUploadAction" method="download">
             <result type="stream">
                  <param name="contentType">application/octet-stream</param>
                  <param name="inputName">inputStream</param>
                  <param name="contentDisposition">attachment;filename=${fileName}</param>
                  <param name="bufferSize">4096</param>
             </result>
        </action>
    </package>
 </struts>

http://blog.csdn.net/itmyhome/article/category/885203/2