java文件上传–基于ajaxFileUpload+struts2详解编程语言

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>