使用ajaxfileupload.js异步上传文件到Servlet

        前段时间帮同学做的毕业设计。。好吧又是帮人做。。。需要上传文件，在这里使用了ajaxfileupload.js进行异步的上传文件到Servlet  ，后台保存了文件以后通过JSON返回文件路径到前端，好了废话不多说，直接上代码了。。。

         前端页面比较简单

     <input maxlength=16 type=file name="pic" id="pic" size=16 /> 

     <input type="button"  id="uploadBut" onclick = "ajaxFileUpload()" value="上传" />

    <script type="text/javascript" src="js/jquery.js"></script>  
    <script type="text/javascript" src="js/ajaxfileupload.js"></script> 

 function ajaxFileUpload() {  
    	    
    	        $.ajaxFileUpload({  
    	            url : 'UploadServlet',// servlet请求路径  
    	            secureuri : false,  
    	            fileElementId : 'pic',// 上传控件的id  
    	            dataType : 'json',
    	            success : function(data)
    	            {
    	            	alert(data.msg);
    	            	alert("文件路径："+data.filePath);
    	            	document.getElementById("imagePath").value= data.filePath;
    	            }  
    	        })  
    	        return false;  
    	    }  

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

		        //从request当中获取流信息
				InputStream fileSource = request.getInputStream();
				String tempFileName = "C:/tempFile";
				//tempFile指向临时文件
				File tempFile = new File(tempFileName);
				//outputStram文件输出流指向这个临时文件
				FileOutputStream outputStream = new FileOutputStream(tempFile);
				byte b[] = new byte[2 * 1024];
				int n;
				while(( n = fileSource.read(b)) != -1){
					outputStream.write(b, 0, n);
				}
				//关闭输出流、输入流
				outputStream.close();
				fileSource.close();
				
				//获取上传文件的名称
				RandomAccessFile randomFile = new RandomAccessFile(tempFile,"r");
				randomFile.readLine();
				String str = randomFile.readLine();
				System.out.println(str);
				
				int endIndex = str.lastIndexOf("\"");
				String beginStr = str.substring(0,endIndex);
				int beginIndex = beginStr.lastIndexOf("\"") +1;
				String filename = beginStr.substring(beginIndex, beginStr.length());
				
				System.out.println("filename:" + filename);
				
				//重新定位文件指针到文件头
				randomFile.seek(0);
				long startPosition = 0;
				int i = 1;
				//获取文件内容 开始位置
				while(( n = randomFile.readByte()) != -1 && i <=4){
					if(n == '\n'){
						startPosition = randomFile.getFilePointer();
						i ++;
					}
				}
				startPosition = randomFile.getFilePointer() -1;
				//获取文件内容 结束位置
				randomFile.seek(randomFile.length());
				long endPosition = randomFile.getFilePointer();
				int j = 1;
				while(endPosition >=0 && j<=2){
					endPosition--;
					randomFile.seek(endPosition);
					if(randomFile.readByte() == '\n'){
						j++;
					}
				}
				endPosition = endPosition -1;
				
				//设置保存上传文件的路径
				String realPath = getServletContext().getRealPath("/") + "images";
				File fileupload = new File(realPath);
				if(!fileupload.exists()){
					fileupload.mkdir();
				}
				File saveFile = new File(realPath,filename);
				RandomAccessFile randomAccessFile = new RandomAccessFile(saveFile,"rw");
				
				//从临时文件当中读取文件内容（根据起止位置获取）
				randomFile.seek(startPosition);
				while(startPosition < endPosition){
					randomAccessFile.write(randomFile.readByte());
					startPosition = randomFile.getFilePointer();
				}
				//关闭输入输出流、删除临时文件
				randomAccessFile.close();
				randomFile.close();
				tempFile.delete();
				System.out.println(saveFile.toString());
				PrintWriter writer = response.getWriter();
				writer.print(" { ");
				writer.print(" \"success\" : \"true\" ,\"msg\" : \"上传成功！ \", \"filePath\" : \"images/" +filename+" \" ");
				writer.print(" } ");
				writer.close(); 
		
	}