如何使用fileupload工具来实现文件上传

1。需要两个夹包文件：
commons-fileupload-1.2.1.jar、
commons-io-1.4.jar

2。页面文件上传

	<form action="upload" method="post" enctype="multipart/form-data">
  		file:<input type="file" name="file" /><br/>
  		username:<input type="text" name="username"/><br/>
  		<input type="submit" value="submit"/>
  	</form>
  </body>

3.servlet处理页面请求；

package org.yinhe.servlet;

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

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 UpLoadServlet extends HttpServlet {


	@SuppressWarnings("unchecked")
	public void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		DiskFileItemFactory factory = new DiskFileItemFactory();
		ServletFileUpload upload = new ServletFileUpload(factory);
		try {
			FileItem item = null;
			List<FileItem> items = upload.parseRequest(request);
			for (int i = 0; i < items.size(); i++) {
				item = items.get(i);
				if(item.isFormField()){
					//如果是普通的控件
					String fileName = item.getFieldName();
					String username = item.getString();
					System.out.println(fileName + ":" + username);
				}else{
					//如果是文件上传的控件，一般我们需要将
					//其内容转化为一个文件，并保存到服务器上面。
					//item.getName()返回的文件名:某些操作系统
					//，返回的文件名包含了路径，有一些不包含。
					String name = item.getName();
					String name2 = name.substring(name.lastIndexOf("/")+1);
					System.out.println("name:"+name2);
					//获取保存文件的路径
					//getRealPath:返回服务器的某个目录的绝对路径。
					String path = this.getServletContext().getRealPath("upload");
					System.out.println("path:" + path);
					item.write(new File(path+"/" + name2));
				}
			}
		} catch (Exception e) {
			throw new ServletException(e.getMessage());
		}
		response.sendRedirect("sucess.jsp");
	}

}