上传文件组件

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Java Servlet Apache JSP BBS

   在很多的jsp 项目中，我们要上传附件，如很多的BBS也有这样的功能，邮件也一样，相信大家已非常熟悉了，这里就介绍他是怎么实现的；
这里我们选择第三方组件，你可以选择：commons-fileupload 或jspSmartUpload
这里我们选择apache的commons-fileupload;

   这个组件的包你可以在：http://jakarta.apache.org/site/downloads/下载
可以在左边的导航中找到Commons然后在里面找到commons-fileupload
在用这个包的同时我们还用到了apache的io包，它同样在Commons里可以找到；

下面是书上的一个实例代码：
    upload.jsp

<%@ page language="java" contentType="text/html;charset=GBK"
    pageEncoding="GBK"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>Insert title here</title>
</head>
<body>

  common file upload 上传实例<br>
  <form method="post" action="FileUpload" ENCTYPE="multipart/form-data">
  文件:<input type="file" name="file"/>
  <input type="submit" value="上传" name="submit">
  </form>


</body>
</html>

下面是一个处理的servlet
FileUpload.java

package servlet;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;

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.FileItemFactory;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class FileUpload extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public FileUpload() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) 
	throws ServletException, IOException {
		this.doPost(request, response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
		boolean isMultipart=ServletFileUpload.isMultipartContent(request);
		if(isMultipart){
			FileItemFactory factory=new DiskFileItemFactory();
			ServletFileUpload upload=new ServletFileUpload(factory);
			Iterator items;
			
			
			try{
				items=upload.parseRequest(request).iterator();
				while(items.hasNext()){
					FileItem item=(FileItem)items.next();
					if(!item.isFormField()){
						String name=item.getName();
						String fileName=name.substring(name.lastIndexOf('\\')+1, name.length());
						String path=request.getRealPath("file")+
						File.separatorChar+fileName;
						File uploadFile=new File(path);
						item.write(uploadFile);
						
						response.setContentType("text/html");
						response.setCharacterEncoding("gb2312");
						PrintWriter out=response.getWriter();
						out.print("<font size='12'>上传文件为"+name+"<br>");
						out.print("保存地址为"+path+"<br>");
					}
				}
				
			}catch(Exception e){
				e.printStackTrace();
			}
			
		}
	}

}

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