FileUpload

一upload原理：

　　　　　　1.表单的method必须是post方法

　　　　　　2.enctype属性必须是“mutipatr/form-data”类型

　　　　　　　enctype默认的属性是“application/x-www-form-urlencoded”

　　　　　　　enctype的作用是：告知服务器请求正文的MIME类型

　　　　　　application/x-www-form-urlencoded:username=aaa&password=123

　　　　　　ServletRequest.getParameter(String name)，该方法是专门用来读取enctype是“application/x-www-form-urlencoded”时的方法

　　　　　　3.在Servlet里面通过request.getInputStream()方法就可以获得文件输入流

　　　　　　　　byte[] b= new byte[1024];

　　　　　　　　int len=0;

　　　　　　　　InputStream is = request.getInputStream();
　　　　　　　　while((len=is.read(b)) != -1){
　　　　　　　　System.out.println(new String(b,0 ,len));
　　　　　　　　}

代码示例

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 <form action="${pageContext.request.contextPath}/UploadServlet" method="post" enctype="multipart/form-data">
11     请输入FileName<input type="text" name="FileName"/>
12                 <input type="file"name="file"/>
13                 <input type="submit" value="提交"/>
14                 ${pageContext.request.contextPath}
15                 
16                 
17     
18     
19 </form>
20 
21 </body>
22 </html>

jspShow

 1 package jcbc.ds.test1;
 2 
 3 import java.io.IOException;
 4 import java.io.InputStream;
 5 import java.util.List;
 6 
 7 import javax.servlet.ServletException;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 
12 import org.apache.commons.fileupload.FileItem;
13 import org.apache.commons.fileupload.FileUploadException;
14 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
15 import org.apache.commons.fileupload.servlet.ServletFileUpload;
16 
17 /**
18  * Servlet implementation class UploadServlet
19  */
20 public class UploadServlet extends HttpServlet {
21     private static final long serialVersionUID = 1L;
22        
23     /**
24      * @see HttpServlet#HttpServlet()
25      */
26     public UploadServlet() {
27         super();
28         
29     }
30 
31     /**
32      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
33      */
34     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
35         
36         //创建DiskFileItemFactory对象
37         //DiskFileItemFactory dis = new DiskFileItemFactory();
38         //创建ServletFileUpload对象
39         /*ServletFileUpload servletupload = new ServletFileUpload(dis);*/
40         byte[] b= new byte[1024];
41         int len=0;
42         InputStream is = request.getInputStream();
43         while((len=is.read(b)) != -1){
44             System.out.println(new String(b,0 ,len));
45         }
46         /*try {
47             List<FileItem>    fileItem = servletupload.parseRequest(request);
48             for(FileItem items : fileItem) {
49                 System.out.println(items.getName());
50                 //进行解析传过来的数据进行封装
51             }
52             is.close();
53             
54         } catch (FileUploadException e) {
55             // TODO Auto-generated catch block
56             e.printStackTrace();
57         }*/
58         
59     }
60 
61 }

ServerServlet

二借助第三方组件实现文件上传：

　　步骤：

　　1.拷贝jar包commons-fileupload.jar commons-io.jar

　　　　具体参考http://commons.apache.org/proper/commons-fileupload/using.html　　

　　2.//创建DiskFileItemFactory对象

　　 DiskFileItemFactory disfileitemfactory = new DiskFileItemFactory();
　　 //创建ServletFileUpload对象
　　 ServletFileUpload servletupload = new ServletFileUpload(disfileitemfactory);

　　3.获取封装信息

　　　　List<FileItem> fileItem = servletupload.parseRequest(request);//这里会抛异常

　　具体步骤代码如下：

 1 package jcbc.ds.test1;
 2 
 3 import java.io.File;
 4 import java.io.IOException;
 5 import java.io.InputStream;
 6 import java.io.OutputStream;
 7 import java.util.List;
 8 
 9 import javax.servlet.ServletException;
10 import javax.servlet.http.HttpServlet;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpServletResponse;
13 
14 import org.apache.commons.fileupload.FileItem;
15 import org.apache.commons.fileupload.FileUploadException;
16 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
17 import org.apache.commons.fileupload.servlet.ServletFileUpload;
18 import org.apache.commons.io.FileUtils;
19 
20 /**
21  * Servlet implementation class UploadServlet
22  */
23 public class UploadServlet extends HttpServlet {
24     private static final long serialVersionUID = 1L;
25        
26     /**
27      * @see HttpServlet#HttpServlet()
28      */
29     public UploadServlet() {
30         super();
31         
32     }
33 
34     /**
35      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
36      */
37     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
38         response.setContentType("text/html; charset=gbk");
39         //创建DiskFileItemFactory对象
40         DiskFileItemFactory disfileitemfactory = new DiskFileItemFactory();
41         //创建ServletFileUpload对象
42         ServletFileUpload servletupload = new ServletFileUpload(disfileitemfactory);
43         
44         try {
45             //封装
46             List<FileItem>    fileItem = servletupload.parseRequest(request);
47             for(FileItem files : fileItem ){
48                 if(files.isFormField()){
49                     System.out.println(files.getFieldName());
50                 }
51                 else{
52                     InputStream is = files.getInputStream();
53                     String name = files.getName();
54                     //截取文件名
55                     String fileName = name.substring(name.lastIndexOf("\")+1);
56                     System.out.println(fileName);//打印结果为huxuebing.txt
57                     
58                     System.out.println(request.getServletContext().getRealPath("/fileName"));
59                     //创建File类对象
60                     File file = new File(request.getServletContext().getRealPath("/")+fileName);
61                     //判断该文件是否存在如果不存在就创建，存在就不创建
62                     if(file.exists()==false){
63                         System.out.println("==================");
64                         file.createNewFile();
65                         System.out.println("==================");
66                     }
67                     try {
68                         //向创建的文件写入
69                         files.write(file);
70                     } catch (Exception e) {
71                         // TODO Auto-generated catch block
72                         e.printStackTrace();
73                     }
74                     
75                 }
76                         
77             }
78             
79         } catch (FileUploadException e) {
80             // TODO Auto-generated catch block
81             e.printStackTrace();
82         }
83         
84     }
85 
86 }

commontsUploadFiles

FileName
huxuebing.txt
D:workSpaceweb2.metadata.pluginsorg.eclipse.wst.server.core	mp0wtpwebappsday18fileName
==================
==================

result