11.12易科
使用SESSION对象判断用户输入的用户名和密码是否正确
string name = TextBox1.Text;
string pass = TextBox2.Text;
if (name == "admin" && pass == "123")
{
Session["abc"] = "admin";
Session.Timeout = 1;
Response.Redirect("main.aspx");
}//main.aspx 页面 if (Session["abc"] == null)
{
Response.Redirect("Default.aspx");
}
else
{
Label1.Text = "欢迎你,"+Session["abc"].ToString();
}
getPart()和getParts()取得上传的文件和Part接口的介绍
一。在Servlet中增加了Part接口。可以更加方便的进行文件上传处理，可以通过request的getPart()方法取得Part接口。
下面的HTML是上传文件的代码。
<!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=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="upload2.do" method="post" enctype="multipart/form-data">
上传照片:<input type="file" name="photo"><br/><br/>
<input type="submit" value="上传" name="upload">
</form>
</body>
</html>
用下面的servlet来处理上传的文件
1 package com.sunyongxing.servlet;
2
3 import java.io.FileOutputStream;
4 import java.io.IOException;
5 import java.io.InputStream;
6 import java.io.OutputStream;
7
8 import javax.servlet.ServletException;
9 import javax.servlet.annotation.MultipartConfig;
10 import javax.servlet.annotation.WebServlet;
11 import javax.servlet.http.HttpServlet;
12 import javax.servlet.http.HttpServletRequest;
13 import javax.servlet.http.HttpServletResponse;
14 import javax.servlet.http.Part;
15
16 /**
17 * Servlet implementation class UploadServlet
18 */
19 @MultipartConfig
20 @WebServlet("/upload.do")
21 public class UploadServlet extends HttpServlet {
22 private static final long serialVersionUID = 1L;
23
24 protected void doPost(HttpServletRequest request,
25 HttpServletResponse response) throws ServletException, IOException {
26 request.setCharacterEncoding("utf-8");
27 Part part = request.getPart("photo");
28 String fileName = getFileName(part);
29 writeTo(fileName,part);
30 }
31
32 private void writeTo(String fileName, Part part)throws IOException {
33 InputStream in = part.getInputStream();
34 OutputStream out = new FileOutputStream("d:/"+fileName);
35 byte[] b = new byte[1024];
36 int length = -1;
37 while((length = in.read(b))!=-1)
38 {
39 out.write(b, 0, length);
40 }
41 in.close();
42 out.close();
43 }
44
45 private String getFileName(Part part) {
46 String head = part.getHeader("Content-Disposition");
47 String fileName = head.substring(head.indexOf("filename=\"")+10, head.lastIndexOf("\""));
48 System.out.println(fileName);
49 return fileName;
50 }
51
52 }
Tomcat中必须设置@MultipartConfig标注才能使用getPart()相关API，否则会返回null。getFileName()方法获取上传的文件名是通过对标头信息的解析，因为每一个multipart/form-data发送的每个内容区段（这些内容可以通过request的getReade()方法获得，见getReader的文件），都会有以下的标头信息:
Content-Disposition:form-data;name="photo";filename="haha.jpg"
Content-Type:image/jpeg
.......
对@MultipartConfig标注的说明。@MultipartConfig标注有一下的属性可用。
fileSizeThreshold:整数值设置，默认值为0，若上传文件的大小超过了这个值，就会先写入缓存文件。
location:字符串设置，默认值为空字符串。如果设置这个属性，缓存文件就是写到制定目录，下面举例说明
maxFileSize:限制文件上传大小。默认值为-1L，表示不限制大小。
maxRequestSize:限制multipart/form-data请求格式，默认值为-1L，表示不限制个数。
二。Part接口的进一步介绍
Part接口有一个write()方法。可以直接将上传文件写入磁盘中，参数为上传的文件名，写入的路径就是@MultipartConfig的location设置的路径，见下面的servlet。
1 package com.sunyongxing.servlet;
2
3 import java.io.IOException;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.annotation.MultipartConfig;
7 import javax.servlet.annotation.WebServlet;
8 import javax.servlet.http.HttpServlet;
9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 import javax.servlet.http.Part;
12
13 /**
14 * Servlet implementation class UploadServlet
15 */
16 @MultipartConfig(location="E:/jsp")
17 @WebServlet("/upload2.do")
18 public class UploadServlet2 extends HttpServlet {
19 private static final long serialVersionUID = 1L;
20
21 protected void doPost(HttpServletRequest request,
22 HttpServletResponse response) throws ServletException, IOException {
23 request.setCharacterEncoding("utf-8");
24 Part part = request.getPart("photo");
25 String fileName = getFileName(part);
26 part.write(fileName);
27 }
28
29
30
31 private String getFileName(Part part) {
32 String head = part.getHeader("Content-Disposition");
33 String fileName = head.substring(head.indexOf("filename=\"")+10, head.lastIndexOf("\""));
34 System.out.println(fileName);
35 return fileName;
36 }
37
38 }
三。上传多个文件的处理方法。
如果一次上传多个文件，可以使用getParts()方法，会返回一个Collection
1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
2 <html>
3 <head>
4 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
5 <title>Insert title here</title>
6 </head>
7 <body>
8 <form action="upload3.do" method="post" enctype="multipart/form-data">
9 上传文件:
10 <input type="file" name="photo1"><br/>
11 <input type="file" name="photo2"><br/>
12 <input type="file" name="photo3"><br/>+
13 <input type="submit" value="上传" name="upload">
14 </form>
15 </body>
16 </html>
处理多个文件同时上传的servlet如下
1 package com.sunyongxing.servlet;
2
3 import java.io.IOException;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.annotation.MultipartConfig;
7 import javax.servlet.annotation.WebServlet;
8 import javax.servlet.http.HttpServlet;
9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 import javax.servlet.http.Part;
12
13 /**
14 * Servlet implementation class UploadServlet
15 */
16 @MultipartConfig(location = "E:/jsp")
17 @WebServlet("/upload3.do")
18 public class UploadServlet3 extends HttpServlet {
19 private static final long serialVersionUID = 1L;
20
21 protected void doPost(HttpServletRequest request,
22 HttpServletResponse response) throws ServletException, IOException {
23 request.setCharacterEncoding("utf-8");
24 for (Part part : request.getParts()) {
25 if (part.getName().startsWith("photo")) {
26 String fileName = getFileName(part);
27 part.write(fileName);
28 }
29
30 }
31 }
32
33 private String getFileName(Part part) {
34 String head = part.getHeader("Content-Disposition");
35 String fileName = head.substring(head.indexOf("filename=\"") + 10,
36 head.lastIndexOf("\""));
37 System.out.println(fileName);
38 return fileName;
39 }
40
41 }
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