struts2文件的上传和下载-优快云博客

本文链接：https://blog.youkuaiyun.com/zhglhy/article/details/83979191

本文详细介绍了在Struts2框架中实现文件上传和下载的方法，包括使用不同技术手段和配置来完成文件操作的过程。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

【Java EE】struts2文件的上传和下载

（一）从底层透析文件上传的实现，此时并没有介入struts2
1、upload.jsp，在form中属性method默认为get，涉及文件上传时必须改为post，默认 enctype ="application/x-www-form-urlencoded" ，我们暂且不修改，看会有什么结果

@ page language="java" contentType="text/html; charset=GBK"
2

pageEncoding="GBK" %>
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=GB18030" >
7

< title > Insert title here </ title >
8

</ head >
9

< body >
10

< form action ="result.jsp" method ="post"
11

enctype ="application/x-www-form-urlencoded" >
12

Information:
13

< input type ="text" name ="info" >
14

< br >
15

File:
16

< input type ="file" name ="file" >
17

< br >
18

< input type ="submit" name ="submit" value =" submit " >
19

</ form >
20

</ body >
21

</ html >

result.jsp

@ page language="java" contentType="text/html; charset=GBK"
2

pageEncoding="GBK" %>
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=GB18030" >
7

< title > Insert title here </ title >
8

</ head >
9

< body >
10

Information: <% = request.getParameter( " info " ) %> < br >
11

File: <% = request.getParameter( " file " ) %> < br >
12

</ body >
13

</ html >

结果：

2、修改result.jsp页面代码，输出读入的流

@ page import="java.io.*" %>

< body >

InputStream is = request.getInputStream();

BufferedReader br = new BufferedReader(new InputStreamReader(is));

String buffer = null;

while ((buffer = br.readLine()) != null) {

out.print(buffer + "<br>");

}

</ body >

结果：

这个结果可以断定，文件的上传并没有成功，而仅仅是上传了文件的路径信息而已

3、把upload.jsp中form的enctype属性改为 enctype ="multipart/form-data"

< form action ="result.jsp" method ="post" enctype ="multipart/form-data" >

Information:

< input type ="text" name ="info" >

< br >

File:

< input type ="file" name ="file" >

< br >

< input type ="submit" name ="submit" value =" submit " >

</ form >

结果：

说明文件上传是成功的。

（二）手动采用fileupload组建进行文件上传
upload2.jsp

@ page language="java" contentType="text/html; charset=GB18030"
2

pageEncoding="GB18030" %>
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=GB18030" >
7

< title > Insert title here </ title >
8

</ head >
9

< body >
10

< form action ="/MyStruts2/UploadServlet" method ="post" enctype ="multipart/form-data" >
11

username:
12

< input type ="text" name ="username" >
13

< br >
14

password:
15

< input type ="password" name ="password" >
16

< br >
17

file1:
18

< input type ="file" name ="file1" >
19

< br >
20

file2:
21

< input type ="file" name ="file2" >
22

< br >
23

< input type ="submit" value =" submit " >
24

</ form >
25

</ body >
26

</ html >

web.xml中的配置

< servlet >

< servlet-name > UploadServlet </ servlet-name >

< servlet-class > com.test.servlet.UploadServlet </ servlet-class >

</ servlet >

< servlet-mapping >

< servlet-name > UploadServlet </ servlet-name >

< url-pattern > /UploadServlet </ url-pattern >

</ servlet-mapping >

UploadServle.java

package com.test.servlet;
2

import java.io.File;
4

import java.io.FileOutputStream;
5

import java.io.IOException;
6

import java.io.InputStream;
7

import java.io.OutputStream;
8

import java.util.List;
9

import javax.servlet.ServletException;
11

import javax.servlet.http.HttpServlet;
12

import javax.servlet.http.HttpServletRequest;
13

import javax.servlet.http.HttpServletResponse;
14

import org.apache.commons.fileupload.FileItem;
16

import org.apache.commons.fileupload.FileUploadException;
17

import org.apache.commons.fileupload.disk.DiskFileItemFactory;
18

import org.apache.commons.fileupload.servlet.ServletFileUpload;
19

@SuppressWarnings( " serial " )
21

public class UploadServlet extends HttpServlet

{
22

@SuppressWarnings(

{ "unchecked", "deprecation" })
23

public void doPost(HttpServletRequest request, HttpServletResponse response)
24

throws ServletException, IOException

{
25

DiskFileItemFactory factory = new DiskFileItemFactory();
27

String path = request.getRealPath("/upload");
29

factory.setRepository(new File(path));
31

factory.setSizeThreshold(1024 * 1024);
33

ServletFileUpload upload = new ServletFileUpload(factory);
35

try

{
37

List<FileItem> list = upload.parseRequest(request);
38

for (FileItem item : list)

{
40

if (item.isFormField())

{
41

String name = item.getFieldName();
42

String value = item.getString("gbk");
44

System.out.println(name);
46

request.setAttribute(name, value);
48

} else

{
49

String name = item.getFieldName();
50

String value = item.getName();
52

int start = value.lastIndexOf("\\");
54

String fileName = value.substring(start + 1);
56

request.setAttribute(name, fileName);
58

item.write(new File(path, fileName));
60

OutputStream os = new FileOutputStream(new File(path,
62

fileName));
63

InputStream is = item.getInputStream();
65

byte[] buffer = new byte[400];
67

int length = 0;
69

while ((length = is.read(buffer)) > 0)

{
71

os.write(buffer, 0, length);
72

}
73

os.close();
75

is.close();
77

}
79

}
80

}
81

catch (Exception ex)

{
83

ex.printStackTrace();
84

}
85

request.getRequestDispatcher("upload/result2.jsp").forward(request,
86

response);
87

}
88

}

结果：

（三）使用struts2进行文件上传、下载
需引入两个jar包

commons-fileupload-1.2.1.jar

commons-io-1.3.2.jar

这两个jar包在struts2.1.6版本中已经自带，较低版本需到apache网站下载，网址： http://commons.apache.org/

1、单文件上传
upload3.jsp

@ page language="java" contentType="text/html; charset=GB18030"
2

pageEncoding="GB18030" %>
3

@ taglib prefix="s" uri="/struts-tags" %>
4

<! DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd" >
5

< html >
6

< head >
7

< meta http-equiv ="Content-Type" content ="text/html; charset=GB18030" >
8

< title > Insert title here </ title >
9

</ head >
10

< body >
11

< s:form action ="upload" method ="post" theme ="simple"
12

enctype ="multipart/form-data" >
13

< table align ="center" width ="50%" border ="1" >
14

< tr >
15

< td >
16

username
17

</ td >
18

< td >
19

< s:textfield name ="username" ></ s:textfield >
20

</ td >
21

</ tr >
22

< tr >
23

< td >
24

password
25

</ td >
26

< td >
27

< s:password name ="password" ></ s:password >
28

</ td >
29

</ tr >
30

< tr >
31

< td >
32

file
33

</ td >
34

< td >
36

< s:file name ="file" ></ s:file >
37

</ td >
39

</ tr >
40

< tr >
41

< td >
42

< s:submit value =" submit " ></ s:submit >
43

</ td >
44

< td >
45

< s:reset value =" reset " ></ s:reset >
46

</ td >
47

</ tr >
48

</ table >
49

</ s:form >
50

</ body >
51

</ html >

web.xml中的配置

< filter >

< filter-name > struts2 </ filter-name >

< filter-class >

org.apache.struts2.dispatcher.FilterDispatcher

</ filter-class >

</ filter >

< filter-mapping >

< filter-name > struts2 </ filter-name >

< url-pattern > /* </ url-pattern >

</ filter-mapping >

struts.xml中的配置

<? xml version="1.0" encoding="GBK" ?>
2

<! DOCTYPE struts PUBLIC
3

"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
4

"http://struts.apache.org/dtds/struts-2.0.dtd" >
5

< struts >
7

< constant name ="struts.i18n.encoding" value ="gbk" ></ constant >
8

< constant name ="struts.multipart.saveDir" value ="c:\" ></ constant >
9

< package name ="struts2" extends ="struts-default" >
10

< action name ="upload" class ="com.test.action.UploadAction" >
11

< result name ="success" > /upload/result3.jsp </ result >
12

</ action >
13

</ package >
14

</ struts >

UploadAction.java

package com.test.action;
2

import java.io.File;
4

import java.io.FileInputStream;
5

import java.io.FileOutputStream;
6

import java.io.InputStream;
7

import java.io.OutputStream;
8

import org.apache.struts2.ServletActionContext;
10

import com.opensymphony.xwork2.ActionSupport;
12

@SuppressWarnings( " serial " )
14

public class UploadAction extends ActionSupport

{
15

private String username;
16

private String password;
17

private File file;
18

private String fileFileName;
19

private String fileContentType;
20

public String getUsername()

{
22

return username;
23

}
24

public void setUsername(String username)

{
26

this.username = username;
27

}
28

public String getPassword()

{
30

return password;
31

}
32

public void setPassword(String password)

{
34

this.password = password;
35

}
36

public File getFile()

{
38

return file;
39

}
40

public void setFile(File file)

{
42

this.file = file;
43

}
44

public String getFileFileName()

{
46

return fileFileName;
47

}
48

public void setFileFileName(String fileFileName)

{
50

this.fileFileName = fileFileName;
51

}
52

public String getFileContentType()

{
54

return fileContentType;
55

}
56

public void setFileContentType(String fileContentType)

{
58

this.fileContentType = fileContentType;
59

}
60

@SuppressWarnings("deprecation")
62

@Override
63

public String execute() throws Exception

{
64

InputStream is = new FileInputStream(file);
65

String root = ServletActionContext.getRequest().getRealPath("/upload");
66

File destFile = new File(root, this.getFileFileName());
67

OutputStream os = new FileOutputStream(destFile);
68

byte[] buffer = new byte[400];
69

int length = 0;
71

while ((length = is.read(buffer)) > 0)

{
73

os.write(buffer, 0, length);
74

}
75

is.close();
76

os.close();
77

return SUCCESS;
78

}
79

}

结果：

2、多文件上传
修改action

private List < File > file;

private List < String > fileFileName;

private List < String > fileContentType;

public String execute() throws Exception

{

for (int i = 0; i < file.size(); ++i)

{

InputStream is = new FileInputStream(file.get(i));

String root = ServletActionContext.getRequest().getRealPath(

"/upload");

File destFile = new File(root, this.getFileFileName().get(i));

OutputStream os = new FileOutputStream(destFile);

byte[] buffer = new byte[400];

int length = 0;

while ((length = is.read(buffer)) > 0)

{

os.write(buffer, 0, length);

}

is.close();

os.close();

}

return SUCCESS;

}

修改upload3.jsp

< tr >

< td >

file1

</ td >

< td >

< s:file name ="file" ></ s:file >

</ td >

</ tr >

< tr >

< td >

file2

</ td >

< td >

< s:file name ="file" ></ s:file >

</ td >

</ tr >

< tr >

< td >

file3

</ td >

< td >

< s:file name ="file" ></ s:file >

</ td >

</ tr >

结果：

3、任意数量文件上传
在多文件上传的基础上修改upload3.jsp

< script type ="text/javascript" >

function addMore()

{

var td = document.getElementById("more");

var br = document.createElement("br");

var input = document.createElement("input");

var button = document.createElement("input");

input.type = "file";

input.name = "file";

button.type = "button";

button.value = "Remove";

button.onclick = function()

{

td.removeChild(br);

td.removeChild(input);

td.removeChild(button);

}

td.appendChild(br);

td.appendChild(input);

td.appendChild(button);

}

</ script >

< tr >

< td >

file1

</ td >

< td id ="more" >

< s:file name ="file" ></ s:file >

< input type ="button" value ="Add More.." onclick ="addMore()" >

</ td >

</ tr >

结果：

（四）文件上传类型、大小的限制
使用struts的拦截器，struts2-core-2.1.6.jar/org.apache.struts2.interceptor.FileUploadInterceptor.class的源码中我们可以看到：

public class FileUploadInterceptor extends AbstractInterceptor {

private static final long serialVersionUID = -4764627478894962478L;

protected static final Logger LOG = LoggerFactory.getLogger(FileUploadInterceptor.class);

private static final String DEFAULT_MESSAGE = "no.message.found";

protected boolean useActionMessageBundle;

protected Long maximumSize;

protected Set < String > allowedTypesSet = Collections.emptySet();

protected Set < String > allowedExtensionsSet = Collections.emptySet();

所以我们只需的struts.xml中配置它的属性allowedTypesSet即可。在action节点中修改拦截器（默认的拦截器中已经有fileUpload拦截器，我们必须提取出来进行参数设置，然后在加上默认的拦截器）。

< action name ="upload" class ="com.test.action.UploadAction" >

< result name ="success" > /upload/result3.jsp </ result >

< result name ="input" > /upload/upload3.jsp </ result >

< interceptor-ref name ="fileUpload" >

< param name ="maximumSize" > 409600 </ param >

< param name ="allowedTypes" >

application/vnd.ms-powerpoint

</ param >

</ interceptor-ref >

< interceptor-ref name ="defaultStack" ></ interceptor-ref >

</ action >

其中 < param name ="allowedTypes" > application/vnd.ms-powerpoint </ param >的allowedTypes的值可在C:\Tomcat 6.0\conf的web.xml文件中查找。

报错信息：

严重: Content - Type not allowed: file " intrl.txt " " upload__138d8aca_120b73e9cf4__8000_00000002.tmp " text / plain

（五）文件的下载
download.jsp

< s:a href ="/MyStruts2/download.action" > download </ s:a >

DownloadAction.java

package com.test.action;
2

import java.io.InputStream;
4

import org.apache.struts2.ServletActionContext;
6

import com.opensymphony.xwork2.ActionSupport;
8

public class DownloadAction extends ActionSupport

{
10

public InputStream getDownloadFile()

{
11

return ServletActionContext.getServletContext().getResourceAsStream(
12

"/upload/intrl.ppt");
13

}
14

@Override
16

public String execute() throws Exception

{
17

return SUCCESS;
18

}
19

}
20

web.xml中action配置

< action name ="download"

class ="com.test.action.DownloadAction" >

< result name ="success" type ="stream" >

< param name ="contentType" >

application/vnd.ms-powerpoint

</ param >

< param name ="contentDisposition" >

filename="intrl.ppt"

</ param >

< param name ="inputName" > downloadFile </ param >

</ result >

</ action >

结果：

FROM:http://www.cnitblog.com/intrl/archive/2009/04/18/56447.html