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

1 <% @pagelanguage="java"contentType="text/html;charset=GBK"
2pageEncoding="GBK" %>
3 <! DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//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 > Inserttitlehere </ 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

1 <% @pagelanguage="java"contentType="text/html;charset=GBK"
2pageEncoding="GBK" %>
3 <! DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//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 > Inserttitlehere </ 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

<% @pageimport="java.io.*" %>

< body >
<%
InputStreamis=request.getInputStream();
BufferedReaderbr=newBufferedReader(newInputStreamReader(is));
Stringbuffer=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

1 <% @pagelanguage="java"contentType="text/html;charset=GB18030"
2pageEncoding="GB18030" %>
3 <! DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//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 > Inserttitlehere </ 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

1 package com.test.servlet;
2
3 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
10 import javax.servlet.ServletException;
11 import javax.servlet.http.HttpServlet;
12 import javax.servlet.http.HttpServletRequest;
13 import javax.servlet.http.HttpServletResponse;
14
15 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
20 @SuppressWarnings( " serial " )
21 public class UploadServlet extends HttpServlet {
22@SuppressWarnings({"unchecked","deprecation"})
23publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)
24throwsServletException,IOException{
25
26DiskFileItemFactoryfactory=newDiskFileItemFactory();
27
28Stringpath=request.getRealPath("/upload");
29
30factory.setRepository(newFile(path));
31
32factory.setSizeThreshold(1024*1024);
33
34ServletFileUploadupload=newServletFileUpload(factory);
35
36try{
37List<FileItem>list=upload.parseRequest(request);
38
39for(FileItemitem:list){
40if(item.isFormField()){
41Stringname=item.getFieldName();
42
43Stringvalue=item.getString("gbk");
44
45System.out.println(name);
46
47request.setAttribute(name,value);
48}else{
49Stringname=item.getFieldName();
50
51Stringvalue=item.getName();
52
53intstart=value.lastIndexOf("\\");
54
55StringfileName=value.substring(start+1);
56
57request.setAttribute(name,fileName);
58
59item.write(newFile(path,fileName));
60
61OutputStreamos=newFileOutputStream(newFile(path,
62fileName));
63
64InputStreamis=item.getInputStream();
65
66byte[]buffer=newbyte[400];
67
68intlength=0;
69
70while((length=is.read(buffer))>0){
71os.write(buffer,0,length);
72}
73
74os.close();
75
76is.close();
77
78}
79}
80}
81
82catch(Exceptionex){
83ex.printStackTrace();
84}
85request.getRequestDispatcher("upload/result2.jsp").forward(request,
86response);
87}
88
89}

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

1 <% @pagelanguage="java"contentType="text/html;charset=GB18030"
2pageEncoding="GB18030" %>
3 <% @taglibprefix="s"uri="/struts-tags" %>
4 <! DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//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 > Inserttitlehere </ 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
35 < td >
36 < s:file name ="file" ></ s:file >
37
38 </ 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

1 <? xmlversion="1.0"encoding="GBK" ?>
2 <! DOCTYPEstrutsPUBLIC
3 "-//ApacheSoftwareFoundation//DTDStrutsConfiguration2.0//EN"
4 "http://struts.apache.org/dtds/struts-2.0.dtd" >
5
6 < 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

1 package com.test.action;
2
3 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
9 import org.apache.struts2.ServletActionContext;
10
11 import com.opensymphony.xwork2.ActionSupport;
12
13 @SuppressWarnings( " serial " )
14 public class UploadAction extends ActionSupport {
15privateStringusername;
16privateStringpassword;
17privateFilefile;
18privateStringfileFileName;
19privateStringfileContentType;
20
21publicStringgetUsername(){
22returnusername;
23}
24
25publicvoidsetUsername(Stringusername){
26this.username=username;
27}
28
29publicStringgetPassword(){
30returnpassword;
31}
32
33publicvoidsetPassword(Stringpassword){
34this.password=password;
35}
36
37publicFilegetFile(){
38returnfile;
39}
40
41publicvoidsetFile(Filefile){
42this.file=file;
43}
44
45publicStringgetFileFileName(){
46returnfileFileName;
47}
48
49publicvoidsetFileFileName(StringfileFileName){
50this.fileFileName=fileFileName;
51}
52
53publicStringgetFileContentType(){
54returnfileContentType;
55}
56
57publicvoidsetFileContentType(StringfileContentType){
58this.fileContentType=fileContentType;
59}
60
61@SuppressWarnings("deprecation")
62@Override
63publicStringexecute()throwsException{
64InputStreamis=newFileInputStream(file);
65Stringroot=ServletActionContext.getRequest().getRealPath("/upload");
66FiledestFile=newFile(root,this.getFileFileName());
67OutputStreamos=newFileOutputStream(destFile);
68byte[]buffer=newbyte[400];
69
70intlength=0;
71
72while((length=is.read(buffer))>0){
73os.write(buffer,0,length);
74}
75is.close();
76os.close();
77returnSUCCESS;
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 Stringexecute() throws Exception {
for(inti=0;i<file.size();++i){
InputStreamis=newFileInputStream(file.get(i));
Stringroot=ServletActionContext.getRequest().getRealPath(
"/upload");
FiledestFile=newFile(root,this.getFileFileName().get(i));
OutputStreamos=newFileOutputStream(destFile);
byte[]buffer=newbyte[400];

intlength=0;

while((length=is.read(buffer))>0){
os.write(buffer,0,length);
}
is.close();
os.close();
}
returnSUCCESS;
}

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" >
functionaddMore()
{
vartd=document.getElementById("more");
varbr=document.createElement("br");
varinput=document.createElement("input");
varbutton=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 ="AddMore.." 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：

publicclassFileUploadInterceptorextendsAbstractInterceptor{

privatestaticfinallongserialVersionUID=-4764627478894962478L;

protectedstaticfinalLoggerLOG=LoggerFactory.getLogger(FileUploadInterceptor.class);
privatestaticfinalStringDEFAULT_MESSAGE="no.message.found";

protectedbooleanuseActionMessageBundle;

protectedLongmaximumSize;
protectedSet < String > allowedTypesSet=Collections.emptySet();
protectedSet < 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<paramname="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 - Typenotallowed: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

1 package com.test.action;
2
3 import java.io.InputStream;
4
5 import org.apache.struts2.ServletActionContext;
6
7 import com.opensymphony.xwork2.ActionSupport;
8
9 public class DownloadAction extends ActionSupport {
10publicInputStreamgetDownloadFile(){
11returnServletActionContext.getServletContext().getResourceAsStream(
12"/upload/intrl.ppt");
13}
14
15@Override
16publicStringexecute()throwsException{
17returnSUCCESS;
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：