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 <% @ 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

 1 <% @ 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

 1 <% @ 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

 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" })
23    public void doPost(HttpServletRequest request, HttpServletResponse response)
24            throws ServletException, IOException {
25
26        DiskFileItemFactory factory = new DiskFileItemFactory();
27
28        String path = request.getRealPath("/upload");
29
30        factory.setRepository(new File(path));
31
32        factory.setSizeThreshold(1024 * 1024);
33
34        ServletFileUpload upload = new ServletFileUpload(factory);
35
36        try {
37            List<FileItem> list = upload.parseRequest(request);
38
39            for (FileItem item : list) {
40                if (item.isFormField()) {
41                    String name = item.getFieldName();
42
43                    String value = item.getString("gbk");
44
45                    System.out.println(name);
46
47                    request.setAttribute(name, value);
48                } else {
49                    String name = item.getFieldName();
50
51                    String value = item.getName();
52
53                    int start = value.lastIndexOf("\\");
54
55                    String fileName = value.substring(start + 1);
56
57                    request.setAttribute(name, fileName);
58
59                    item.write(new File(path, fileName));
60
61                    OutputStream os = new FileOutputStream(new File(path,
62                            fileName));
63
64                    InputStream is = item.getInputStream();
65
66                    byte[] buffer = new byte[400];
67
68                    int length = 0;
69
70                    while ((length = is.read(buffer)) > 0) {
71                        os.write(buffer, 0, length);
72                    }
73
74                    os.close();
75
76                    is.close();
77
78                }
79            }
80        }
81
82        catch (Exception ex) {
83            ex.printStackTrace();
84        }
85        request.getRequestDispatcher("upload/result2.jsp").forward(request,
86                response);
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 <% @ 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
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 <? 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     
 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  {
15    private String username;
16    private String password;
17    private File file;
18    private String fileFileName;
19    private String fileContentType;
20
21    public String getUsername() {
22        return username;
23    }
24
25    public void setUsername(String username) {
26        this.username = username;
27    }
28
29    public String getPassword() {
30        return password;
31    }
32
33    public void setPassword(String password) {
34        this.password = password;
35    }
36
37    public File getFile() {
38        return file;
39    }
40
41    public void setFile(File file) {
42        this.file = file;
43    }
44
45    public String getFileFileName() {
46        return fileFileName;
47    }
48
49    public void setFileFileName(String fileFileName) {
50        this.fileFileName = fileFileName;
51    }
52
53    public String getFileContentType() {
54        return fileContentType;
55    }
56
57    public void setFileContentType(String fileContentType) {
58        this.fileContentType = fileContentType;
59    }
60
61    @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
70        int length = 0;
71
72        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

 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  {
10    public InputStream getDownloadFile() {
11        return ServletActionContext.getServletContext().getResourceAsStream(
12                "/upload/intrl.ppt");
13    }
14
15    @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：