fileupload文件上传简单实例

1. 首先需要下载需要的组件。

下载commons-fileupload-1.2.1-bin.zip，下载网址：

http://commons.apache.org/downloads/download_fileupload.cgi

下载commons-io-1.4-bin.zip，下载网址：

http://commons.apache.org/downloads/download_io.cgi

2. 用开源的FileUpload组件，可以很方便的给自己的系统添加功能强大的文件上传模块。下图为文件上传的基本流程图。

3. 将commons-fileupload-1.2.1-bin.zip包中的commons-fileupload-1.2.1.jar文件和commons-io-1.4-bin.zip包中的commons-io-1.4.jar文件拷贝到web工程下的WEB-INF\lib目录下。

4. 在服务器端创建处理文件上传的Servlet类。源代码如下：

Java代码

1. packagecom.bjsxt.shopping.servlet;
3. importjava.io.File;
4. importjava.io.IOException;
5. importjava.io.PrintWriter;
6. importjava.util.Iterator;
7. importjava.util.List;
8. importjavax.servlet.ServletException;
9. importjavax.servlet.http.HttpServlet;
10. importjavax.servlet.http.HttpServletRequest;
11. importjavax.servlet.http.HttpServletResponse;
12. importorg.apache.commons.fileupload.FileItem;
13. importorg.apache.commons.fileupload.FileUploadException;
14. importorg.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
15. importorg.apache.commons.fileupload.disk.DiskFileItemFactory;
16. importorg.apache.commons.fileupload.servlet.ServletFileUpload;
18. publicclassFileUploadServletextendsHttpServlet
19. {
20. privatestaticfinallongserialVersionUID=1L;
22. publicFileUploadServlet()
23. {
24. super();
25. }
27. protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException
28. {
29. this.doPost(request,response);
30. }
32. protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException
33. {
34. request.setCharacterEncoding("utf-8");
35. finallongMAX_SIZE=300*1024*1024;//设置上传文件最大值
36. //允许上传的文件格式的列表
37. finalString[]allowedExt=newString[]{"jpg","jpeg","gif","txt","doc","mp3","wma","m4a","rar","zip"};
38. response.setContentType("text/html");
39. //设置字符编码为UTF-8,统一编码，处理出现乱码问题
40. response.setCharacterEncoding("UTF-8");
41. //实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
42. DiskFileItemFactorydfif=newDiskFileItemFactory();
43. dfif.setSizeThreshold(4096);//设置上传文件时用于临时存放文件的内存大小,这里是4K.多于的部分将临时存在硬盘
44. dfif.setRepository(newFile(request.getRealPath("/")+"ImagesUploadTemp"));//设置存放临时文件的目录,web根目录下的ImagesUploadTemp目录
46. //用以上工厂实例化上传组件
47. ServletFileUploadsfu=newServletFileUpload(dfif);
48. //设置最大上传大小
49. sfu.setSizeMax(MAX_SIZE);
50. PrintWriterout=response.getWriter();
51. //从request得到所有上传域的列表
52. ListfileList=null;
53. try
54. {
55. fileList=sfu.parseRequest(request);
56. }catch(FileUploadExceptione)
57. {//处理文件尺寸过大异常
58. if(einstanceofSizeLimitExceededException)
59. {
60. out.println("文件尺寸超过规定大小:"+MAX_SIZE+"字节<p/>");
61. out.println("<ahref=\"./admin/manager/productlist.jsp\">返回</a>");
62. return;
63. }
64. e.printStackTrace();
65. }
66. //没有文件上传
67. if(fileList==null||fileList.size()==0)
68. {
69. out.println("请选择上传文件<p/>");
70. out.println("<ahref=\"./admin/manager/productlist.jsp\">返回</a>");
71. return;
72. }
73. //得到所有上传的文件
74. IteratorfileItr=fileList.iterator();
75. //循环处理所有文件
76. while(fileItr.hasNext())
77. {
78. FileItemfileItem=null;
79. Stringpath=null;
80. longsize=0;
81. //得到当前文件
82. fileItem=(FileItem)fileItr.next();
83. //忽略简单form字段而不是上传域的文件域(<inputtype="text"/>等)
84. if(fileItem==null||fileItem.isFormField())
85. {
86. continue;
87. }
88. //得到文件的完整路径
89. path=fileItem.getName();
90. //得到文件的大小
91. size=fileItem.getSize();
92. if("".equals(path)||size==0)
93. {
94. out.println("请选择上传文件<p/>");
95. out.println("<ahref=\"./admin/manager/productlist.jsp\">返回</a>");
96. return;
97. }
98. //得到去除路径的文件名
99. Stringt_name=path.substring(path.lastIndexOf("\\")+1);
100. //得到文件的扩展名(无扩展名时将得到全名)
101. Stringt_ext=t_name.substring(t_name.lastIndexOf(".")+1);
102. //拒绝接受规定文件格式之外的文件类型
103. intallowFlag=0;
104. intallowedExtCount=allowedExt.length;
105. for(;allowFlag<allowedExtCount;allowFlag++)
106. {
107. if(allowedExt[allowFlag].equals(t_ext))
108. break;
109. }
110. if(allowFlag==allowedExtCount)
111. {
112. out.println("请上传以下类型的文件<p/>");
113. for(allowFlag=0;allowFlag<allowedExtCount;allowFlag++)
114. out.println("*."+allowedExt[allowFlag]+"");
115. out.println("<p/><ahref=\"./admin/manager/productlist.jsp\">返回</a>");
116. return;
117. }
119. //longnow=System.currentTimeMillis();
120. //根据系统时间生成上传后保存的文件名
121. //Stringprefix=String.valueOf(now);
122. //保存的最终文件完整路径,保存在web根目录下的ImagesUploaded目录下
123. //Stringu_name=request.getRealPath("/")+"ImagesUploaded/"
124. //+prefix+"."+t_ext;
125. Stringfilename=t_name;
126. System.out.println(t_name);
127. try
128. {
129. //保存文件到C:\\upload目录下
130. fileItem.write(newFile("C:\\upload\\"+filename));
131. //System.out.println(filename);
132. out.println("文件上传成功.已保存为:"+filename+"文件大小:"+size+"字节<p/>");
133. out.println("<ahref=\"./admin/manager/productlist.jsp\">继续上传</a>");
134. }catch(Exceptione)
135. {
136. e.printStackTrace();
137. }
138. }
139. }
140. }

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


public class FileUploadServlet extends HttpServlet {
 private static final long serialVersionUID = 1L;

 public FileUploadServlet() {
  super();
 }
 protected void doGet(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  this.doPost(request, response);
 }

 protected void doPost(HttpServletRequest request,
   HttpServletResponse response) throws ServletException, IOException {
  
  final long MAX_SIZE = 300 * 1024 * 1024;// 设置上传文件最大值
  // 允许上传的文件格式的列表
  final String[] allowedExt = new String[] {"jpg", "jpeg", "gif", "txt",
    "doc","mp3", "wma", "m4a","rar","zip" };
  response.setContentType("text/html");
  // 设置字符编码为UTF-8, 统一编码，处理出现乱码问题
  response.setCharacterEncoding("UTF-8");

  // 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
  DiskFileItemFactory dfif = new DiskFileItemFactory();
  dfif.setSizeThreshold(4096);// 设置上传文件时用于临时存放文件的内存大小,这里是4K.多于的部分将临时存在硬盘
  dfif.setRepository(new File(request.getRealPath("/")
    + "ImagesUploadTemp"));// 设置存放临时文件的目录,web根目录下的ImagesUploadTemp目录

  // 用以上工厂实例化上传组件
  ServletFileUpload sfu = new ServletFileUpload(dfif);
  // 设置最大上传大小
  sfu.setSizeMax(MAX_SIZE);

  PrintWriter out = response.getWriter();
  // 从request得到所有上传域的列表
  List fileList = null;
  try {
   fileList = sfu.parseRequest(request);
  } catch (FileUploadException e) {// 处理文件尺寸过大异常
   if (e instanceof SizeLimitExceededException) {
    out.println("文件尺寸超过规定大小:" + MAX_SIZE + "字节<p />");
    out
      .println("<a href=\"FileUpload.html\" target=\"_top\">返回</a>");
    return;
   }
   e.printStackTrace();
  }
  // 没有文件上传
  if (fileList == null || fileList.size() == 0) {
   out.println("请选择上传文件<p />");
   out.println("<a href=\"FileUpload.html\" target=\"_top\">返回</a>");
   return;
  }
  // 得到所有上传的文件
  Iterator fileItr = fileList.iterator();
  // 循环处理所有文件
  while (fileItr.hasNext()) {
   FileItem fileItem = null;
   String path = null;
   long size = 0;
   // 得到当前文件
   fileItem = (FileItem) fileItr.next();
   // 忽略简单form字段而不是上传域的文件域(<input type="text" />等)
   if (fileItem == null || fileItem.isFormField()) {
    continue;
   }
   // 得到文件的完整路径
   path = fileItem.getName();
   // 得到文件的大小
   size = fileItem.getSize();
   if ("".equals(path) || size == 0) {
    out.println("请选择上传文件<p />");
    out
      .println("<a href=\"FileUpload.html\" target=\"_top\">返回</a>");
    return;
   }

   // 得到去除路径的文件名
   String t_name = path.substring(path.lastIndexOf("\\") + 1);
   // 得到文件的扩展名(无扩展名时将得到全名)
   String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
   // 拒绝接受规定文件格式之外的文件类型
   int allowFlag = 0;
   int allowedExtCount = allowedExt.length;
   for (; allowFlag < allowedExtCount; allowFlag++) {
    if (allowedExt[allowFlag].equals(t_ext))
     break;
   }
   if (allowFlag == allowedExtCount) {
    out.println("请上传以下类型的文件<p />");
    for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
     out.println("*." + allowedExt[allowFlag]
       + "");
    out
      .println("<p /><a href=\"FileUpload.html\" target=\"_top\">返回</a>");
    return;
   }

   long now = System.currentTimeMillis();
   // 根据系统时间生成上传后保存的文件名
   String prefix = String.valueOf(now);
   // 保存的最终文件完整路径,保存在web根目录下的ImagesUploaded目录下
//   String u_name = request.getRealPath("/") + "ImagesUploaded/"
//     + prefix + "." + t_ext;
   String filename = prefix + "." + t_ext;
   try {
    // 保存文件到C:\\upload目录下
    fileItem.write(new File("C:\\upload\\"+filename));
    System.out.println(filename);
    out.println("文件上传成功. 已保存为: " + prefix + "." + t_ext
      + " 文件大小: " + size + "字节<p />");
    out
      .println("<a href=\"FileUpload.html\" target=\"_top\">继续上传</a>");
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
 }
}

5. 在客户端创建上传文件页面

Html代码

1. 1.<!DOCTYPEhtmlPUBLIC"-//W3C//DTDHTML4.01Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
2. 2.<html>
3. 3.<head>
4. 4.<metahttp-equiv="Content-Type"content="text/html;charset=UTF-8">
5. 5.<title>文件上传</title>
6. 6.</head>
7. 7.<body>
8. 8.<formaction="FileUploadServlet"method="post"
9. 9.enctype="multipart/form-data">
10. 10.<inputtype="file"size="30"
11. 11.name="file01"/><br/>
12. 12.<inputtype="file"size="30"
13. 13.name="file02"/><br/>
14. 14.<inputname="up"type="submit"value="上传"/></form>
15. 15.</body>
16. 16.</html>