文件上传在web应用中非常普遍,要在jsp环境中实现文件上传功能是非常容易的,因为网上有许多用java开发的文件上传组件,本文以commons-fileupload组件为例,为jsp应用添加文件上传功能。
common-fileupload组件是apache的一个开源项目之一,可以从http://jakarta.apache.org/commons/fileupload/下载。
用该组件可实现一次上传一个或多个文件,并可限制文件大小。
下载后解压zip包,将commons-fileupload-1.0.jar复制到tomcat的webapps你的webappWEB-INFlib下,目录不存在请自建目录。
新建一个servlet: Upload.java用于文件上传:
import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; import org.apache.commons.fileupload.*; public class Upload extends HttpServlet { private String uploadPath = "C:upload"; // 上传文件的目录 private String tempPath = "C:uploadtmp"; // 临时文件目录 public void doPost(HttpServletRequest request,HttpServletResponse response)
throws IOException, ServletException { } }
在doPost()方法中,当servlet收到浏览器发出的Post请求后,实现文件上传。以下是示例代码:
public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException { try { DiskFileUpload fu = new DiskFileUpload(); // 设置最大文件尺寸,这里是4MB fu.setSizeMax(4194304); // 设置缓冲区大小,这里是4kb fu.setSizeThreshold(4096); // 设置临时目录: fu.setRepositoryPath(tempPath); // 得到所有的文件: List fileItems = fu.parseRequest(request); Iterator i = fileItems.iterator(); // 依次处理每一个文件: while(i.hasNext()) { FileItem fi = (FileItem)i.next(); // 获得文件名,这个文件名包括路径: String fileName = fi.getName(); // 在这里可以记录用户和文件信息 // ... // 写入文件,暂定文件名为a.txt,可以从fileName中提取文件名: fi.write(new File(uploadPath + "a.txt")); } } catch(Exception e) { // 可以跳转出错页面 } }
如果要在配置文件中读取指定的上传文件夹,可以在init()方法中执行:
public void init() throws ServletException { uploadPath = .... tempPath = .... // 文件夹不存在就自动创建: if(!new File(uploadPath).isDirectory()) new File(uploadPath).mkdirs(); if(!new File(tempPath).isDirectory()) new File(tempPath).mkdirs(); }
编译该servlet,注意要指定classpath,确保包含commons-upload-1.0.jar和tomcatcommonlibservlet-api.jar。
配置servlet,用记事本打开tomcatwebapps你的webappWEB-INFweb.xml,没有的话新建一个。
典型配置如下:
<?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> <web-app> <servlet> <servlet-name>Upload</servlet-name> <servlet-class>Upload</servlet-class> </servlet> <servlet-mapping> <servlet-name>Upload</servlet-name> <url-pattern>/fileupload</url-pattern> </servlet-mapping> </web-app>
配置好servlet后,启动tomcat,写一个简单的html测试:
<form action="fileupload" method="post" enctype="multipart/form-data" name="form1"> <input type="file" name="file"> <input type="submit" name="Submit" value="upload"> </form>
注意action="fileupload"其中fileupload是配置servlet时指定的url-pattern。
下面是某个大虾的代码:
这个Upload比smartUpload好用多了.完全是我一个个byte调试出来的,不象smartUpload的bug具多.
调用方法:
Upload up = new Upload();
up.init(request);
/**
此处可以调用setSaveDir(String saveDir);设置保存路径
调用setMaxFileSize(long size)设置上传文件的最大字节.
调用setTagFileName(String)设置上传后文件的名字(只对第一个文件有效)
*/
up. uploadFile();
然后String[] names = up.getFileName();得到上传的文件名,文件绝对路径应该是
保存的目录saveDir+"/"+names[i];
可以通过up.getParameter("field");得到上传的文本或up.getParameterValues("filed")
得到同名字段如多个checkBox的值.
其它的自己试试.
源码:____________________________________________________________
package com.inmsg.beans; import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; public class Upload { private String saveDir = "."; //要保存文件的路径 private String contentType = ""; //文档类型 private String charset = ""; //字符集 private ArrayList tmpFileName = new ArrayList(); //临时存放文件名的数据结构 private Hashtable parameter = new Hashtable(); //存放参数名和值的数据结构 private ServletContext context; //程序上下文,用于初始化 private HttpServletRequest request; //用于传入请求对象的实例 private String boundary = ""; //内存数据的分隔符 private int len = 0; //每次从内在中实际读到的字节长度 private String queryString; private int count; //上载的文件总数 private String[] fileName; //上载的文件名数组 private long maxFileSize = 1024 * 1024 * 10; //最大文件上载字节; private String tagFileName = ""; public final void init(HttpServletRequest request) throws ServletException { this.request = request; boundary = request.getContentType().substring(30); //得到内存中数据分界符 queryString = request.getQueryString(); } public String getParameter(String s) { //用于得到指定字段的参数值,重写request.getParameter(String s) if (parameter.isEmpty()) { return null; } return (String) parameter.get(s); } public String[] getParameterValues(String s) { //用于得到指定同名字段的参数数组,重写request.getParameterValues(String s) ArrayList al = new ArrayList(); if (parameter.isEmpty()) { return null; } Enumeration e = parameter.keys(); while (e.hasMoreElements()) { String key = (String) e.nextElement(); if ( -1 != key.indexOf(s + "||||||||||") || key.equals(s)) { al.add(parameter.get(key)); } } if (al.size() == 0) { return null; } String[] value = new String[al.size()]; for (int i = 0; i < value.length; i++) { value[i] = (String) al.get(i); } return value; } public String getQueryString() { return queryString; } public int getCount() { return count; } public String[] getFileName() { return fileName; } public void setMaxFileSize(long size) { maxFileSize = size; } public void setTagFileName(String filename) { tagFileName = filename; } public void setSaveDir(String saveDir) { //设置上载文件要保存的路径 this.saveDir = saveDir; File testdir = new File(saveDir); //为了保证目录存在,如果没有则新建该目录 if (!testdir.exists()) { testdir.mkdirs(); } } public void setCharset(String charset) { //设置字符集 this.charset = charset; } public boolean uploadFile() throws ServletException, IOException { //用户调用的上载方法 setCharset(request.getCharacterEncoding()); return uploadFile(request.getInputStream()); } private boolean uploadFile(ServletInputStream servletinputstream) throws //取得央存数据的主方法 ServletException, IOException { String line = null; byte[] buffer = new byte[256]; while ( (line = readLine(buffer, servletinputstream, charset)) != null) { if (line.startsWith("Content-Disposition: form-data;")) { int i = line.indexOf("filename="); if (i >= 0) { //如果一段分界符内的描述中有filename=,说明是文件的编码内容 String fName = getFileName(line); if (fName.equals("")) { continue; } if (count == 0 && tagFileName.length() != 0) { String ext = fName.substring( (fName.lastIndexOf(".") + 1)); fName = tagFileName + "." + ext; } tmpFileName.add(fName); count++; while ( (line = readLine(buffer, servletinputstream, charset)) != null) { if (line.length() <= 2) { break; } } File f = new File(saveDir, fName); FileOutputStream dos = new FileOutputStream(f); long size = 0l; while ( (line = readLine(buffer, servletinputstream, null)) != null) { if (line.indexOf(boundary) != -1) { break; } size += len; if (size > maxFileSize) { throw new IOException("文件超过" + maxFileSize + "字节!"); } dos.write(buffer, 0, len); } dos.close(); } else { //否则是字段编码的内容 String key = getKey(line); String value = ""; while ( (line = readLine(buffer, servletinputstream, charset)) != null) { if (line.length() <= 2) { break; } } while ( (line = readLine(buffer, servletinputstream, charset)) != null) { if (line.indexOf(boundary) != -1) { break; } value += line; } put(key, value.trim(), parameter); } } } if (queryString != null) { String[] each = split(queryString, "&"); for (int k = 0; k < each.length; k++) { String[] nv = split(each[k], "="); if (nv.length == 2) { put(nv[0], nv[1], parameter); } } } fileName = new String[tmpFileName.size()]; for (int k = 0; k < fileName.length; k++) { fileName[k] = (String) tmpFileName.get(k); //把ArrayList中临时文件名倒入数据中供用户调用 } if (fileName.length == 0) { return false; //如果fileName数据为空说明没有上载任何文件 } return true; } private void put(String key, String value, Hashtable ht) { if (!ht.containsKey(key)) { ht.put(key, value); } else { //如果已经有了同名的KEY,就要把当前的key更名,同时要注意不能构成和KEY同名 try { Thread.currentThread().sleep(1); //为了不在同一ms中产生两个相同的key } catch (Exception e) {} key += "||||||||||" + System.currentTimeMillis(); ht.put(key, value); } } /* 调用ServletInputstream.readLine(byte[] b,int offset,length)方法,该方法是从ServletInputstream流中读一行 到指定的byte数组,为了保证能够容纳一行,该byte[]b不应该小于256,重写的readLine中,调用了一个成员变量len为 实际读到的字节数(有的行不满256),则在文件内容写入时应该从byte数组中写入这个len长度的字节而不是整个byte[] 的长度,但重写的这个方法返回的是String以便分析实际内容,不能返回len,所以把len设为成员变量,在每次读操作时 把实际长度赋给它. 也就是说在处理到文件的内容时数据既要以String形式返回以便分析开始和结束标记,又要同时以byte[]的形式写到文件 输出流中. */ private String readLine(byte[] Linebyte, ServletInputStream servletinputstream, String charset) { try { len = servletinputstream.readLine(Linebyte, 0, Linebyte.length); if (len == -1) { return null; } if (charset == null) { return new String(Linebyte, 0, len); } else { return new String(Linebyte, 0, len, charset); } } catch (Exception _ex) { return null; } } private String getFileName(String line) { //从描述字符串中分离出文件名 if (line == null) { return ""; } int i = line.indexOf("filename="); line = line.substring(i + 9).trim(); i = line.lastIndexOf(""); if (i < 0 || i >= line.length() - 1) { i = line.lastIndexOf("/"); if (line.equals("""")) { return ""; } if (i < 0 || i >= line.length() - 1) { return line; } } return line.substring(i + 1, line.length() - 1); } private String getKey(String line) { //从描述字符串中分离出字段名 if (line == null) { return ""; } int i = line.indexOf("name="); line = line.substring(i + 5).trim(); return line.substring(1, line.length() - 1); } public static String[] split(String strOb, String mark) { if (strOb == null) { return null; } StringTokenizer st = new StringTokenizer(strOb, mark); ArrayList tmp = new ArrayList(); while (st.hasMoreTokens()) { tmp.add(st.nextToken()); } String[] strArr = new String[tmp.size()]; for (int i = 0; i < tmp.size(); i++) { strArr[i] = (String) tmp.get(i); } return strArr; } }
下载其实非常简单,只要如下处理,就不会发生问题。
public void downLoad(String filePath,HttpServletResponse response,boolean isOnLine) throws Exception{ File f = new File(filePath); if(!f.exists()){ response.sendError(404,"File not found!"); return; } BufferedInputStream br = new BufferedInputStream(new FileInputStream(f)); byte[] buf = new byte[1024]; int len = 0; response.reset(); //非常重要 if(isOnLine){ //在线打开方式 URL u = new URL("file:///"+filePath); response.setContentType(u.openConnection().getContentType()); response.setHeader("Content-Disposition", "inline; filename="+f.getName()); //文件名应该编码成UTF-8 } else{ //纯下载方式 response.setContentType("application/x-msdownload"); response.setHeader("Content-Disposition", "attachment; filename=" + f.getName()); } OutputStream out = response.getOutputStream(); while((len = br.read(buf)) >0) out.write(buf,0,len); br.close(); out.close(); }