用該組件可實(shí)現(xiàn)一次上傳一個或多個文件，并可限制文件大小。


下載后解壓zip包，將commons-fileupload-1.0.jar復(fù)制到tomcat的webapps你的webappWEB-INFlib下，目錄不存在請自建目錄。
新建一個servlet: Upload.java用于文件上傳：
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"; // 上傳文件的目錄
private String tempPath = "C:uploadtmp"; // 臨時文件目錄

public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException
{
}
}
在doPost()方法中，當(dāng)servlet收到瀏覽器發(fā)出的Post請求后，實(shí)現(xiàn)文件上傳。以下是示例代碼：
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException
{
try {
DiskFileUpload fu = new DiskFileUpload();
// 設(shè)置最大文件尺寸，這里是4MB
fu.setSizeMax(4194304);
// 設(shè)置緩沖區(qū)大小，這里是4kb
fu.setSizeThreshold(4096);
// 設(shè)置臨時目錄：
fu.setRepositoryPath(tempPath);

// 得到所有的文件：
List fileItems = fu.parseRequest(request);
Iterator i = fileItems.iterator();
// 依次處理每一個文件：
while(i.hasNext()) {
FileItem fi = (FileItem)i.next();
// 獲得文件名，這個文件名包括路徑：
String fileName = fi.getName();
// 在這里可以記錄用戶和文件信息
// ...
// 寫入文件，暫定文件名為a.txt，可以從fileName中提取文件名：
fi.write(new File(uploadPath + "a.txt"));
}
}
catch(Exception e) {
// 可以跳轉(zhuǎn)出錯頁面
}
}
如果要在配置文件中讀取指定的上傳文件夾，可以在init()方法中執(zhí)行：
public void init() throws ServletException {
uploadPath = ....
tempPath = ....
// 文件夾不存在就自動創(chuàng)建：
if(!new File(uploadPath).isDirectory())
new File(uploadPath).mkdirs();
if(!new File(tempPath).isDirectory())
new File(tempPath).mkdirs();
}
編譯該servlet，注意要指定classpath，確保包含commons-upload-1.0.jar和tomcatcommonlibservlet-api.jar。
配置servlet，用記事本打開tomcatwebapps你的webappWEB-INFweb.xml，沒有的話新建一個。
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./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，啟動tomcat，寫一個簡單的html測試：
<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時指定的url-pattern。


下面是某個大蝦的代碼：

這個Upload比smartUpload好用多了.完全是我一個個byte調(diào)試出來的,不象smartUpload的bug具多.
調(diào)用方法:
Upload up = new Upload();
up.init(request);
/**
此處可以調(diào)用setSaveDir(String saveDir);設(shè)置保存路徑
調(diào)用setMaxFileSize(long size)設(shè)置上傳文件的最大字節(jié).
調(diào)用setTagFileName(String)設(shè)置上傳后文件的名字(只對第一個文件有效)
*/
up. uploadFile();

然后String[] names = up.getFileName();得到上傳的文件名,文件絕對路徑應(yīng)該是
保存的目錄saveDir+"/"+names[i];
可以通過up.getParameter("field");得到上傳的文本或up.getParameterValues("filed")
得到同名字段如多個checkBox的值.
其它的自己試試.

源碼:____________________________________________________________
package com.inmsg.beans;

import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class Upload {
private String saveDir = "."; //要保存文件的路徑
private String contentType = ""; //文檔類型
private String charset = ""; //字符集
private ArrayList tmpFileName = new ArrayList(); //臨時存放文件名的數(shù)據(jù)結(jié)構(gòu)
private Hashtable parameter = new Hashtable(); //存放參數(shù)名和值的數(shù)據(jù)結(jié)構(gòu)
private ServletContext context; //程序上下文,用于初始化
private HttpServletRequest request; //用于傳入請求對象的實(shí)例
private String boundary = ""; //內(nèi)存數(shù)據(jù)的分隔符
private int len = 0; //每次從內(nèi)在中實(shí)際讀到的字節(jié)長度
private String queryString;
private int count; //上載的文件總數(shù)
private String[] fileName; //上載的文件名數(shù)組
private long maxFileSize = 1024 * 1024 * 10; //最大文件上載字節(jié);
private String tagFileName = "";

public final void init(HttpServletRequest request) throws ServletException {
this.request = request;
boundary = request.getContentType().substring(30); //得到內(nèi)存中數(shù)據(jù)分界符
queryString = request.getQueryString();
}

public String getParameter(String s) { //用于得到指定字段的參數(shù)值,重寫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參數(shù)數(shù)組,重寫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) { //設(shè)置上載文件要保存的路徑
this.saveDir = saveDir;
File testdir = new File(saveDir); //為了保證目錄存在,如果沒有則新建該目錄
if (!testdir.exists()) {
testdir.mkdirs();
}
}

public void setCharset(String charset) { //設(shè)置字符集
this.charset = charset;
}

public boolean uploadFile() throws ServletException, IOException { //用戶調(diào)用的上載方法
setCharset(request.getCharacterEncoding());
return uploadFile(request.getInputStream());
}

private boolean uploadFile(ServletInputStream servletinputstream) throws //取得央存數(shù)據(jù)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) { //如果一段分界符內(nèi)的描述中有filename=,說明是文件的編碼內(nèi)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("文件超過" + maxFileSize + "字節(jié)!");
}
dos.write(buffer, 0, len);
}
dos.close();
}
else { //否則是字段編碼的內(nèi)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中臨時文件名倒入數(shù)據(jù)中供用戶調(diào)用
}
if (fileName.length == 0) {
return false; //如果fileName數(shù)據(jù)為空說明沒有上載任何文件
}
return true;
}

private void put(String key, String value, Hashtable ht) {
if (!ht.containsKey(key)) {
ht.put(key, value);
}
else { //如果已經(jīng)有了同名的KEY,就要把當(dāng)前的key更名,同時要注意不能構(gòu)成和KEY同名
try {
Thread.currentThread().sleep(1); //為了不在同一ms中產(chǎn)生兩個相同的key
}
catch (Exception e) {}
key += "||||||||||" + System.currentTimeMillis();
ht.put(key, value);
}
}

/*
調(diào)用ServletInputstream.readLine(byte[] b,int offset,length)方法,該方法是從ServletInputstream流中讀一行
到指定的byte數(shù)組,為了保證能夠容納一行,該byte[]b不應(yīng)該小于256,重寫的readLine中,調(diào)用了一個成員變量len為
實(shí)際讀到的字節(jié)數(shù)(有的行不滿256),則在文件內(nèi)容寫入時應(yīng)該從byte數(shù)組中寫入這個len長度的字節(jié)而不是整個byte[]
的長度,但重寫的這個方法返回的是String以便分析實(shí)際內(nèi)容,不能返回len,所以把len設(shè)為成員變量,在每次讀操作時
把實(shí)際長度賦給它.
也就是說在處理到文件的內(nèi)容時數(shù)據(jù)既要以String形式返回以便分析開始和結(jié)束標(biāo)記,又要同時以byte[]的形式寫到文件
輸出流中.
*/
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) { //從描述字符串中分離出文件名
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) { //從描述字符串中分離出字段名
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;
}
}

下載其實(shí)非常簡單，只要如下處理，就不會發(fā)生問題。

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){ //在線打開方式
URL u = new URL("file:///"+filePath);
response.setContentType(u.openConnection().getContentType());
response.setHeader("Content-Disposition", "inline; filename="+f.getName());
//文件名應(yīng)該編碼成UTF-8
}
else{ //純下載方式
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();
}