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(shí)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(qǐng)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(shí)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(gè)文件：
while(i.hasNext()) {
FileItem fi = (FileItem)i.next(); 
// 獲得文件名，這個(gè)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(cuò)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(dòng)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(gè)。

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，啟動(dòng)tomcat，寫一個(gè)簡單的html測(cè)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(shí)指定的url-pattern。

下面是某個(gè)大蝦的代碼：

這個(gè)Upload比smartUpload好用多了.完全是我一個(gè)個(gè)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(duì)第一個(gè)文件有效)
*/
up. uploadFile();

然后String[] names = up.getFileName(); 得到上傳的文件名,文件絕對(duì)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(gè)checkBox的值.

其它的自己試試.

源碼如下所示:____________________________________________________________

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(shí)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(qǐng)求對(duì)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(shí)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(shí)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(gè)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(gè)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(shí)應(yīng)該從byte數(shù)組中寫入這個(gè)len長度的字節(jié)而不是整個(gè)byte[]
的長度,但重寫的這個(gè)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(shí)
把實(shí)際長度賦給它.
也就是說在處理到文件的內(nèi)容時(shí)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(shí)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(huì)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(); 
}

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