iLeichun

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:upload mp”; // 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” >
<input type=”file” >
<input type=”submit” value=”upload”>
</form>
注意action=”fileupload”其中fileupload是配置servlet时指定的url-pattern。

文件的下载用servlet实现
public void doGet(HttpServletRequest request,
HttpServletResponse response)
{
String aFilePath = null;    //要下载的文件路径
String aFileName = null;    //要下载的文件名
FileInputStream in = null;  //输入流
ServletOutputStream out = null;  //输出流

try
{

aFilePath = getFilePath(request);
aFileName = getFileName(request);

response.setContentType(getContentType(aFileName) + “; charset=UTF-8″);
response.setHeader(”Content-disposition”, “attachment; filename=” + aFileName);

in = new  FileInputStream(aFilePath + aFileName); //读入文件
out = response.getOutputStream();
out.flush();
int aRead = 0;
while((aRead = in.read()) != -1 & in != null)
{
out.write(aRead);
}
out.flush();
}
catch(Throwable e)
{
log.error(”FileDownload doGet() IO error!”,e);
}
finally
{
try
{
in.close();
out.close();
}
catch(Throwable e)
{
log.error(”FileDownload doGet() IO close error!”,e);
}
}
}

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-Dis;”)) {
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(”>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();
}