package com.upload;

import java.io.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletException;

public class upload{
private static String newline = " ";
private String uploadDirectory = ".";
private String ContentType = "";
private String CharacterEncoding = "";

private String getFileName(String s){
int i = s.lastIndexOf("");
if(i < 0 // i >= s.length() - 1){
i = s.lastIndexOf("/");
if(i < 0 // i >= s.length() - 1)
return s;
}
return s.substring(i + 1);
}

public void setUploadDirectory(String s){
uploadDirectory = s;
}

public void setContentType(String s){
ContentType = s;
int j;
if((j = ContentType.indexOf("boundary=")) != -1){
ContentType = ContentType.substring(j + 9);
ContentType = "--" + ContentType;
}
}

public void setCharacterEncoding(String s){
CharacterEncoding = s;
}

public void uploadFile( HttpServletRequest req) throws ServletException, IOException{
setCharacterEncoding(req.getCharacterEncoding());
setContentType(req.getContentType());
uploadFile(req.getInputStream());
}

public void uploadFile( ServletInputStream servletinputstream) throws ServletException, IOException{

String s5 = null;
String filename = null;
byte Linebyte[] = new byte[4096];
byte outLinebyte[] = new byte[4096];
int ai[] = new int[1];
int ai1[] = new int[1];

String line;
//得到文件名
while((line = readLine(Linebyte, ai, servletinputstream, CharacterEncoding)) != null){
int i = line.indexOf("filename=");
if(i >= 0){
line = line.substring(i + 10);
if((i = line.indexOf(""")) > 0)
line = line.substring(0, i);
break;
}
}

filename = line;

if(filename != null && !filename.equals(""")){
filename = getFileName(filename);

String sContentType = readLine(Linebyte, ai, servletinputstream, CharacterEncoding);
if(sContentType.indexOf("Content-Type") >= 0)
readLine(Linebyte, ai, servletinputstream, CharacterEncoding);

//File(String parent, String child)
//Creates a new File instance from a parent pathname string
//and a child pathname string.
File file = new File(uploadDirectory, filename);

//FileOutputStream(File file)
//Creates a file output stream to write to the file represented
//by the specified File object.
FileOutputStream fileoutputstream = new FileOutputStream(file);

while((sContentType = readLine(Linebyte, ai, servletinputstream, CharacterEncoding)) != null){
if(sContentType.indexOf(ContentType) == 0 && Linebyte[0] == 45)
break;

if(s5 != null){
//write(byte[] b, int off, int len)
//Writes len bytes from the specified byte array starting
//at offset off to this file output stream.
fileoutputstream.write(outLinebyte, 0, ai1[0]);
fileoutputstream.flush();
}
s5 = readLine(outLinebyte, ai1, servletinputstream, CharacterEncoding);
if(s5 == null // s5.indexOf(ContentType) == 0 && outLinebyte[0] == 45)
break;
fileoutputstream.write(Linebyte, 0, ai[0]);
fileoutputstream.flush();
}

byte byte0;
if(newline.length() == 1)
byte0 = 2;
else
byte0 = 1;
if(s5 != null && outLinebyte[0] != 45 && ai1[0] > newline.length() * byte0)
fileoutputstream.write(outLinebyte, 0, ai1[0] - newline.length() * byte0);
if(sContentType != null && Linebyte[0] != 45 && ai[0] > newline.length() * byte0)
fileoutputstream.write(Linebyte, 0, ai[0] - newline.length() * byte0);

fileoutputstream.close();
}
}

private String readLine(byte Linebyte[], int ai[],
ServletInputStream servletinputstream,
String CharacterEncoding){

try{
//readLine(byte[] buffer, int offset, int length)
//Reads a line from the POST data.
ai[0] = servletinputstream.readLine(Linebyte, 0, Linebyte.length);
if(ai[0] == -1)
return null;
}catch(IOException _ex){
return null;
}
try{
if(CharacterEncoding == null){
//用缺省的编码方式把给定的byte数组转换为字符串
//String(byte[] bytes, int offset, int length)
return new String(Linebyte, 0, ai[0]);
}else{
//用给定的编码方式把给定的byte数组转换为字符串
//String(byte[] bytes, int offset, int length, String enc)
return new String(Linebyte, 0, ai[0], CharacterEncoding);
}
}catch(Exception _ex){
return null;
}
}
/*
public int readLine(byte[] buffer,
int offset,
int length) throws java.io.IOException
从POST来的数据中读一行
参数:
buffer - buffer to hold the line data
offset - offset into the buffer to start
length - maximum number of bytes to read.
Returns:
number of bytes read or -1 on the end of line.
*/
}


upload.jsp
<%@page import="com.upload.upload"%>
<%
String Dir = "/home/tonywan/upload";

upload upload = new upload();
upload.setUploadDirectory(Dir);
upload.uploadFile(request);
out.print("<center><font color=red>成功上载文件至" + Dir + "</font></center>");
%>


upload.html
<center>File upload test</center>
<br>
<table><tr>
<form method="post" enctype="multipart/form-data" action="upload.jsp">
<td> <input type=file size=20 name="fname"> </td>
<td> <input type=Submit value=Upload> </td> </form>
</tr></table>



不知道大家看地懂吗？反正使用起来很简单的，只要设置一下上传路径就可以了。