抓住自己最有兴趣的东西，由浅入深，循序渐进地学……
Servlet3.0支持文件的上传，而不必另外调用common-fileupload.jar等第三方组件。
Tomcat7.0开始支持Servlet3.0，Resin4.0也支持Servlet3.0。
但是最近使用Resin4+Servlet3.0实现文件上传操作时，发现一个问题-就是当调用直接写入文件的part.write("服务器文件写入绝对路径")这一句时，resin4.0总是会提示string越界-1的错误，但是同样的程序使用Tomcat7.0运行没有问题可以直接上传文件，而且在resin4.0下运行时从header中获取的中文文件名也是乱码。经过一番研究，终获解决（并参考了网上流行的一段乱码解决方案的代码，同时解决中文乱码的兼容性问题）。现录于此，仅供参考。
java端代码：
package com.test;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
//IOStream
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
//Servlet3.0 specific annotations
import javax.servlet.annotation.WebServlet;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.http.Part;
@WebServlet(description = "FileUploadServlet Description", urlPatterns = { "/FileUploadServlet" })
@MultipartConfig
public class FileUploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public FileUploadServlet() {
super();
System.out.println("FileUploadServlet Initialized & Instantiated.");
}
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//System.out.println("Accept-Encoding : " + request.getHeader("Accept-Encoding"));
//System.out.println("request编码方式："+request.getCharacterEncoding());
request.setCharacterEncoding("UTF-8");
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html; charset=utf-8");
//System.out.println("request编码方式："+request.getCharacterEncoding());
//System.out.println("Accept-Encoding : " + request.getHeader("Accept-Encoding"));
PrintWriter out = response.getWriter();
out.println("<html><head><body>");
for (Part part : request.getParts()) {
//String fileName = "";
String partHeader = part.getHeader("content-disposition");
//byte[]t=partHeader.getBytes();
//System.out.println("是否乱码：="+toUTF8(partHeader));
//if(partHeader.indexOf("?")>-1)//判断有乱码时自动重新尝试编码
partHeader=toUTF8(partHeader);//new String(partHeader.getBytes("ISO-8859-1"),"UTF-8");//resin4
long partSize = part.getSize();
out.println("<BR>Part Name = " + part.getName());
out.println("<BR>Part Header = " + partHeader);
out.println("<BR>Part Size = " + partSize);
System.out.println(">>>>>>>part.getHeader(\"content-disposition\") = "+ partHeader);
}
out.println("<center><h1>++++File Upload Completed Successfully</h1></center></body></html>");
// **** Custom Option ****//
System.out.println("自定义上传文件名");
fileUploadWithDesiredFilePathAndName(request);
System.out.println("使用自定义方式上传文件.");
}
/*
* Following method allows us to place the uploaded file in a desired
* Location on the server along with the desired fileName
*/
public void fileUploadWithDesiredFilePathAndName(HttpServletRequest request)
throws IOException, ServletException {
/******** Following part of code is not needed ********/
InputStream inputStream = null;
FileOutputStream outputStream = null;
try {
for (Part part : request.getParts()) {
System.out.println(part.getName());
inputStream = request.getPart(part.getName()).getInputStream();
int i = inputStream.available();
byte[] b = new byte[i];
inputStream.read(b);
System.out.println("Length : " + b.length);
// Finding the fileName //
String fileName = "";
String partHeader = part.getHeader("content-disposition");
//if(partHeader.indexOf("?")>-1)//判断有乱码时自动重新尝试编码
partHeader=toUTF8(partHeader);//new String(partHeader.getBytes("ISO-8859-1"),"UTF-8");//resin4
System.out.println("Part Header = " + partHeader);
System.out.println("====part.getHeader(\"content-disposition\") = "+ partHeader);
for (String temp : partHeader.split(
";")) {
if (temp.trim().startsWith("filename")) {
fileName = temp.substring(temp.indexOf('=') + 1).trim().replace("\"", "");
}
}
String tempExtName=fileName.substring(fileName.lastIndexOf(".") + 1).toLowerCase().trim();
fileName=""+System.currentTimeMillis()+"."+tempExtName;
//System.out.println(new String(fileName.getBytes(),"UTF-8"));
//System.out.println(new String(fileName.getBytes(),"GBK"));
//fileName=new String(fileName.getBytes("ISO-8859-1"),"UTF-8");
System.out.println(fileName);
//System.out.println(new String(fileName.getBytes("ISO-8859-1"),"GBK"));
// Writing contents to desired FilePath & FileName //
String uploadDir = "c:/temp/";
System.out.println("File will be Uploaded at: " + uploadDir
+ "/" + fileName);
outputStream = new FileOutputStream(uploadDir + "/" + fileName);
outputStream.write(b);
inputStream.close();
}
} catch (Exception e) {
System.out.println("Unable to Upload File: " + e);
e.printStackTrace();
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (outputStream != null) {
try {
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
private static String toUTF8(String str) {
if (str == null) return null;
String retStr = str;
byte b[];
try {
b = str.getBytes("ISO8859_1");
for (int i = 0; i < b.length; i++) {
byte b1 = b[i];
if (b1 == 63)
break; //1
else if (b1 > 0)
continue;//2
else if (b1 < 0) { //不可能为0，0为字符串结束符
//小于0乱码
retStr = new String(b, "UTF-8");
break;
}
}
} catch (UnsupportedEncodingException e) {
// e.printStackTrace();
}
return retStr;
}
}
html页面代码：
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>FileUpload</title>
</head>
<body>
<center>
<h1>FileUpload Demo Using Servlet3.0</h1>
<form id="formId" action="FileUploadServlet" enctype="multipart/form-data" method="post">
<input type="file" id="FileUploadId" name="Upload" />
<!-- input type="file" id="FileUploadId2" name="Upload2" / -->
<input type="submit" id="uploadButtonId" value="开始上传" />
</form>
</center>
</body>
</html>
