今天帮同学实现一个上传的servlet，本来以为很简单，最后做起来，才发现还是比较复杂的，虽然现在已经用惯了spring，但是基本的servlet也不能忘记。今天做这个收获颇多，特贴出来，以便以后使用。其实写的不是优雅，但也基本能完成任务。
对于文件上传有这么几点，首先是servlet接受到文件上传表单的数据后，并未提取出文件名等信息，需要自己分析。而且在文件数据前后都有一个添加上去的头和尾信息，需要自己去除。下面是我的代码：
html页面：import java.io.DataInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HandleFileServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path = "D:\\";
String filename = "";
// System.out.println(getServletContext().getContextPath());
System.out.println("content type:" + request.getContentType());
System.out.println("file length:" + request.getContentLength());
ServletInputStream is = request.getInputStream();
int readLen = 0, conLen = request.getContentLength();
byte[] b = new byte[1024];
int len = 0;
String terminator = "";
// read the head infomation
while ((len = is.readLine(b, 0, b.length)) != -1) {
readLen += len;
String str = new String(b,0,len);
System.out.println("a line: " + "length:" + len + "data:" + str);
int pos = -1;
//got terminate string
if (str.startsWith("---------------------------")) {
terminator = str;
terminator += "--";
System.out.println(terminator);
}
//got filename
if ((pos = str.indexOf("filename=\"")) != -1) {
pos += "filename=\"".length();
filename = str.substring(pos, str.lastIndexOf("\""));
System.out.println("got filename:" + filename);
}
// quit read head data
if (b[0] == '\r' && b[1] == '\n') {
System.out.println("break from rn");
break;
}
}
if (filename.length() == 0)
filename = "unknown_name.txt";
File f = new File(path, filename);
if (!f.createNewFile()) {
System.out.println("Cannot create file");
}
FileOutputStream fos = new FileOutputStream(f);
byte[] data = new byte[2048];
int toReadLen = data.length;
System.out.println("read length:"+readLen);
System.out.println("content length:"+ conLen);
System.out.println("conLen - terminator.length() " + (conLen - terminator.length()));
if(readLen + data.length > ( conLen - terminator.length()))
{
toReadLen = conLen - terminator.length() - readLen-2;
}
while ((len = is.read(data, 0,toReadLen))!= 0 ) {
readLen += len;
//String tempStr = new String(data, 0, len);
fos.write(data, 0, len);
if(readLen + data.length > ( conLen - terminator.length()))
{
toReadLen = conLen - terminator.length() - readLen-2;
}
}
fos.close();
System.out.println("read after header:" + new String(data));
}
}
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>文件上传测试</title>
</head>
<body>
<h1>选择一个文本文件上传：</h1>
<form action="servlet/upload" method="post"
enctype="multipart/form-data">
<input type="file" name="file" id="file1" />
<input type="submit" value="上传" />
</form>
</body>
</html>
--
Be yourself.
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