httpserver.java

java应用开发详解

import java.net.*;
import java.io.*;
import java.util.*;

public class HTTPServer 
{
	String serverName;
 	String Version;
 	int serverPort;

 	// 构造一个server，并运行
 	public static void main(String args[])
 	{
  		HTTPServer server = new HTTPServer("HTTPServer", "1.0", 80);
  		server.run();
 	}
 	// 定义server的名字、版本号、端口
 	public HTTPServer(String name, String version, int port) 
 	{
  		this.serverName = name;
  		this.Version = version;
  		this.serverPort = port;
 	}
 
 	public void run() 
 	{
  		// 显示名字和版本号
  		System.out.println(serverName+" version "+Version);
  		try 
  		{
   			// 得到服务监听端口
   			ServerSocket server = getServerSocket();
   
   			do 
   			{
    				// 等待连接请求
    				Socket client = server.accept();
    				// 为连接请求分配一个线程
    				(new HTTPServerThread(client)).start();
   			}while(true);
  		} 
  		catch(Exception e) 
  		{
   			e.printStackTrace();
   			System.exit(1);
  		}
 	}
 	
 	//服务器的构造方法，
 	//我们可以对其构造方法进行扩展，
 	//参考JSSE技术一章中的SSL扩展
 	ServerSocket getServerSocket() throws Exception 
 	{
  		return new ServerSocket(serverPort);
 	}
}

// Handle a single server connection
class HTTPServerThread extends Thread 
{
 	Socket client;

 	public HTTPServerThread(Socket client) 
 	{
  		this.client = client;
 	}

 	public void run() 
 	{
  		try 
  		{
   			describeConnectionInfo(client);

   			BufferedOutputStream outStream = new 
				BufferedOutputStream(client.getOutputStream());
			//HTTPInputStream是自定义的过滤流
   			HTTPInputStream inStream = new HTTPInputStream(client.getInputStream());

   			//得到请求头
   			HTTPRequest request = inStream.getRequest();
   			//显示头信息
   			request.log();
   			//只处理GET请求
   			if(request.isGetRequest())
    				processGetRequest(request,outStream);
   			System.out.println("Request completed. Closing connection.");
   			//非持久性
   			client.close();
  		}
  		catch(IOException e) 
  		{
   			System.out.println("IOException occurred .");
   			e.printStackTrace();
  		}
  		
  	
	}
 	
 	// Display info about the connection
	void describeConnectionInfo(Socket client) 
	{
  		//服务端主机名
  		String destName = client.getInetAddress().getHostName();
  		//服务端IP地址
  		String destAddr = client.getInetAddress().getHostAddress();
  		//服务端端口
  		int destPort = client.getPort();
  		//打印信息
  		System.out.println("Accepted connection to "+destName+" ("+destAddr+")"+" on port "+destPort+".");
 	}
 	
 	// 处理GET请求
 	void processGetRequest(HTTPRequest request,BufferedOutputStream outStream)
   		throws IOException 
   	{
  		String fileName = request.getFileName();
  		File file = new File(fileName);
  		// Give them the requested file
  		if(file.exists()) sendFile(outStream,file);
  		else System.out.println("File "+file.getCanonicalPath()+" does not exist.");
 	}
 	// A simple HTTP 1.0 response
 	void sendFile(BufferedOutputStream out,File file) 
 	{
  		try 
  		{
   			DataInputStream in = new DataInputStream(new FileInputStream(file));
   			int len = (int) file.length();
   			byte buffer[] = new byte[len];
   			in.readFully(buffer);
   			in.close();
   			out.write("HTTP/1.0 200 OK\r\n".getBytes());
   			out.write(("Content-Length: " + buffer.length + "\r\n").getBytes());
   			out.write("Content-Type: text/html\r\n\r\n".getBytes());
   			out.write(buffer);
   			out.flush();
   			out.close();
   			System.out.println("File sent: "+file.getCanonicalPath());
   			System.out.println("Number of bytes: "+len);
  		}
  		catch(Exception e)
  		{
   			try 
   			{
    				out.write(("HTTP/1.0 400 " + "No can do" + "\r\n").getBytes());
    				out.write("Content-Type: text/html\r\n\r\n".getBytes());
   			}
   			catch(IOException ioe) 
   			{
   			}
   			System.out.println("Error retrieving "+file);
  		}
 	}
}


// 实现读客户端请求的帮助类
class HTTPInputStream extends FilterInputStream 
{
	public HTTPInputStream(InputStream in) 
	{
  		super(in);
 	}
 	// 读一行
 	public String readLine() throws IOException 
 	{
  		StringBuffer result=new StringBuffer();
  		boolean finished = false;
  		//回车符
  		boolean cr = false;
  		do 
  		{
   			int ch = -1;
   			ch = read();
   			if(ch==-1) return result.toString();
   			result.append((char) ch);
   			//去掉最后的'\n'
   			if(cr && ch==10)
   			{
    				result.setLength(result.length()-2);
    				return result.toString();
   			}
   			//读到回车符，设置标识
   			if(ch==13) cr = true;
   			else cr=false;
  		} while (!finished);
  		return result.toString();
 	}
 	// 得到所有的请求
 	public HTTPRequest getRequest() throws IOException 
 	{
  		HTTPRequest request = new HTTPRequest();
  		String line;
  		do 
  		{
   			line = readLine();
   			//将请求填入容器
   			if(line.length()>0) request.addLine(line);
   			else break;
  		}while(true);
  		return request;
 	}
}

// 客户端请求的封装类
class HTTPRequest 
{
	Vector lines = new Vector();

 	public HTTPRequest() 
 	{
 	}
 	public void addLine(String line) 
 	{
  		lines.addElement(line);
 	}
 	// 判断是否是Get请求
	 boolean isGetRequest() 
	 {
  		if(lines.size() > 0) 
  		{
   			String firstLine = (String) lines.elementAt(0);
   			if(firstLine.length() > 0)
    			if(firstLine.substring(0,3).equalsIgnoreCase("GET"))
     			return true;
  		}
  		return false;
 	}	
 	// 从请求中解析到文件名
 	String getFileName() 
 	{
  		if(lines.size()>0) 
  		{
   			//得到vector中第一个元素
   			String firstLine = (String) lines.elementAt(0);
   			//得到文件名
   			//根据http消息格式
   			String fileName = firstLine.substring(firstLine.indexOf(" ")+1);
   			int n = fileName.indexOf(" ");
   			//URL在两个空格之间
   			if(n!=-1) fileName = fileName.substring(0,n);
   			
   			//去掉第一个'/'
   			try 
   			{
    				if(fileName.charAt(0) == '/') fileName = fileName.substring(1);
   			} 
   			catch(StringIndexOutOfBoundsException ex) {}
   			
   			//默认首页
   			//类似于'http://localhost:80'的情况
   			if(fileName.equals("")) fileName = "index.htm";
   			//类似于'http://localhost:80//'的情况
   			if(fileName.charAt(fileName.length()-1)=='/')
    			fileName+="index.htm";
   			return fileName;
  		}else return "";
 	}
 	// 显示请求信息
 	void log() 
 	{
  		System.out.println("Received the following request:");
  		for(int i=0;i<lines.size();++i)
   		System.out.println((String) lines.elementAt(i));
 	}
}