out.write(header);        //寫入Http報(bào)文頭部部分
out.write(content);       //寫入Http報(bào)文數(shù)據(jù)部分
out.flush();              //刷新輸出流，確保緩沖區(qū)內(nèi)數(shù)據(jù)已經(jīng)發(fā)送完成

package com.dragon;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class HttpServer {
	private static ServerSocket server;
	
	/**
	 * 啟動(dòng)服務(wù)
	 * */
	public void start() {
	    try {
	    	server = new ServerSocket(10000);
	    	System.out.println("服務(wù)啟動(dòng)成功...");
	    	this.receiveRequest();
	    } catch (IOException e) {
	    	e.printStackTrace();
	    	System.out.println("服務(wù)啟動(dòng)失??！");
	    }
	}

	
	/**
	 * 接收請(qǐng)求
	 * */
	public void receiveRequest() {
		ExecutorService pool = Executors.newFixedThreadPool(10);
		while (true) {
			try {
				Socket client = server.accept();
				System.out.println("用戶"+client.getInetAddress().toString()+"建立連接" + client.toString());
				pool.submit(new Connection(client));  //使用線程處理每一個(gè)請(qǐng)求。
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
	
	/**
	 * 停止服務(wù)
	 * 注：一般是不需要關(guān)閉服務(wù)的。
	 * */
	public void stop() {
		try {
			if (server != null) {
				server.close();
			}
		} catch (IOException e) {
			e.printStackTrace();
			System.out.println("服務(wù)器關(guān)閉失?。?);
		}
	}
}

package com.dragon;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

public class Connection implements Runnable {
	private static final String BLANK = " ";
	private static final String CRLF = "\r\n";
	private byte[] content;
	private byte[] header;
	private Socket client;
	
	public Connection(Socket client) {
		this.client = client;
	}
	
	@Override
	public void run() {
		//這里不對(duì)請(qǐng)求進(jìn)行處理，只是收到請(qǐng)求之后會(huì)進(jìn)行響應(yīng)，而不管是什么請(qǐng)求
		//這里模擬服務(wù)器最原始的功能：請(qǐng)求、響應(yīng)。
		this.response();
		System.out.println("線程執(zhí)行結(jié)束了！");
	}
	
	/**
	 * 接收請(qǐng)求信息，這里只是一個(gè)簡(jiǎn)單的模擬，這里只能接收get請(qǐng)求。
	 * @throws IOException 
	 * */
	public String getRequestInfo(InputStream in) throws IOException {
		//只讀取第一行，這是我們需要的全部內(nèi)容
		StringBuilder requestLine = new StringBuilder(80);
		while (true) {
			int c = in.read();
			if (c == '\r' || c == '\n' || c == -1) break;
			requestLine.append((char)c);
		}
		return requestLine.toString();
	}
	
	/**
	 * 響應(yīng)信息
	 * */
	public void response() {
		InputStream in = null;
		OutputStream out = null; 
		try {
			in = new BufferedInputStream(client.getInputStream());
			out = new BufferedOutputStream(client.getOutputStream());   //獲取輸出流
			String requestInfo = this.getRequestInfo(in);           //如果不讀取客戶端發(fā)來的數(shù)據(jù)，服務(wù)器就會(huì)出錯(cuò)。
			System.out.println(requestInfo);
		} catch (IOException e1) {
			e1.printStackTrace();
		}       //獲取輸入流
		
		
		//響應(yīng)體數(shù)據(jù)
		File file = new File("D:/DragonFile/target/attitude.jpg");
		String contentType = null;  //文件的 MIME 類型
		try {
			content = Files.readAllBytes(file.toPath());           //使用 Files 工具類，一次性讀取文件
			contentType = Files.probeContentType(file.toPath());   //獲取文件的 MIME 類型
			long length = file.length();                           //獲取文件字節(jié)長度
			header = this.getHeader(contentType, length);          // 填充響應(yīng)頭
 		} catch (IOException e) {
			e.printStackTrace();
		}
		
		try {
			out.write(header);        //寫入Http報(bào)文頭部部分
			out.write(content);       //寫入Http報(bào)文數(shù)據(jù)部分
			out.flush();              //刷新輸出流，確保緩沖區(qū)內(nèi)數(shù)據(jù)已經(jīng)發(fā)送完成
			
			System.out.println("報(bào)文總大小（字節(jié)）：" + (header.length + content.length));
		} catch (IOException e) {
			e.printStackTrace();
			System.out.println("客戶斷開連接或者發(fā)送失??！");
		} finally {
			//此處關(guān)閉 client 會(huì)導(dǎo)致程序出現(xiàn)問題，但是原因不清楚。
			try {
				if (client != null) {
					client.close();
				}
				System.out.println("請(qǐng)求結(jié)束了");
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
    }
	
	//響應(yīng)頭
	private byte[] getHeader(String contentType, long length) {
		return new StringBuilder()
				.append("HTTP/1.1").append(BLANK).append(200).append(BLANK).append("OK").append(CRLF)  // 響應(yīng)頭部
				.append("Server:"+"CrazyDragon").append(CRLF)
				.append("Date:").append(BLANK).append(this.getDate()).append(CRLF)
				.append("Content-Type:").append(BLANK).append(contentType).append(CRLF) //文件的 Content-Type 可通過Java獲取。
				.append("Content-Length:").append(BLANK).append(length).append(CRLF).append(CRLF)
				.toString()
				.getBytes(Charset.forName("UTF-8"));
	}
	
	//獲取時(shí)間
	private String getDate() {
		Date date = new Date();
		SimpleDateFormat format = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss 'GMT'", Locale.US);
		format.setTimeZone(TimeZone.getTimeZone("GMT")); // 設(shè)置時(shí)區(qū)為GMT  
		return format.format(date);
	}
}

package com.dragon;

public class Test {
	public static void main(String[] args) {
		HttpServer httpServer = new HttpServer();
		httpServer.start();
	}
}