自己动手实现HTTP协议

package designpattern.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.util.Iterator;

public class NIOServer {

    public static void main(String[] args) throws IOException {
        // 创建ServerSocketChannel,监听8080端口
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        serverSocketChannel.socket().bind(new InetSocketAddress(8080));

        // 设置为非阻塞模式
        serverSocketChannel.configureBlocking(false);

        // 为serverSocketChannel注册选择器
        Selector selector = Selector.open();
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

        // 创建处理器
        while (true) {
            // 等待请求,每次等待阻塞3s,超过3s后线程继续向下运行,如果传入0或者不传入参数将一直阻塞
            if (selector.select(3000) == 0) {
                System.out.println("等待请求超时....");
                continue;
            }
            System.out.println("处理请求....");

            // 获取待处理的SelectionKey
            Iterator<SelectionKey> keyIter = selector.selectedKeys().iterator();
            while (keyIter.hasNext()) {
                SelectionKey key = keyIter.next();
                // 启动新线程处理SelectionKey
                new Thread(new HttpHandler(key)).run();
                // 处理完毕,从待处理的SelectionKey迭代器中移除当前所使用的key
                keyIter.remove();
            }
        }
    }
}

package designpattern.nio;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;

import org.apache.commons.lang3.StringUtils;

public class HttpHandler implements Runnable {

    private int bufferSize = 1024;
    private String localCharset = "UTF-8";
    private SelectionKey key;

    public HttpHandler() {

    }

    public HttpHandler(SelectionKey key) {
        this.key = key;
    }

    public void handlerAccept() throws IOException {
        SocketChannel clientChannel = ((ServerSocketChannel) key.channel()).accept();
        clientChannel.configureBlocking(false);
        clientChannel.register(key.selector(), SelectionKey.OP_READ, ByteBuffer.allocate(bufferSize));
    }

    public void handleRead() throws IOException {
        // 获取channel
        SocketChannel socketChannel = (SocketChannel) key.channel();

        // 获取buffer并重置
        ByteBuffer buffer = (ByteBuffer) key.attachment();
        buffer.clear();

        // 没有读到内容则关闭
        if (socketChannel.read(buffer) == -1) {
            socketChannel.close();
        } else {
            // 接收请求数据
            buffer.flip();
            String receivedString = Charset.forName(localCharset).newDecoder().decode(buffer).toString();

            // 控制台打印请求报文头
            String[] requestMessage = receivedString.split("\r\n");
            for (String s : requestMessage) {
                System.out.println(s);

                // 遇到空行说明报文头已经打印完
                if (StringUtils.isEmpty(s)) {
                    break;
                }
            }

            // 控制台打印首行信息
            String[] firstLine = requestMessage[0].split(" ");
            System.out.println();
            System.out.println("Method:\t" + firstLine[0]);
            System.out.println("url:\t" + firstLine[1]);
            System.out.println("HTTP Version:\t" + firstLine[2]);
            System.out.println();

            // 返回客户端
            StringBuilder sendString = new StringBuilder();
            sendString.append("HTTP/1.1 200 OK\r\n");// 响应报文首行,200表示处理成功
            sendString.append("Content-Type:text/html;charset=" + localCharset + "\r\n");
            sendString.append("\r\n");// 报文头结束后加一个空行
            sendString.append("<html><head><title>显示报文</title></head></body>");
            sendString.append("接收到请求报文是:<br/>");
            for (String s : requestMessage) {
                sendString.append(s + "<br/>");
            }
            sendString.append("</body></html>");

            buffer = ByteBuffer.wrap(sendString.toString().getBytes(localCharset));
            socketChannel.write(buffer);
            socketChannel.close();
        }

    }

    @Override
    public void run() {
        try {
            // 接收到连接请求时
            if (key.isAcceptable()) {
                handlerAccept();
            }

            // 读数据
            if (key.isReadable()) {
                handleRead();
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}
自己动手实现HTTP协议

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