一个简单的 web 服务器

Web 服务器也成为超文本传输协议(HTTP)服务器，因为它使用 HTTP 来跟客户端进行通信的，这通常是个 web 浏览器。一个基于 java 的 web 服务器 使用两个重要的类:java.net.Socket 和 java.net.ServerSocket，并通过 HTTP 消息进行通信。

• 一个简单的web 服务器：

HttpServer

package tomcat;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * @author haishen
 * @date 2018/8/6
 */
public class HttpServer {
    public static final String WEB_ROOT = System.getProperty("user.dir") + File.separatorChar + "webRoot";
    private static final String SHUTDOWN_COMMAND = "/SHUTDOWN";
    private boolean shutdown = false;

    public static void main(String[] args) {
        HttpServer server = new HttpServer();
        server.await();
    }

    public void await() {
        ServerSocket serverSocket = null;
        int port = 8080;
        try {
            serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1"));
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }
        while (!shutdown) {
            Socket socket = null;
            InputStream in = null;
            OutputStream out = null;
            try {
                socket = serverSocket.accept();
                in = socket.getInputStream();
                out = socket.getOutputStream();
                Request request = new Request(in);
                request.parse();
                Response response = new Response(out);
                response.setRequest(request);
                response.sendStaticResource();
                socket.close();
                shutdown = request.getUri().equals("SHUTDOWN_COMMAND");
            } catch (IOException e) {
                e.printStackTrace();
                continue;
            }
        }
    }
}

Request

package tomcat;

import java.io.IOException;
import java.io.InputStream;

/**
 * @author haishen
 * @date 2018/8/6
 */


public class Request {
    private InputStream input;
    private String uri;

    public Request(InputStream input) {
        this.input = input;
    }

    public void parse() {
        StringBuffer request = new StringBuffer(2048);
        int i;
        byte[] buffer = new byte[2048];
        try {
            i = input.read(buffer);
        } catch (IOException e) {
            e.printStackTrace();
            i = -1;
        }
        for (int j = 0; j < i; j++) {
            request.append((char) buffer[j]);
        }
        System.out.println(request.toString());
        uri = parseUri(request.toString());
    }

    private String parseUri(String requestString) {
        int index1, index2;
        index1 = requestString.indexOf(' ');
        if (index1 != -1) {
            index2 = requestString.indexOf(' ', index1 + 1);
            if (index2 > index1) {
                return requestString.substring(index1 + 1, index2);
            }
        }
        return null;
    }

    public String getUri() {
        return uri;
    }
}

---

package tomcat;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * @author haishen
 * @date 2018/8/6
 */

public class Response {
    private static final int BUFFER_SIZE = 1024;
    Request request;
    OutputStream out;

    public Response(OutputStream out) {
        this.out = out;
    }

    public void setRequest(Request request) {
        this.request = request;
    }

    public void sendStaticResource() throws IOException {
        byte[] bytes = new byte[BUFFER_SIZE];
        FileInputStream fis = null;
        try {
            File file = new File(HttpServer.WEB_ROOT, request.getUri());
            if (file.exists()) {
                fis = new FileInputStream(file);
                int ch = fis.read(bytes, 0, BUFFER_SIZE);
                while (ch != -1) {
                    out.write(bytes, 0, ch);
                    ch = fis.read(bytes, 0, BUFFER_SIZE);
                }
            } else {
                String errorMessage = "HTTP/1.1 404 File Not Found\n" +
                        "Content-Type:text/html\n" +
                        "Content-Length:23\n" +
                        "\n" +
                        "<h1>File not Found</h1>";
                out.write(errorMessage.getBytes());
            }
        } catch (Exception e) {
            System.out.println(e.toString());
        } finally {
            if (fis != null)
                fis.close();
        }
    }
}