import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
 
public class ResourceWebServer {
    private static final int SERVER_PORT = 8888;
    private static final int MAX_CONNECTION_LENGTH = 1;
 
    public static void main(String[] args) throws IOException {
        log("======服務(wù)器啟動=====");
        ResourceWebServer server = new ResourceWebServer();
        server.startServer();
    }
 
    public void startServer() throws IOException {
        ServerSocket serverSocket = new ServerSocket(SERVER_PORT, MAX_CONNECTION_LENGTH, InetAddress.getByName("localhost"));
 
        log("======準(zhǔn)備接收請求=====");
        while (true) {
            Socket socket = serverSocket.accept();
            try (InputStream inputStream = socket.getInputStream();
                 OutputStream outputStream = socket.getOutputStream()) {
 
                String requestUri = getRequestUri(inputStream);
                log("請求文件：" + requestUri);
 
                writeHeaders(outputStream);
 
                Path path = Paths.get(getClass().getClassLoader().getResource(requestUri.substring(1)).toURI());
                Files.copy(path, outputStream);
            } catch (Exception e) {
                log("發(fā)生錯誤啦！");
                e.printStackTrace();
            }
        }
    }
 
    private void writeHeaders(OutputStream outputStream) throws IOException {
        //必須包含返回頭，否則瀏覽器不識別
        outputStream.write("HTTP/1.1 200 OK\r\n".getBytes());
        //一個\r\n代表換行添加新的頭，2次\r\n代表頭結(jié)束
        outputStream.write("Content-Type: text/html\r\n\r\n".getBytes());
    }
 
    private String getRequestUri(InputStream inputStream) throws IOException {
        StringBuilder stringBuilder = new StringBuilder(2048);
        byte[] buffer = new byte[2048];
        int size = inputStream.read(buffer);
 
        for (int i = 0; i < size; i++) {
            stringBuilder.append((char) buffer[i]);
        }
 
        String requestUri = stringBuilder.toString();
        //此時的uri還包含了請求頭等信息，需要去掉
        //GET /index.html HTTP/1.1...
        int index1, index2;
        index1 = requestUri.indexOf(" ");
        if (index1 != -1) {
            index2 = requestUri.indexOf(" ", index1 + 1);
            if (index2 > index1) {
                return requestUri.substring(index1 + 1, index2);
            }
        }
        return "";
    }
 
    private static void log(Object object) {
        System.out.println(object);
    }
}