一、实现Response

对回复的抽象处理

实现ConnectorUtils

获取资源主目录对应的路径

  1. package connector;
  3. import java.io.File;
  5. /**
  6.  * @ClassName:
  7.  * @Description:
  8.  * @author: hszjj
  9.  * @date: 2019/11/26 12:54
  10.  */
  11. public class ConnectorUtils {
  12.     public static final String WEB_ROOT =
  13.             System.getProperty("user.dir") + File.separator + "webroot";
  14.     public static final String PROTOCOL = "HTTP/1.1";
  16.     public static final String CARRIAGE = "\r";
  18.     public static final String NEWLINE = "\n";
  20.     public static final String SPACE = " ";
  22.     public static String renderStatus(HttpStatus status){
  23.         StringBuilder sb=new StringBuilder(PROTOCOL)
  24.                 .append(SPACE)
  25.                 .append(status.getStatusCode())
  26.                 .append(SPACE)
  27.                 .append(status.getReason())
  28.                 .append(CARRIAGE).append(NEWLINE)
  29.                 .append(CARRIAGE).append(NEWLINE);
  30.         return sb.toString();
  31.     }
  32. }

实现HttpStatus

获取网络状态

  1. package connector;
  3. /**
  4.  * @ClassName:
  5.  * @Description:
  6.  * @author: hszjj
  7.  * @date: 2019/11/26 13:07
  8.  */
  9. public enum  HttpStatus {
  10.     SC_OK(200,"OK"),
  11.     SC_NOT_FOUND(404,"File Not Found");
  13.     private int statusCode;
  14.     private String reason;
  16.     HttpStatus(int Code,String reason){
  17.         this.statusCode=Code;
  18.         this.reason=reason;
  19.     }
  21.     public int getStatusCode() {
  22.         return statusCode;
  23.     }
  25.     public String getReason() {
  26.         return reason;
  27.     }
  28. }

实现Response

  1. package connector;
  3. import java.io.*;
  5. /**
  6.  * @ClassName:
  7.  * @Description:HTTP/1.1 200 OK
  8.  * @author: hszjj
  9.  * @date: 2019/11/26 12:49
  10.  */
  11. public class Response {
  12.     private static final int BUFFER_SIZE = 1024;
  14.     Request request;
  15.     OutputStream output;
  17.     public Response(OutputStream output) {
  18.         this.output = output;
  19.     }
  21.     public void setRequest(Request request) {
  22.         this.request = request;
  23.     }
  25.     public void sendStaticResource() throws IOException {
  26.         File file = new File(ConnectorUtils.WEB_ROOT, request.getRequestUri());
  27.         try {
  28.             write(file, HttpStatus.SC_OK);
  29.         } catch (IOException e) {
  30.             write(new File(ConnectorUtils.WEB_ROOT, "404.html"), HttpStatus.SC_NOT_FOUND);
  31.         }
  32.     }
  34.     private void write(File resource, HttpStatus status) throws IOException {
  35.         try (FileInputStream input = new FileInputStream(resource)) {
  36.             output.write(ConnectorUtils.renderStatus(status).getBytes());
  37.             byte[] buffer = new byte[BUFFER_SIZE];
  38.             int lenth = 0;
  39.             while ((lenth = input.read(buffer, 0, BUFFER_SIZE)) != -1) {
  40.                 output.write(buffer, 0, lenth);
  41.             }
  42.         }
  43.     }
  44. }

二、Response测试

TestUtils

工具类

  1. package test.util;
  3. import connector.Request;
  5. import java.io.ByteArrayInputStream;
  6. import java.io.File;
  7. import java.io.IOException;
  8. import java.io.InputStream;
  9. import java.nio.file.Files;
  10. import java.nio.file.Path;
  11. import java.nio.file.Paths;
  13. /**
  14.  * @ClassName:
  15.  * @Description:
  16.  * @author: hszjj
  17.  * @date: 2019/11/26 13:43
  18.  */
  19. public class TestUtils {
  21.     public static Request createRequest(String requestString){
  22.         InputStream input=new ByteArrayInputStream(requestString.getBytes());
  23.         Request request=new Request(input);
  24.         request.parse();
  25.         return request;
  26.     }
  28.     public static String readFileToString(String filename) throws IOException {
  29.         return new String(Files.readAllBytes(Paths.get(filename)));
  30.     }
  31. }

ResponseTest

  1. package test.connector;
  3. import connector.ConnectorUtils;
  4. import connector.Request;
  5. import connector.Response;
  6. import org.junit.jupiter.api.Assertions;
  7. import org.junit.jupiter.api.Test;
  8. import test.util.TestUtils;
  9. import java.io.ByteArrayOutputStream;
  10. import java.io.IOException;
  12. /**
  13.  * @ClassName:
  14.  * @Description:
  15.  * @author: hszjj
  16.  * @date: 2019/11/26 13:36
  17.  */
  18. public class ResponseTest {
  19.     private static final String VAliD_REQUEST = "GET /index.html HTTP/1.1";
  20.     private static final String INVAliD_REQUEST = "GET /notfound.html HTTP/1.1";
  22.     private static final String STATUS200 = "HTTP/1.1 200 OK\r\n\r\n";
  23.     private static final String STATUS404 = "HTTP/1.1 404 File Not Found\r\n\r\n";
  25.     @Test
  26.     public void givenValidRequest_thenReturnStaticResource() throws IOException {
  27.         Request request = TestUtils.createRequest(VAliD_REQUEST);
  28.         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
  29.         Response response = new Response(outputStream);
  30.         response.setRequest(request);
  31.         response.sendStaticResource();
  33.         Assertions.assertEquals(
  34.                 (STATUS200 + TestUtils.readFileToString(ConnectorUtils.WEB_ROOT + request.getRequestUri())),
  35.                 outputStream.toString()
  36.         );
  37.     }
  39.     @Test
  40.     public void givenInvalidRequest_thenReturnError() throws IOException {
  41.         Request request = TestUtils.createRequest(INVAliD_REQUEST);
  42.         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
  43.         Response response = new Response(outputStream);
  44.         response.setRequest(request);
  45.         response.sendStaticResource();
  46.         String resource=TestUtils.readFileToString(ConnectorUtils.WEB_ROOT +"/404.html");
  47.         Assertions.assertEquals(
  48.                 (STATUS404 + resource),
  49.                 outputStream.toString()
  50.         );
  51.     }
  52. }

三、实现Connector和Processor

Processor

处理用户发送的请求，把请求对应的Response准备好

  1. package processor;
  3. import connector.Request;
  4. import connector.Response;
  6. import java.io.IOException;
  8. /**
  9.  * @ClassName:
  10.  * @Description:
  11.  * @author: hszjj
  12.  * @date: 2019/11/26 14:15
  13.  */
  14. public class StaticProcessor {
  16.     public void process(Request request, Response response){
  17.         try {
  18.             response.sendStaticResource();
  19.         } catch (IOException e) {
  20.             e.printStackTrace();
  21.         }
  22.     }
  23. }

Connector

  1. package connector;
  3. import processor.ServletProcessor;
  4. import processor.StaticProcessor;
  6. import java.io.Closeable;
  7. import java.io.IOException;
  8. import java.io.InputStream;
  9. import java.io.OutputStream;
  10. import java.net.ServerSocket;
  11. import java.net.Socket;
  13. public class Connector implements Runnable {
  14.     private static final int DEFAULT_PORT=9999;
  16.     private ServerSocket server;
  17.     private int  port;
  19.     private void shutDown(Closeable...closeables){
  20.         try {
  21.             for (Closeable shut:closeables){
  22.                 if (shut!=null){
  23.                     shut.close();
  24.                 }
  25.             }
  26.         } catch (IOException e) {
  27.             e.printStackTrace();
  28.         }
  29.     }
  31.     public Connector(int port){
  32.         this.port=port;
  33.     }
  34.     public Connector(){
  35.         this(DEFAULT_PORT);
  36.     }
  38.     public void start(){
  39.         new Thread(this).start();
  40.     }
  42.     @Override
  43.     public void run() {
  44.         try {
  45.             server=new ServerSocket(port);
  46.             System.out.println("服务器已启动，监听端口【"+port+"】");
  47.             while (true){
  48.                 Socket socket=server.accept();
  49.                 InputStream input=socket.getInputStream();
  50.                 OutputStream output=socket.getOutputStream();
  52.                 Request request=new Request(input);
  53.                 request.parse();
  54.                 Response response=new Response(output);
  55.                 response.setRequest(request);
  57.                 if (request.getRequestUri().startsWith("/servlet/")){
  58.                     ServletProcessor processor=new ServletProcessor();
  59.                     processor.process(request,response);
  60.                 }else {
  61.                     StaticProcessor processor = new StaticProcessor();
  62.                     processor.process(request, response);
  63.                 }
  65.                 shutDown(socket);
  66.             }
  67.         } catch (IOException e) {
  68.             e.printStackTrace();
  69.         }
  70.     }
  71. }

服务器主函数Bootstrap

  1. import connector.Connector;
  3. /**
  4.  * @ClassName:
  5.  * @Description:
  6.  * @author: hszjj
  7.  * @date: 2019/11/26 14:29
  8.  */
  9. public class Bootstrap {
  10.     public static void main(String[] args) {
  11.         Connector connector=new Connector();
  12.         connector.start();
  13.     }
  14. }

四、测试服务器

启动客户端

  1. package test;
  3. import java.io.IOException;
  4. import java.io.InputStream;
  5. import java.io.OutputStream;
  6. import java.net.Socket;
  8. /**
  9.  * @ClassName:
  10.  * @Description:
  11.  * @author: hszjj
  12.  * @date: 2019/11/26 14:33
  13.  */
  14. public class TestClient {
  15.     public static void main(String[] args) {
  16.         try {
  17.             Socket socket=new Socket("localhost",9999);
  18.             OutputStream outputStream=socket.getOutputStream();
  19.             outputStream.write("GET /index.html HTTP/1.1".getBytes());
  20.             socket.shutdownOutput();
  22.             InputStream inputStream=socket.getInputStream();
  23.             byte[] buffer=new byte[2048];
  24.             int length=inputStream.read(buffer);
  25.             StringBuilder response=new StringBuilder();
  26.             for (int j=0;j<length;j++){
  27.                 response.append((char)buffer[j]);
  28.             }
  29.             System.out.println(response.toString());
  30.             socket.shutdownInput();
  32.             socket.close();
  33.         } catch (IOException e) {
  34.             e.printStackTrace();
  35.         }
  36.     }
  37. }

结果

image.png

效果查看

image.png
image.png

五、实现ServletRequest和ServletResponse

如图使Request继承ServletRequest接口和重写所有方法。
image.png同理，对Response做出同样的修改继承自ServletResponse。
image.png
其中，大部分函数都仅仅用默认修改即可，不过要对Response中的getWriter进行改写，方便动态资源写入进行便捷：

  1. @Override
  2.     public PrintWriter getWriter() throws IOException {
  3.         //自动Flush
  4.         PrintWriter writer=new PrintWriter(output,true);
  5.         return writer;
  6.     }

六、实现Servlet

动态资源的Servlet
public class TimeServlet implements Servlet
主要的Service函数如下：

  1. @Override
  2.     public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
  3.         PrintWriter writer=servletResponse.getWriter();
  4.         writer.println(ConnectorUtils.renderStatus(HttpStatus.SC_OK));
  5.         writer.println("what time is it now?");
  6.         writer.println(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
  7.     }