• 需求

• • 支持浏览器客户端接入

  • 根据请求的资源路径响应正确的结果

  • 支持访问静态资源

  • 支持访问动态资源

  • 当资源不存在时响应404提示

  • 当发生异常时提示500错误

  • 为保证服务器安全稳定，服务器端不可无限开启新线程

• 思路

• • 启动ServerSocket，监听指定端口

  • 等待客户端接入，将接入的客户端交给线程池去处理，主线程继续监听客户端接入

  • 静态资源：从指定的静态资源路径去查找文件，将文件转换为字节，写入输出流

  • 动态资源：从类路径下查找响应的Servlet，调用Servlet的service处理程序，将返回值写入输出流

  • 当请求的资源不存在，将404.html文件写入输出流

  • 当发生异常，将500.html文件写入输出流

在实现HTTP服务器之前，我们需要先来了解一下HTTP的报文结构。

# HTTP报文结构

• 可参考

• • https://developer.mozilla.org/zh-CN/docs/Web/HTTP/Messages

• Request与Response的报文结构

• Request的报文结构

• 所以按照约定的报文格式进行消息的解析与发送即可~

# 资源准备

• 静态资源

• 动态资源，Servlet

• • Servlet规范

/*** Servlet规范接口** @author futao* @date 2020/7/6*/
public interface Servlet {/*** 业务处理程序** @return 响应*/Object service();
}

• Servlet服务端小程序

/*** 返回字符串** @author futao* @date 2020/7/6*/
public class HelloServlet implements Servlet {@Overridepublic Object service() {return "greet from dynamic server...";}
}--------------------------------------------------------
--------------------------------------------------------/*** 返回list集合** @author futao* @date 2020/7/6*/
public class UserListServlet implements Servlet {@Overridepublic Object service() {ArrayList<User> users = new ArrayList<>();for (int i = 0; i < 10; i++) {users.add(User.builder().name("喜欢天文的pony站长").age(i).address("浙江杭州").build());}return users;}@Getter@Setter@Builderstatic class User {private String name;private int age;private String address;}
}--------------------------------------------------------
--------------------------------------------------------/*** 返回当前时间** @author futao* @date 2020/7/6*/
public class CurTimeServlet implements Servlet {private static final DateTimeFormatter DATE_TIME_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");@Overridepublic Object service() {return "当前时间为: " + DATE_TIME_FORMATTER.format(LocalDateTime.now(ZoneOffset.ofHours(8)));}
}--------------------------------------------------------
--------------------------------------------------------/*** 模拟异常的Servlet** @author futao* @date 2020/7/6*/
public class ExceptionServlet implements Servlet {@Overridepublic Object service() {throw new RuntimeException("发生了异常");}
}

# 服务器代码编写

• 核心代码:

/*** 基于BIO实现的静态 and 动态服务器** @author futao* @date 2020/7/6*/
public class BIODynamicServer {private static final Logger logger = LoggerFactory.getLogger(BIODynamicServer.class);/*** 用于处理客户端接入的线程池*/private static final ExecutorService THREAD_POOL = Executors.newFixedThreadPool(10);/*** 静态资源路径*/private static final String STATIC_RESOURCE_PATH = System.getProperty("user.dir") + "/practice/src/main/resources/pages/";/*** Servlet的类路径*/private static final String DYNAMIC_RESOURCE_CLASS_PATH = "com.futao.practice.chatroom.bio.v6server.servlet.";/*** Servlet后缀*/private static final String SERVLET_SUFFIX = "Servlet";/*** Servlet缓存*/private static final Map<String, Servlet> SERVLET_MAP = new HashMap<>();/*** 默认页面*/private static final String DEFAULT_PAGE = STATIC_RESOURCE_PATH + "index.html";/*** 响应的基础信息*/public static final String BASIC_RESPONSE = "HTTP/1.1 200 OK\r\n" +"Content-Type: text/html;charset=utf-8\r\n" +"Vary: Accept-Encoding\r\n";/*** 回车换行符*/private static final String carriageReturn = "\r\n";public void start() {ServerSocket serverSocket = null;try {serverSocket = new ServerSocket(Constants.SERVER_PORT);logger.debug("========== 基于BIO实现的服务器，开始提供服务 ==========");while (true) {Socket socket = serverSocket.accept();THREAD_POOL.execute(() -> {try {InputStream inputStream = socket.getInputStream();OutputStream outputStream = socket.getOutputStream();byte[] bytes = new byte[1024];int curByteLength = inputStream.read(bytes);byte[] dest = new byte[curByteLength];System.arraycopy(bytes, 0, dest, 0, curByteLength);//请求报文String request = new String(dest);logger.info("接收到客户端的数据:\n{}\n{}", request, StringUtils.repeat("=", 50));// 解析请求地址String requestUri = BIODynamicServer.getRequestUri(request);// 静态资源处理器boolean staticHandler = staticHandler(requestUri, outputStream);if (!staticHandler) {//动态资源处理器if (!dynamicHandler(requestUri, outputStream)) {//动态资源不存在，响应404logger.debug("资源[{}]不存在，响应404", requestUri);staticHandler("404.html", outputStream);}}} catch (IOException e) {e.printStackTrace();}});}} catch (IOException e) {e.printStackTrace();}}
}

• 解析请求地址

    /*** 获取请求的资源地址** @param request* @return*/private static String getRequestUri(String request) {//GET /index.html HTTP/1.1int firstBlank = request.indexOf(" ");String excludeMethod = request.substring(firstBlank + 2);return excludeMethod.substring(0, excludeMethod.indexOf(" "));}

• 处理静态资源

    /*** 静态资源处理器** @return*/public boolean staticHandler(String page, OutputStream outputStream) throws IOException {//资源的绝对路径String filePath = BIODynamicServer.STATIC_RESOURCE_PATH + page;boolean fileExist = false;File file = new File(filePath);if (file.exists() && file.isFile()) {logger.debug("静态资源[{}]存在", page);fileExist = true;//读取文件内容byte[] bytes = Files.readAllBytes(Paths.get(filePath));//写入响应BIODynamicServer.writeResponse(outputStream, bytes);}return fileExist;}

• 处理动态资源

/*** 动态资源处理器** @param requestUri   请求资源名* @param outputStream 输出流* @return* @throws IOException*/private boolean dynamicHandler(String requestUri, OutputStream outputStream) throws IOException {//Servlet是否存在boolean servletExist = false;//ServletServlet servletInstance = null;//从缓存中取Servlet servlet = SERVLET_MAP.get(requestUri);if (servlet == null) {//缓存中不存在try {//反射获取ClassClass<Servlet> aClass = (Class<Servlet>) Class.forName(BIODynamicServer.DYNAMIC_RESOURCE_CLASS_PATH + requestUri + BIODynamicServer.SERVLET_SUFFIX);//创建Servlet对象servletInstance = aClass.newInstance();//缓存SERVLET_MAP.put(requestUri, servletInstance);servletExist = true;logger.debug("动态资源[{}]存在", requestUri);} catch (ClassNotFoundException | IllegalAccessException | InstantiationException e) {return false;}} else {//缓存中存在servletInstance = servlet;servletExist = true;logger.debug("动态资源[{}]存在", requestUri);}//执行业务逻辑try {Object result = servletInstance.service();String resp = JSON.toJSONString(result, SerializerFeature.PrettyFormat);//结果写入输出流BIODynamicServer.writeResponse(outputStream, resp.getBytes(Constants.CHARSET));} catch (Exception e) {//响应500staticHandler("500.html", outputStream);}return servletExist;}

• 将结果写入输出流

    /*** 写入响应** @param outputStream 输出流* @param content      内容* @throws IOException*/private static void writeResponse(OutputStream outputStream, byte[] content) throws IOException {//写入基础响应头outputStream.write(BASIC_RESPONSE.getBytes(Constants.CHARSET));//写入服务器信息outputStream.write(("Server: futaoServer/1.1" + BIODynamicServer.carriageReturn).getBytes(Constants.CHARSET));//写入传输的正文内容大小outputStream.write(("content-length: " + content.length + BIODynamicServer.carriageReturn).getBytes(Constants.CHARSET));//响应头与响应体之间需要空一行outputStream.write(BIODynamicServer.carriageReturn.getBytes(Constants.CHARSET));//写入响应正文outputStream.write(content);outputStream.flush();}

• 测试

• • index.html

  • 静态资源

• 动态资源

• 异常情况

# 源代码

• 源代码都给你了你还不看看?

• https://github.com/FutaoSmile/learn-IO/tree/master/practice/src/main/java/com/futao/practice/chatroom/bio/v6server

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