利用Socket搭建簡單的Http服務器

一直不理解Http協議，覺得很抽象很神祕，看 《how tomcat work》時看到搭建了一個簡單的http服務器，發現協議其實就是對消息格式的規範，就是大家都按這個規範約定的格式發消息收消息。

1.建立sockerserver服務

ServerSocket serverSocket = null; int port = 8088; try { serverSocket = new ServerSocket(port, 1, InetAddress .getByName("127.0.0.1")); log.info("服務啓動"); } catch (IOException e) { e.printStackTrace(); System.exit(1); }

2.監聽相應端口

socket = serverSocket.accept(); input = socket.getInputStream(); output = socket.getOutputStream();

3.對監聽到的字節進行解析

// create Request object and parse Request request = new Request(input); request.parse();

Request 實際上就是解析HTTP協議並得到資源的請求路徑uri。

public void parse() { // Read a set of characters from the socket 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]); } log.info("request head /n"+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; }

4.對請求進行響應

// create Response object Response response = new Response(output); response.setRequest(request); response.sendStaticResource();

這裏實際上根據request分析的uri進行資源的字節化，輸出到socket的out

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) { output.write(bytes, 0, ch); ch = fis.read(bytes, 0, BUFFER_SIZE); } } else { // file not found String errorMessage = "HTTP/1.1 404 File Not Found/r/n" + "Content-Type: text/html/r/n" + "Content-Length: 23/r/n" + "/r/n" + "<h1>File Not Found</h1>"; output.write(errorMessage.getBytes()); } } catch (Exception e) { // thrown if cannot instantiate a File object System.out.println(e.toString()); } finally { if (fis != null) fis.close(); } }

可以看到其實就是簡單的將資源用字節流輸出。

最後提供完整的代碼包（http://download.csdn.net/source/3194644），運行HttpServer.java 後可以通過瀏覽器訪問：http://localhost:8088/index.htm 可以看到靜態頁面，通過後臺可以看到請求的Http信息。