一個簡單的Java web服務器實現，比較簡單，基於java.net.Socket和java.net.ServerSocket實現；
一、程序執行步驟
1.創建一個ServerSocket對象；
2.調用ServerSocket對象的accept方法，等待連接，連接成功會返回一個Socket對象，否則一直阻塞等待；
3.從Socket對像中獲取InputStream和OutputStream字節流，這兩個流分別對應request請求和response響應；
4.處理請求：讀取InputStream字節流信息，轉成字符串形式，並解析，這裡的解析比較簡單，僅僅獲取uri(統一資源標識符)信息;
5.處理響應：根據解析出來的uri信息，從WEB_ROOT目錄中尋找請求的資源資源文件, 讀取資源文件，並將其寫入到OutputStream字節流中；
6.關閉Socket對象；
7.轉到步驟2，繼續等待連接請求；
二、代碼實現
服務器實現：
package ex01.pyrmont;import java.net.Socket;import java.net.ServerSocket;import java.net.InetAddress;import java.io.InputStream;import java.io.OutputStream;import java.io.IOException;import java.io.File;public class HttpServer { /** * WEB_ROOT是HTML和其它文件存放的目錄. 這裡的WEB_ROOT為工作目錄下的webroot目錄*/ public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot"; // 關閉服務命令private static final String SHUTDOWN_COMMAND = "/SHUTDOWN"; public static void main(String[] args) { HttpServer server = new HttpServer(); //等待連接請求server.await(); } public void await() { ServerSocket serverSocket = null; int port = 8080; try { //服務器套接字對象serverSocket = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1")); } catch (IOException e) { e.printStackTrace(); System.exit(1); } // 循環等待一個請求while (true) { Socket socket = null; InputStream input = null; OutputStream output = null; try { //等待連接，連接成功後，返回一個Socket對象socket = serverSocket.accept(); input = socket.getInputStream(); output = socket.getOutputStream(); // 創建Request對象並解析Request request = new Request(input); request.parse(); // 檢查是否是關閉服務命令if (request.getUri().equals(SHUTDOWN_COMMAND)) { break; } // 創建Response 對象Response response = new Response(output); response.setRequest(request); response.sendStaticResource(); // 關閉socket 對象socket.close(); } catch (Exception e) { e.printStackTrace(); continue; } } }}Request類：
package ex01.pyrmont;import java.io.InputStream;import java.io.IOException;public class Request { private InputStream input; private String uri; public Request(InputStream input) { this.input = input; } //從InputStream中讀取request信息，並從request中獲取uri值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.print(request.toString()); uri = parseUri(request.toString()); } /** * * requestString形式如下： * GET /index.html HTTP/1.1 * Host: localhost:8080 * Connection: keep-alive * Cache-Control: max-age=0 * ... * 該函數目的就是為了獲取/index.html字符串*/ 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; }} Response類：
package ex01.pyrmont;import java.io.OutputStream;import java.io.IOException;import java.io.FileInputStream;import java.io.File;/* HTTP Response = Status-Line *(( general-header | response-header | entity-header ) CRLF) CRLF [ message-body ] Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase CRLF*/public class Response { private static final int BUFFER_SIZE = 1024; Request request; OutputStream output; public Response(OutputStream output) { this.output = output; } public void setRequest(Request request) { this.request = request; } public void sendStaticResource() throws IOException { byte[] bytes = new byte[BUFFER_SIZE]; FileInputStream fis = null; try { //將web文件寫入到OutputStream字節流中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(); } }}三、結果測試
訪問存在的資源文件(注意存放在工程目錄的webroot文件夾裡)：
訪問不存在的資源文件：
關閉服務器：
參考資料：《深入剖析Tomcat》
@author 風一樣的碼農
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