package ex01.pyrmont; import java.io.IOException; import java.io.InputStream; public class Request { private InputStream input; private String uri; public Request(InputStream input) { this.input = input; } public String getUri() { return uri; } /** * 读取InputStream中内容,转化成字符串,调用解析字符串方法解析 */ public void parse() { //从socket中读取字符 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.println("HTTP Request:"); System.out.print(request.toString()); uri = parseURI(request.toString()); } /** *截取requestString第一个空格和第二个空格之间的内容返回 */ private String parseURI(String requestString) { int index1; int index2; index1 = requestString.indexOf(' '); if(index1 != -1) { index2 = requestString.indexOf(' ', index1 + 1); if (index2 > index1) { return requestString.substring(index1 + 1, index2); } } return ""; } }
2.Response类(模拟HttpServletResponse)
package ex01.pyrmont; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.OutputStream; /** *HTTP Response = * 状态行 Status-Line=HTTP-Version SP Status-Code SP Reason-Phrase CRLF * 响应头部字段 ((general-header | response-header | entity-header) CRLF) * 空行 CRLF * 响应主体 message-body */ public class Response { private static final int BUFFER_SIZE = 1024; Request request; OutputStream output; public Response(OutputStream output) { this.output = output; } public void setRequset(Request request) { this.request = request; } public void sendStaticResource() { 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 { //文件不存在 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) { e.printStackTrace(); } finally { if(fis != null) { try { fis.close(); } catch (IOException e) { e.printStackTrace(); } } } } }
3.HttpServer类(模拟主服务)
package ex01.pyrmont; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.InetAddress; import java.net.ServerSocket; import java.net.Socket; public class HttpServer { /** * WEB_ROOT是html文件和其他文件所存放的目录 System.getProperty("user.dir")获得的是该文件编译后存放的目录 * 对于这个包,WEB_ROOT是在工作目录下的"webroot" * 工作目录是在系统中java命令被执行的地方 */ public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot"; // shutdown command private static final String SHUTDOWN_COMMAND = "/SHUTDOWN"; // 判断是否关闭服务器标志 private boolean shutdown = false; public void await() { ServerSocket server = null; int port = 9999; try { server = new ServerSocket(port, 1, InetAddress.getByName("127.0.0.1")); } catch (IOException e) { e.printStackTrace(); System.exit(1); } //循环等待请求 while(!shutdown) { Socket socket = null; InputStream input = null; OutputStream output = null; try { socket = server.accept(); input = socket.getInputStream(); output = socket.getOutputStream(); //创建一个Requset对象并解析 Request request = new Request(input); request.parse(); //创建一个Response对象来输出内容 Response response = new Response(output); response.setRequset(request); response.sendStaticResource(); //关闭socket socket.close(); //检查URI是否是关闭命令 shutdown = request.getUri().equals(SHUTDOWN_COMMAND); } catch (IOException e) { e.printStackTrace(); } } } public static void main(String[] args) { HttpServer server = new HttpServer(); server.await(); } }
4.运行程序
在浏览器输入:localhost:9999/aaa.txt等会返回相应文件,或找不到提示
这三个类实现了一个简单的web服务器是如何工作的