在web的最初阶段是不支持web服务器与用户的交互的.也就是说web服务器不能动态的生成用户要访问的页面,web服务器提供给用户的页面都是提前生成好的.所以也说这种页面是静态页面.
比如说用户请求访问http://localhost:8088/hello1.htm, 那么web服务器从自己的想要目录下获取hello1.htm(已经存在).然后通过HTTP协议返回给用户.
下面我们来模拟一下这个过程.因为HTTP协议是应用层协议,基于TCP,所以我们用Java的socket来编写HTTP服务器.
编写HttpServer
import java.io.*;
import java.net.*;
public class HttpServer {
private static final int port = 8088;
private ServerSocket serverSocket = null;
public HttpServer() throws IOException {
serverSocket = new ServerSocket(port);
System.out.println("HTTPServer startup OK...");
}
public String getRequest(Socket socket) throws IOException {
InputStream socketIn = socket.getInputStream();
int size = socketIn.available();
byte[] requestBuff = new byte[size];
socketIn.read(requestBuff);
return new String(requestBuff);
}
public String getURI(String request) {
String firstLine = request.substring(0, request.indexOf("\r\n"));
String[] parts = firstLine.split(" ");
return parts[1];
}
public String getContentType(String URI) {
/* 决定HTTP响应正文的类型 */
String contentType;
if (URI.indexOf("html") != -1 || URI.indexOf("htm") != -1)
contentType = "text/html";
else if (URI.indexOf("jpg") != -1 || URI.indexOf("jpeg") != -1)
contentType = "image/jpeg";
else if (URI.indexOf("gif") != -1)
contentType = "image/gif";
else
contentType = "application/octet-stream";
return contentType;
}
public InputStream getResponseContent(String URI)
throws FileNotFoundException {
InputStream htmlInputStream = new FileInputStream(
System.getProperty("user.dir") + "/WebRoot" + URI);
return htmlInputStream;
}
public String assembleResponseHead(String URI, String contentType) {
/* 创建HTTP响应结果 */
// HTTP响应的第一行
String responseFirstLine = "HTTP/1.1 200 OK\r\n";
// HTTP响应头
String responseHeader = "Content-Type:" + contentType + "\r\n\r\n";
return responseFirstLine + responseHeader;
}
public void service() throws InterruptedException {
while (true) {
Socket socket;
try {
socket = serverSocket.accept();
String request = getRequest(socket);
System.out.println("HttpServer receive request:\n" + request);
String URI = getURI(request);
String contentType = getContentType(URI);
OutputStream out = socket.getOutputStream();
out.write(assembleResponseHead(URI, contentType).getBytes());
int len = 0;
byte[] buffer = new byte[128];
InputStream htmlInputStream = getResponseContent(URI);
while ((len = htmlInputStream.read(buffer)) != -1)
out.write(buffer, 0, len);
Thread.sleep(1000);
socket.close(); // 关闭TCP连接
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static void main(String[] args) throws IOException,
InterruptedException {
HttpServer httpServer = new HttpServer();
// System.out.println(System.getProperty("user.dir"));
httpServer.service();
}
}创建hello1.htm
然后在项目的目录/WebRoot下放置一个hello1.htm页面:
hello1.htm很简单,显示标题HelloWorld
<html>
<head>
<title>HelloWorld</title>
</head>
<body >
<h1>Hello</h1>
</body>
</html>访问hello1.htm
启动HTTPServer,在浏览器访问http://localhost:8088/hello1.htm,看到eclipse的Console输出
GET /hello1.htm HTTP/1.1
Host: localhost:8088
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.125 Safari/537.36
Accept-Encoding: gzip, deflate, sdch
Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.6,en;q=0.4
这是浏览器请求的HTTP消息,包括了HTTP头,请求方式,有时也有请求正文(这里没有).
浏览器显示为:
这样简单的HTTPSever就算完成了,后续我将继续研究模拟一下Servlet的HTTP服务器.
时间： 2024-11-10 00:29:18