一个简单的Web服务器
一．运行机制
一．一个简单的B/S架构包括：
1. 一台Web服务器；
2. 一台客户机；
二．事物交互的过程：
1． HTTP请求.
2． HTTP响应
三．HTTP请求：
1. 请求行：
请求方法 统一资源标识符 协议/版本
2. 请求头
3. 实体
实例：
POST /example/default.jsp HTTP/1.1
Accept: text/html; text/html
Accept-Language:en-gb
Connection:Keep-Active
Host:localhost
User-Agent:Mozilla/4.0(compatible;MSIE 4.01,Windows98)
Content-length:33
Content-Type:applition/x-www-form-urlencoded
Accept-Encoding:gzip deflate
LastName=Jay&FirstName=King
四．HTTP响应
1. 响应行
协议-状态码-描述
2. 响应头
3. 响应段
实例：
HTTP/1.1 200 OK
Server:Microsoft-IIS/4.0
Date:Mon,5, May 2018 16:09:09 GMT
Last-Modified:Mon,5 May 2018 16:09:02 GMT
Content-Length:112
<html>
<head>
<title>HTTP Response Example</titel>
</head>
<body>
Hello Tomcat!
</body>
</html>
二．实战代码
1. HttpServer
package JayKing.ASimpleWebServer;
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;
import java.net.UnknownHostException;
public class HttpServer {
public static final String WEB_ROOT = System.getProperty("user.dir") + File.separator + "webroot";
public static final String SHUTDOWN_COMMAND = "./SHUTDOWN";
public boolean shutdown = false;
public static int port = 8080;
public static void main(String args[]) {
HttpServer server = new HttpServer();
server.await();
}
private void await() {
ServerSocket serversocket = null;
try {
serversocket = new ServerSocket(port,100, InetAddress.getByName("127.0.0.1"));
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.exit(1);
}
while (!shutdown) {
Socket socket = null;
InputStream in = null;
OutputStream out = null;
try {
socket = serversocket.accept();//服务器没接受一次请求就创建一个socket对象
in = socket.getInputStream();
out = socket.getOutputStream();
Request request = new Request(in);
request.parse();
Response response = new Response(out);
response.setRequest(request);
response.sendStaticResourse();
socket.close();
shutdown = request.getUri().equals("SHUTDOWN_COMMAND");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
continue;
}
}
}
}
2. Request
package JayKing.ASimpleWebServer;
import java.io.IOException;
import java.io.InputStream;
public class Request {
private InputStream in;
private String uri;
public Request(InputStream in) {
this.in = in;
}
public void parse() {
StringBuffer request = new StringBuffer(2048);// StringBuffer是变量，可以更改，而String是常量，一旦创建就不可更改.
int i;
byte[] buffer = new byte[2048];
try {
i = in.read(buffer);// 每次读取2048个字节
} catch (IOException e) {
e.printStackTrace();
i = -1;
}
for (int j = 0; j < i; j++) {
request.append((char) buffer[j]);
}
System.out.println(request.toString());
uri = parseUri(request.toString());
}
public 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;
}
}
3. Response
package JayKing.ASimpleWebServer;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
public class Response {
private static final int BUFFER_SIZE = 1024;
Request request;
OutputStream out;
public Response(OutputStream out) {
this.out = out;
}
public void setRequest(Request request) {
this.request = request;
}
public void sendStaticResourse() throws IOException {
byte[] bytes = new byte[BUFFER_SIZE];
FileInputStream fis = null;
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) {
out.write(bytes, 0, ch);
ch = fis.read(bytes, 0, ch);
}
} else {
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>";
out.write(errorMessage.getBytes());
}
fis.close();
}
}
三．运行应用程序
打开浏览器在地址栏中输入URL：Http：//localhost:8080/index.html