HttpURLConnection

public class HttpURLConnectionDemo {

	public static void main(String[] args) throws Exception {
		URL url = new URL("http://localhost:8080/day14_web/servlet/DemoServlet");
		HttpURLConnection conn = (HttpURLConnection)url.openConnection();
		request(conn);
	}
	//获取服务器的响应
	private static void response(HttpURLConnection conn) throws IOException{
		//响应码
		int code = conn.getResponseCode();
		//响应码描述
		String message = conn.getResponseMessage();
		//响应头
		String headerValue = conn.getHeaderField("Server");
		//响应正文
		InputStream in = conn.getInputStream();
		byte b[] = new byte[1024];
		int len = -1;
		while((len=in.read(b))!=-1){
			System.out.println(new String(b,0,len));
		}
		in.close();
		conn.disconnect();
	}
	//向服务器发请求
	private static void request(HttpURLConnection conn) throws IOException{
		conn.setDoOutput(true);
		//请求方式
		conn.setRequestMethod("POST");
		//请求头
		conn.setRequestProperty("bigheader", "bigheadervalue");
		//请求正文：请求参数。name=value
		OutputStream out = conn.getOutputStream();
		out.write("username=中国".getBytes());
		
		int code = conn.getResponseCode();
		System.out.println(code);
		
	}
}