JAVA如何取得HTTP请求头

在利用Java网络编程时，利用Java获取HTTP Request 和 Response头字段；

可以利用Java语言根据需要添加自定义的HTTP头字段，而不必拘泥于标准HTTP定义的头字段。

代码如下：

public class TestURL {
	public static void main(String[] args) {
		String destURLStr= "http://www.baidu.com";
		URL destURL = null;
		URLConnection urlCon = null;
		HttpURLConnection httpUrlCon= null;
		String readResFile = "C:/Users/zhoujw/Desktop/readResFile.html";
		BufferedWriter bw = null;
		try {
			bw = new BufferedWriter(new FileWriter(readResFile));
			destURL = new URL(destURLStr);
			urlCon = destURL.openConnection();
			httpUrlCon = (HttpURLConnection)urlCon;
			//set request property
			httpUrlCon.setRequestProperty("Accept-Encoding", "gzip,deflate,sdch");
			//可根据需要添加自定义请求头
			httpUrlCon.setRequestProperty("Test Header1", "test1");
			httpUrlCon.setRequestProperty("Test Header2", "test2");
			httpUrlCon.connect();
			BufferedReader br = new BufferedReader(new InputStreamReader(httpUrlCon.getInputStream(), "gbk"));
			String webpage = null;
			while((( webpage = br.readLine()) != null))
			{
//				System.out.println(webpage);
				bw.write(webpage);
				bw.flush();
			}
			//debug
			System.out.println("Self Define Headers:");
			System.out.println(" Test Header1: " + httpUrlCon.getRequestProperty("Test Header1"));
			System.out.println(" Test Header2: " + httpUrlCon.getRequestProperty("Test Header2"));
			System.out.println();
			//echo request property
			echoRequestHeaders(httpUrlCon);
			//echo response property
			echoResponseHeaders(httpUrlCon);
		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void echoRequestHeaders(HttpURLConnection httpUrlCon){
		System.out.println("Request Headers:");
		System.out.println(" " + httpUrlCon.getRequestMethod() + " / " + " HTTP/1.1");
		System.out.println(" Host: " + httpUrlCon.getRequestProperty("Host"));
		System.out.println(" Connection: " + httpUrlCon.getRequestProperty("Connection"));
		System.out.println(" Accept: " + httpUrlCon.getRequestProperty("Accept"));
		System.out.println(" User-Agent: " + httpUrlCon.getRequestProperty("User-Agent"));
		System.out.println(" Accept-Encoding: " + httpUrlCon.getRequestProperty("Accept-Encoding"));
		System.out.println(" Accept-Language: " + httpUrlCon.getRequestProperty("Accept-Language"));
		System.out.println(" Cookie: " + httpUrlCon.getRequestProperty("Cookie"));
		System.out.println(" Connection: " + httpUrlCon.getHeaderField("Connection"));//利用另一种读取HTTP头字段
		System.out.println();
	}

	public static void echoResponseHeaders(HttpURLConnection httpUrlCon) throws IOException{
		System.out.println("Response Headers:");
		System.out.println(" " + "HTTP/1.1 " + httpUrlCon.getResponseCode() + " " + httpUrlCon.getResponseMessage());
		System.out.println(" status: " + httpUrlCon.getResponseCode() + " " + httpUrlCon.getResponseMessage());
		System.out.println(" content-encoding: " + httpUrlCon.getContentEncoding());
		System.out.println(" content-length : " + httpUrlCon.getContentLength());
		System.out.println(" content-type: " + httpUrlCon.getContentType());
		System.out.println(" Date: " + httpUrlCon.getDate());
		System.out.println(" ConnectTimeout: " + httpUrlCon.getConnectTimeout());
		System.out.println(" expires: " + httpUrlCon.getExpiration());
		System.out.println(" content-type: " + httpUrlCon.getHeaderField("content-type"));//利用另一种读取HTTP头字段
		System.out.println();
	}
}

运行结果：

Self Define Headers:
 Test Header1: test1
 Test Header2: test2

Request Headers:
 GET /  HTTP/1.1
 Host: www.baidu.com
 Connection: keep-alive
 Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
 User-Agent: Java/1.6.0_20
 Accept-Encoding: gzip,deflate,sdch
 Accept-Language: null
 Cookie: null
 Connection: Keep-Alive
http://www.baidu.com

Response Headers:
 HTTP/1.1 200 OK
 status: 200 OK
 content-encoding: gzip
 content-length : -1
 content-type: text/html; charset=utf-8
 Date: 1427817028000
 ConnectTimeout: 0
 expires: 1427817001000
 content-type: text/html; charset=utf-8