java - 获取原始 HTTP 响应 header

Question

有什么方法可以获取原始响应 http header 吗？

getHeaderField() 方法对我不起作用，因为服务器吐出多个“Set-Cookie”，其中一些丢失了。

Answer 1

The getHeaderField() method doesn't work for me

您是在 java.net.URLConnection 的上下文中问这个问题的， 是吗？不，使用 URLconnection 无法获取原始 HTTP 响应 header 。你需要回退到低级别 Socket编程。这是一个 SSCCE ，只需复制'n'粘贴'然后运行它。

package com.stackoverflow.q2307291;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;

public class Test {

    public static void main(String[] args) throws IOException {
        String hostname = "stackoverflow.com";
        int port = 80;

        Socket socket = null;
        PrintWriter writer = null;
        BufferedReader reader = null;

        try {
            socket = new Socket(hostname, port);
            writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
            writer.println("GET / HTTP/1.1");
            writer.println("Host: " + hostname);
            writer.println("Accept: */*");
            writer.println("User-Agent: Java"); // Be honest.
            writer.println(""); // Important, else the server will expect that there's more into the request.
            writer.flush();

            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            for (String line; (line = reader.readLine()) != null;) {
                if (line.isEmpty()) break; // Stop when headers are completed. We're not interested in all the HTML.
                System.out.println(line);
            }
        } finally {
            if (reader != null) try { reader.close(); } catch (IOException logOrIgnore) {} 
            if (writer != null) { writer.close(); }
            if (socket != null) try { socket.close(); } catch (IOException logOrIgnore) {} 
        }
    }

}

为了避免 SO 被尝试此代码段的每个人过载，输出如下所示:

HTTP/1.1 200 OKCache-Control: privateContent-Type: text/html; charset=utf-8Expires: Sun, 21 Feb 2010 20:39:08 GMTServer: Microsoft-IIS/7.5Date: Sun, 21 Feb 2010 20:39:07 GMTConnection: closeContent-Length: 208969

To learn more about sending HTTP requests the low-level way, read the HTTP specification.

However, you probably want to make use of getHeaderFields() method instead to retrieve a header with multiple values. The getHeaderField() namely only returns the last value, as per the linked API doc.

List<String> cookies = connection.getHeaderFields().get("Set-Cookie");