如何在JAVA中使用HTTP請求通過TCP套接字獲取網頁

我的大學作業是使用 TCP 套接字和 HTTPGET請求通過 URL 從任何 Web 服務器獲取網頁。

我沒有收到HTTP/1.0 200 OK任何服務器的回應。

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.URL;
import java.util.Scanner;
import java.net.*;
public class DCCN042 {

    public static void main(String[] args) {
            Scanner inpt = new Scanner(System.in);
                System.out.print("Enter URL: ");
                String url = inpt.next();
                TCPConnect(url); 
            }
   public static void TCPConnect(String url) {
        try {
            String hostname = new URL(url).getHost();
            System.out.println("Loading contents of Server: "   hostname);
            InetAddress ia = InetAddress.getByName(hostname);
            String ip = ia.getHostAddress();
            System.out.println(ip   " is IP Adress for  "   hostname);
            String path = new URL(url).getPath();
            System.out.println("Requested Path on the server: "   path);
            Socket socket = new Socket(ip, 80);
            // Create input and output streams to read from and write to the server
            PrintStream out = new PrintStream(socket.getOutputStream());
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            // Follow the HTTP protocol of GET <path> HTTP/1.0 followed by an empty line
            if (hostname ! = url) {
                //Request Line
                out.println("GET "   path   " HTTP/1.1");
                out.println("Host: "   hostname);
                //Header Lines
                out.println("User-Agent: Java/13.0.2");
                out.println("Accept-Language: en-us");
                out.println("Accept: */*");
                out.println("Connection: keep-alive");
                out.println("Accept-Encoding: gzip, deflate, br");
                // Blank Line
                out.println();
            } else {
                //Request Line
                out.println("GET / HTTP/1.0");
                out.println("Host: "   hostname);
                //Header Lines
                out.println("User-Agent: Java/13.0.2");
                out.println("Accept-Language: en-us");
                out.println("Accept: */*");
                out.println("Connection: keep-alive");
                out.println("Accept-Encoding: gzip, deflate, br");
                // Blank Line
                out.println();
            }
            // Read data from the server until we finish reading the document
            String line = in.readLine();
            while (line != null) {
                System.out.println(line);
                line = in.readLine();
            }
            // Close our streams
            in.close();
            out.close();
            socket.close();
        } catch (Exception e) {
            System.out.println("Invalid URl");
            e.printStackTrace();
        }
    }
}

我創建了一個 TCP 套接字并傳遞我從Web 服務器接收到的 IP 地址InetAddress.getHostAddress()和埠80，并使用getPath()和getHost()將路徑和主機名與 URL 分開，并在 HTTPGET請求中使用相同的路徑和主機名。

來自服務器的回應：

Enter URL: https://stackoverflow.com/questions/33015868/java-simple-http-get-request-using-tcp-sockets
    Loading contents of Server: stackoverflow.com
    151.101.65.69 is IP Adress for  stackoverflow.com
    Requested Path on the server: /questions/33015868/java-simple-http-get-request-using-tcp-sockets
    HTTP/1.1 301 Moved Permanently
    cache-control: no-cache, no-store, must-revalidate
    location: https://stackoverflow.com/questions/33015868/java-simple-http-get-request-using-tcp-sockets
    x-request-guid: 5f2af765-40c2-49ca-b9a1-daa321373682
    feature-policy: microphone 'none'; speaker 'none'
    content-security-policy: upgrade-insecure-requests; frame-ancestors 'self' https://stackexchange.com
    Accept-Ranges: bytes
    Transfer-Encoding: chunked
    Date: Mon, 27 Dec 2021 15:00:17 GMT
    Via: 1.1 varnish
    Connection: keep-alive
    X-Served-By: cache-qpg1263-QPG
    X-Cache: MISS
    X-Cache-Hits: 0
    X-Timer: S1640617217.166650,VS0,VE338
    Vary: Fastly-SSL
    X-DNS-Prefetch-Control: off
    Set-Cookie: prov=149aa0ef-a3a6-8001-17c1-128d6d4b7273; domain=.stackoverflow.com; expires=Fri, 01-Jan-2055 00:00:00 GMT; path=/; HttpOnly
    
    0

我的要求是獲取此網頁的 HTML 源代碼和HTTP/1.0 200 OK回應。

uj5u.com熱心網友回復：

發生這種情況是因為您使用的是Socket帶有硬編碼 port的純文本80。這意味著，與在輸入中使用 ahttp或httpsurl無關，您是通過不安全協議進行請求的http。

在這種情況下，服務器會告訴您，正如塞繆爾·杰克遜 (Samuel L. Jackson) 會說的那樣：“嘿，mf！您正試圖通過不安全的協議 HTTP 與我聯系。使用安全的 mf，f HTTPS。 ”，等等，它以301回應（這僅表示“使用此 URL，而不是原始 URL”），Location標頭指向正確的 URL，即https。

顯然301 Location是相同的 URL，但事實并非如此，因為在您的代碼中您是硬編碼的http，并且服務器回應重定向到https.

要使您的代碼與 一起使用https，而不是簡單地Socket使用：

SSLSocketFactory factory = (SSLSocketFactory)SSLSocketFactory.getDefault();
SSLSocket socket = (SSLSocket)factory.createSocket(ia, 443);

做筆記，我不是使用ip，因為https你需要的證書對應的域名，如果你使用的IP，你會得到一個CertificateExpiredException。

現在，是使用Socket還是SSLSocket必須根據用戶輸入以編程方式管理的東西。

標籤：爪哇 html http 插座 客户端

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