java - 将 Java 应用程序绑定(bind)到接口(interface)

Question

我对具有 2 个界面的 GNU/Linux 服务器有 root 访问权限。我正在使用 Jericho 和 HtmlUnit 来抓取一些网页。我想指定哪个接口(interface)应该用于 HTTP 连接。有没有办法在命令行或 Java 中执行此操作？

Answer 1

I want to specify which interface should be used for the HTTP connection.

每个网络接口(interface)都有自己唯一的 IP 地址。您可以通过连接到接口(interface) IP 地址上的端口来绑定(bind)到接口(interface)。

I don't have access to sockets. I'm giving HtmlUnit a URL.

无论您是使用套接字(通过 Socket/InetAddress)还是 HTTP 连接(通过 URL)，您都使用相同的方法 - 绑定(bind)到 IP 地址 + 端口。

确定哪个接口(interface)有哪个地址

• 使用 Linux 命令:

   ip a
   ip link show
   /sbin/ifconfig -a
   lshw -class network
  

• 使用 Java(java.net.NetworkInterface 类):

   import java.io.*;
   import java.net.*;
   import java.util.*;
   import static java.lang.System.out;
  
   public class ListNIFs {
       public static void main(String args[]) throws SocketException {
           Enumeration<NetworkInterface> nets = 
               NetworkInterface.getNetworkInterfaces();
  
           for (NetworkInterface netIf : Collections.list(nets)) {
               out.printf("Display name: %s\n", netIf.getDisplayName());
               out.printf("Name: %s\n", netIf.getName());
               Enumeration<InetAddress> inetAddresses = netIf.getInetAddresses();
               for (InetAddress add : Collections.list(inetAddresses)) {
                   out.printf("Address: %s\n", add.getName().getAddress().getHostAddress());
               }
               displaySubInterfaces(netIf);
               out.printf("\n");
           }
       }
  
       static void displaySubInterfaces(NetworkInterface netIf) throws SocketException {
           Enumeration<NetworkInterface> subIfs = netIf.getSubInterfaces();            
           for (NetworkInterface subIf : Collections.list(subIfs)) {
               out.printf("\tSub Interface Display name: %s\n", subIf.getDisplayName());
               out.printf("\tSub Interface Name: %s\n", subIf.getName());
               Enumeration<InetAddress> inetAddresses = subIf.getInetAddresses();
               for (InetAddress add : Collections.list(inetAddresses)) {
                   out.printf("\t Sub Interface Address: %s\n", add.getName().getAddress().getHostAddress());
               }
           }
        }
   }  
  

HTML 单元:指定 IP 地址和端口

如果您正在调用 HTMLUnit 的 WebClient，例如:

com.gargoylesoftware.htmlunit.WebClient webClient = new WebClient();
com.gargoylesoftware.htmlunit.html.HtmlPage page = 
    webClient.getPage("http://mycompany.org/mypage");

然后您可以执行以下任一操作:

com.gargoylesoftware.htmlunit.html.HtmlPage page = 
    webClient.getPage("http://255.255.255.0:80/mypage");

java.net.URL url = new java.net.URL("http://255.255.255.0:80/mypage");
page = webClient.getPage(url);

com.gargoylesoftware.htmlunit.WebRequest req = 
    new com.gargoylesoftware.htmlunit.WebRequest(url, com.gargoylesoftware.htmlunit.HttpMethod.GET);
page = webClient.getPage(req);

您还可以使用 HTMLUnit HttpWebConnection:

com.gargoylesoftware.htmlunit.HttpWebConnection conn = 
    new com.gargoylesoftware.htmlunit.HttpWebConnection(webClient);
java.net.URL url = new java.net.URL("http://255.255.255.0/mypage");
com.gargoylesoftware.htmlunit.WebRequest req = 
    new com.gargoylesoftware.htmlunit.WebRequest(url, com.gargoylesoftware.htmlunit.HttpMethod.POST);
com.gargoylesoftware.htmlunit.WebRequest resp = conn.getResponse(req);

核心 Java:为 HTTP 连接指定 URL 的选项

创建一个 URL 以连接到资源(文件、网页等)。您可以使用主机字符串(自动 DNS 查找)或 IP 地址指定 URL。您可以选择添加端口:

    // does not encode URL for you (manually include %20, etc)
    java.net.URL url = 
        new URL("http://255.255.255.20:80/docs/books/tutorial/index.html?name=networking#DOWNLOADING");
    java.net.URL url2 = new URL("http", "255.255.255.20", 80, 
                                "/docs/books/tutorial/index.html?name=networking#DOWNLOADING");
    java.net.URL url3 = new java.net.URL("https://maps.google.com/maps?q=sydney");
    java.net.URL url4 = new java.net.URL("https", "maps.google.com", 80, "/maps?q=sydney");

    // does encoding of URL string for you 
    java.net.URI uri5 = new URI("http", "example.com", "/hello world/", "");
    java.net.URL url5 = uri2.toURL();

    // Can then pass URL to HTMLUnit, or invoke yourself 
    // (see Java Network Tutorial for details):

    java.net.URLConnection conn = url.openConnection();
    java.net.HttpConnection httpConn = (HttpConnection)conn;
    // preconnection: call setAllowUserInteraction/setDoInput/setDoOutput/    
    //                     setIfModifiedSince/setUseCaches/setRequestProperty
    httpConn.connect();  // or getInputStream/getOutputStream/getContent/getHeaderField
    // postconnection: call getContentEncoding/getContentLength/getContentType
    //                      getDate/getExpiration/getLastModifed

核心 Java:指定 InetAddress 的选项(用于套接字连接)

使用 IP 地址

    // 4 bytes:
    byte[] ip4Address = {101,119,11,106};  
    java.net.InetAddress addressObj = java.net.InetAddress.getByAddress(ip4Address); 

    // or use ip6Address, 16 bytes (2001:0db8:85a3:0000:0000:8a2e:0370:7334):
    // Any hex value above 0x7f must be cast to byte, because byte is signed (-128 to 127)
    byte[] ip6Address = {0x20,0x01,0x0d,(byte)0xb8,(byte)0x85,(byte)0xa3,0x00,0x00,0x00,0x00,(byte)0x8a,0x2e,0x03,0x70,0x73,0x34}; 

使用 URL 字符串(DNS 查找)

    java.net.InetAddress addressObj = java.net.InetAddress.getByName("www.google.com");