java - 如何使用Stun和ice4j接收公共(public)IP和端口

Question

我会尽量简短。

我希望在两个java应用程序之间创建通信(稍后将传输到android)而不通过服务器。因此，我花了几周时间四处寻找，经过大量工作后我发现了 stun 和ice4j。我找到的关于如何使用ice4j的最好解释here ，它几乎向我展示了如何通过以下代码将 stun 服务器添加到代理(我真的不知道代理是什么，只是它管理我与 STUN 和 TURN 的通信):

import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.ice4j.Transport;
import org.ice4j.TransportAddress;
import org.ice4j.ice.Agent;
import org.ice4j.ice.IceMediaStream;
import org.ice4j.ice.harvest.StunCandidateHarvester;

public class ice4jTesting {

    public static void main(String[] args) {

        Agent agent = new Agent();
        String[] hostnames = new String[] {"jitsi.org", "numb.viagenie.ca", "stun.ekiga.net"};

        for(String hostname: hostnames) {
            try {
                TransportAddress address;

                address = new TransportAddress(InetAddress.getByName(hostname), 3478, Transport.UDP);
                agent.addCandidateHarvester(new StunCandidateHarvester(address));
            } catch (UnknownHostException ex) {
                Logger.getLogger(SimpleStun.class.getName()).log(Level.SEVERE, null, ex);
            }
        }

        IceMediaStream stream = agent.createMediaStream("audio");
        int port = 5000;
        try {
            agent.createComponent(stream, Transport.UDP, port, port, port+100);
            // The three last arguments are: preferredPort, minPort, maxPort
        } catch (IllegalArgumentException | IOException ex) {
            Logger.getLogger(SimpleStun.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

但是，在此之后，本教程将使用 SDPUtils，这是我在github 上找到的ice4j 源代码中的一个类。 ，从代理接收SDP信息。但是我从 the central maven repository 得到了ice4j.jar ，并将其添加到我的 netbeans 常规项目中(我这样做是因为我对 Maven 不太熟悉，只是想要在我的常规项目上有一个常规库)。这个 jar 库没有 SDPUtils 类，并且由于我对这段代码的理解不够，无法自己修复它，我想知道你们中的任何人是否可以帮助我修复上面的代码，或者向我展示如何回答标题问题的示例。

但是，除非您可以按照我在上一句中所说的操作，或者向我指出一些示例代码，否则您的帮助很可能没有用，因为我在精神上无法完全理解其背后的理论，因为很多概念我不知道。

我必须在本周末之前弄清楚这一点，如果我不这样做，我就完蛋了。因此，如果您可以或认识可以提供帮助的人，我将非常感激。

感谢您到目前为止阅读并尝试提供帮助:)

Answer 1

就这样
SdpUtils.java

Actually i'm also working on the same as my University project. From last week i'm digging web for p2p connection establish over nat.
I know that form where you got above Code snipet, i would like to inform you that there is errors in that code Here is the one that i corrected

import java.io.IOException;
import java.net.BindException;
import java.net.InetAddress;
import org.ice4j.Transport;
import org.ice4j.TransportAddress;
import org.ice4j.ice.Agent;
import org.ice4j.ice.IceMediaStream;
import org.ice4j.ice.harvest.StunCandidateHarvester;

public class IceTest {

public static void main(String[] args) throws Exception {
    Agent agent = new Agent(); // A simple ICE Agent

    /*** Setup the STUN servers: ***/
    String[] hostnames = new String[] { "jitsi.org", "numb.viagenie.ca", "stun.ekiga.net" };
    // Look online for actively working public STUN Servers. You can find
    // free servers.
    // Now add these URLS as Stun Servers with standard 3478 port for STUN
    // servrs.
    for (String hostname : hostnames) {
        try {
            // InetAddress qualifies a url to an IP Address, if you have an
            // error here, make sure the url is reachable and correct
            TransportAddress ta = new TransportAddress(InetAddress.getByName(hostname), 3478, Transport.UDP);
            // Currently Ice4J only supports UDP and will throw an Error
            // otherwise
            agent.addCandidateHarvester(new StunCandidateHarvester(ta));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /*
     * Now you have your Agent setup. The agent will now be able to know its
     * IP Address and Port once you attempt to connect. You do need to setup
     * Streams on the Agent to open a flow of information on a specific
     * port.
     */

    IceMediaStream stream = agent.createMediaStream("audio");
    int port = 5000; // Choose any port
    try {
        agent.createComponent(stream, Transport.UDP, port, port, port + 100);
        // The three last arguments are: preferredPort, minPort, maxPort
    } catch (BindException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    /*
     * Now we have our port and we have our stream to allow for information
     * to flow. The issue is that once we have all the information we need
     * each computer to get the remote computer's information. Of course how
     * do you get that information if you can't connect? There might be a
     * few ways, but the easiest with just ICE4J is to POST the information
     * to your public sever and retrieve the information. I even use a
     * simple PHP server I wrote to store and spit out information.
     */
    String toSend = null;
    try {
        toSend = SdpUtils.createSDPDescription(agent);
        // Each computersends this information
        // This information describes all the possible IP addresses and
        // ports
    } catch (Throwable e) {
        e.printStackTrace();
    }

    /*The String "toSend" should be sent to a server. You need to write a PHP, Java or any server. 
     * It should be able to have this String posted to a database. 
     * Each program checks to see if another program is requesting a call. 
     * If it is, they can both post this "toSend" information and then read eachother's "toSend" SDP string. 
     * After you get this information about the remote computer do the following for ice4j to build the connection:*/

    String remoteReceived = ""; // This information was grabbed from the server, and shouldn't be empty.
    SdpUtils.parseSDP(agent, remoteReceived); // This will add the remote information to the agent.
    //Hopefully now your Agent is totally setup. Now we need to start the connections:

    agent.addStateChangeListener(new StateListener()); // We will define this class soon
    // You need to listen for state change so that once connected you can then use the socket.
    agent.startConnectivityEstablishment(); // This will do all the work for you to connect
}

}

This code Requires SIP server to be setup and the one on ice4j test is saying something else just have a look at Ice.java