如何使用 Stun 和 ice4j 接收公共 IP 和端口

Question

我会尽量简短。

我希望在不通过服务器的情况下创建 2 个 java 应用程序（稍后将被传输到 android）之间的通信。因此，我花了数周时间环顾四周，经过大量工作，我发现了 stun 和 ice4j。我找到了here 对如何使用 ice4j 的最佳解释，它几乎向我展示了如何将 stun 服务器添加到代理（我真的不知道代理是什么，只是它管理我的通信使用 STUN 和 TURN），通过以下代码：

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);
        }
    }
}

然而，在此之后，本教程使用SDPUtils（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 获得了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 不是很熟悉，只是想在我的常规项目中添加一个常规库）。这个 jar 库没有 SDPUtils 类，而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，或者给我看一个例子关于如何回答标题上的问题。

但是，除非您可以按照我在上一句中所说的进行操作，或者向我指出一些示例代码，否则您的帮助很可能不会有用，因为我在精神上无法完全理解这背后的理论，因为很多我不知道的概念。

我必须在本周末之前解决这个问题，如果我不这样做，我会很糟糕。因此，如果您可以或知道有人可以提供帮助，我将不胜感激。

感谢您到目前为止阅读并尝试提供帮助:)

Answer 1

你去吧
SdpUtils.java

实际上，我也在从事与我的大学项目相同的工作。从上周开始，我正在挖掘网络以通过 nat 建立 p2p 连接。
我知道您在代码片段上方获得的表格，我想通知您该代码中有错误这是我更正的那个

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
}

}

此代码需要设置 SIP 服务器，并且在 ice4j 测试中的那个说的是别的，看看Ice.java