编写Java sip示例

下面是一个简单的Java SIP示例，演示如何使用SIP协议栈发送SIP请求和处理SIP响应：

import javax.sip.*;
import javax.sip.address.*;
import javax.sip.header.*;
import javax.sip.message.*;

public class SipDemo implements SipListener {
    private SipFactory sipFactory;
    private SipStack sipStack;
    private SipProvider sipProvider;
    private HeaderFactory headerFactory;
    private AddressFactory addressFactory;
    private MessageFactory messageFactory;
    private String toUser = "sip:to@example.com";
    private String fromUser = "sip:from@example.com";
    private String proxyHost = "proxy.example.com";
    private int proxyPort = 5060;
    
    public SipDemo() {
        try {
            // 创建SIP协议栈
            sipFactory = SipFactory.getInstance();
            sipFactory.setPathName("gov.nist");
            sipStack = sipFactory.createSipStack(null);
            // 创建SIP消息工厂、地址工厂、头部工厂
            messageFactory = sipFactory.createMessageFactory();
            addressFactory = sipFactory.createAddressFactory();
            headerFactory = sipFactory.createHeaderFactory();
            // 创建SIP用户代理
            ListeningPoint listeningPoint = sipStack.createListeningPoint("127.0.0.1", 5060, "udp");
            sipProvider = sipStack.createSipProvider(listeningPoint);
            sipProvider.addSipListener(this);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    // 发送SIP请求
    public void sendRequest(String method) {
        try {
            // 创建请求地址、请求头部、请求消息
            Address toAddress = addressFactory.createAddress(toUser);
            Address fromAddress = addressFactory.createAddress(fromUser);
            CallIdHeader callIdHeader = sipProvider.getNewCallId();
            CSeqHeader cSeqHeader = headerFactory.createCSeqHeader(1L, method);
            MaxForwardsHeader maxForwardsHeader = headerFactory.createMaxForwardsHeader(70);
            Request request = messageFactory.createRequest(toAddress.getURI(), method, callIdHeader, cSeqHeader, fromAddress, maxForwardsHeader);
            // 添加Via头部和Route头部
            ViaHeader viaHeader = headerFactory.createViaHeader("127.0.0.1", 5060, "udp", null);
            request.addHeader(viaHeader);
            RouteHeader routeHeader = headerFactory.createRouteHeader(addressFactory.createAddress("sip:" + proxyHost + ":" + proxyPort + ";lr"));
            request.addHeader(routeHeader);
            // 发送请求
            ClientTransaction transaction = sipProvider.getNewClientTransaction(request);
            transaction.sendRequest();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    // 处理SIP响应
    public void processResponse(ResponseEvent event) {
        Response response = event.getResponse();
        int status = response.getStatusCode();
        if (status >= 200 && status <= 299) {
            System.out.println("SIP响应成功：" + response);
        } else {
            System.out.println("SIP响应失败：" + response);
        }
    }
    
    public static void main(String[] args) {
        SipDemo demo = new SipDemo();
        demo.sendRequest(Request.INVITE);
    }
    
    // 其他SipListener接口方法
    public void processRequest(RequestEvent event) {}
    public void processTimeout(TimeoutEvent event) {}
    public void processIOException(IOExceptionEvent event) {}
    public void processTransactionTerminated(TransactionTerminatedEvent event) {}
    public void processDialogTerminated(DialogTerminatedEvent event) {}
}

这个示例演示了如何创建SIP协议栈、SIP用户代理、发送SIP请求、处理SIP响应。需要注意的是，具体的SIP请求和响应内容需要根据实际情况进行编写。