java使用httpclient异步调用webservice的代码

以下是使用Apache HttpClient异步调用WebService的Java代码示例：

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.soap.MessageFactory;
import javax.xml.soap.MimeHeaders;
import javax.xml.soap.SOAPBody;
import javax.xml.soap.SOAPException;
import javax.xml.soap.SOAPHeader;
import javax.xml.soap.SOAPMessage;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactoryConfigurationError;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.concurrent.FutureCallback;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
import org.apache.http.impl.nio.client.HttpAsyncClients;
import org.apache.http.util.EntityUtils;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;

public class AsyncWebServiceClient {

    private static final String SOAP_ACTION = "http://tempuri.org/HelloWorld";

    private static final String ENDPOINT = "http://localhost/HelloWorldService/HelloWorldService.asmx";

    private static final String SOAP_REQUEST = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
            + "<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
            + "               xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"\n"
            + "               xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n"
            + "  <soap:Body>\n" + "    <HelloWorld xmlns=\"http://tempuri.org/\" />\n" + "  </soap:Body>\n"
            + "</soap:Envelope>";

    public static void main(String[] args) throws Exception {
        HttpClient httpClient = HttpAsyncClients.createDefault();

        CloseableHttpAsyncClient httpclient = (CloseableHttpAsyncClient) httpClient;
        httpclient.start();

        try {
            HttpPost httpPost = new HttpPost(ENDPOINT);
            httpPost.setHeader("Content-Type", "text/xml;charset=UTF-8");
            httpPost.setHeader("SOAPAction", SOAP_ACTION);

            StringEntity entity = new StringEntity(SOAP_REQUEST, ContentType.TEXT_XML.withCharset(StandardCharsets.UTF_8));
            httpPost.setEntity(entity);

            Future<HttpResponse> future = httpclient.execute(httpPost, new FutureCallback<HttpResponse>() {

                @Override
                public void completed(HttpResponse response) {
                    try {
                        HttpEntity responseEntity = response.getEntity();
                        String responseBody = EntityUtils.toString(responseEntity);
                        System.out.println(responseBody);

                        Document document = DocumentBuilderFactory.newInstance()
                                .newDocumentBuilder()
                                .parse(IOUtils.toInputStream(responseBody, StandardCharsets.UTF_8));

                        QName qName = new QName("http://tempuri.org/", "HelloWorldResponse");
                        SOAPBody soapBody = MessageFactory.newInstance().createMessage().getSOAPBody();
                        Document responseDocument = soapBody.getOwnerDocument();
                        SOAPHeader soapHeader = responseDocument.createElementNS("http://schemas.xmlsoap.org/soap/envelope/", "soap:Header");
                        soapBody.addChildElement(qName).appendChild(responseDocument.createTextNode("Hello World!"));

                        SOAPMessage soapMessage = MessageFactory.newInstance().createMessage(new MimeHeaders(),
                                IOUtils.toInputStream(responseDocument.getDocumentElement().getTextContent(),
                                        StandardCharsets.UTF_8));
                        String soapResponse = IOUtils.toString(soapMessage.getSOAPPart().getContent(),
                                StandardCharsets.UTF_8);
                        System.out.println(soapResponse);
                    } catch (IOException | UnsupportedOperationException | SOAPException | ParserConfigurationException | SAXException | TransformerFactoryConfigurationError | TransformerException e) {
                        e.printStackTrace();
                    }
                }

                @Override
                public void failed(Exception ex) {
                    ex.printStackTrace();
                }

                @Override
                public void cancelled() {
                }
            });

            HttpResponse response = future.get();
            System.out.println(response);
        } finally {
            httpclient.close();
        }
    }
}

以上代码使用Apache HttpClient库异步地调用了一个基于SOAP协议的Web Service，实现了将响应报文解析为SOAP消息的功能。在代码中，我们使用了Java自带的XML解析器和SOAP库，也可以使用第三方库实现相同的功能。