使用 java 向 WebService 发出 SOAP 请求

SOAP 请求是一个 XML 文件，由要发送到服务器的参数组成。

SOAP 响应同样是一个 XML 文件，但现在包含了服务想要提供的所有内容。

基本上，WSDL 是一个 XML 文件，用于解释这两个 XML 的结构。

要在Java中实现简单的SOAP客户端，您可以使用SAAJ框架（它与JSE 1.6及更高版本一起提供）：

SOAP with Attachments API for Java （SAAJ） 主要用于直接处理 SOAP Request/Response 消息，这些消息在任何 Web Service API 的幕后发生。它允许开发人员直接发送和接收 soap 消息，而不是使用 JAX-WS。

请参阅下面的一个工作示例（运行它！）使用 SAAJ 的 SOAP Web 服务调用。它调用此 Web 服务。

import javax.xml.soap.*;

public class SOAPClientSAAJ {

    // SAAJ - SOAP Client Testing
    public static void main(String args[]) {
        /*
            The example below requests from the Web Service at:
             http://www.webservicex.net/uszip.asmx?op=GetInfoByCity


            To call other WS, change the parameters below, which are:
             - the SOAP Endpoint URL (that is, where the service is responding from)
             - the SOAP Action

            Also change the contents of the method createSoapEnvelope() in this class. It constructs
             the inner part of the SOAP envelope that is actually sent.
         */
        String soapEndpointUrl = "http://www.webservicex.net/uszip.asmx";
        String soapAction = "http://www.webserviceX.NET/GetInfoByCity";

        callSoapWebService(soapEndpointUrl, soapAction);
    }

    private static void createSoapEnvelope(SOAPMessage soapMessage) throws SOAPException {
        SOAPPart soapPart = soapMessage.getSOAPPart();

        String myNamespace = "myNamespace";
        String myNamespaceURI = "http://www.webserviceX.NET";

        // SOAP Envelope
        SOAPEnvelope envelope = soapPart.getEnvelope();
        envelope.addNamespaceDeclaration(myNamespace, myNamespaceURI);

            /*
            Constructed SOAP Request Message:
            <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:myNamespace="http://www.webserviceX.NET">
                <SOAP-ENV:Header/>
                <SOAP-ENV:Body>
                    <myNamespace:GetInfoByCity>
                        <myNamespace:USCity>New York</myNamespace:USCity>
                    </myNamespace:GetInfoByCity>
                </SOAP-ENV:Body>
            </SOAP-ENV:Envelope>
            */

        // SOAP Body
        SOAPBody soapBody = envelope.getBody();
        SOAPElement soapBodyElem = soapBody.addChildElement("GetInfoByCity", myNamespace);
        SOAPElement soapBodyElem1 = soapBodyElem.addChildElement("USCity", myNamespace);
        soapBodyElem1.addTextNode("New York");
    }

    private static void callSoapWebService(String soapEndpointUrl, String soapAction) {
        try {
            // Create SOAP Connection
            SOAPConnectionFactory soapConnectionFactory = SOAPConnectionFactory.newInstance();
            SOAPConnection soapConnection = soapConnectionFactory.createConnection();

            // Send SOAP Message to SOAP Server
            SOAPMessage soapResponse = soapConnection.call(createSOAPRequest(soapAction), soapEndpointUrl);

            // Print the SOAP Response
            System.out.println("Response SOAP Message:");
            soapResponse.writeTo(System.out);
            System.out.println();

            soapConnection.close();
        } catch (Exception e) {
            System.err.println("\nError occurred while sending SOAP Request to Server!\nMake sure you have the correct endpoint URL and SOAPAction!\n");
            e.printStackTrace();
        }
    }

    private static SOAPMessage createSOAPRequest(String soapAction) throws Exception {
        MessageFactory messageFactory = MessageFactory.newInstance();
        SOAPMessage soapMessage = messageFactory.createMessage();

        createSoapEnvelope(soapMessage);

        MimeHeaders headers = soapMessage.getMimeHeaders();
        headers.addHeader("SOAPAction", soapAction);

        soapMessage.saveChanges();

        /* Print the request message, just for debugging purposes */
        System.out.println("Request SOAP Message:");
        soapMessage.writeTo(System.out);
        System.out.println("\n");

        return soapMessage;
    }

}

当 WSDL 可用时，只需执行两个步骤即可调用该 Web 服务。

步骤 1：从工具生成客户端源WSDL2Java

步骤 2：使用以下命令调用操作：

YourService service = new YourServiceLocator();
Stub stub = service.getYourStub();
stub.operation();

如果进一步查看，您会注意到该类用于调用作为 Web 服务部署在远程位置的服务。调用它时，客户端实际上会生成 SOAP 请求并进行通信。同样，Web 服务将响应作为 SOAP 发送。借助 Wireshark 等工具，您可以查看交换的 SOAP 消息。Stub

但是，由于您已经请求了有关基础知识的更多解释，因此我建议您参考此处并使用其客户端编写Web服务以进一步学习。