JSP如何调用Web服务

在JSP中调用Web服务，可以使用多种方法。这里，我将向您展示如何使用java.net.HttpURLConnection和javax.xml.ws.handler.MessageContext来实现这一目标。

方法1：使用java.net.HttpURLConnection

<%@ page import="java.io.BufferedReader" %>
<%@ page import="java.io.InputStreamReader" %>
<%@ page import="java.net.HttpURLConnection" %>
<%@ page import="java.net.URL" %>

<%
    try {
        // 替换为您的Web服务URL
        String webServiceUrl = "https://example.com/webservice";
        URL url = new URL(webServiceUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        connection.setRequestProperty("Content-Type", "application/json; utf-8");
        connection.setRequestProperty("Accept", "application/json");
        connection.setDoOutput(true);

        int responseCode = connection.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String inputLine;
            StringBuilder response = new StringBuilder();

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            in.close();

            // 输出响应
            out.println("Response: " + response.toString());
        } else {
            out.println("GET request failed");
        }
    } catch (Exception e) {
        e.printStackTrace();
        out.println("Error: " + e.getMessage());
    }
%>

方法2：使用javax.xml.ws.handler.MessageContext

首先，您需要生成Web服务的客户端代理类。您可以使用Apache CXF、JAX-WS或Eclipse IDE等工具生成客户端代码。这里假设您已经生成了名为MyWebServiceService的服务接口和MyWebService的服务实现类。

<%@ page import="javax.xml.ws.BindingProvider" %>
<%@ page import="com.example.MyWebServiceService" %>
<%@ page import="com.example.MyWebService" %>

<%
    try {
        // 创建Web服务客户端代理
        MyWebServiceService service = new MyWebServiceService();
        MyWebService port = service.getMyWebServicePort();

        // 设置请求上下文
        BindingProvider bindingProvider = (BindingProvider) port;
        MessageContext messageContext = bindingProvider.getRequestContext();
        messageContext.put("http.request.headers", Collections.singletonMap("Content-Type", Collections.singletonList("application/json")));

        // 调用Web服务方法
        String response = port.myWebServiceMethod();

        // 输出响应
        out.println("Response: " + response);
    } catch (Exception e) {
        e.printStackTrace();
        out.println("Error: " + e.getMessage());
    }
%>

请注意，这些示例仅用于演示目的。在实际应用中，您可能需要根据具体需求对代码进行调整。