如何使用SAP云平台 + JNDI访问Internet Service

如何使用SAP云平台 + JNDI访问Internet Service，针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。

以Internet Service http://maps.googleapis.com/maps/api/distancematrix/xml?origins=Walldorf&destinations=Berlin为例，

在浏览器里访问这个url，得到输出：从Walldorf到Berlin的距离。

如何让一个部署到SAP云平台的Java应用也能访问到该internet service呢？

首先在SAP云平台里创建一个destination，维护service的end point：

在Java代码里使用SAP云平台里创建的destination：

然后使用JNDI service读取destination里配置的url：

部署到SAP云平台之后，在Eclipse里看到preview结果：

SAP云平台Cockpit显示如下：

浏览器访问如下：

web.xml:

    ConnectivityServlet com.sap.cloud.sample.connectivity.ConnectivityServlet   ConnectivityServlet /    connectivityConfiguration com.sap.core.connectivity.api.configuration.ConnectivityConfiguration  

package com.sap.cloud.sample.connectivity; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.InetSocketAddress; import java.net.Proxy; import java.net.URL; import javax.annotation.Resource; import javax.naming.Context; import javax.naming.InitialContext; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.sap.cloud.account.TenantContext; import com.sap.core.connectivity.api.configuration.ConnectivityConfiguration; import com.sap.core.connectivity.api.configuration.DestinationConfiguration; public class ConnectivityServlet extends HttpServlet { @Resource private TenantContext  tenantContext; private static final long serialVersionUID = 1L; private static final int COPY_CONTENT_BUFFER_SIZE = 1024; private static final Logger LOGGER = LoggerFactory.getLogger(ConnectivityServlet.class); private static final String ON_PREMISE_PROXY = "OnPremise"; @Override public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        HttpURLConnection urlConnection = null;        String destinationName = request.getParameter("destname"); if (destinationName == null) {            destinationName = "google_map";        } try {            Context ctx = new InitialContext();            ConnectivityConfiguration configuration = (ConnectivityConfiguration) ctx.lookup("java:comp/env/connectivityConfiguration");            DestinationConfiguration destConfiguration = configuration.getConfiguration(destinationName); if (destConfiguration == null) {                response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,                        String.format("Destination %s is not found. Hint:" + " Make sure to have the destination configured.", destinationName)); return;            }            String value = destConfiguration.getProperty("URL");            URL url = new URL(value + "xml?origins=Walldorf&destinations=Paris");            String proxyType = destConfiguration.getProperty("ProxyType");            Proxy proxy = getProxy(proxyType);            urlConnection = (HttpURLConnection) url.openConnection(proxy);            injectHeader(urlConnection, proxyType);            InputStream instream = urlConnection.getInputStream();            OutputStream outstream = response.getOutputStream();            copyStream(instream, outstream);        } catch (Exception e) {            String errorMessage = "Connectivity operation failed with reason: " + e.getMessage()                    + ". See " + "logs for details. Hint: Make sure to have an HTTP proxy configured in your " + "local environment in case your environment uses " + "an HTTP proxy for the outbound Internet " + "communication.";            LOGGER.error("Connectivity operation failed", e);            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,                    errorMessage);        }    } private Proxy getProxy(String proxyType) {        Proxy proxy = Proxy.NO_PROXY;        String proxyHost = null;        String proxyPort = null; if (ON_PREMISE_PROXY.equals(proxyType)) { // Get proxy for on-premise destinations proxyHost = System.getenv("HC_OP_HTTP_PROXY_HOST");            proxyPort = System.getenv("HC_OP_HTTP_PROXY_PORT");        } else { // Get proxy for internet destinations proxyHost = System.getProperty("https.proxyHost");            proxyPort = System.getProperty("https.proxyPort");        } if (proxyPort != null && proxyHost != null) { int proxyPortNumber = Integer.parseInt(proxyPort);            proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyHost, proxyPortNumber));        } return proxy;    } private void injectHeader(HttpURLConnection urlConnection, String proxyType) { if (ON_PREMISE_PROXY.equals(proxyType)) { // Insert header for on-premise connectivity with the consumer account name urlConnection.setRequestProperty("SAP-Connectivity-ConsumerAccount",                    tenantContext.getTenant().getAccount().getId());        }    } private void copyStream(InputStream inStream, OutputStream outStream) throws IOException { byte[] buffer = new byte[COPY_CONTENT_BUFFER_SIZE]; int len; while ((len = inStream.read(buffer)) != -1) {            outStream.write(buffer, 0, len);        }    }}

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