使用SAP云平台 + JNDI访问Internet Service

摘要：以，在浏览器里访问这个，得到输出从到的距离。如何让一个部署到云平台的应用也能访问到该呢首先在云平台里创建一个，维护的在代码里使用云平台里创建的然后使用读取里配置的部署到云平台之后，在里看到结果云平台显示如下浏览器访问如下

以Internet Service http://maps.googleapis.com/ma...，

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);
        }
    }
}