Add default proxy settings from System proerties

Aether apparently doesn't use the java.net.* APIs for
TCP connections so it doesn't notice when a user sets
-Dhttp.Proxy*. To fix it is painful, and leads me to
suspect that actually we might want to parse a
settings.xml at some point (however unpalatable that
is).

For now I have added a Proxy to all RemoteRepository
instances that we create in the CLI if the user
has set -Dhttp.proxyHost (and/or -Dhttps.proxyHost for
a secure repository).

TODO: authentication. Is there a standard way to specify
that globally via system properties.

TODO: maybe use per-repository settings if provided
(e.g. in settings.xml).

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/GroovyCompiler.java

@@ -140,7 +140,8 @@ public class GroovyCompiler {
 						RepositoryPolicy.UPDATE_POLICY_NEVER,
 						RepositoryPolicy.CHECKSUM_POLICY_IGNORE));
 			}
-
+			builder.setProxy(AetherGrapeEngine.defaultProxy(repositoryConfiguration
+					.getUri().getScheme()));
 			repositories.add(builder.build());
 		}
 		return repositories;

spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/AetherGrapeEngine.java

@@ -42,6 +42,7 @@ import org.eclipse.aether.impl.DefaultServiceLocator;
 import org.eclipse.aether.internal.impl.DefaultRepositorySystem;
 import org.eclipse.aether.repository.LocalRepository;
 import org.eclipse.aether.repository.LocalRepositoryManager;
+import org.eclipse.aether.repository.Proxy;
 import org.eclipse.aether.repository.RemoteRepository;
 import org.eclipse.aether.resolution.ArtifactResolutionException;
 import org.eclipse.aether.resolution.ArtifactResult;
@@ -94,6 +95,33 @@ public class AetherGrapeEngine implements GrapeEngine {
 		this.progressReporter = getProgressReporter(session);
 	}
 
+	public static Proxy defaultProxy(String protocol) {
+		// TODO: proxy authentication
+		if ("http".equals(protocol) || "dav".equals(protocol)) {
+			String proxyHost = System.getProperty("http.proxyHost");
+			if (proxyHost != null) {
+				// Use defaults from normal JVM proxy handler
+				return new Proxy("http", proxyHost, new Integer(System.getProperty(
+						"http.proxyPort", "80")));
+			}
+		}
+		else if ("https".equals(protocol) || "davs".equals(protocol)) {
+			String secureProxyHost = System.getProperty("https.proxyHost");
+			if (secureProxyHost != null) {
+				return new Proxy("https", secureProxyHost, new Integer(
+						System.getProperty("https.proxyPort", "443")));
+			}
+		}
+		else if ("ftp".equals(protocol)) {
+			String secureProxyHost = System.getProperty("ftp.proxyHost");
+			if (secureProxyHost != null) {
+				return new Proxy("ftp", secureProxyHost, new Integer(System.getProperty(
+						"ftp.proxyPort", "443")));
+			}
+		}
+		return null;
+	}
+
 	private ServiceLocator createServiceLocator() {
 		DefaultServiceLocator locator = MavenRepositorySystemUtils.newServiceLocator();
 		locator.addService(RepositorySystem.class, DefaultRepositorySystem.class);
@@ -245,9 +273,13 @@ public class AetherGrapeEngine implements GrapeEngine {
 	public void addResolver(Map<String, Object> args) {
 		String name = (String) args.get("name");
 		String root = (String) args.get("root");
+		RemoteRepository.Builder builder = new RemoteRepository.Builder(name, "default",
+				root);
+		String protocol = root.contains(":") ? root.substring(0, root.indexOf(":"))
+				: "none";
+		builder.setProxy(AetherGrapeEngine.defaultProxy(protocol));
 
-		this.repositories
-				.add(new RemoteRepository.Builder(name, "default", root).build());
+		this.repositories.add(builder.build());
 	}
 
 	@Override