feat(spanner): add jdbc support for external hosts

Author: sagnghos

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java

@@ -628,11 +628,15 @@ private Builder() {}
     public static final String SPANNER_URI_FORMAT =
         "(?:cloudspanner:)(?<HOSTGROUP>//[\\w.-]+(?:\\.[\\w\\.-]+)*[\\w\\-\\._~:/?#\\[\\]@!\\$&'\\(\\)\\*\\+,;=.]+)?/projects/(?<PROJECTGROUP>(([a-z]|[-.:]|[0-9])+|(DEFAULT_PROJECT_ID)))(/instances/(?<INSTANCEGROUP>([a-z]|[-]|[0-9])+)(/databases/(?<DATABASEGROUP>([a-z]|[-]|[_]|[0-9])+))?)?(?:[?|;].*)?";
 
+    public static final String EXTERNAL_HOST_FORMAT =
+        "(?:cloudspanner:)(?<HOSTGROUP>//[\\w.-]+(?::\\d+)?)(/instances/(?<INSTANCEGROUP>[a-z0-9-]+))?(/databases/(?<DATABASEGROUP>[a-z0-9_-]+))(?:[?;].*)?";
     private static final String SPANNER_URI_REGEX = "(?is)^" + SPANNER_URI_FORMAT + "$";
 
     @VisibleForTesting
     static final Pattern SPANNER_URI_PATTERN = Pattern.compile(SPANNER_URI_REGEX);
 
+    static final Pattern EXTERNAL_HOST_PATTERN = Pattern.compile(EXTERNAL_HOST_FORMAT);
+
     private static final String HOST_GROUP = "HOSTGROUP";
     private static final String PROJECT_GROUP = "PROJECTGROUP";
     private static final String INSTANCE_GROUP = "INSTANCEGROUP";
@@ -643,6 +647,10 @@ private boolean isValidUri(String uri) {
       return SPANNER_URI_PATTERN.matcher(uri).matches();
     }
 
+    private boolean isValidExternalHostUri(String uri) {
+      return EXTERNAL_HOST_PATTERN.matcher(uri).matches();
+    }
+
     /**
      * Sets the URI of the Cloud Spanner database to connect to. A connection URI must be specified
      * in this format:
@@ -700,9 +708,11 @@ private boolean isValidUri(String uri) {
      * @return this builder
      */
     public Builder setUri(String uri) {
-      Preconditions.checkArgument(
-          isValidUri(uri),
-          "The specified URI is not a valid Cloud Spanner connection URI. Please specify a URI in the format \"cloudspanner:[//host[:port]]/projects/project-id[/instances/instance-id[/databases/database-name]][\\?property-name=property-value[;property-name=property-value]*]?\"");
+      if (!isValidExternalHostUri(uri)) {
+        Preconditions.checkArgument(
+            isValidUri(uri),
+            "The specified URI is not a valid Cloud Spanner connection URI. Please specify a URI in the format \"cloudspanner:[//host[:port]]/projects/project-id[/instances/instance-id[/databases/database-name]][\\?property-name=property-value[;property-name=property-value]*]?\"");
+      }
       ConnectionPropertyValue<Boolean> value =
           cast(ConnectionProperties.parseValues(uri).get(LENIENT.getKey()));
       checkValidProperties(value != null && value.getValue(), uri);
@@ -829,7 +839,14 @@ public static Builder newBuilder() {
   private final SpannerOptionsConfigurator configurator;
 
   private ConnectionOptions(Builder builder) {
-    Matcher matcher = Builder.SPANNER_URI_PATTERN.matcher(builder.uri);
+    Matcher matcher;
+    boolean isExternalHost = false;
+    if (builder.isValidExternalHostUri(builder.uri)) {
+      matcher = Builder.EXTERNAL_HOST_PATTERN.matcher(builder.uri);
+      isExternalHost = true;
+    } else {
+      matcher = Builder.SPANNER_URI_PATTERN.matcher(builder.uri);
+    }
     Preconditions.checkArgument(
         matcher.find(), String.format("Invalid connection URI specified: %s", builder.uri));
 
@@ -947,12 +964,18 @@ && getInitialConnectionPropertyValue(OAUTH_TOKEN) == null
       this.sessionPoolOptions = SessionPoolOptions.newBuilder().setAutoDetectDialect(true).build();
     }
 
-    String projectId = matcher.group(Builder.PROJECT_GROUP);
+    String projectId = "default";
+    String instanceId = matcher.group(Builder.INSTANCE_GROUP);
+    if (!isExternalHost) {
+      projectId = matcher.group(Builder.PROJECT_GROUP);
+    } else if (instanceId == null) {
+      instanceId = "default";
+    }
     if (Builder.DEFAULT_PROJECT_ID_PLACEHOLDER.equalsIgnoreCase(projectId)) {
       projectId = getDefaultProjectId(this.credentials);
     }
     this.projectId = projectId;
-    this.instanceId = matcher.group(Builder.INSTANCE_GROUP);
+    this.instanceId = instanceId;
     this.databaseName = matcher.group(Builder.DATABASE_GROUP);
   }