Package oracle.dbtools.plugin.api.di

Enum AvailableDependencies

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Comparable<AvailableDependencies>
    public enum AvailableDependencies
extends java.lang.Enum<AvailableDependencies>
    Enumerates the publicly available services that can be injected into plugins via the Inject annotation on a type's constructor. Unless otherwise noted these services will always be available.
    Author:
    cdivilly

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description
      ANNOTATIONS
      Provide an API for working with Annotation instances.
      CONFIGURATION
      Provides a Configuration instance appropriate for the backing store that the current request is targeted to.
      CONNECTION
      Provides a Connection connected to the appropriate database pool and schema, inferred from mapping the request URL.
      INSTANCE_LOCATOR
      Provides an API for discovering at run-time the available implementations of a service.
      IO
      Provides IOStreams service for manipulating input and output streams.
      JSON
      Provides access to the JSONStreams service, which can be used to parse character streams into JSON (using JSONReader) and to generate JSON using JSONWriter.
      JSON_OBJECTS
      Provides access to the JSONObjects service, which can be used to build in memory representations of JSON object graphs.
      LOCALE
      Provides the most preferred Locale for a request
      LOCALE_PREFERENCE
      Provides a LocalePreference instance, which enumerates the preferred Locales for a request from most to least preferred.
      LOG
      Provides access to the the JDK Logger service.
      PATH_TEMPLATES
      Provides methods for working with PathTemplateMatch instances

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.annotation.Annotation[] constraints()
      The Annotations that may constrain the scope of the dependency
      java.lang.Class<?> type()
      The type of the dependency
      static AvailableDependencies valueOf​(java.lang.String name)
      Returns the enum constant of this type with the specified name.
      static AvailableDependencies[] values()
      Returns an array containing the constants of this enum type, in the order they are declared.

      • Methods inherited from class java.lang.Enum

        clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait

    • Enum Constant Detail

      • ANNOTATIONS

        public static final AvailableDependencies ANNOTATIONS

        Provide an API for working with Annotation instances. This API may be useful in unit tests to define expected Annotation values.

        Usage

         @Provides
 class SomeTestFixture {
   @Inject
   SomeTestFixture(Annotations annotations) {
     this.expectedNamedAnnotation = annotations.literal(Named.class,"foo");
   }
   ...
 }

      • CONFIGURATION

        public static final AvailableDependencies CONFIGURATION

        Provides a Configuration instance appropriate for the backing store that the current request is targeted to. If this service is called from an ApplicationScoped service, then the global configuration is used.

        Usage

         @Provides
 @Dispatches(@PathTemplate("/some/service"))
 class SomeService extends HttpServlet {
   @Inject
   SomeService(Configuration conf) {
     this.conf = conf;
   }
 
   public void doGet(HttpServletRequest request,
       HttpServletResponse response) throws ServletException, IOException {
     String setting = conf.get(SOME_CONFIG_SETTING);
     response.getWriter()
         .println("The value of the setting is: " + setting);
   }
 
   private final Configuration conf;
 
   private final static String SOME_CONFIG_SETTING = "my.really.important.setting";
 }

        The above example retrieves the value of the setting and displays it in the response.

        N.B. Care must be exercised when working with Configuration instances to ensure that a vector to reveal sensitive configuration data is not created. For example if the value of my.really.important.setting is sensitive, then printing it's value in the response to a GET request is entirely inappropriate and dangerous. Similarly any code that allows an attacker to control over displaying of configuration data in the delivered response is dangerous.

      • CONNECTION

        public static final AvailableDependencies CONNECTION

        Provides a Connection connected to the appropriate database pool and schema, inferred from mapping the request URL. This dependency will only be available during processing of requests that have been mapped to a JDBC backing store.

        Usage

         @Provides
 @Dispatches(@PathTemplate("/some/service"))
 class SomeService extends HttpServlet {
   @Inject
   SomeService(Connection conn) {
     this.conn = conn;
   }
 
   public void doGet(HttpServletRequest request,
       HttpServletResponse response) throws ServletException, IOException {
     PreparedStatement ps = conn.prepareStatement(
         "select sys_context('USERENV','CURRENT_USER') from dual");
     ResultSet rs = ps.execute();
     rs.next();
     String user = rs.getString(1);
     response.getWriter().println("mapped database user is: " + user);
     rs.close();
     ps.close();
   }
 
   private final Connection conn;
 }

        A Connection can only be injected for request URLs where the runtime has been able to the map the URL to a database pool and schema. If the runtime was not able to map the URL to a database/schema, then it will not attempt to dispatch a service that depends on Connection, even if it's URL pattern matches the request URL.

        For example attempting to access the above service at: 

         http://localhost:8080/ords/some/service

        Will result in a 404 Not Found status because the URL does not contain enough information to identify a database/schema to map to.

        By contrast, the following URL: 

         http://localhost:8080/ords/test_schema/some/service

        Will execute correctly assuming a schema named test_schema exists in the default database pool

      • JSON_OBJECTS

        public static final AvailableDependencies JSON_OBJECTS
        Provides access to the JSONObjects service, which can be used to build in memory representations of JSON object graphs.

      • LOCALE

        public static final AvailableDependencies LOCALE
        Provides the most preferred Locale for a request

      • LOCALE_PREFERENCE

        public static final AvailableDependencies LOCALE_PREFERENCE
        Provides a LocalePreference instance, which enumerates the preferred Locales for a request from most to least preferred.

      • LOG

        public static final AvailableDependencies LOG

        Provides access to the the JDK Logger service. All Logging must be done through this service.

        Usage

         @Provides
 class SomeService {
   @Inject
   SomeService(Logger log) {
     this.log = log;
   }
 
   public void someMethod() {
     log.info("doing something");
   }
 
   private final Logger log;
 }

      • PATH_TEMPLATES

        public static final AvailableDependencies PATH_TEMPLATES

        Provides methods for working with PathTemplateMatch instances

        Usage

         @Provides
 class SomeService {
   @Inject
   SomeService(PathTemplates pathTemplates) {
     this.pathTemplates = pathTemplates;
   }
 
   private final PathTemplates pathTemplates;
 }

      • INSTANCE_LOCATOR

        public static final AvailableDependencies INSTANCE_LOCATOR

        Provides an API for discovering at run-time the available implementations of a service. Typically it is preferred to directly inject service implementations via an @Inject annotated constructor, but there are occasional use cases where it can be useful to locate dependencies dynamically at run-time. For example it may be necessary to discover if a given dependency is available or has multiple providers.

        Usage of this API should be limited as overuse implies reliance on the Service Locator Pattern rather than the Dependency Injection Pattern.

        Usage

         @Provides
 class SomeService {
   @Inject
   SomeService(InstanceLocator locator) {
     boolean widgetAvailable = !locator.select(Widget.class)
         .isUnsatisfied();
   }
 
   public void someMethod() {
     if (widgetAvailable) {
       // go down the preferred code path
     } else {
       // go down a fallback code path
     }
   }
 }

    • Method Detail

      • values

        public static AvailableDependencies[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: 
        for (AvailableDependencies c : AvailableDependencies.values())
    System.out.println(c);
        Returns:
        an array containing the constants of this enum type, in the order they are declared

      • valueOf

        public static AvailableDependencies valueOf​(java.lang.String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        java.lang.IllegalArgumentException - if this enum type has no constant with the specified name
        java.lang.NullPointerException - if the argument is null

      • constraints

        public java.lang.annotation.Annotation[] constraints()
        The Annotations that may constrain the scope of the dependency
        Returns:
        Annotations that the depedency must be matche against

      • type

        public java.lang.Class<?> type()
        The type of the dependency
        Returns:
        dependency type