AdapterDefinition (Carbonado 1.2.3 API)

+
+

@Documented
+@Retention(value=RUNTIME)
+@Target(value=ANNOTATION_TYPE)
+public @interface AdapterDefinition

Allows annotations to be defined for supporting property types which are not + natively supported by the underlying storage layer. Repositories must always + attempt to match property types to the best matching native type, but they + may have to rely on an adapter to make a conversion. + +

The annotation is just a pointer to an adapter implementation class. If + the adapter class is not explicitly provided, it defaults to a static inner + class named "Adapter" in the annotation itself. + +

The adapter class must have a public constructor that accepts the + annotation that has the AdapterDefinition annotation. It must also define + several adapt methods which convert property values. An adapt method needs + to start with "adapt", accept one parameter and return something. +

+ Example true/false adapter for booleans: +

+ @Documented
+ @Retention(RetentionPolicy.RUNTIME)
+ @Target(ElementType.METHOD)
+ @AdapterDefinition
+ public @interface TrueFalseAdapter {
+
+     public static class Adapter {
+         private final String propertyName;
+
+         // Constructor may throw a MalformedTypeException if
+         // params supplied by annotation are illegal.
+
+         /**
+          * @param type optional type of object that contains the adapted property
+          * @param propertyName name of property with adapter
+          * @param annotation specific annotation that binds to this adapter class
+          */
+         public Adapter(Class type, String propertyName, TrueFalseAdapter annotation) {
+             this.propertyName = propertyName;
+         }
+
+         // Define at least two adapt methods for each supported property type.
+
+         /**
+          * @param propertyValue value to convert from
+          */
+         public char adaptToChar(boolean propertyValue) {
+             return value ? 'T' : 'F';
+         }
+
+         /**
+          * @param propertyValue value to convert from
+          */
+         public boolean adaptToBoolean(char propertyValue) {
+             if (propertyValue == 'T') { return true; };
+             if (propertyValue == 'F') { return false; };
+             throw new IllegalArgumentException
+                 ("Cannot adapt '" + value + "' into boolean for property \"" +
+                   propertyName + '"');
+         }
+     }
+ }
+

+ + The newly defined adapter can be applied to property accessors. + +

+ public interface UserInfo extends Storable {
+     @TrueFalseAdapter
+     boolean isAdministrator();
+     void setAdministrator(boolean admin);
+ }
+

Author:: Brian S O'Neill

+ +

+ + +

Optional Element Summary

+ + + + + + + + + + + + + + +

Optional Elements
Modifier and Type	Optional Element and Description
`java.lang.Class`	`implementation` + Specify class which will perform property adaptation. +
`java.lang.Class[]`	`storageTypePreferences` + Optionally specify the set of preferred storage types for storing the + adapted property, in order of most preferred to least preferred. +

+ +
- + + +
  Element Detail
  + + + +
  - +
    implementation
    +
```
public abstract java.lang.Class implementation
```
    +
    Specify class which will perform property adaptation. Must have a public + constructor with the signature + (Class type, String propertyName, Annotation), + where Annotation refers to the annotation with the + adapter definition. + +
    The implementation class need not be explicitly specified. By + default, the adapter class must be a static inner class of the + annotation, named "Adapter".
    +
    +
    Default:
    +
    void.class
    +
    +
  + + + +
  - +
    storageTypePreferences
    +
```
public abstract java.lang.Class[] storageTypePreferences
```
    +
    Optionally specify the set of preferred storage types for storing the + adapted property, in order of most preferred to least preferred. A type + in the set must be supported by the adapt methods to be considered. + +
    If the repository is independent, it needs help on deciding exactly + how to store the adapted property. A dependent repository will not have + as much flexibility in selecting an appropriate type, but it may still + need a hint.
    +
    +
    Default:
    +
    {}
    +
    +
  +
+

Annotation Type AdapterDefinition

Optional Element Summary

Element Detail

implementation

storageTypePreferences