org.fest.reflect.field
Class Invoker<T>

java.lang.Object
  org.fest.reflect.field.Invoker<T>

Type Parameters:

T - the declared type for the field to access.

public final class Invoker<T>
extends Object

Understands the use of reflection to access a field from an object.

The following is an example of proper usage of this class:

   // Retrieves the value of the field "name"
   String name = field("name").ofType(String.class).in(person).get();
 
   // Sets the value of the field "name" to "Yoda"
   field("name").ofType(String.class).in(person).set("Yoda");
 
   // Retrieves the value of the static field "count"
   int count = staticField("count").ofType(int.class).in(Person.class).get();
 
   // Sets the value of the static field "count" to 3
   field("count").ofType(int.class).in(Person.class).set(3);
 

Author:

Alex Ruiz, Ivan Hristov

Method Summary

T	get() Returns the value of the field managed by this class.
Field	info() Returns the "real" field managed by this class.
DecoratedInvoker<T>	postDecorateWith(T decorator) Post-decorates a targeted object's methods.
DecoratedInvoker<T>	preDecorateWith(T decorator) Pre-decorates a targeted object's methods.
void	set(T value) Sets a value in the field managed by this class.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

set

public void set(T value)

Sets a value in the field managed by this class.

Parameters:

value - the value to set.

Throws:

ReflectionError - if the given value cannot be set.

preDecorateWith

public DecoratedInvoker<T> preDecorateWith(T decorator)

Pre-decorates a targeted object's methods.

Each execution of a targeted object's method will be first performed on the same method of the decorator object. The result (if any) from the invocation of the targeted object's method will be returned but you can choose to return the decorator result if you want to.

Be aware:

The type of a targeted object should be an interface for this functionality to work

Any exception caused by an invocation of a decorator object's method will result in disrupting the default program's flow

Example: Assuming we have the following code:

 interface IUploadFileService { 
   boolean upload(String file, String destination); 
 }
 
 public class FileManager {
     
   private IUploadFileService uploadFileService;
   private static final String DEFAULT_DESTINATION = "http://example.org/default/destination/";
 
   public void manage(String fileName) {
     if( uploadFileService.upload(fileName, DEFAULT_DESTINATION) ) {
       System.out.println("File "+fileName+" sent to "+DEFAULT_DESTINATION);
     } else {
       System.out.println("Unable to sent "+fileName+" to "+DEFAULT_DESTINATION);
     } 
   }
 }
 

Let's say we want to decorate the uploadFileService.upload(...) part, so that additional functionality is executed before the actual uploadFileService.upload(...) logic, the following code will do the job:

 IUploadFileService uploadFileServiceDecorator = ...; 
 FileManager fileManager = new FileManager();
 
 field("uploadFileService").ofType(IUploadFileService.class)
                           .in(fileManager)
                           .preDecorateWith(uploadFileServiceDecorator);
 

However, if there is an exception when calling uploadFileServiceDecorator.upload(fileName, DEFAULT_DESTINATION) the default program's flow will be interrupted and the uploadFileService.upload(fileName, DEFAULT_DESTINATION) will not be executed.

Parameters:

decorator - which methods be called before the same targeted object methods

Returns:

the DecoratedInvoker pre decorating the target field interface with given decorator.

postDecorateWith

public DecoratedInvoker<T> postDecorateWith(T decorator)

Post-decorates a targeted object's methods.

After each execution of a targeted object's method, the same method of the decorator object will be called. The result (if any) from the invocation of the targeted object's method will be returned but you can choose to return the decorator result if you want to.

Be aware:

The type of a targeted object should be an interface for this functionality to work

Any exception caused by an invocation of a decorator object's method will result in disrupting the default program's flow

Example: Assuming we have the following code:

 interface IUploadFileService { 
   boolean upload(String file, String destination); 
 }
 
 public class FileManager {
     
   private IUploadFileService uploadFileService;
   private static final String DEFAULT_DESTINATION = "http://example.org/default/destination/";
 
   public void manage(String fileName) {
     if( uploadFileService.upload(fileName, DEFAULT_DESTINATION) ) {
       System.out.println("File "+fileName+" sent to "+DEFAULT_DESTINATION);
     } else {
       System.out.println("Unable to sent "+fileName+" to "+DEFAULT_DESTINATION);
     } 
   }
 }
 

Let's say we want to decorate the uploadFileService.upload(...) part, so that additional functionality is executed before the actual uploadFileService.upload(...) logic, the following code will do the job:

 IUploadFileService uploadFileServiceDecorator = ...; 
 FileManager fileManager = new FileManager();
 
 field("uploadFileService").ofType(IUploadFileService.class)
                           .in(fileManager)
                           .postDecorateWith(uploadFileServiceDecorator);
 

However, if there is an exception when calling uploadFileServiceDecorator.upload(fileName, DEFAULT_DESTINATION) the default program's flow will be interrupted and the uploadFileService.upload(fileName, DEFAULT_DESTINATION) will not be executed.

Parameters:

decorator - which methods be called after the same targeted object methods

Returns:

the DecoratedInvoker post decorating the target field interface with given decorator.

get

public T get()

Returns the value of the field managed by this class.

Returns:

the value of the field managed by this class.

Throws:

ReflectionError - if the value of the field cannot be retrieved.

info

public Field info()

Returns the "real" field managed by this class.

Returns:

the "real" field managed by this class.