From 62b93916f9dddb8b993d3e1c6c479ef817980b76 Mon Sep 17 00:00:00 2001
From: DmitriyMX <dimon550@gmail.com>
Date: Fri, 17 Apr 2020 18:29:46 +0300
Subject: [PATCH] =?UTF-8?q?=D0=B4=D0=BE=D0=B1=D0=B0=D0=B2=D0=BB=D0=B5?=
 =?UTF-8?q?=D0=BD=D1=8B=20=D0=BC=D0=B5=D1=82=D0=BE=D0=B4=D1=8B=20=D0=BF?=
 =?UTF-8?q?=D0=BE=D0=B8=D1=81=D0=BA=D0=B0=20=D0=BF=D0=BE=D0=BB=D0=B5=D0=B9?=
 =?UTF-8?q?=20=D0=BF=D0=BE=20=D0=B0=D0=BD=D0=BD=D0=BE=D1=82=D0=B0=D1=86?=
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---
 .../ru/dmitriymx/reflection/ReflectionField.java   |  5 +++++
 .../ru/dmitriymx/reflection/ReflectionObject.java  | 12 ++++++++++++
 .../dmitriymx/reflection/ReflectionObjectTest.java | 14 ++++++++++++++
 .../ru/dmitriymx/reflection/SomeAnnotation.java    | 12 ++++++++++++
 .../java/ru/dmitriymx/reflection/SomeObject.java   |  2 ++
 5 files changed, 45 insertions(+)
 create mode 100644 src/test/java/ru/dmitriymx/reflection/SomeAnnotation.java

diff --git a/src/main/java/ru/dmitriymx/reflection/ReflectionField.java b/src/main/java/ru/dmitriymx/reflection/ReflectionField.java
index 4eeba2b..fc3c74b 100644
--- a/src/main/java/ru/dmitriymx/reflection/ReflectionField.java
+++ b/src/main/java/ru/dmitriymx/reflection/ReflectionField.java
@@ -2,6 +2,7 @@ package ru.dmitriymx.reflection;
 
 import lombok.EqualsAndHashCode;
 
+import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 
@@ -67,6 +68,10 @@ public class ReflectionField {
         return Modifier.isStatic(field.getModifiers());
     }
 
+    public <T extends Annotation> T annotation(Class<T> annotationType) {
+        return field.getAnnotation(annotationType);
+    }
+
     @Override
     public String toString() {
         return "ReflectionField{" +
diff --git a/src/main/java/ru/dmitriymx/reflection/ReflectionObject.java b/src/main/java/ru/dmitriymx/reflection/ReflectionObject.java
index ded8434..51d01a1 100644
--- a/src/main/java/ru/dmitriymx/reflection/ReflectionObject.java
+++ b/src/main/java/ru/dmitriymx/reflection/ReflectionObject.java
@@ -2,11 +2,14 @@ package ru.dmitriymx.reflection;
 
 import lombok.ToString;
 
+import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 @ToString
 public class ReflectionObject {
@@ -45,6 +48,15 @@ public class ReflectionObject {
         }
     }
 
+    public List<ReflectionField> fieldsWithAnnotation(final Class<? extends Annotation> annotationType) {
+        final Class clazz = object.getClass();
+
+        return Stream.of(clazz.getDeclaredFields())
+                .filter(field -> field.isAnnotationPresent(annotationType))
+                .map(field -> new ReflectionField(object, field))
+                .collect(Collectors.toList());
+    }
+
     public ReflectionField field(String name) {
         final Class clazz = object.getClass();
 
diff --git a/src/test/java/ru/dmitriymx/reflection/ReflectionObjectTest.java b/src/test/java/ru/dmitriymx/reflection/ReflectionObjectTest.java
index 92c36f3..b396217 100644
--- a/src/test/java/ru/dmitriymx/reflection/ReflectionObjectTest.java
+++ b/src/test/java/ru/dmitriymx/reflection/ReflectionObjectTest.java
@@ -86,6 +86,20 @@ public class ReflectionObjectTest {
         ReflectionMethod refSetter = refField.setter();
         assertNotNull(refSetter);
     }
+
+    @Test
+    public void fieldsWithAnnotation() {
+        ReflectionObject refObj = new ReflectionObject(new SomeObject());
+
+        List<ReflectionField> list = refObj.fieldsWithAnnotation(SomeAnnotation.class);
+        assertEquals(1, list.size());
+
+        ReflectionField refField = list.get(0);
+        assertEquals("someIntField", refField.name());
+
+        SomeAnnotation annotation = refField.annotation(SomeAnnotation.class);
+        assertNotNull(annotation);
+    }
     //endregion
 
     //region Method tests
diff --git a/src/test/java/ru/dmitriymx/reflection/SomeAnnotation.java b/src/test/java/ru/dmitriymx/reflection/SomeAnnotation.java
new file mode 100644
index 0000000..1878b16
--- /dev/null
+++ b/src/test/java/ru/dmitriymx/reflection/SomeAnnotation.java
@@ -0,0 +1,12 @@
+package ru.dmitriymx.reflection;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface SomeAnnotation {
+
+}
diff --git a/src/test/java/ru/dmitriymx/reflection/SomeObject.java b/src/test/java/ru/dmitriymx/reflection/SomeObject.java
index 393d390..3becadf 100644
--- a/src/test/java/ru/dmitriymx/reflection/SomeObject.java
+++ b/src/test/java/ru/dmitriymx/reflection/SomeObject.java
@@ -5,6 +5,8 @@ class SomeObject {
     private static final int MAGIC_NUMBER = 33;
     private final String finalizedField = "value123";
     private String simpleField = "defaultValue";
+
+    @SomeAnnotation
     private int someIntField;
 
     public String getSimpleField() {