Java reflection api (#18738)

* BAEL-9216 - Java Reflection Beans Property API

* BAEL-9216 - Java Reflection Beans Property API

* BAEL-9216 - Java Reflection Beans Property API

Author: Alexandru-Borza

core-java-modules/core-java-reflection-3/pom.xml

@@ -30,6 +30,11 @@
             <artifactId>reflections</artifactId>
             <version>${reflections.version}</version>
         </dependency>
+        <dependency>
+            <groupId>commons-beanutils</groupId>
+            <artifactId>commons-beanutils</artifactId>
+            <version>1.11.0</version>
+        </dependency>
     </dependencies>
 
     <build>

core-java-modules/core-java-reflection-3/src/main/java/com/baeldung/reflectionbeans/BeanUtilsDemo.java

@@ -0,0 +1,36 @@
+package com.baeldung.reflectionbeans;
+
+import org.apache.commons.beanutils.BeanUtils;
+
+import java.util.Map;
+
+public class BeanUtilsDemo {
+
+    public static void main(String[] args) throws Exception {
+        Post post = new Post();
+        BeanUtils.setProperty(post, "title", "Commons BeanUtils Rocks");
+        String title = BeanUtils.getProperty(post, "title");
+
+        Map<String, Object> data = Map.of(
+                "title", "Map → Bean",
+                "author", "Baeldung Team"
+        );
+
+        BeanUtils.populate(post, data);
+        Post source = new Post();
+        source.setTitle("Source");
+        source.setAuthor("Alice");
+
+        Post target = new Post();
+        BeanUtils.copyProperties(target, source);
+        System.out.println(title);
+    }
+
+    public static void safeCopy(Object target, Object source) {
+        try {
+            BeanUtils.copyProperties(target, source);
+        } catch (ReflectiveOperationException ex) {
+            throw new IllegalStateException(ex);
+        }
+    }
+}

core-java-modules/core-java-reflection-3/src/main/java/com/baeldung/reflectionbeans/Post.java

@@ -0,0 +1,13 @@
+package com.baeldung.reflectionbeans;
+
+public class Post {
+
+    private String title;
+    private String author;
+
+    public String getTitle() { return title; }
+    public void setTitle(String title) { this.title = title; }
+
+    public String getAuthor() { return author; }
+    public void setAuthor(String author) { this.author = author; }
+}

core-java-modules/core-java-reflection-3/src/main/java/com/baeldung/reflectionbeans/PropertyDescriptorDemo.java

@@ -0,0 +1,29 @@
+package com.baeldung.reflectionbeans;
+
+import java.beans.BeanInfo;
+import java.beans.Introspector;
+import java.beans.PropertyDescriptor;
+import java.lang.reflect.Method;
+
+public class PropertyDescriptorDemo {
+
+    public static void main(String[] args) throws Exception {
+        BeanInfo beanInfo = Introspector.getBeanInfo(Post.class);
+
+        for (PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) {
+            System.out.println(pd.getName());
+        }
+
+        Post post = new Post();
+        PropertyDescriptor titlePd = new PropertyDescriptor("title", Post.class);
+
+        Method write = titlePd.getWriteMethod();
+        Method read = titlePd.getReadMethod();
+
+
+        write.invoke(post, "Reflections in Java");
+        String value = (String) read.invoke(post);
+
+        System.out.println(value);
+    }
+}

core-java-modules/core-java-reflection-3/src/test/java/com/baeldung/reflectionbeans/BeanUtilsUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.reflectionbeans;
+
+import org.apache.commons.beanutils.BeanUtils;
+import org.junit.Test;
+
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+public class BeanUtilsUnitTest {
+
+    @Test
+    public void givenPost_whenPopulate_thenFieldsAreSet() throws Exception {
+        Post post = new Post();
+        Map<String, Object> data = Map.of("title", "Populate Test", "author", "Dana");
+
+        BeanUtils.populate(post, data);
+
+        assertEquals("Populate Test", BeanUtils.getProperty(post, "title"));
+        assertEquals("Dana", BeanUtils.getProperty(post, "author"));
+    }
+
+    @Test
+    public void givenTwoPosts_whenCopyProperties_thenTargetMatchesSource() throws Exception {
+        Post source = new Post();
+        source.setTitle("Copy");
+        source.setAuthor("Eve");
+
+        Post target = new Post();
+        BeanUtils.copyProperties(target, source);
+
+        assertEquals("Copy", target.getTitle());
+        assertEquals("Eve", target.getAuthor());
+    }
+}
+

core-java-modules/core-java-reflection-3/src/test/java/com/baeldung/reflectionbeans/PropertyDescriptorUnitTest.java

@@ -0,0 +1,19 @@
+package com.baeldung.reflectionbeans;
+
+import org.junit.Test;
+
+import java.beans.PropertyDescriptor;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class PropertyDescriptorUnitTest {
+
+    @Test
+    public void givenPost_whenUsingPropertyDescriptor_thenReadAndWrite() throws Exception {
+        Post post = new Post();
+        PropertyDescriptor pd = new PropertyDescriptor("author", Post.class);
+
+        pd.getWriteMethod().invoke(post, "Chris");
+        assertEquals("Chris", pd.getReadMethod().invoke(post));
+    }
+}