Merge pull request #10743 from tirumani03/dev/tirumani03/findingClassesInPackage

[BAEL-4279] Finding All Classes in a Java Package

core-java-modules/core-java-reflection-2/pom.xml

@@ -22,6 +22,16 @@
             <version>${spring.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.reflections</groupId>
+            <artifactId>reflections</artifactId>
+            <version>0.9.12</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>30.1.1-jre</version>
+        </dependency>
     </dependencies>
 
     <build>

core-java-modules/core-java-reflection-2/src/main/java/com/baeldung/reflection/access/packages/AccessingAllClassesInPackage.java

@@ -0,0 +1,58 @@
+package com.baeldung.reflection.access.packages;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.reflections.Reflections;
+import org.reflections.scanners.SubTypesScanner;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.reflect.ClassPath;
+
+@SuppressWarnings("rawtypes")
+public class AccessingAllClassesInPackage {
+
+    private static final Logger LOG = LoggerFactory.getLogger(AccessingAllClassesInPackage.class);
+
+    public Set<Class> findAllClassesUsingClassLoader(String packageName) {
+        InputStream stream = ClassLoader.getSystemClassLoader()
+            .getResourceAsStream(packageName.replaceAll("[.]", "/"));
+        BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
+        return reader.lines()
+            .filter(line -> line.endsWith(".class"))
+            .map(line -> getClass(line, packageName))
+            .collect(Collectors.toSet());
+    }
+
+    private Class getClass(String className, String packageName) {
+        try {
+            return Class.forName(packageName + "." + className.substring(0, className.lastIndexOf('.')));
+        } catch (ClassNotFoundException e) {
+            LOG.error("<<Class not found>>");
+        }
+        return null;
+    }
+
+    public Set<Class> findAllClassesUsingReflectionsLibrary(String packageName) {
+        Reflections reflections = new Reflections(packageName, new SubTypesScanner(false));
+        return reflections.getSubTypesOf(Object.class)
+            .stream()
+            .collect(Collectors.toSet());
+    }
+
+    public Set<Class> findAllClassesUsingGoogleGuice(String packageName) throws IOException {
+        return ClassPath.from(ClassLoader.getSystemClassLoader())
+            .getAllClasses()
+            .stream()
+            .filter(clazz -> clazz.getPackageName()
+                .equalsIgnoreCase(packageName))
+            .map(clazz -> clazz.load())
+            .collect(Collectors.toSet());
+    }
+
+}

core-java-modules/core-java-reflection-2/src/main/java/com/baeldung/reflection/access/packages/search/ClassExample.java

@@ -0,0 +1,6 @@
+package com.baeldung.reflection.access.packages.search;
+
+public class ClassExample {
+    class NestedClassExample {
+    }
+}

core-java-modules/core-java-reflection-2/src/main/java/com/baeldung/reflection/access/packages/search/InterfaceExample.java

@@ -0,0 +1,4 @@
+package com.baeldung.reflection.access.packages.search;
+
+public interface InterfaceExample {
+}

core-java-modules/core-java-reflection-2/src/main/java/com/baeldung/reflection/access/packages/search/Searchable.java

@@ -0,0 +1,5 @@
+package com.baeldung.reflection.access.packages.search;
+
+public @interface Searchable {
+
+}

core-java-modules/core-java-reflection-2/src/main/java/com/baeldung/reflection/access/packages/search/package-info.java

@@ -0,0 +1,2 @@
+@Searchable
+package com.baeldung.reflection.access.packages.search;

core-java-modules/core-java-reflection-2/src/test/java/com/baeldung/reflection/access/packages/AccessingAllClassesInPackageUnitTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.reflection.access.packages;
+
+import java.io.IOException;
+import java.util.Set;
+
+import org.junit.Rule;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.rules.ExpectedException;
+
+@SuppressWarnings("rawtypes")
+public class AccessingAllClassesInPackageUnitTest {
+    @Rule
+    public final ExpectedException exception = ExpectedException.none();
+
+    private static final String PACKAGE_NAME = "com.baeldung.reflection.access.packages.search";
+
+    @Test
+    public void when_findAllClassesUsingClassLoader_thenSuccess() {
+        AccessingAllClassesInPackage instance = new AccessingAllClassesInPackage();
+        Set<Class> classes = instance.findAllClassesUsingClassLoader(PACKAGE_NAME);
+        Assertions.assertEquals(5, classes.size());
+    }
+
+    @Test
+    public void when_findAllClassesUsingReflectionsLibrary_thenSuccess() {
+        AccessingAllClassesInPackage instance = new AccessingAllClassesInPackage();
+        Set<Class> classes = instance.findAllClassesUsingReflectionsLibrary(PACKAGE_NAME);
+        Assertions.assertEquals(5, classes.size());
+    }
+
+    @Test
+    public void when_findAllClassesUsingGoogleGuice_thenSuccess() throws IOException {
+        AccessingAllClassesInPackage instance = new AccessingAllClassesInPackage();
+        Set<Class> classes = instance.findAllClassesUsingGoogleGuice(PACKAGE_NAME);
+        Assertions.assertEquals(5, classes.size());
+    }
+
+}