ahucoder · ahucoder · Jun 6, 2025 · Jun 6, 2025
diff --git a/pom.xml b/pom.xml
@@ -14,24 +14,28 @@
         <maven.compiler.release>21</maven.compiler.release>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <junit.version>5.8.2</junit.version>
+        <lombok.version>1.18.36</lombok.version>
+        <spring-boot-starter-web.version>3.4.5</spring-boot-starter-web.version>
+        <guava.version>33.4.0-jre</guava.version>
+        <commons-lang3.version>3.12.0</commons-lang3.version>
     </properties>
 
     <dependencies>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
-            <version>1.18.36</version>
+            <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
-            <version>3.4.5</version>
+            <version>${spring-boot-starter-web.version}</version>
         </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
-            <version>33.4.0-jre</version>
+            <version>${guava.version}</version>
         </dependency>
         <!-- JUnit 5 -->
         <dependency>
@@ -49,7 +53,7 @@
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
-            <version>3.12.0</version>
+            <version>${commons-lang3.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>

diff --git a/src/main/java/proxy/dynamicproxy/App.java b/src/main/java/proxy/dynamicproxy/App.java
@@ -0,0 +1,25 @@
+package proxy.dynamicproxy;
+
+import proxy.service.OrderService;
+
+import java.math.BigDecimal;
+
+public class App {
+
+    public static void main(String[] args) {
+        // jdk dynamic proxy
+        OrderService proxy = new OrderServiceJdkProxyFactory().createProxy();
+        proxy.createOrder("user123", "prod456", new BigDecimal("199.99"));
+        System.out.println();
+        proxy.cancelOrder("order789");
+
+        System.out.println("========================================================");
+
+        // cglib dynamic proxy
+        proxy = new OrderServiceCglibProxyFactory().createProxy();
+        proxy.createOrder("user123", "prod456", new BigDecimal("199.99"));
+        System.out.println();
+        proxy.cancelOrder("order789");
+    }
+
+}
diff --git a/src/main/java/proxy/dynamicproxy/OrderServiceCglibProxyFactory.java b/src/main/java/proxy/dynamicproxy/OrderServiceCglibProxyFactory.java
@@ -0,0 +1,50 @@
+package proxy.dynamicproxy;
+
+import org.springframework.cglib.proxy.Enhancer;
+import org.springframework.cglib.proxy.MethodInterceptor;
+import org.springframework.cglib.proxy.MethodProxy;
+import proxy.service.AuthService;
+import proxy.service.LogService;
+import proxy.service.OrderService;
+import proxy.service.impl.AuthServiceImpl;
+import proxy.service.impl.LogServiceImpl;
+import proxy.service.impl.OrderServiceImpl;
+
+import java.lang.reflect.Method;
+
+public class OrderServiceCglibProxyFactory {
+    private final OrderService orderService;
+    private final AuthService authService;
+    private final LogService logService;
+    private final OrderServiceProxyProcess orderServiceProxyProcess;
+
+    public OrderServiceCglibProxyFactory() {
+        this.orderService = new OrderServiceImpl();
+        this.authService = new AuthServiceImpl();
+        this.logService = new LogServiceImpl();
+        this.orderServiceProxyProcess = new OrderServiceProxyProcess();
+    }
+
+    public OrderService createProxy() {
+        Enhancer enhancer = new Enhancer();
+        enhancer.setSuperclass(orderService.getClass());
+        enhancer.setCallback(new OrderServiceMethodInterceptor());
+        return (OrderService) enhancer.create();
+    }
+
+    private class OrderServiceMethodInterceptor implements MethodInterceptor {
+        @Override
+        public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
+            // before
+            orderServiceProxyProcess.processBefore(method, args, authService, logService);
+
+            // invoke real objects
+            Object result = proxy.invokeSuper(obj, args);
+
+            // after
+            orderServiceProxyProcess.processAfter(method, args, authService, logService);
+
+            return result;
+        }
+    }
+}
diff --git a/src/main/java/proxy/dynamicproxy/OrderServiceJdkProxyFactory.java b/src/main/java/proxy/dynamicproxy/OrderServiceJdkProxyFactory.java
@@ -0,0 +1,50 @@
+package proxy.dynamicproxy;
+
+import proxy.service.AuthService;
+import proxy.service.LogService;
+import proxy.service.OrderService;
+import proxy.service.impl.AuthServiceImpl;
+import proxy.service.impl.LogServiceImpl;
+import proxy.service.impl.OrderServiceImpl;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+public class OrderServiceJdkProxyFactory {
+    private final OrderService orderService;
+    private final AuthService authService;
+    private final LogService logService;
+    private final OrderServiceProxyProcess orderServiceProxyProcess;
+
+    public OrderServiceJdkProxyFactory() {
+        this.orderService = new OrderServiceImpl();
+        this.authService = new AuthServiceImpl();
+        this.logService = new LogServiceImpl();
+        this.orderServiceProxyProcess = new OrderServiceProxyProcess();
+    }
+
+    public OrderService createProxy() {
+        return (OrderService) Proxy.newProxyInstance(
+                orderService.getClass().getClassLoader(),
+                orderService.getClass().getInterfaces(),
+                new OrderServiceInvocationHandler()
+        );
+    }
+
+    private class OrderServiceInvocationHandler implements InvocationHandler {
+        @Override
+        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+            // before
+            orderServiceProxyProcess.processBefore(method, args, authService, logService);
+
+            // invoke real objects
+            Object result = method.invoke(orderService, args);
+
+            // after
+            orderServiceProxyProcess.processAfter(method, args, authService, logService);
+
+            return result;
+        }
+    }
+}
diff --git a/src/main/java/proxy/dynamicproxy/OrderServiceProxyProcess.java b/src/main/java/proxy/dynamicproxy/OrderServiceProxyProcess.java
@@ -0,0 +1,40 @@
+package proxy.dynamicproxy;
+
+import proxy.service.AuthService;
+import proxy.service.LogService;
+
+import java.lang.reflect.Method;
+
+public class OrderServiceProxyProcess {
+
+    public void processBefore(Method method, Object[] args, AuthService authService, LogService logService) {
+        String methodName = method.getName();
+        if ("createOrder".equals(methodName)) {
+            String userId = (String) args[0];
+            authService.checkPermission(userId, "CREATE_ORDER");
+            logService.log("Begin to create order", userId, (String) args[1], args[2].toString());
+        } else if ("cancelOrder".equals(methodName)) {
+            String orderId = (String) args[0];
+            String userId = getUserIdByOrderId(orderId);
+            authService.checkPermission(userId, "CANCEL_ORDER");
+            logService.log("Start canceling orders", userId, orderId);
+        }
+    }
+
+    public void processAfter(Method method, Object[] args, AuthService authService, LogService logService) {
+        String methodName = method.getName();
+        if ("createOrder".equals(methodName)) {
+            String userId = (String) args[0];
+            logService.log("Order creation completed", userId, (String) args[1], args[2].toString());
+        } else if ("cancelOrder".equals(methodName)) {
+            String orderId = (String) args[0];
+            String userId = getUserIdByOrderId(orderId);
+            logService.log("Order cancellation completed", userId, orderId);
+        }
+    }
+
+    private String getUserIdByOrderId(String orderId) {
+        return STR."user_\{orderId.hashCode()}"; // Mock
+    }
+
+}
diff --git a/src/main/java/proxy/service/AuthService.java b/src/main/java/proxy/service/AuthService.java
@@ -0,0 +1,5 @@
+package proxy.service;
+
+public interface AuthService {
+    void checkPermission(String userId, String permission);
+}
diff --git a/src/main/java/proxy/service/LogService.java b/src/main/java/proxy/service/LogService.java
@@ -0,0 +1,5 @@
+package proxy.service;
+
+public interface LogService {
+    void log(String action, String... params);
+}
diff --git a/src/main/java/proxy/service/OrderService.java b/src/main/java/proxy/service/OrderService.java
@@ -0,0 +1,9 @@
+package proxy.service;
+
+import java.math.BigDecimal;
+
+public interface OrderService {
+    void createOrder(String userId, String productId, BigDecimal amount);
+
+    void cancelOrder(String orderId);
+}
diff --git a/src/main/java/proxy/service/impl/AuthServiceImpl.java b/src/main/java/proxy/service/impl/AuthServiceImpl.java
@@ -0,0 +1,11 @@
+package proxy.service.impl;
+
+import proxy.service.AuthService;
+
+public class AuthServiceImpl implements AuthService {
+    @Override
+    public void checkPermission(String userId, String permission) {
+        System.out.printf("[validate permission] user[%s] permission[%s]\n", userId, permission);
+        //do sth...
+    }
+}
diff --git a/src/main/java/proxy/service/impl/LogServiceImpl.java b/src/main/java/proxy/service/impl/LogServiceImpl.java
@@ -0,0 +1,12 @@
+package proxy.service.impl;
+
+import proxy.service.LogService;
+
+import java.util.Arrays;
+
+public class LogServiceImpl implements LogService {
+    @Override
+    public void log(String action, String... params) {
+        System.out.printf("[log record] operation[%s] params%s\n", action, Arrays.toString(params));
+    }
+}
diff --git a/src/main/java/proxy/service/impl/OrderServiceImpl.java b/src/main/java/proxy/service/impl/OrderServiceImpl.java
@@ -0,0 +1,19 @@
+package proxy.service.impl;
+
+import proxy.service.OrderService;
+
+import java.math.BigDecimal;
+
+public class OrderServiceImpl implements OrderService {
+    @Override
+    public void createOrder(String userId, String productId, BigDecimal amount) {
+        System.out.printf("create order: user[%s] product[%s] amount[%s]\n", userId, productId, amount);
+        // do sth...
+    }
+
+    @Override
+    public void cancelOrder(String orderId) {
+        System.out.printf("cancel order: [%s]\n", orderId);
+        // do sth...
+    }
+}
diff --git a/src/main/java/proxy/staticproxy/App.java b/src/main/java/proxy/staticproxy/App.java
@@ -0,0 +1,14 @@
+package proxy.staticproxy;
+
+import java.math.BigDecimal;
+
+public class App {
+    public static void main(String[] args) {
+        OrderServiceStaticProxy proxy = new OrderServiceStaticProxy();
+
+        proxy.createOrder("user123", "prod456", new BigDecimal("199.99"));
+        System.out.println();
+        proxy.cancelOrder("order789");
+    }
+
+}
diff --git a/src/main/java/proxy/staticproxy/OrderServiceStaticProxy.java b/src/main/java/proxy/staticproxy/OrderServiceStaticProxy.java
@@ -0,0 +1,52 @@
+package proxy.staticproxy;
+
+import proxy.service.AuthService;
+import proxy.service.LogService;
+import proxy.service.OrderService;
+import proxy.service.impl.AuthServiceImpl;
+import proxy.service.impl.LogServiceImpl;
+import proxy.service.impl.OrderServiceImpl;
+
+import java.math.BigDecimal;
+
+public class OrderServiceStaticProxy {
+    private final OrderService orderService;
+    private final AuthService authService;
+    private final LogService logService;
+
+    public OrderServiceStaticProxy() {
+        this.orderService = new OrderServiceImpl();
+        this.authService = new AuthServiceImpl();
+        this.logService = new LogServiceImpl();
+    }
+
+    public void createOrder(String userId, String productId, BigDecimal amount) {
+        // before
+        authService.checkPermission(userId, "CREATE_ORDER");
+        logService.log("Begin to create order", userId, productId, amount.toString());
+
+        // invoke real objects
+        orderService.createOrder(userId, productId, amount);
+
+        // after
+        logService.log("Order creation completed", userId, productId, amount.toString());
+    }
+
+    public void cancelOrder(String orderId) {
+        // before
+        String userId = getUserIdByOrderId(orderId);
+        authService.checkPermission(userId, "CANCEL_ORDER");
+        logService.log("Start canceling orders", userId, orderId);
+
+        // invoke real objects
+        orderService.cancelOrder(orderId);
+
+        // after
+        logService.log("Order cancellation completed", userId, orderId);
+    }
+
+    private String getUserIdByOrderId(String orderId) {
+        return STR."user_\{orderId.hashCode()}"; // Mock
+    }
+
+}
diff --git a/...gleton/DoubleCheckedLockingSingleton.java → ...gleton/DoubleCheckedLockingSingleton.java b/...gleton/DoubleCheckedLockingSingleton.java → ...gleton/DoubleCheckedLockingSingleton.java
@@ -1,4 +1,4 @@
-package Singleton;
+package singleton;
 
 import java.io.Serial;
 import java.io.Serializable;

diff --git a/src/main/java/Singleton/EnumSingleton.java → src/main/java/singleton/EnumSingleton.java b/src/main/java/Singleton/EnumSingleton.java → src/main/java/singleton/EnumSingleton.java
@@ -1,4 +1,4 @@
-package Singleton;
+package singleton;
 
 public enum EnumSingleton {
     INSTANCE

diff --git a/.../Singleton/StaticInnerClassSingleton.java → .../singleton/StaticInnerClassSingleton.java b/.../Singleton/StaticInnerClassSingleton.java → .../singleton/StaticInnerClassSingleton.java
@@ -1,4 +1,4 @@
-package Singleton;
+package singleton;
 
 public final class StaticInnerClassSingleton {
     private StaticInnerClassSingleton() {}

diff --git a/src/test/java/singleton/DoubleCheckedLockingSingletonTest.java b/src/test/java/singleton/DoubleCheckedLockingSingletonTest.java
@@ -1,10 +1,10 @@
 package singleton;
 
-import Singleton.DoubleCheckedLockingSingleton;
 import common.utils.SerializationUtils;
 import org.junit.jupiter.api.Test;
 
 import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
 
 import static org.junit.jupiter.api.Assertions.*;
 
@@ -32,7 +32,7 @@ public void testReflectionAttack() {
             DoubleCheckedLockingSingleton instance1 = DoubleCheckedLockingSingleton.getInstance();
 
             //Attempt to create a second instance through reflection
-            assertThrows(RuntimeException.class, () -> {
+            assertThrows(InvocationTargetException.class, () -> {
                 DoubleCheckedLockingSingleton instance2 = constructor.newInstance();
             }, "An exception should be thrown to prevent reflection from creating an instance");