Add MyOwnTransactionBeanPostProcessor.java

Author: JcoderPaul

Spring_part_3/src/main/java/spring/oldboy/bean_post_processor/MyOwnTransactionBeanPostProcessor.java

@@ -0,0 +1,46 @@
+package spring.oldboy.bean_post_processor;
+
+/* Пример самописного пост-процессора с основным ...AfterInitialization методом */
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.stereotype.Component;
+
+import java.lang.reflect.Proxy;
+import java.util.HashMap;
+import java.util.Map;
+
+@Component
+public class MyOwnTransactionBeanPostProcessor implements BeanPostProcessor {
+
+    private final Map<String, Class<?>> transactionBeans = new HashMap<>();
+
+    @Override
+    public Object postProcessBeforeInitialization(Object bean, String beanName)
+                                                                    throws BeansException {
+        if (bean.getClass().isAnnotationPresent(MyOwnTransaction.class)) {
+            transactionBeans.put(beanName, bean.getClass());
+        }
+        return bean;
+    }
+
+    @Override
+    public Object postProcessAfterInitialization(Object bean, String beanName)
+                                                                    throws BeansException {
+        Class<?> beanClass = transactionBeans.get(beanName);
+        if (beanClass != null) {
+            return Proxy.newProxyInstance(beanClass.getClassLoader(), beanClass.getInterfaces(),
+                    (proxy, method, args) -> {
+                        /* Эмулируем открытие транзакции */
+                        System.out.println("Open transaction");
+                        try {
+                            return method.invoke(bean, args);
+                        } finally {
+                        /* Эмулируем закрытие транзакции */
+                            System.out.println("Close transaction");
+                        }
+                    });
+        }
+        return bean;
+    }
+}