afterhill · April 24, 2013 14:44 · Apr 24, 2013
diff --git a/BaseDao.java b/BaseDao.java
@@ -0,0 +1,5 @@
+package daoannotation;
+
+public interface BaseDao {
+
+}
diff --git a/DaoProxyFactory.java b/DaoProxyFactory.java
@@ -0,0 +1,70 @@
+package daoannotation;
+
+import java.lang.annotation.AnnotationFormatError;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+public class DaoProxyFactory {
+
+  @SuppressWarnings("unchecked")
+	public static <T> T newRoleDaoProxy(Class<T> dao) {
+		Implement implAnnotation = dao.getAnnotation(Implement.class);
+
+		if (implAnnotation == null) {
+			throw new AnnotationFormatError("this is no annotation for this interface: " + 
+					dao.getSimpleName().toString());
+		}
+
+		BaseDao implClass = null;
+
+		try {
+			implClass = implAnnotation.value().newInstance();
+		} catch (Exception e) {
+			throw new RuntimeException("this interface cannot be instanized!", e);
+		}
+
+		return (T) Proxy.newProxyInstance(
+				DaoProxyFactory.class.getClassLoader(), 
+				new Class<?>[] { dao }, 
+				new RoleInovationHandler(implClass));
+
+	}
+
+	private static final class RoleInovationHandler implements InvocationHandler {
+		private BaseDao target;
+
+		public RoleInovationHandler(BaseDao target) {
+			this.target = target;
+		}
+
+		@Override
+		public Object invoke(Object proxy, Method method, Object[] args)
+				throws Throwable {
+			Permission permitAnnotation = method.getAnnotation(Permission.class);
+
+			outter:
+			if (permitAnnotation != null) {
+				Role currentRole = RoleContext.INSTANCE.getCurrentRole();
+
+				for (Role role : permitAnnotation.value()) {
+					if (role.equals(currentRole)) {
+						break outter;
+					}
+				}
+
+				throw new SecurityException("user is not allowed to this operation!");
+
+			}
+			return method.invoke(target, args);
+		}
+
+	}
+
+	public static void main(String[] args) {
+		UserDao userDao = DaoProxyFactory.newRoleDaoProxy(UserDao.class);
+		userDao.save();
+		userDao.delete();
+		//userDao.query();
+	}
+}
diff --git a/Implement.java b/Implement.java
@@ -0,0 +1,12 @@
+package daoannotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Implement {
+  Class<? extends UserDao> value();
+}
diff --git a/Permission.java b/Permission.java
@@ -0,0 +1,12 @@
+package daoannotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Permission {
+  Role[] value();
+}
diff --git a/Role.java b/Role.java
@@ -0,0 +1,15 @@
+package daoannotation;
+
+public enum Role {
+
+  ADMINISTRATOR,
+	SYSTEM;
+
+
+	public Role get() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+
+}
diff --git a/RoleContext.java b/RoleContext.java
@@ -0,0 +1,19 @@
+package daoannotation;
+
+public enum RoleContext {
+  INSTANCE;
+
+	private ThreadLocal<Role> role = new ThreadLocal<>();
+
+	public Role getCurrentRole() {
+		return Role.SYSTEM;
+	}
+
+	public void setCurrentRole(Role role) {
+		this.role.set(role);
+	}
+
+	public static void main(String[] args) {
+		System.out.println(RoleContext.INSTANCE.getCurrentRole());
+	}
+}
diff --git a/UserDao.java b/UserDao.java
@@ -0,0 +1,13 @@
+package daoannotation;
+
+@Implement(UserDaoImpl.class)
+public interface UserDao extends BaseDao {
+  @Permission({Role.ADMINISTRATOR, Role.SYSTEM})
+	void save();
+
+	@Permission(Role.SYSTEM)
+	void delete();
+
+	@Permission(Role.ADMINISTRATOR)
+	void query();
+}
diff --git a/UserDaoImpl.java b/UserDaoImpl.java
@@ -0,0 +1,22 @@
+package daoannotation;
+
+public class UserDaoImpl implements UserDao {
+
+  @Override
+	public void save() {
+		System.out.println("UserDaoImpl.save()!");
+	}
+
+	@Override
+	public void delete() {
+		System.out.println("UserDaoImpl.delete()!");
+
+	}
+
+	@Override
+	public void query() {
+		System.out.println("UserDaoImpl.query()!");
+
+	}
+
+}