joor，一个基于fluent API设计的反射API

       你也许用过大名鼎鼎的JOOQ，该项目git主页上也有个joor仓库，里面设计了一种非常方便的java反射API。

地址：https://github.com/jOOQ/jOOR   

      看一些例子：

/**
	 * @see https://github.com/jOOQ/jOOR
	 */
	@Test
	public void test_simple_example() {
		Reflect reflectForString = Reflect.on(String.class).create("Hello doctor who");
		String world = reflectForString.call("substring", 6).call("toString").get();
		assertThat(world, equalTo("doctor who"));
	}

是不是比java反射api方便多了，其api设计也比较好用，源文件仅一个java文件。

joor也给出了一个访问java.lang.reflect.Proxy API的方法：

例如：

	@Test
	public void test_proxy_abstraction() {
		String substring = Reflect.on(String.class).create("doctor").as(StringProxy.class).substring(1);
		assertThat(substring, equalTo("octor"));
	}

	interface StringProxy {
		String substring(int beginIndex);
	}

      不过，这种动态代理只是Create a proxy for the wrapped object allowing to typesafely invoke methods on it using a custom interface。

      那么AOP切面如何实现呢。

     我改动以下这个方法：

@SuppressWarnings("unchecked")
	public <P, T> P as(Class<P> proxyType, Consumer<T> before, Consumer<T> after, T t) {
		final boolean isMap = (object instanceof Map);
		final InvocationHandler handler = new InvocationHandler() {
			@Override
			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
				String name = method.getName();

				// Actual method name matches always come first
				try {
					before.accept(t);
					Object result = on(object).call(name, args).get();
					after.accept(t);
					return result;
				}

				// [#14] Simulate POJO behaviour on wrapped map objects
				catch (ReflectException e) {
					if (isMap) {
						Map<String, Object> map = (Map<String, Object>) object;
						int length = (args == null ? 0 : args.length);

						if (length == 0 && name.startsWith("get")) {
							return map.get(property(name.substring(3)));
						}
						else if (length == 0 && name.startsWith("is")) {
							return map.get(property(name.substring(2)));
						}
						else if (length == 1 && name.startsWith("set")) {
							map.put(property(name.substring(3)), args[0]);
							return null;
						}
					}

					throw e;
				}
			}
		};

		return (P) Proxy.newProxyInstance(proxyType.getClassLoader(), new Class[] { proxyType }, handler);
	}

利用java8的函数式，实现aop。

例子：

@Test
	public void test_aop() {
		com.doctor.org.joor.Reflect.on(Person.class).create().as(Pepole.class, t -> {
			System.out.println("before....");
		}, t -> {
			System.out.println("after....");
		}, null).doWalk();
	}

interface Pepole {
		void doWalk();

		void doEate();
	}

	static class Person implements Pepole {
		private String name = "doctor who";
		private int age;

		public String getName() {
			return name;
		}

		public void setName(String name) {
			this.name = name;
		}

		public int getAge() {
			return age;
		}

		public void setAge(int age) {
			this.age = age;
		}

		@Override
		public void doWalk() {
			System.out.println(name + " do walk");

		}

		@Override
		public void doEate() {
			System.out.println(name + " do eate");
		}

	}

输出：

before....
doctor who do walk
after....