👊 【Spring技术特性】带你看看那些可能你还不知道的特性技巧哦！

{"type":"doc","content":[{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"前提介绍","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"本文主要介绍相关Spring框架的一些新特性问题机制，包含了一些特定注解方面的认识。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"@Lazy可以延迟依赖注入","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"@Lazy注解修饰在类层面！","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Lazy\n@Service\npublic class UserService extends BaseService { }\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以把@Lazy放在@Autowired之上，即依赖注入也是延迟的；当我们调用userService时才会注入。即延迟依赖注入到使用时。同样适用于@Bean。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Lazy\n@Autowired\nprivate UserService userService;\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"@Conditional","attrs":{}}]},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"@Conditional类似于@Profile","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"一般用于如有开发环境、测试环境、正式机环境，为了方便切换不同的环境可以使用@Profile指定各个环境的配置。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通过某个配置来开启某个环境，方便切换，但是@Conditional的优点是允许自己定义规则，可以指定在如@Component、@Bean、@Configuration等注解的类上，以绝对Bean是否创建等。","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"首先来看看使用@Profile的用例，假设我们有个用户模块：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"numberedlist","attrs":{"start":1,"normalizeStart":1},"content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":1,"align":null,"origin":null},"content":[{"type":"text","text":"在测试/开发期间调用本机的模拟接口方便开发；","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":2,"align":null,"origin":null},"content":[{"type":"text","text":"在部署到正式机时换成调用远程接口；","attrs":{}}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public abstract class UserService extends BaseService { }\n\n@Profile(\"local\")\n@Service\npublic class LocalUserService extends UserService {}\n\n@Profile(\"remote\")\n@Service\npublic class RemoteUserService extends UserService {}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我们在写测试用例时，可以指定我们使用哪个Profile：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@ActiveProfiles(\"remote\")\n@RunWith(SpringJUnit4ClassRunner.class)\n@ContextConfiguration(locations = \"classpath:spring-config.xml\")\npublic class ServiceTest {\n @Autowired\n private UserService userService;\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果想自定义如@Profile之类的注解等，那么@Conditional就派上用场了，假设我们系统中有好多本地/远程接口，那么我们定义两个注解@Local和@Remote注解要比使用@Profile方便的多；如：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":" @Retention(RetentionPolicy.RUNTIME)\n@Target({ElementType.TYPE, ElementType.METHOD})\n@Conditional(CustomCondition.class)\npublic @interface Local { }\n\n@Retention(RetentionPolicy.RUNTIME)\n@Target({ElementType.TYPE, ElementType.METHOD})\n@Conditional(CustomCondition.class)\npublic @interface Remote {}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public class CustomCondition implements Condition {\n @Override\n public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {\n boolean isLocalBean = metadata.isAnnotated(\"com.xxx.Local\");\n boolean isRemoteBean = metadata.isAnnotated(\"com.xxx.Remote\");\n //如果bean没有注解@Local或@Remote，返回true，表示创建Bean\n if(!isLocalBean && !isRemoteBean) {\n return true;\n }\n boolean isLocalProfile = context.getEnvironment().acceptsProfiles(\"local\");\n //如果profile=local 且 bean注解了@Local，则返回true 表示创建bean\n if(isLocalProfile) {\n return isLocalBean;\n }\n // 否则默认返回注解了@Remote或没有注解@Remote的Bean\n return isRemoteBean;\n }\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"然后我们使用这两个注解分别注解我们的Service：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Local\n@Service\npublic class LocalUserService extends UserService { }\n@Remote\n@Service\npublic class RemoteUserService extends UserService {}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"首先在@Local和@Remote注解上使用@Conditional(CustomCondition.class)指定条件。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"然后使用@Local和@Remote注解我们的Service，这样当加载Service时，会先执行条件然后判断是否加载为Bean。","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"@Profile实现的Condition是：org.springframework.context.annotation.ProfileCondition。","attrs":{}}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"AsyncRestTemplate非阻塞异步(已废弃WebClient代替之)","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"提供AsyncRestTemplate用于客户端非阻塞异步支持。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"服务器端","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@RestController\npublic class UserController {\n private UserService userService;\n @Autowired\n public UserController(UserService userService) {\n this.userService = userService;\n }\n @RequestMapping(\"/api\")\n public Callable api() {\n return new Callable() {\n @Override\n public User call() throws Exception {\n Thread.sleep(10L * 1000); //暂停两秒\n User user = new User();\n user.setId(1L);\n user.setName(\"haha\");\n return user;\n }\n };\n }\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"非常简单，服务器端暂停10秒再返回结果（但是服务器也是非阻塞的）。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"客户端","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public static void main(String[] args) {\n AsyncRestTemplate template = new AsyncRestTemplate();\n //调用完后立即返回（没有阻塞）\n ListenableFuture> future = template.getForEntity(\"http://localhost:9080/rest/api\", User.class);\n //设置异步回调\n future.addCallback(new ListenableFutureCallback>() {\n @Override\n public void onSuccess(ResponseEntity result) {\n System.out.println(\"======client get result : \" + result.getBody());\n }\n @Override\n public void onFailure(Throwable t) {\n System.out.println(\"======client failure : \" + t);\n }\n });\n System.out.println(\"==no wait\");\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"承接上面的内容：Future增强，提供了一个ListenableFuture，其是jdk的Future的封装，用来支持回调（成功/失败），借鉴了com.google.common.util.concurrent.ListenableFuture。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Test\npublic void test() throws Exception {\n ListenableFutureTask task = new ListenableFutureTask(new Callable() { \n @Override \n public Object call() throws Exception { \n Thread.sleep(10 * 1000L); \n System.out.println(\"=======task execute\"); \n return \"hello\"; \n } \n }); \n task.addCallback(new ListenableFutureCallback() { \n @Override \n public void onSuccess(String result) { \n System.out.println(\"===success callback 1\"); \n } \n \n @Override \n public void onFailure(Throwable t) { \n } \n }); \n task.addCallback(new ListenableFutureCallback() { \n @Override \n public void onSuccess(String result) { \n System.out.println(\"===success callback 2\"); \n } \n \n @Override \n public void onFailure(Throwable t) { \n } \n }); \n \n ExecutorService executorService = Executors.newSingleThreadExecutor(); \n executorService.submit(task); \n String result = task.get(); \n System.out.println(result); \n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以通过addCallback添加一些回调，当执行成功/失败时会自动调用。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"此处使用Future来完成非阻塞，这样的话我们也需要给它一个回调接口来拿结果；","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Future和Callable是一对，一个消费结果，一个产生结果。调用完模板后会立即返回，不会阻塞；有结果时会调用其回调。","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"horizontalrule","attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"AsyncRestTemplate默认使用SimpleClientHttpRequestFactory，即通过java.net.HttpURLConnection实现；","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"另外可以使用apache的http components，使用template.setAsyncRequestFactory(new HttpComponentsAsyncClientHttpRequestFactory())，设置即可。","attrs":{}}]}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"Spring对Java8的时间类型支持","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"对jsr310的支持，只要能发现java.time.LocalDate，DefaultFormattingConversionService就会自动注册对jsr310的支持，只需要在实体/Bean上使用DateTimeFormat注解：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@DateTimeFormat(pattern = \"yyyy-MM-dd HH:mm:ss\")\nprivate LocalDateTime dateTime;\n\n@DateTimeFormat(pattern = \"yyyy-MM-dd\")\nprivate LocalDate date;\n\n@DateTimeFormat(pattern = \"HH:mm:ss\")\nprivate LocalTime time;\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"比如我们在springmvc中：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@RequestMapping(\"/test\")\npublic String test(@ModelAttribute(\"entity\") Entity entity) {\n return \"test\";\n}\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"当前端页面请求：","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"text"},"content":[{"type":"text","text":"localhost:9080/spring4/test?dateTime=2013-11-11 11:11:11&date=2013-11-11&time=12:12:12\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"会自动进行类型转换","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"另外spring4也提供了对TimeZone的支持，比如在springmvc中注册了LocaleContextResolver相应实现的话（如CookieLocaleResolver），我们就可以使用如下两种方式得到相应的TimeZone：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"RequestContextUtils.getTimeZone(request)\nLocaleContextHolder.getTimeZone()\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不过目前的缺点是不能像Local那样自动的根据当前请求得到相应的TimeZone，如果需要这种功能需要覆盖相应的如CookieLocaleResolver中的如下方法来得到：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"protected TimeZone determineDefaultTimeZone(HttpServletRequest request) { \n return getDefaultTimeZone(); \n} \n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"另外还提供了DateTimeContextHolder，其用于线程绑定DateTimeContext；而DateTimeContext提供了如：Chronology、ZoneId、DateTimeFormatter等上下文数据，如果需要这种上下文信息的话，可以使用这个API进行绑定。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"比如在进行日期格式化时，就会去查找相应的DateTimeFormatter，因此如果想自定义相应的格式化格式，那么使用DateTimeContextHolder绑定即可。","attrs":{}}]}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"泛型操作控制","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"随着泛型用的越来越多，获取泛型实际类型信息的需求也会出现，如果用原生API，需要很多步操作才能获取到泛型，比如：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ParameterizedType parameterizedType = \n (ParameterizedType) ABService.class.getGenericInterfaces()[0]; \nType genericType = parameterizedType.getActualTypeArguments()[1]; \n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Spring提供的ResolvableType API，提供了更加简单易用的泛型操作支持，如：","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"接口层的泛型处理","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType1 = ResolvableType.forClass(ABService.class);\nresolvableType1.as(Service.class).getGeneric(1).resolve();\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"对于获取更复杂的泛型操作ResolvableType更加简单。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"假设我们的API是：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public interface Service { }\[email protected]\npublic class ABService implements Service { }\[email protected]\npublic class CDService implements Service {}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"得到类型的泛型信息","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType1 = ResolvableType.forClass(ABService.class);\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通过如上API，可以得到类型的ResolvableType，如果类型被Spring AOP进行了CGLIB代理，请使用","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"ClassUtils.getUserClass(ABService.class)","attrs":{}}],"attrs":{}},{"type":"text","text":"得到原始类型，可以通过如下得到泛型参数的第1个位置（从0开始）的类型信息","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"resolvableType1.getInterfaces()[0].getGeneric(1).resolve()\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"泛型信息放在 Service 上，所以需要resolvableType1.getInterfaces()[0]得到；","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通过getGeneric（泛型参数索引）得到某个位置的泛型；","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"resolve()把实际泛型参数解析出来","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"得到字段级别的泛型信息","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"假设我们的字段如下：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Autowired\n private Service abService;\n @Autowired\n private Service cdService;\n private List> list;\n private Map> map;\n private List[] array;\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通过如下API可以得到字段级别的ResolvableType","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType2 = \n ResolvableType.forField(ReflectionUtils.findField(GenricInjectTest.class, \"cdService\")); \n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"然后通过如下API得到Service的第0个位置上的泛型实参类型，即C","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"resolvableType2.getGeneric(0).resolve()\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"比如 List> list;是一种嵌套的泛型用例，我们可以通过如下操作获取String类型：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType3 =\n ResolvableType.forField(ReflectionUtils.findField(GenricInjectTest.class, \"list\"));\nresolvableType3.getGeneric(0).getGeneric(0).resolve();\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"更简单的写法","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"resolvableType3.getGeneric(0, 0).resolve(); //List> 即String\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"比如，Map> map;我们想得到Integer，可以使用：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType4 =\n ResolvableType.forField(ReflectionUtils.findField(GenricInjectTest.class, \"map\"));\nresolvableType4.getGeneric(1).getGeneric(1).resolve();\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"更简单的写法","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"resolvableType4.getGeneric(1, 1).resolve() \n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"得到方法返回值的泛型信息","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"private HashMap> method() { \n return null; \n} \n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"得到Map中的List中的String泛型实参：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType5 = ResolvableType.forMethodReturnType(ReflectionUtils.findMethod(GenricInjectTest.class, \"method\"));\nresolvableType5.getGeneric(1, 0).resolve();\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"得到构造器参数的泛型信息","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"假设我们的构造器如下：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public Const(List> list, Map> map) { }\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我们可以通过如下方式得到第1个参数（ Map>）中的Integer：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType6 = ResolvableType.forConstructorParameter(ClassUtils.getConstructorIfAvailable(Const.class, List.class, Map.class), 1);\nresolvableType6.getGeneric(1, 0).resolve();\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"得到数组组件类型的泛型信息","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如对于private List[] array; 可以通过如下方式获取List的泛型实参String：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType7 = ResolvableType.forField(ReflectionUtils.findField(GenricInjectTest.class, \"array\"));\nresolvableType7.isArray();//判断是否是数组 \nresolvableType7.getComponentType().getGeneric(0).resolve(); \n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"自定义泛型类型","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType8 = ResolvableType.forClassWithGenerics(List.class, String.class);\n ResolvableType resolvableType9 = ResolvableType.forArrayComponent(resolvableType8); \nresolvableType9.getComponentType().getGeneric(0).resolve(); \nResolvableType.forClassWithGenerics(List.class, String.class)相当于创建一个List类型；\nResolvableType.forArrayComponent(resolvableType8);：相当于创建一个List[]数组；\nresolvableType9.getComponentType().getGeneric(0).resolve()：得到相应的泛型信息；\n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"泛型等价比较：","attrs":{}}]},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"resolvableType7.isAssignableFrom(resolvableType9)\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如下创建一个List[]数组，与之前的List[]数组比较，将返回false。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"ResolvableType resolvableType10 = ResolvableType.forClassWithGenerics(List.class, Integer.class);\nResolvableType resolvableType11= ResolvableType.forArrayComponent(resolvableType10); \nresolvableType11.getComponentType().getGeneric(0).resolve(); \nresolvableType7.isAssignableFrom(resolvableType11); \n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"从如上操作可以看出其泛型操作功能十分完善，尤其在嵌套的泛型信息获取上相当简洁。目前整个Spring环境都使用这个API来操作泛型信息。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"注解方面的改进","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Spring对注解API和ApplicationContext获取注解Bean做了一点改进，取注解的注解，如@Service是被@Compent注解的注解，可以通过如下方式获取@Componet注解实例：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"Annotation service = AnnotationUtils.findAnnotation(ABService.class, org.springframework.stereotype.Service.class); \nAnnotation component = AnnotationUtils.getAnnotation(service, org.springframework.stereotype.Component.class); \n","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":5},"content":[{"type":"text","text":"获取重复注解：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"比如在使用hibernate validation时，我们想在一个方法上加相同的注解多个，需要使用如下方式：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Length.List( \n value = { \n @Length(min = 1, max = 2, groups = A.class), \n @Length(min = 3, max = 4, groups = B.class) \n } \n) \npublic void test() {}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以通过如下方式获取@Length：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"Method method = ClassUtils.getMethod(AnnotationUtilsTest.class, \"test\"); \nSet set = AnnotationUtils.getRepeatableAnnotation(method, Length.List.class, Length.class);\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"当然，如果你使用Java8，那么本身就支持重复注解，比如spring的任务调度注解，","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE}) \n@Retention(RetentionPolicy.RUNTIME)\n@Documented\n@Repeatable(Schedules.class)\npublic @interface Scheduled {}\n\n@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE}) \n@Retention(RetentionPolicy.RUNTIME) \n@Documented\npublic @interface Schedules {\n Scheduled[] value();\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"这样的话，我们可以直接同时注解相同的多个注解：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Scheduled(cron = \"123\")\n@Scheduled(cron = \"234\")\npublic void test\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"但是获取的时候还是需要使用如下方式：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"AnnotationUtils.getRepeatableAnnotation(ClassUtils.getMethod(TimeTest.class, \"test\"), Schedules.class, Scheduled.class)\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"ApplicationContext和BeanFactory提供了直接通过注解获取Bean的方法：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Test\npublic void test() {\n AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();\n ctx.register(GenericConfig.class);\n ctx.refresh();\n Map beans = ctx.getBeansWithAnnotation(org.springframework.stereotype.Service.class); \n System.out.println(beans);\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"另外和提供了一个AnnotatedElementUtils用于简化java.lang.reflect.AnnotatedElement的操作。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"ScriptEvaluator脚本的支持","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"spring也提供了类似于javax.script的简单封装，用于支持一些脚本语言，核心接口是：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"public interface ScriptEvaluator {\n Object evaluate(ScriptSource script) throws ScriptCompilationException;\n Object evaluate(ScriptSource script, Map arguments) throws ScriptCompilationException;\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"比如我们使用groovy脚本的话，可以这样：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Test\npublic void test() throws ExecutionException, InterruptedException {\n ScriptEvaluator scriptEvaluator = new GroovyScriptEvaluator();\n //ResourceScriptSource 外部的\n ScriptSource source = new StaticScriptSource(\"i+j\");\n Map args = new HashMap<>();\n args.put(\"i\", 1);\n args.put(\"j\", 2);\n System.out.println(scriptEvaluator.evaluate(source, args));\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"另外还提供了BeanShell（BshScriptEvaluator）和javax.script（StandardScriptEvaluator）的简单封装。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"MvcUriComponentsBuilder","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"MvcUriComponentsBuilder类似于ServletUriComponentsBuilder，但是可以直接从控制器获取URI信息，如下所示：假设我们的控制器是：","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Controller\n@RequestMapping(\"/user\")\npublic class UserController {\n @RequestMapping(\"/{id}\")\n public String view(@PathVariable(\"id\") Long id) {\n return \"view\";\n }\n @RequestMapping(\"/{id}\")\n public A getUser(@PathVariable(\"id\") Long id) {\n return new A();\n }\n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"注：如果在真实mvc环境，存在两个@RequestMapping(\"/{id}\")是错误的。当前只是为了测试。","attrs":{}}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"numberedlist","attrs":{"start":1,"normalizeStart":1},"content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":1,"align":null,"origin":null},"content":[{"type":"text","text":"需要静态导入 import static org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder.*;","attrs":{}}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"@Test \npublic void test() { \n MockHttpServletRequest req = new MockHttpServletRequest(); \n RequestContextHolder.setRequestAttributes(new ServletRequestAttributes(req)); \n \n //MvcUriComponentsBuilder类似于ServletUriComponentsBuilder，但是直接从控制器获取 \n //类级别的 \n System.out.println( \n fromController(UserController.class).build().toString() \n ); \n \n //方法级别的 \n System.out.println( \n fromMethodName(UserController.class, \"view\", 1L).build().toString() \n ); \n \n //通过Mock方法调用得到 \n System.out.println( \n fromMethodCall(on(UserController.class).getUser(2L)).build() \n ); \n}\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"注意：当前MvcUriComponentsBuilder实现有问题，只有JDK环境支持，大家可以复制一份，然后修改：method.getParameterCount() （Java 8才支持）到method.getParameterTypes().length","attrs":{}}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"Socket支持","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"提供了获取Socket TCP/UDP可用端口的工具，如","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":"java"},"content":[{"type":"text","text":"SocketUtils.findAvailableTcpPort()\nSocketUtils.findAvailableTcpPort(min, max) \nSocketUtils.findAvailableUdpPort()\n","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}}]}