关于如何有效避免空指针，并减少空指针的重复申明。 参考stackoverflow的讨论
一、需要一个类继承HttpServletRequestWrapper，该类继承了ServletRequestWrapper并实现了HttpS
# 一般声明 def printUser(id,name,sex,age,email,phone,group): printUser(1,'ming','male',18,'',110,'default') # 默认值 def printUser(id,name,sex,age,email='',phone=110,group='default'): printUser(1,'ming','male',18) # 位置参数和关键字参数 def printUser(id,name,sex,/,age,email,*,phone,group): # 位置参数就是调用的时候直接赋值 # 关键字参数就是调用的时候通过 key=value 的形式赋值 # 斜杠之前
全局filter @Component @Order(1) public class FirstFilter extends Filter { @Override public void doFilter( ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { ... chain.doFilter(request, response); } } 全局过滤直接实现Filter即可，如需设定顺序，使用@Order注解 URL
交于Spring管理的类，通过注解调用 @Component public class Test{ @Autowired private HttpServletRequest httpServletRequest; } 通过静态方法调用 HttpServletRequest httpServletRequest = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();
Description Below I present you two different ways to get the current Class: Using Thread Using getClass() The simplest way to get the name of the class where your code is being executed in is using the getClass() method present in every java object. Like here: String clazz = this.getClass().getName(); This works only if executed in an Object, namely an instanciated class. If you try to execute the code above
所谓观察者模式，指的某个状态信息的改变，会影响其他一系列的操作，这时就可以将这些操作抽象化，同时创建一个类统一的管理和执行这些操作。把这些抽