SpringBoot配置拦截器的示例
在SpringBoot中配置拦截器,主要有下面两个步骤:
1、继承接口 HandlerInterceptor,根据需要重写其中的三个类。
2、在配置类中注入该类。
public class MyInterceptor implements HandlerInterceptor { //controller执行之前 @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println("preHandler......"); return true; } //执行完controller执行之后、视图渲染前调用,可以在该方法里获取或者修改model @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println("postHandler......"); } //一般用于清理资源 @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { System.out.println("afterCompletion......"); } }
@Configuration public class WebMvcConfig implements WebMvcConfigurer { @Override public void addInterceptors(InterceptorRegistry registry) { //1、全部拦截 // registry.addInterceptor(myInterceptor()).addPathPatterns("/**"); //2、拦截指定路径 registry.addInterceptor(myInterceptor()).addPathPatterns("/hello"); } @Bean MyInterceptor myInterceptor(){ return new MyInterceptor(); } }
写个controller测试一下
@RestController public class HelloController { @RequestMapping("/hello") public String hello(){ System.out.println("hello"); return "hello"; } @RequestMapping("/world") public String world(){ System.out.println("world"); return "world"; } }
测试结果:
preHandler......
hello
postHandler......
afterCompletion......
world
SpringBoot中还有一终拦截器,WebRequestInterceptor
public class MyWebRequestInterceptor implements WebRequestInterceptor { @Override public void preHandle(WebRequest webRequest) throws Exception { } @Override public void postHandle(WebRequest webRequest, ModelMap modelMap) throws Exception { } @Override public void afterCompletion(WebRequest webRequest, Exception e) throws Exception { } }
和HandlerInterceptor比较相似,但是可以发现,该拦截器的preHandler返回值为空,说明该方法并不影响后面方法的执行。那么这个拦截器存在的目的是什么呐?
点进WebRequest:
public interface WebRequest extends RequestAttributes { @Nullable String getHeader(String var1); @Nullable String[] getHeaderValues(String var1); Iterator<String> getHeaderNames(); @Nullable String getParameter(String var1); @Nullable String[] getParameterValues(String var1); Iterator<String> getParameterNames(); Map<String, String[]> getParameterMap(); Locale getLocale(); String getContextPath(); @Nullable String getRemoteUser(); @Nullable Principal getUserPrincipal(); boolean isUserInRole(String var1); boolean isSecure();
发现对reques请求中参数做了进一步处理(@Nullable表示可以为空),更加的方便调用。所以两个拦截器的侧重点不同,HandlerInterceptor功能较为强大,可以拦截请求,可以实现WebRequestInterceptor的所有功能,只是要写的逻辑代码要多一点。更而WebRequestInterceptor倾向于简化获取request参数的过程以及预设参数供后面的流程使用。
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