SpringBoot配置攔截器的示例
在SpringBoot中配置攔截器,主要有下面兩個步驟:
1、繼承接口 HandlerInterceptor,根據需要重寫其中的三個類。
2、在配置類中注入該類。
public class MyInterceptor implements HandlerInterceptor { //controller執行之前 @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println('preHandler......'); return true; } //執行完controller執行之后、視圖渲染前調用,可以在該方法里獲取或者修改model @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { System.out.println('postHandler......'); } //一般用于清理資源 @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { System.out.println('afterCompletion......'); }}
@Configurationpublic class WebMvcConfig implements WebMvcConfigurer { @Override public void addInterceptors(InterceptorRegistry registry) { //1、全部攔截// registry.addInterceptor(myInterceptor()).addPathPatterns('/**'); //2、攔截指定路徑 registry.addInterceptor(myInterceptor()).addPathPatterns('/hello'); } @Bean MyInterceptor myInterceptor(){ return new MyInterceptor(); }}
寫個controller測試一下
@RestControllerpublic class HelloController { @RequestMapping('/hello') public String hello(){ System.out.println('hello'); return 'hello'; } @RequestMapping('/world') public String world(){ System.out.println('world'); return 'world'; }}
測試結果:
preHandler......hellopostHandler......afterCompletion......world
SpringBoot中還有一終攔截器,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比較相似,但是可以發現,該攔截器的preHandler返回值為空,說明該方法并不影響后面方法的執行。那么這個攔截器存在的目的是什么吶?
點進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();
發現對reques請求中參數做了進一步處理(@Nullable表示可以為空),更加的方便調用。所以兩個攔截器的側重點不同,HandlerInterceptor功能較為強大,可以攔截請求,可以實現WebRequestInterceptor的所有功能,只是要寫的邏輯代碼要多一點。更而WebRequestInterceptor傾向于簡化獲取request參數的過程以及預設參數供后面的流程使用。
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