如何配置拦截器
step1: 自定义拦截器
/**
* 自定义拦截器
*/
public class MyInterceptor implements HandlerInterceptor {
private static final Logger logger = LoggerFactory.getLogger(MyInterceptor.class);
/**
* 在请求匹配controller之前执行，返回true才行进行下一步
* @param request
* @param response
* @param handler
* @return
* @throws Exception
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
return false;
}
/**
* 已经执行完controller了，但是还没有进入视图渲染
* @param request
* @param response
* @param handler
* @param modelAndView
* @throws Exception
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
}
/**
* 视图也渲染完了，此时我可以做一些清理工作了
* @param request
* @param response
* @param handler
* @param ex
* @throws Exception
*/
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
}
}
step2：配置拦截器
@Configuration
public class MyInterceptorConfig extends WebMvcConfigurationSupport {
@Override
protected void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**"); // 拦截所有内容:/** 拦截部分内容:/admin/**
super.addInterceptors(registry);
}
}
拦截器设置容易出现的问题
静态资源被拦截
MyInterceptorConfig 继承 WebMvcConfigurationSupport类时，会导致resources/static下的静态资源也被拦截，如果我们不想静态资源被拦截，可以尝试以下两种方法。
/**
* 在MyInterceptorConfig中重写addResourceHandlers方法，重新指定静态资源
* 推荐在前后端分离时使用，后台不需要访问静态资源
*
* @param registry
*/
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/**").addResourceLocations(
"classpath:/static/");
super.addResourceHandlers(registry);
}
/**
* 将MyInterceptorConfig类由继承WebMvcConfigurationSupport改为实现WebMvcConfigurer
* 推荐在非前后端分离时使用，后台需要访问静态资源
*
*/
@Configuration
public class MyInterceptorConfig implements WebMvcConfigurer {
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**"); // 拦截所有内容:/** 拦截部分内容:/admin/**
}
}
如何取消拦截操作
step1：自定义注解
/**
* 自定义注解用来指定某个方法不用拦截
*/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface UnInterception {
}
step2：修改拦截器MyInterceptor中的preHandle方法
/**
* 在请求匹配controller之前执行
* @param request
* @param response
* @param handler
* @return
* @throws Exception
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
UnInterception unInterception = method.getAnnotation(UnInterception.class);
if(null != unInterception) {
logger.info("不需要拦截，可以执行");
return true;
}
// 返回true才会执行方法，返回false不会执行
return false;
}
step3：在不需要拦截的controller上加上UnInterception注解
@Controller
@RequestMapping("/interceptor")
public class InterceptorController {
@UnInterception
@RequestMapping("/test")
public String test() {
return "hello";
}
}
实例-登录验证
用拦截器实现一个登录验证功能
step1：自定义拦截器
import com.kimmel.course13.annotation.UnInterception;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;
/**
* 自定义拦截器
*/
public class MyInterceptor implements HandlerInterceptor {
private static final Logger logger = LoggerFactory.getLogger(MyInterceptor.class);
/**
* 在请求匹配controller之前执行
* @param request
* @param response
* @param handler
* @return
* @throws Exception
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
HandlerMethod handlerMethod = (HandlerMethod) handler;
Method method = handlerMethod.getMethod();
String methodName = method.getName();
// 判断用户有没有登录，一般登录之后的用户都有一个对应的token
UnInterception unInterception = method.getAnnotation(UnInterception.class);
String token = request.getParameter("token");
if (null == token || "".equals(token)) {
logger.info("用户未登录，没有权限执行{}请登录", methodName);
return false;
}
// 返回true才会执行方法，返回false不会执行
return true;
}
/**
* 已经执行完controller了，但是还没有进入视图渲染
* @param request
* @param response
* @param handler
* @param modelAndView
* @throws Exception
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
HandlerMethod handlerMethod = (HandlerMethod) handler;
Method method = handlerMethod.getMethod();
String methodName = method.getName();
logger.info("已经执行完{}了，但是还没有进入视图渲染", methodName);
}
/**
* 视图也渲染完了，此时我可以做一些清理工作了
* @param request
* @param response
* @param handler
* @param ex
* @throws Exception
*/
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
logger.info("视图也渲染完了，此时我可以做一些清理工作了");
}
}
step2：配置拦截器
import com.kimmel.course13.Interceptor.MyInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
@Configuration
public class MyInterceptorConfig extends WebMvcConfigurationSupport {
@Override
protected void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**"); // 拦截所有内容:/** 拦截部分内容:/admin/**
super.addInterceptors(registry);
}
/**
* 发现如果继承了WebMvcConfigurationSupport，则在yml中配置的相关内容会失效。 需要重新指定静态资源
*
* @param registry
*/
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/**").addResourceLocations(
"classpath:/static/");
registry.addResourceHandler("swagger-ui.html").addResourceLocations(
"classpath:/META-INF/resources/");
registry.addResourceHandler("/webjars/**").addResourceLocations(
"classpath:/META-INF/resources/webjars/");
super.addResourceHandlers(registry);
}
}
step3：自定义测试controller
@Controller
@RequestMapping("/interceptor")
public class InterceptorController {
@RequestMapping("/test")
public String test() {
return "hello";
}
}
step4：测试
进入浏览器，输入http://localhost:8080/interceptor/test
结果：无法进入，日志：用户未登录，没有权限执行 test 请登录
进入浏览器，输入http://localhost:8080/interceptor/test?token=1
结果：成功进入hello.html
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