SpringBoot拦截器的使用与配置

SpringBoot拦截器的使用与配置

• 一、新建拦截器实现HandlerInterceptor接口
• 二、新建WebConfigurer配置拦截器

一、新建拦截器实现HandlerInterceptor接口

判断是否登录的拦截器

package com.briup.interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.springframework.web.servlet.HandlerInterceptor;

public class isLoginInterceptor implements HandlerInterceptor{

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		HttpSession session = request.getSession();
		Object obj = session.getAttribute("customer");
		System.out.println("isLoginInterceptor");
		if(obj!=null) {
			return true;
		}else {
			request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
			return false;
		}
	}
}

二、新建WebConfigurer配置拦截器

- - 方法一：实现WebMvcConfigurer接口

推荐使用

package com.briup.interceptor;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebConfigurer implements WebMvcConfigurer {

	@Autowired
	private isLoginInterceptor isLoginInterceptor;
	
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		 registry.addInterceptor(isLoginInterceptor).addPathPatterns("/user/*");
	}
}

注意： 使用@Autowired注入，拦截器isLoginInterceptor上必须有 @Component 注解
否则会出现如下错误：
Could not resolve view with name ‘index’ in servlet with name ‘dispatcherServlet’

Description:

Field isLoginInterceptor in com.briup.interceptor.InterceptorConfig required a bean of type 'com.briup.interceptor.isLoginInterceptor' that could not be found.

- - 方法二：继承WebMvcConfigurationSupport类

非常不推荐使用，在spring boot的自定义配置类继承 WebMvcConfigurationSupport 后，
自动配置的静态资源路径（classpath:/META/resources/，classpath:/resources/，classpath:/static/，classpath:/public/）不生效。

原因：
容易出现问题
这是因为在 springboot的web自动配置类 WebMvcAutoConfiguration 上有条件注解

@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)

@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
这个注解的意思是在项目类路径中 缺少 WebMvcConfigurationSupport类型的bean时该自动配置类才会生效

使用：

package com.briup.interceptor;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

@Configuration
public class WebConfigurer extends WebMvcConfigurationSupport {

	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		 registry.addInterceptor(new isLoginInterceptor()).addPathPatterns("/user/*");
	}
}

注意： WebMvcConfigurationSupport 类使用 @Autowired 或者 @bean 自动注入页面可能出现如下错误，直接new对象也可能出现如下错误，并且可能会失去css样式：
Could not resolve view with name ‘index’ in servlet with name ‘dispatcherServlet’

Could not resolve view with name 'index' in servlet with name 'dispatcherServlet'

- - 方法三：继承WebMvcConfigurerAdapter 类

不推荐使用，在spring5.0版本后这个类WebMvcConfigurerAdapter被丢弃了 ，虽然还可以用，但是看起来不好

package com.briup.interceptor;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfigurer extends WebMvcConfigurerAdapter {

	@Bean
	public isLoginInterceptor isLoginInterceptor() {
		 return new isLoginInterceptor();
	};

	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		registry.addInterceptor(isLoginInterceptor()).addPathPatterns("/user/*");
	}
}

注意： 使用Bean，拦截器类上不能有@Component注解，否则会出现如下错误：
Description:
The bean ‘isLoginInterceptor’, defined in class path resource [com/briup/interceptor/InterceptorConfig.class], could not be registered. A bean with that name has already been defined in file [F:\sts\estore_spingboot\target\classes\com\briup\interceptor\isLoginInterceptor.class] and overriding is disabled.

Description:
The bean 'isLoginInterceptor', defined in class path resource [com/briup/interceptor/InterceptorConfig.class], could not be registered. A bean with that name has already been defined in file [F:\sts\estore_spingboot\target\classes\com\briup\interceptor\isLoginInterceptor.class] and overriding is disabled.

本文地址：https://blog.csdn.net/qq_48225834/article/details/112644887