Spring Boot中拦截器的使用

一、为什么使用拦截器，使用场景在哪里？

拦截器顾名思义就是对你的操作web应用具体为一次请求进行拦截，为什么要进行拦截呢？拦截的好处是防止不法分子对请求数据的篡改，进而破坏系统的业务逻辑，导致用户数据的泄露，不容小觑！

使用场景：

1、对所有请求进行统一日志处理，比如你调用接口的时候打印日志logger.info("----method A invoke begin at time----")

2、对用户请求的签名检验(比如校验请求的合法性，采用MD5加密验证，校验请求的唯一性，采用时间戳机制等等)

二、Spring boot中如何配置拦截器？

• 1、创建自己的类并实现HandlerInterceptor接口，重写该接口的方法
• 2、创建一个配置类，将拦截器注册给容器

三、实例解析

• 创建自己的拦截器类

package club.wokao666.common;

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

public class NewInterceptor implements HandlerInterceptor {
	@Override
	public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2,
			Exception arg3) throws Exception {
		System.err.println("after");
	}
	@Override
	public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2,
			ModelAndView arg3) throws Exception {

		System.err.println("do");
	}
	@Override
	public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2)
			throws Exception {
		System.err.println("before");
		return true;
	}
}

• 创建配置类

package club.wokao666.common;

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 Conf extends WebMvcConfigurerAdapter {
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		super.addInterceptors(registry);
		registry.addInterceptor(new NewInterceptor()).addPathPatterns("/user/gettoken.json");
	}
}

• 相关接口

	/**
	 * 获取用户令牌 token
	 * @param sid
	 * @return
	 */
	@RequestMapping(value = "/gettoken.json", method = RequestMethod.POST)
	public ReturnMsg getToken(@RequestParam String sid) {
		System.err.println("sad");
		return ReturnMsg.succ();
	}

• 结果如下

2018-04-01 11:41:46.304  INFO 10924 --- [nio-7000-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'
2018-04-01 11:41:46.304  INFO 10924 --- [nio-7000-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started
2018-04-01 11:41:46.307  INFO 10924 --- [nio-7000-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 3 ms
before
sad
do
after