在SpringBoot项目中自定义注解使用

    在SpringBoot的项目中经常会遇到自定义注解的情况，同时需要根据注解来对使用它的类、方法或属性进行操作。下面主要是使用拦截器的方式进行注解的拦截判断，这里主要是使用pom的方式进行开发。

1.因为是使用的拦截器，所以必须导入spring-boot-starter-web的引用：

   <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.7.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

2.自定义一个注解：

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @author liaoyubo
 * @version 1.0 2017/9/14
 * @description 自定义一个注解
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface LoggerAnnotation {
}

3.自定义一个拦截器，用于注解的拦截：

import com.annotation.log.LoggerAnnotation;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;

/**
 * @author liaoyubo
 * @version 1.0 2017/9/14
 * @description 通过拦截器的方式实现自定义的日志记录
 */
public class LoggerInterceptor extends HandlerInterceptorAdapter{

    private Logger logger = LoggerFactory.getLogger(LoggerInterceptor.class);

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HandlerMethod handlerMethod = (HandlerMethod)handler;
        Method method = handlerMethod.getMethod();
        //获取当前方法上的指定注解
        LoggerAnnotation loggerAnnotation = method.getAnnotation(LoggerAnnotation.class);
        //判断当前注解是否存在
        if(loggerAnnotation != null){
            long startTime = System.currentTimeMillis();
            request.setAttribute("startTime",startTime);
            logger.info("进入" + method.getName() + "方法的时间是：" + startTime);
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerMethod handlerMethod = (HandlerMethod)handler;
        Method method = handlerMethod.getMethod();
        //获取当前方法上的指定注解
        LoggerAnnotation loggerAnnotation = method.getAnnotation(LoggerAnnotation.class);
        //判断当前注解是否存在
        if(loggerAnnotation != null){
            long endTime = System.currentTimeMillis();
            long startTime = (Long) request.getAttribute("startTime");
            long periodTime = endTime - startTime;
            logger.info("离开" + method.getName() + "方法的时间是：" + endTime);
            logger.info("在" + method.getName() + "方法的时长是：" + periodTime);
        }
    }
}

4.将拦截器类注入到适配器中，否则不能正常拦截访问。

import com.annotation.interceptor.LoggerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

/**
 * @author liaoyubo
 * @version 1.0 2017/9/14
 * @description 注册自定义的拦截器
 */
@Configuration
@EnableWebMvc
@ComponentScan
public class InterceptorRegister extends WebMvcConfigurerAdapter {



    @Bean
    public LoggerInterceptor loggerInterceptor(){
        return new LoggerInterceptor();
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry){
        registry.addInterceptor(loggerInterceptor());
    }

}

5.定义一个restful类用于测试:

import com.annotation.log.LoggerAnnotation;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author liaoyubo
 * @version 1.0 2017/9/14
 * @description
 */
@RestController
public class LoginController {

    @RequestMapping("/login")
    @LoggerAnnotation
    public void login(){
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}

启动项目，通过访问连接地址http://localhost:8080/annotationTest就可以得到以下

的输出结果:

2017-09-15 13:52:27.015  INFO 407336 --- [nio-8080-exec-1] c.a.interceptor.LoggerInterceptor        : 进入login方法的时间是：1505454747015  
2017-09-15 13:52:32.202  INFO 407336 --- [nio-8080-exec-1] c.a.interceptor.LoggerInterceptor        : 离开login方法的时间是：1505454752202  
2017-09-15 13:52:32.202  INFO 407336 --- [nio-8080-exec-1] c.a.interceptor.LoggerInterceptor        : 在login方法的时长是：5187