使用注解启动AOP的增强实现分页

使用注解启动AOP的增强实现分页

第一步

引入需要的aop与分页的jar包

<!--aop-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
</dependency>

<!--分页插件-->
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.4.5</version>
</dependency>

第二步

创建注解类

import java.lang.annotation.*;

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface PageX {
}

第三步

创建切面类MyAop

import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;

//标注是一个aop
@Aspect
@Component
public class MyAop {
    //切入点设置设置注解
    @Pointcut("@annotation(com.xhlin.annotation.PageX)")
    public void point(){}

    // 环绕通知
    @Around("point()")
    public Object around(ProceedingJoinPoint pjp) throws Throwable {

        System.out.println("环绕前");
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        String pageNum = request.getParameter("pageNum");
        String pageSize = request.getParameter("pageSize");
        if (pageSize !=null && pageNum!= null){
            int page_num = Integer.valueOf(pageNum);
            int page_size = Integer.valueOf(pageSize);
            PageHelper.startPage(page_num,page_size);
        }

        Object proceed = pjp.proceed();
        if (proceed instanceof Page){
            proceed = (Page) proceed;
        }

        System.out.println("环绕后");
        return proceed;
    }

}

这样就可以实现只要在spring ioc容器的方法上添加我们写的注释就可以执行aop进行切面