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1. AspectJ

1.1. AspectJ介绍

AspectJ官网^4

AspectJ文档^1

1.1.1. pointcuts

pointcuts指的是程序中的某些链接点（某些时机），例如call(void Point.setX(int))表示：调用类Point的setX(int)方法时

pointcuts可以使用与或非表达式（||,&&,!）连接，比如 call(void Point.setX(int)) || call(void Point.setY(int))

pointcuts可以被定义为变量，如下面代码中的move()

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pointcut move():
    call(void FigureElement.setXY(int,int)) ||
    call(void Point.setX(int))              ||
    call(void Point.setY(int))              ||
    call(void Line.setP1(Point))            ||
    call(void Line.setP2(Point));

当然pointcuts定义的时候还可以使用通配符，比如call(void Figure.make*(..))代表Figure的以make开头且返回值为void的方法（不关心参数）调用的时候。比如call(public * Figure.* (..))代表Figure的任何方法（不关心方法名，参数，返回值）调用的时候。

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Jps

jps 可以看到运行中的java进程

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sh-4.2$ jps
370 xxx.jar
180682 Jps

Jcmd

jcmd可以看到运行中的java进程以及参数

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sh-4.2$ jcmd
370 /usr/local/xxx.jar config_path=xxx.yaml
180773 sun.tools.jcmd.JCmd

Jmap

jmap是可以查看整个JVM内存的工具。

Java常见异常

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classDiagram
  Object <|-- Throwable
  Throwable <|-- Error
  Throwable <|-- Exception
  Error <|-- OutOfMemoryError
  Error <|-- NoClassDefFoundError
  Error <|-- StackOverflowError
  Exception <|-- IOException
  Exception <|-- RuntimeException
  RuntimeException <|-- NullPointerException
  RuntimeException <|-- IndexOutOfBoundsException

NoClassDefFoundError 异常原因处理

使用Github Packages Repository

这里主要介绍Github packages搭建私服，这种方案上传和下载都需要使用token

步骤1

访问地址 ,点击Generate new token 创建新的token，选择权限 write:packages

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JAVA

IDEA

Spring Boot 启动命令行太长

修改文件.idea/workspace.xml

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<component name="PropertiesComponent">
  <property name="dynamic.classpath" value="true" />

Spring Cloud Gateway

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package com.example.demo;

import java.util.ArrayList;
import java.util.List;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.route.RouteDefinitionRepository;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

// 动态路由
// https://zhuanlan.zhihu.com/p/125018436
@RestController
@SpringBootApplication
public class DemoApplication implements RouteDefinitionRepository, ApplicationEventPublisherAware {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    // event publisher
    ApplicationEventPublisher applicationEventPublisher;

    @Override
    public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
        this.applicationEventPublisher = applicationEventPublisher;
    }


    // router
    List<RouteDefinition> memery = new ArrayList<>();

    private void refreshRoute() {
        applicationEventPublisher.publishEvent(new RefreshRoutesEvent(this));
    }

    @PutMapping
    Mono<Void> putRoute(@RequestBody Mono<RouteDefinition> o) {
        return o.flatMap(routeDefinition -> {
            memery.add(routeDefinition);
            refreshRoute();
            return Mono.empty();
        });
    }

    @PostMapping
    Mono<Void> postRoute(@RequestBody Mono<RouteDefinition> o) {
        return o.flatMap(routeDefinition -> {
            for (int i = 0; i < memery.size(); i++) {
                if (memery.get(i).getId().equals(routeDefinition.getId())) {
                    memery.set(i, routeDefinition);
                }
            }
            refreshRoute();
            return Mono.empty();
        });
    }

    @DeleteMapping
    Mono<Void> deleteRoute(@RequestBody Mono<String> o) {
        return o.flatMap(id -> {
            memery.removeIf(routeDefinition -> routeDefinition.getId().equals(id));
            refreshRoute();
            return Mono.empty();
        });
    }

    @GetMapping
    Mono<List<RouteDefinition>> getRoute(){
        return Mono.just(memery);
    }

    @Override
    public Flux<RouteDefinition> getRouteDefinitions() {
        return Flux.fromIterable(memery);
    }

    @Override
    public Mono<Void> save(Mono<RouteDefinition> route) {
        return Mono.empty();
    }

    @Override
    public Mono<Void> delete(Mono<String> routeId) {
        return Mono.empty();
    }
}

Aware

BeanNameAware

beanNameAware可以获得容器中Bean的名称，作用于每一个Bean。当bean被创建的时候设置他的名字，在基本properties填充完成以后，init调用前执行

摘自： spring-beans:5.3.4 org.springframework.beans.factory.BeanNameAware

Set the name of the bean in the bean factory that created this bean.

Invoked after population of normal bean properties but before an init callback such as {@link InitializingBean#afterPropertiesSet()} or a custom init-method.

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package com.example.demo;

import org.springframework.beans.factory.BeanNameAware;
import org.springframework.stereotype.Component;

@Component
public class BeanNameAwareDemo implements BeanNameAware {
    @Override
    public void setBeanName(String name) {
        System.out.println(name);
    }
}

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