spring-core源码走读

asm

ASM is an all purpose Java bytecode manipulation and analysis framework.
ASM是一个万能的java字节码操纵和分析框架

cglib

Byte Code Generation Library is high level API to generate and transform JAVA byte code
高层级的生成和转换Java字节码的字节码生成库

cglib github地址

objenesis

Objenesis is a small Java library that serves one purpose:To instantiate a new object of a particular class.
Objenesis是一个只为特殊类初始化对象小型Java库

objenesis官网

lang

定义八个注解
- NonNull.class
- NonNullApi.class
- NonNullFields.class
- Nullable.class
- UsesJava7.class
- UsesJava8.class
- UsesSunHttpServer.class
- UsesSunMisc.class

util

backoff

重试算法

定义退避算法
- BackOff.class
- BackOffExecution.class
- ExponentialBackOff.class 指数重试间隔实现
- FixedBackOff.class 固定重试间隔实现
用于封装重试逻辑

使用说明

 BackOffExecution exec = backOff.start();

 // In the operation recovery/retry loop:
 long waitInterval = exec.nextBackOff();
 if (waitInterval == BackOffExecution.STOP) {
     // do not retry operation
 }
 else {
     // sleep, e.g. Thread.sleep(waitInterval)
     // retry operation
 }
 }

测试代码

package com.zby.util.backoff;

import java.util.Date;

import org.springframework.util.backoff.BackOff;
import org.springframework.util.backoff.BackOffExecution;
import org.springframework.util.backoff.ExponentialBackOff;
import org.springframework.util.backoff.FixedBackOff;

public class BackoffDemo {

  public static void main(String[] args) throws Exception {
    //BackOff backOff = new FixedBackOff(1000, 10);
    BackOff backOff = new ExponentialBackOff(500, 2);
    BackOffExecution backOffExecution = backOff.start();
    int successTime=7;
    for(int i=0;;i++) {
      System.out.println("重试："+backOffExecution);
      long waitInterval = backOffExecution.nextBackOff();
      if (waitInterval == BackOffExecution.STOP) {
        System.out.println("执行失败：" + backOffExecution);
        break;
      } else {
        Thread.sleep(waitInterval);
        System.out.println("准备执行操作，当前时间："+new Date());
        boolean success = operation(successTime==i);
        if(success) {
          break;
        }
      }
    }

  }

  public static boolean operation(boolean success) {
    System.out.println("执行结果："+success);
    return success;
  }

}

可以封装一下把公共代码封装起来，提供重试机制，如：

package com.zby.util.backoff;

import java.util.Date;

import org.springframework.util.backoff.BackOff;
import org.springframework.util.backoff.BackOffExecution;
import org.springframework.util.backoff.FixedBackOff;

public abstract class FixedBackOffRunnable implements Runnable{
  
  private BackOffExecution backOffExecution;
  
  public FixedBackOffRunnable(long interval, long maxAttempts) {
    BackOff backOff = new FixedBackOff(interval, maxAttempts);
    backOffExecution = backOff.start();
    
  }
  
  public void run() {
    while (true) {
      System.out.println("重试：" + backOffExecution);
      long waitInterval = backOffExecution.nextBackOff();
      if (waitInterval == BackOffExecution.STOP) {
        System.out.println("执行失败：" + backOffExecution);
        break;
      } else {
        try {
          Thread.sleep(waitInterval);
        } catch (InterruptedException e1) {
          e1.printStackTrace();
        }
        System.out.println("准备执行操作，当前时间：" + new Date());
        boolean retry=false;
        try {
          doRun();
        } catch (RetryableExeception e) {
          retry=true;
        }
        if(!