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Shepherd Advanced Notes

Dedicated to sharing advanced Java technical insights, daily work snippets, and the power of persistent effort.

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Latest from Shepherd Advanced Notes

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Shepherd Advanced Notes

Jul 17, 2023 · Fundamentals

How to Pass Values Between Parent and Child Threads with InheritableThreadLocal and TransmittableThreadLocal

The article explains why regular ThreadLocal cannot share data from a parent thread to its child, introduces InheritableThreadLocal as a built‑in solution, shows its limitation with thread‑pool reuse, and demonstrates how Alibaba's TransmittableThreadLocal overcomes this issue with concrete code examples and output.

InheritableThreadLocalJavaThreadLocal

0 likes · 10 min read

How to Pass Values Between Parent and Child Threads with InheritableThreadLocal and TransmittableThreadLocal

Shepherd Advanced Notes

Jul 10, 2023 · Fundamentals

Understanding ThreadLocal: Usage, Implementation, and Memory Leak Risks

The article explains Java's ThreadLocal mechanism, detailing how each thread maintains its own ThreadLocalMap, provides practical code examples, examines the underlying source implementation—including set and get methods—and discusses potential memory‑leak pitfalls and ways to avoid them.

JavaSpringThreadLocal

0 likes · 11 min read

Understanding ThreadLocal: Usage, Implementation, and Memory Leak Risks

Shepherd Advanced Notes

Jul 4, 2023 · Backend Development

Implement Distributed Log Tracing in Spring Boot with MDC and traceId

This guide explains how to add a unique traceId to each request in a Spring Boot application, configure Logback/MDC to record it, propagate the ID across microservice calls and asynchronous threads using OpenFeign, RestTemplate, and TransmittableThreadLocal, enabling complete distributed log tracing.

Distributed TracingLogbackMDC

0 likes · 18 min read

Implement Distributed Log Tracing in Spring Boot with MDC and traceId

Shepherd Advanced Notes

Jun 27, 2023 · Backend Development

Implementing Distributed Locks in Spring Boot with Redisson

This article explains how Redisson extends Redis to provide a rich set of distributed Java objects and services, walks through integrating Redisson into a Spring Boot project, demonstrates various lock types (reentrant, read‑write, semaphore, latch) with code examples, and details the internal watchdog mechanism that guarantees atomic lock acquisition and automatic renewal.

Distributed LockJavaRedis

0 likes · 19 min read

Implementing Distributed Locks in Spring Boot with Redisson

Shepherd Advanced Notes

Jun 19, 2023 · Backend Development

Elegant Unified Response and Global Exception Handling in Spring Boot

The article explains how Spring Boot projects can adopt a standard JSON response structure using a generic ResponseVO class and achieve automatic wrapping and global exception handling through a custom @ResponseResultBody annotation combined with ResponseBodyAdvice and @ControllerAdvice, reducing repetitive code and improving robustness.

ResponseBodyAdviceResponseVORestControllerAdvice

0 likes · 14 min read

Elegant Unified Response and Global Exception Handling in Spring Boot

Shepherd Advanced Notes

Jun 12, 2023 · Backend Development

How Spring Solves Circular Bean Dependencies with a Three‑Level Cache

The article explains Spring's three‑level cache mechanism for resolving singleton circular bean dependencies, walks through bean lifecycle stages, compares field, setter and constructor injection, shows configuration to enable circular references, and details the internal code paths that expose early bean references.

Bean LifecycleDependency InjectionSingleton

0 likes · 17 min read

How Spring Solves Circular Bean Dependencies with a Three‑Level Cache

Shepherd Advanced Notes

Jun 6, 2023 · Backend Development

Designing an Enterprise-Scale Short URL Service for Hundreds of Millions of Requests

The article details the background, design choices, compression code generation methods, database schema, high‑concurrency handling, and implementation of an enterprise‑grade short‑URL service that pre‑generates collision‑free codes to achieve high performance and secure redirection.

Base64 encodingHigh concurrencyRedis

0 likes · 19 min read

Designing an Enterprise-Scale Short URL Service for Hundreds of Millions of Requests

Shepherd Advanced Notes

May 8, 2023 · Backend Development

Elegant Ways to Boost API Data Security in Spring Boot

The article explains how to protect Spring Boot APIs from unauthorized data access by adding data‑level permission checks, encrypting request parameters with AES and RSA, signing requests with SHA1WithRSA, and encapsulating the logic in a reusable @ApiSecurity annotation and AOP aspect.

AOPAPI SecurityAnnotation

0 likes · 22 min read

Elegant Ways to Boost API Data Security in Spring Boot

Shepherd Advanced Notes

Apr 24, 2023 · Backend Development

Understanding the Full Lifecycle of Spring Beans: From Instantiation to Destruction

This article walks through every stage of a Spring Bean's lifecycle—including instantiation, property population, initialization callbacks, usage, and destruction—while providing concrete code examples, execution traces, and an analysis of the underlying Spring source methods.

Bean LifecycleBeanPostProcessorIOC

0 likes · 13 min read

Understanding the Full Lifecycle of Spring Beans: From Instantiation to Destruction

Shepherd Advanced Notes

Apr 19, 2023 · Backend Development

Spring Extension Point (Part 1): Understanding PostProcessor Mechanisms

This article explains Spring's core post‑processor extension points—BeanDefinitionRegistryPostProcessor, BeanFactoryPostProcessor, and BeanPostProcessor—detailing their purpose, execution order, concrete code examples, and how they fit into the bean lifecycle, including advanced interfaces like InstantiationAwareBeanPostProcessor.

Bean LifecycleDependency InjectionJava

0 likes · 14 min read

Spring Extension Point (Part 1): Understanding PostProcessor Mechanisms