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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

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 InjectionSpring

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 SecuritySigning

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

Shepherd Advanced Notes

Apr 10, 2023 · Backend Development

Understanding Spring @Conditional and Its Derived Annotations

This article explains how Spring Boot’s @Conditional annotation works, shows how to implement custom Condition classes for language switching, and reviews the suite of derived annotations such as @ConditionalOnBean, @ConditionalOnMissingBean, @ConditionalOnClass, @ConditionalOnMissingClass, and @ConditionalOnProperty with concrete code examples.

ConditionalOnBeanConditionalOnPropertyDependency Injection

0 likes · 9 min read

Understanding Spring @Conditional and Its Derived Annotations

Shepherd Advanced Notes

Apr 3, 2023 · Backend Development

Deep Dive into Spring’s @ComponentScan: Usage and Underlying Mechanics

This article explains why Spring Boot is popular, how @ComponentScan discovers @Component, @Controller, @Service, and @Repository beans across packages, demonstrates usage with code examples, and details the internal processing flow involving ConfigurationClassPostProcessor and related parsers.

ConfigurationDependency InjectionSpring

0 likes · 15 min read

Deep Dive into Spring’s @ComponentScan: Usage and Underlying Mechanics

Shepherd Advanced Notes

Mar 30, 2023 · Backend Development

Deep Dive into Spring’s @Import: Usage, Three Scenarios, and Internal Mechanics

This article explains Spring's @Import annotation, compares it to @Bean, demonstrates three distinct usage patterns with concrete code examples, and walks through the underlying processing performed by ConfigurationClassPostProcessor and related internal methods.

JavaSpring Bootimport

0 likes · 16 min read

Deep Dive into Spring’s @Import: Usage, Three Scenarios, and Internal Mechanics

Shepherd Advanced Notes

Mar 27, 2023 · Databases

Why MySQL Uses B+ Trees for Indexing

The article explains the fundamentals of tree data structures, compares B, B+, B*, and red‑black trees, and shows how B+ trees reduce disk I/O and improve range query performance, which is why MySQL adopts B+ trees for its indexes.

B+ TreeMySQLdata structures

0 likes · 15 min read

Shepherd Advanced Notes

Mar 22, 2023 · Databases

Mastering MySQL Indexes: Advanced Concepts and Practical Tips

This article provides a comprehensive deep‑dive into MySQL indexing, covering the definition, pros and cons, differences between clustered and non‑clustered indexes, InnoDB vs MyISAM implementations, B+Tree structure, capacity calculations, adaptive hash indexes, index pushdown optimization, and how to interpret EXPLAIN output to verify index usage.

Adaptive Hash IndexB+ TreeIndex Pushdown

0 likes · 18 min read

Mastering MySQL Indexes: Advanced Concepts and Practical Tips