This tutorial demonstrates how to replace verbose manual checks in Java services with Spring's javax.validation annotation‑based validation, covering built‑in constraints, Maven setup, DTO annotations, validation groups, custom validators, and a global exception handler for unified error responses.
This tutorial explains how to build a lightweight log management module by defining a custom @SystemLog annotation, using Spring AOP to capture method execution details, and sending the log data through RabbitMQ via Spring Cloud Stream for asynchronous persistence in a database.
This article explains the fundamentals of remote procedure call (RPC), presents a complete system architecture diagram, and provides a step‑by‑step implementation of a custom rpc‑spring‑starter using Java, Spring, Zookeeper for service registration, Netty for network communication, and dynamic proxy techniques for client‑side invocation.
This article introduces the Guava‑Retrying library for Java, explains how to add its Maven dependency, demonstrates building a Retryer with customizable retry conditions, stop strategies, wait strategies, and listeners, and provides detailed code examples illustrating each component.
This article explains the origins and purpose of Spring transactions, demonstrates how to quickly set them up with code examples, explores key features and common pitfalls, and provides an in‑depth comparison of the REQUIRED, REQUIRES_NEW, and NESTED propagation types for robust backend development.
This document lists the complete set of lecture PDFs, videos, and supplemental files for a Java backend development curriculum, covering data structures and algorithms, Spring Framework, JVM fundamentals, concurrency, cloud native concepts, and interview-focused topics across eleven chapters.
This article explains common pitfalls of Spring's transaction management—including AOP proxy limitations, unchecked exception handling, self‑invocation, asynchronous execution, multiple data sources, and large transaction issues—and provides practical solutions such as using class‑based proxies, configuring rollback rules, and splitting transactions into smaller units.
This article explains why the Controller layer is essential, identifies common pitfalls such as tangled validation and inconsistent responses, and demonstrates how to refactor Spring MVC controllers using a unified Result wrapper, ResponseBodyAdvice, proper String handling, JSR‑303 validation, custom validators, and global exception handling to produce clean, maintainable backend code.
This article demonstrates how to leverage Spring's ApplicationEvent mechanism to decouple business logic, showing both synchronous and asynchronous event publishing, custom event definitions, listener implementations, unit testing, and enabling async processing with @EnableAsync and @Async annotations.
This article demonstrates how Spring's @Transactional rolls back only RuntimeException subclasses, shows the failure to roll back a checked Exception, and explains how to use rollbackFor to ensure proper transaction rollback for all exception types.
This article provides a comprehensive analysis of Spring AOP, covering its core concepts, configuration parsing, BeanFactoryPostProcessor and BeanPostProcessor mechanisms, namespace handling, the creation of advisors and advice from @Aspect annotations, and the proxy generation process that enables method interception.
This article explains how Spring implements various design patterns—including Simple Factory, Factory Method, Singleton, Adapter, Decorator, Proxy, Observer, Strategy, and Template Method—detailing their implementation approaches, underlying principles, and practical code examples within the Spring container.
This article explains Spring’s transaction propagation behaviors, rollback mechanisms, common pitfalls such as self‑invocation and non‑public methods, and demonstrates how to correctly use @Transactional with AOP proxies, including practical code examples and solutions for ensuring transaction consistency.
This article explains Java reflection’s core concepts, how the JVM dynamically loads Class objects, and provides practical examples—including field retrieval, caching strategies, and integration with Spring—to help developers harness reflection for dynamic code manipulation while avoiding common pitfalls.
This article explains how to use Spring ApplicationEvent to decouple business logic, showing step‑by‑step code for defining custom events, creating listeners with both ApplicationListener and @EventListener, publishing events synchronously and asynchronously, enabling async processing, and verifying behavior with unit tests.
This article outlines the latest Spring Framework 5.3.20 release, highlighting new GraphQL MIME support, SAML logout policy tweaks, numerous bug fixes—including property precedence and logging issues—and a comprehensive list of updated third‑party dependencies.
This article demonstrates how Spring's @Transactional annotation rolls back transactions only for RuntimeException subclasses, shows practical MySQL update tests that trigger ArithmeticException, and explains how to configure rollback for checked exceptions using rollbackFor, with complete code examples.
This article shares several practical coding techniques for backend development, including how to commit Kafka transactions safely, simplify Redis distributed lock usage with Redisson, implement AOP-based method locking, and decouple business logging using thread pools and asynchronous processing.
This article shares practical development techniques, including how to safely commit Kafka messages within transactions, simplify Redis distributed locks with Redisson, implement an AOP‑based lock annotation for method-level locking, and decouple business logging using asynchronous thread pools and helper utilities.
This article explains traditional session and authentication mechanisms, the problems of session sharing in clustered and multi‑service environments, and presents practical SSO solutions—including CAS‑based single sign‑on and its differences from OAuth2—accompanied by complete Java Spring code examples.
The article explains why a unified response format like ResultBean is essential for Java backend APIs, outlines common interface design mistakes, provides concrete coding guidelines for controllers, and demonstrates how to use AOP for exception handling and logging, all illustrated with practical code examples.
This article demonstrates how to use Spring ApplicationEvent to decouple complex business logic, showing both synchronous and asynchronous event publishing, custom event creation, listener implementation, unit testing, and enabling async execution in a Spring Boot application.
This article explains the concepts of coupling, Inversion of Control, and Dependency Injection in the Spring framework, demonstrates various bean instantiation methods—including no‑arg constructors, static and instance factory methods—and provides a complete example of configuring and using Spring beans in a Java application.
This article explains Spring's @Transactional annotation, detailing the various transaction propagation options, the default rollback behavior for unchecked exceptions, common pitfalls such as self‑invocation and non‑public methods, and how to use AOP proxies like AopContext.currentProxy and @EnableAspectJAutoProxy to ensure proper transaction management.
This article compares three stock‑deduction approaches—single‑record MySQL, sharded MySQL, and Redis with Lua scripts—analyzes their performance and concurrency issues, and provides complete Java/Spring code for a Redis‑based solution including distributed locking and initialization callbacks.
This article provides a comprehensive analysis of MyBatis, covering its core architecture, the process of obtaining SqlSessionFactory and SqlSession, the dynamic proxy mechanism for mappers, the execution flow of SQL statements, the plugin system, first‑ and second‑level caching strategies, and how Spring manages MyBatis mappers through factory beans and import registrars.
This article compares three stock‑deduction approaches—single‑record MySQL, multi‑record MySQL, and Redis incrby—analyzes their concurrency drawbacks, and provides a complete Spring Java implementation using a Lua script, distributed lock, and callback for initializing inventory.
The article explains why a unified response format (ResultBean) is essential for Java Spring APIs, lists common interface design mistakes, provides concrete coding guidelines for controllers, and demonstrates how to use AOP for logging and exception handling with clear code examples.
This guide explains why graceful shutdown matters for Java services, describes the three JVM termination scenarios, demonstrates normal, abnormal, and forced shutdowns with code, and provides best‑practice rules and real‑world examples such as Spring integration and custom signal handling.
This article demonstrates how to leverage Spring Application Events to decouple business logic, showing step‑by‑step examples of defining custom events, listeners, publishing events synchronously, and enabling asynchronous handling with @EnableAsync and @Async annotations, complete with code snippets and test results.
The article explores how Java has survived massive industry shifts through a vibrant community, extensive open‑source frameworks, continual language evolution, and emerging opportunities like WebAssembly, illustrating why it stays a cornerstone of enterprise and creative software development.
This article explains how to implement a flexible, annotation‑driven data‑masking solution for Java backend services by defining custom masking annotations, serializers, and integrating them into Spring's ObjectMapper to automatically mask sensitive fields in API responses.
This article explains how to use Spring's org.springframework.util.StopWatch and Apache Commons Lang3 StopWatch to accurately measure and analyze Java code execution time, covering setup, basic usage, advanced features, thread‑safety considerations, and practical code examples for both libraries.
This article explains Spring's @Transactional annotation, detailing propagation behaviors, rollback rules, common pitfalls such as self-invocation and non‑public methods, and provides practical solutions using AOP proxies and AopContext to ensure proper transaction management in Java backend applications.
This article describes a backend solution that uses Redis for configurable rate‑limiting and interface switches, and Hystrix for circuit‑breaking, detailing the requirements, AOP‑based approach, and full Java code implementation for managing non‑core query overloads.
This article demonstrates how to create custom Spring events, define listeners, publish events, and enable asynchronous handling with @EnableAsync and @Async annotations, providing complete code examples and test results for both synchronous and asynchronous scenarios in a Spring Cloud Alibaba micro‑service environment.
This article explores the complete lifecycle of graceful shutdown for Java server applications, detailing how operating‑system signals, JVM shutdown hooks, and framework‑level mechanisms in Spring, Dubbo, and Netty collaborate to safely stop services while preserving in‑flight requests and resources.
This article introduces a Redis lazy‑loading caching strategy combined with Guava local cache, presents design diagrams and Java code examples, analyzes its advantages and disadvantages, and discusses suitable scenarios such as precise query workloads and micro‑service architectures.
This article introduces Spring Expression Language (SpEL), explains its common syntax, demonstrates quick-start examples, shows real-world usage with AOP monitoring, and outlines its internal implementation, providing a concise guide for backend developers working with Spring.
This article provides a detailed tutorial on Activiti 7 workflow engine, covering workflow fundamentals, BPMN modeling, environment setup, Maven dependencies, configuration files, process deployment, instance creation, task querying and completion, process definition management, resource extraction, and historical data inspection, all illustrated with Java code examples.
This article explains how MapStruct simplifies Java object‑to‑DTO mapping by defining mapping rules, demonstrates various features such as default methods, abstract mappers, multiple parameters, @MappingTarget updates, handling of fields without getters/setters, Spring integration, and custom type conversions with clear code examples.
This article explains how to solve cross‑server WebSocket communication in a distributed Java application by using a message queue (Redis or Kafka) to broadcast messages, storing user‑node mappings, and providing complete Spring configuration, code examples, and a demo page for end‑to‑end testing.
This article explains the fundamentals of RPC, describes the components involved in a basic remote call, and provides a complete Java implementation using Spring, custom XML configuration, Netty for network communication, and Zookeeper for service registration and discovery, complete with server and client code examples.
This article explains Spring's core.convert package, the ConversionService API, Formatter SPI, default and custom formatters, annotation-based formatting, and how to configure and use them in Spring MVC and Spring Boot applications.
This article explains how to leverage Spring's org.springframework.util.StopWatch and Apache Commons Lang3 StopWatch for precise Java performance measurement, covering setup, usage examples, source code insights, important considerations, and practical code snippets for both libraries.
This article explains how to mask sensitive fields such as ID numbers, phone numbers, and addresses in Java APIs by creating a custom @Sensitive annotation, defining masking strategies, implementing a Jackson serializer, and testing the solution with a Spring REST controller, providing complete code examples and sample output.
This article explains why the @Transactional annotation in Sharding-JDBC can roll back across multiple databases in some scenarios, clarifies the cases it truly supports, details the internal rollback implementation, and outlines the situations where local transactions cannot guarantee distributed consistency.
This article explains the principles and implementations of Java's built‑in SPI, Dubbo's enhanced SPI, and Spring's SPI mechanisms, compares their designs, walks through concrete code examples, and shows how they can be applied for dynamic extension in real projects.
This article explains the architecture and implementation of a permission system that provides front‑end menu rendering, unified single sign‑on, RBAC‑style permission management, and backend request authorization using Java and Spring technologies.
This article explains the fundamentals of database transactions, the ACID properties, Spring's @Transactional support, various propagation behaviors and isolation levels, and provides practical code examples for both declarative and programmatic transaction management in Java backend development.
This article explains how Spring's @Scheduled annotation works, covering configuration options like cron, fixedDelay and fixedRate, the internal processing by ScheduledAnnotationBeanPostProcessor, method reflection, task registration with ScheduledTaskRegistrar, and the underlying execution using ThreadPoolTaskScheduler and ScheduledThreadPoolExecutor.
This article presents a one‑stop solution that uses dynamic proxies, Spring extensions, and Dubbo generic invocation to let overseas applications call domestic Dubbo services via HTTP without refactoring existing callers, reducing workload and eliminating previous drawbacks.
This article demonstrates how to design a simple Calculator interface, provide both annotation‑based and reflection‑based implementations, and achieve hot deployment by loading user‑supplied JAR files at runtime, including dynamic bean registration and removal in a Spring container.
This article provides a comprehensive tutorial on implementing Single Sign-On using the CAS (Central Authentication Service) framework, covering the concepts of SSO and CAS, required development environment, server-side deployment, client configuration, and end‑to‑end testing with detailed code examples.
This article provides an in‑depth tutorial on Activiti 7 workflow management, covering workflow concepts, system architecture, BPMN modeling, environment setup, Maven dependencies, database configuration, deployment methods, process execution, task handling, and historical data retrieval for Java backend development.
This article explains how to replace repetitive try‑catch blocks in Java Spring applications with a clean, centralized exception handling strategy using @ControllerAdvice, custom Assert utilities, and enum‑based error codes, while also showing how to return consistent error responses across services.
This article explains what circular dependencies are in Spring, describes the three‑level cache mechanism (singletonObjects, earlySingletonObjects, singletonFactories), shows how it resolves singleton bean cycles, and outlines scenarios where the cache cannot break the dependency, such as constructor injection and prototype beans.
This article provides an in‑depth tutorial on Spring Validation, covering basic usage, dependency configuration, requestBody and requestParam validation, unified exception handling, advanced techniques such as group, nested, and collection validation, custom validators, programmatic validation, fail‑fast mode, and the underlying implementation mechanisms.
This article explains how Spring developers can explicitly control bean instantiation order by using dependency‑injection annotations such as @Autowired, @Resource, @Inject, and the @DependsOn annotation, detailing the underlying processors and showing code examples for each mechanism.
To pre‑warm business data before a Spring web service accepts requests, the article explains two approaches—implementing the SmartLifecycle interface with proper phase ordering and using a ContextRefreshedEvent listener—while highlighting code examples, execution timing, and cautions against asynchronous overrides.
This comprehensive guide walks through Spring’s fundamentals—including IoC, DI, core modules, common annotations, AOP concepts, transaction management, MVC workflow, and Spring Boot auto‑configuration—while also covering advanced topics such as bean lifecycle, circular dependencies, proxy mechanisms, and an introduction to Spring Cloud.
This guide explains Spring’s Assert utilities and a comprehensive set of core helper classes—including ObjectUtils, StringUtils, CollectionUtils, FileCopyUtils, ResourceUtils, StreamUtils, ReflectionUtils, AopUtils, and AopContext—detailing their purpose, typical use cases, and providing concise code examples for each method.
SPI (Service Provider Interface) is a service discovery mechanism used in Java, Spring, and Dubbo that loads implementations via configuration files, enabling runtime extensibility, decoupling, and plug‑in architecture, with examples ranging from custom interfaces to MySQL drivers and Dubbo extensions.
This article details Meituan's internal Sonic IDEA plugin, explaining hot‑deployment concepts, why they matter, the technical challenges, and Sonic's architecture—including agents, instrumentation, class reloading, Spring Bean/XML/MyBatis reloads, and real‑world deployment experience—showing how code changes can become effective in seconds instead of minutes.
This article explains how to implement the Singleton pattern in Java using both an enum‑based approach and a static inner‑class technique, providing thread‑safe examples from Spring Data JDBC and MyBatis along with Maven dependency snippets and detailed code illustrations.
This article explains how SQL injection can exploit a Java Spring course‑selection system by concatenating user input into SQL statements, demonstrates various injection techniques such as always‑true conditions and UNION queries, and provides multiple defensive measures including prepared statements, type checking, permission restrictions, and request‑parameter filtering.
Explore multiple Spring bean injection techniques—including XML configuration, annotation-driven @Configuration/@Bean, @Import, FactoryBean, and BeanDefinitionRegistryPostProcessor—through clear explanations, code samples, and practical examples, highlighting their advantages, drawbacks, and how to integrate them into a Spring application.
This article demonstrates how to dramatically speed up updating tens of thousands of records in a Spring‑MyBatis application by switching from automatic per‑operation commits to manual transaction control, applying multithreaded processing, tuning the Hikari connection pool, and using SQL UNION‑based batch updates.
This article explains how Spring Kafka’s KafkaMessageListenerContainer and ConcurrentMessageListenerContainer work, details their start-up process and internal consumer threads, shows how @KafkaListener bridges business logic, and provides configuration examples for single‑message and batch processing in Spring Boot.
This article explores twelve practical multithreading use cases in Java, ranging from simple scheduled tasks and listeners to Excel imports, remote call aggregation, user context handling, MDC logging, high‑concurrency simulation, Kafka message processing, atomic counters, and delayed jobs, providing code examples and best‑practice tips for each scenario.
This article discusses practical techniques for Java developers, covering bean conversion using DTOs and Spring utilities, validation with JSR‑303, leveraging Lombok for cleaner code, applying design patterns, and systematic refactoring to improve readability, maintainability, and overall code quality in backend projects.
This article explains the purpose and usage rules of Spring's @Async annotation, compares built‑in executors, demonstrates how to enable @Async, and provides detailed examples of custom thread‑pool configurations, multiple pool management, and important source‑code analysis for robust asynchronous processing in Java backend applications.
This article introduces MapStruct’s new Spring extension, shows how to replace manual BeanUtil conversions with generated mappers, explains the Spring Converter interface, and demonstrates custom configuration and integration with ConversionService for seamless DTO/VO/PO transformations in Java backend projects.
This article explains how to replace manual BeanUtil mapping with MapStruct, leverage Spring's Converter interface, and use the MapStruct Spring Extensions plugin to automatically register mappers with ConversionService, including custom adapter configuration and integration of built‑in Spring converters.
This article explores the concept of fully interface‑based domain modeling, demonstrates how to design domain objects as interfaces, shows repository implementations for JPA, MyBatis and Elasticsearch, discusses association handling, and explains how such designs enable seamless switching between monolithic, clustered and microservice deployments.
This article explains how MapStruct, a Java annotation‑processor library, can automatically generate mapper implementations to convert between entities and DTOs, covering basic usage, default methods, abstract classes, multiple source parameters, update operations, handling fields without getters/setters, Spring injection and custom type conversions.
This article demonstrates how to create a request‑logging aspect in Spring Boot using AOP annotations, shows code for pointcuts, advices, high‑concurrency optimizations, exception handling, and trace‑ID propagation, and explains the underlying concepts and practical tips.
This article provides an in‑depth tutorial on Spring Validation, covering basic usage, dependency setup, requestBody and requestParam validation, DTO constraints, group and nested validation, collection handling, custom validators, programming‑style validation, fail‑fast mode, and the underlying implementation mechanisms in Spring MVC.
This article explores practical Java backend techniques, including IDE selection, domain vs entity naming, DTO conversion strategies with BeanUtils and custom interfaces, validation with JSR‑303, Lombok shortcuts, builder patterns, static constructors, and design‑pattern considerations, offering concrete code examples and refactoring tips for seasoned developers.
Field injection in Spring looks concise, but it introduces hidden dependencies, violates the Single Responsibility Principle, hampers immutability, and tightly couples code to the DI container; the article compares constructor, setter, and field injection, explains their drawbacks, and recommends using constructors for mandatory dependencies and setters for optional ones.
This Spring AOP tutorial explains how to modularize cross‑cutting concerns such as timing by defining an aspect with @Before, @After, @AfterReturning, @AfterThrowing and @Around advice, demonstrates refactoring a calculation service, and compares Spring’s proxy mechanisms to a custom JDK dynamic proxy implementation.
This article explains the background, concepts, and implementation details of Aspect‑Oriented Programming in Java, covering joinpoint interface design, advice abstraction, static and dynamic weaving, and how Spring AOP applies these principles with illustrative code and diagrams.
This article explains how Spring's three‑level cache (singleton, early‑singleton, and singleton‑factory caches) works together with bean post‑processors to break circular dependencies and correctly create AOP proxies, while also showing how to disable circular references when needed.
This article compares native JDK ScheduledExecutorService, Spring Task, Redis‑based approaches, and popular distributed scheduling frameworks such as Quartz, Elastic‑Job, LTS, and XXL‑Job, providing code examples, usage scenarios, advantages, and best‑practice recommendations for implementing reliable timed jobs in microservice environments.
This article explains three common situations where Spring's @Transactional annotation becomes ineffective—non‑public methods, internal self‑calls, and swallowed exceptions—detailing the underlying proxy mechanism, code examples, test results, and practical workarounds to ensure proper transaction management.
This article provides a detailed overview of the most frequently used Spring annotations—including core, MVC/REST, Boot, stereotype, data access, scheduling, and testing annotations—explaining their purposes, usage rules, and providing Java code examples for each.
This article demonstrates how to create a Spring AOP request‑logging aspect that captures IP, URL, HTTP method, class method, parameters, results and execution time, and extends it with high‑concurrency handling, error logging, and TraceId propagation for better traceability.
This article explains how Spring implements broadcast and listener functionality through ApplicationEventPublisher and ApplicationListener, analyzes the underlying bean post‑processor workflow, and provides complete source‑code examples for custom events, publishers, listeners, and a REST client to demonstrate end‑to‑end event handling.
This article explains how to create a Spring AOP request‑logging aspect, covering basic pointcut and advice definitions, parameter extraction, high‑concurrency optimizations with unified JSON logs, exception handling, and adding traceId support for end‑to‑end request tracing.
This article explains how to implement single-node scheduled tasks using JDK's ScheduledExecutorService and Spring @Scheduled, compares Redis‑based approaches with ZSet and key‑space notifications, and reviews popular distributed scheduling frameworks such as Quartz, elastic‑job‑lite, LTS, and XXL‑Job for microservice environments.
This article explores the precise moment a Spring @Transactional transaction is committed relative to a surrounding lock release, revealing that commits occur after the method finishes, and demonstrates how to verify this through source code inspection, debugging techniques, and proper lock‑usage to prevent overselling.
This article explains how to prevent duplicate user requests on the server side by leveraging unique request IDs or business‑parameter MD5 hashes with Redis, provides Java helper utilities, code examples, and practical tips for handling time‑related fields and atomic SETNX operations.
This article presents a design pattern for a unified, annotation‑driven HTTP client in a Spring‑based payment system, detailing custom annotations, dynamic proxy enhancement, and bean registration via FactoryBean and ImportBeanDefinitionRegistrar, with complete code examples and a summary of key concepts.
This article explains three common reasons why the @Transactional annotation may not work in Spring—non‑public methods, self‑invocation, and catching exceptions—provides code examples for each case, and details the underlying proxy and transaction management mechanisms to help developers resolve the issues.
This article details the discovery, official announcement, prerequisite conditions, and step‑by‑step reproduction of the critical Spring Framework remote code execution vulnerability (CVE‑2022‑22965), including exploit payloads, JSP backdoor creation, and practical mitigation insights.
A recent Spring Framework 0‑day remote code execution vulnerability, caused by unsafe use of SerializationUtils#deserialize, affects Java versions above 8, is rated dangerous by security analysts, and highlights the risks of indiscriminate JDK upgrades.
This article compares traditional object creation with Spring’s dependency injection, demonstrating how injecting DAO beans via XML configuration decouples service and data layers, includes Java code examples, test results, and visual analogies of gear systems to illustrate reduced coupling.
This article explains the officially announced Spring Framework remote code execution vulnerability CVE‑2022‑22965, outlines the affected environments, provides upgrade paths for Spring and Spring Boot, and shares safe code‑based mitigation techniques for developers.
This article reveals a newly disclosed Spring framework RCE 0‑day vulnerability caused by unsafe Java serialization, rates it as dangerous, explains why Java 8 remains unaffected, and warns developers against indiscriminate JDK upgrades while comparing it to the Log4j2 incident.
The article investigates the circulating rumors of a massive Spring framework vulnerability, clarifies its actual scope—affecting Java 9+ projects—and explains why the alleged CVE differs from official reports, while warning readers to rely only on verified security advisories.
