Learn how to use Spring's @ControllerAdvice, @ExceptionHandler, @InitBinder, and @ModelAttribute annotations to implement global exception handling, data binding, and pre-processing, including custom exceptions, order control with @Order, and practical code examples for robust backend development.
This article explains the timing of Spring's @Transactional commit relative to lock release, analyzes why committing after unlock can cause overselling, shows how to trace the transaction lifecycle in the source code, and offers practical solutions to ensure atomicity in high‑concurrency scenarios.
This article demonstrates how to design a simple Calculator interface in Java, implement it using both Spring‑managed and reflection‑based approaches, and achieve hot deployment by loading user‑provided JAR files at runtime, including code for class loading, bean registration, and cleanup.
The article explains how to handle distributed consistency when a financial reimbursement process involves MySQL writes and remote calls to BPM and SAP systems, analyzes failure scenarios, and proposes a split‑transaction approach using a task table, scheduled jobs, and Spring's afterCommit hook.
This article explains the differences between @Autowired and @Resource in Spring, why IDEA warns only on @Autowired field injection, and outlines the pros and cons of constructor, setter, and field injection methods.
This article explores the default behavior of Spring's @Autowired annotation, how to resolve bean name conflicts, use @Qualifier and @Primary, apply @Autowired on constructors, methods, parameters, and collections, and troubleshoot common issues such as missing annotations, filter injection, component scanning, and circular dependencies.
This guide walks through implementing a complete product management module in a Java e‑commerce system, covering Snowflake distributed ID generation, database schema design for SPU and SKU tables, CRUD operations, category‑brand linking, audit workflow, status toggling, batch processing, and logical deletion, all with concrete code examples.
This article explains nine typical scenarios that cause the Spring @Async annotation to fail—ranging from missing @EnableAsync to improper method visibility, return types, static or final modifiers, missing @Service, manual object creation, and incorrect component scanning—providing clear explanations and code examples for each case.
This article explains how to achieve graceful service startup and shutdown in Java projects, covering monolithic and microservice architectures, Spring and SpringBoot mechanisms, service registration with Eureka and Nacos, Kubernetes probes, thread‑pool and MQ graceful termination, and provides practical code examples for each scenario.
This article explains how to design and implement a fixed‑size FIFO export queue in a Java Spring application to control concurrent MySQL data exports, detailing the related entities, code implementation with EasyExcel, a test controller, and observed results.
IDEA flags @Autowired field injection but not @Resource because Spring advises against field injection—seeing it as tightly coupled and hard to test—while @Resource is a standard JSR‑250 annotation, so the IDE applies the warning only to the Spring‑specific @Autowired usage.
This article explains Spring AOP fundamentals, demonstrates XML‑based and annotation‑based configurations, and provides a comprehensive guide to using ProxyFactoryBean—including its properties, proxy‑interface and proxy‑class scenarios, CGLIB considerations, and wildcard interceptor matching—complete with runnable code examples.
The article explains the limitations of Spring's BeanUtils.copyProperties—such as type mismatches, null overwriting, and reflection overhead—and demonstrates how MapStruct provides a faster, compile‑time generated alternative for copying properties between Java objects, with usage examples and Maven setup.
The article explains how moving cache operations out of business code and into Spring Cache annotations—@Cacheable, @CachePut, and @CacheEvict—creates a clean, loosely‑coupled design, simplifies maintenance, and enables custom extensions such as breakdown protection and multi‑level caching for high‑concurrency applications.
This article explains several powerful Lombok annotations—including @onX, @Delegate, @Cleanup, @Builder with @Singular, and @With—showing how they simplify Spring‑based Java code through automatic constructor generation, method delegation, resource management, and fluent builders, while also warning against overuse.
This article explains how Spring solves circular dependencies by using a three‑level cache system, walks through the underlying source‑code execution flow, clarifies the purpose of each cache level, and discusses why the design is essential for AOP‑enabled beans.
This article explains how Spring's @Transactional and @Async annotations can be applied to the same service methods, the implications for transaction boundaries across threads, and the precautions developers must take to maintain data consistency and proper transaction management.
This article examines whether every Service and DAO class in a Spring‑based backend should implement an interface, discusses the three traditional reasons for using interfaces, explains why they often do not hold up, and proposes practical structuring alternatives for single‑ and multi‑implementation scenarios.
This article explains how to use Spring's TransactionSynchronizationManager to detect active transactions and register callbacks that asynchronously send Kafka messages only after a transaction successfully commits, illustrated with a payment‑system case study and complete code examples.
The article details how Dewu’s new product onboarding workflow was refactored into a Spring StateMachine‑driven architecture that separates channel‑specific logic via a Strategy‑pattern operation layer, defines clear enum status domains, and uses guards, actions, and choice states to achieve maintainable, extensible, and idempotent state transitions.
This article provides a comprehensive guide to Spring’s essential infrastructure, covering Java and Spring resource management, environment property handling, type conversion APIs, data binding mechanisms, generic type inspection with ResolvableType, internationalization support, the BeanFactory and ApplicationContext architecture, and the built‑in event system, all illustrated with code examples and diagrams.
This article presents fourteen actionable Java backend code‑optimization techniques—including configuration‑file management, Lombok’s @RequiredArgsConstructor, modularization, exception handling, database query reduction, null‑avoidance, strategic use of design patterns, IDE shortcuts, and efficient collection handling—to help developers write cleaner, more maintainable, and higher‑performance code.
This article explains Spring's bean creation process, focusing on the populateBean method and the AutowiredAnnotationBeanPostProcessor, and shows why static fields are ignored during field injection while also offering a way to inject them via a non‑static @Autowired method.
This article explains the distinct roles of Spring's @Configuration and @Component annotations, demonstrates their behavior through code examples, compares bean initialization and proxy generation, and reveals how Spring's ConfigurationClassPostProcessor and related enhancers ensure singleton beans across method calls.
Explore a comprehensive guide to Spring’s core mechanisms—including resource handling, environment configuration, type conversion, data binding, generic processing, internationalization, BeanFactory, ApplicationContext, and event publishing—complete with detailed explanations, code demos, diagrams, and practical insights for mastering backend development with Spring.
This article explains how to use Spring's TransactionSynchronizationManager to detect active transactions and register synchronization callbacks so that Kafka messages are sent asynchronously after transaction commit, illustrated with a payment‑system logging scenario and complete Java code examples.
This article demonstrates how to use Spring's MethodReplacer to substitute arbitrary bean methods with custom implementations, covering code preparation, bean registration, handling overloaded methods, and XML configuration, all illustrated with a complete runnable example.
This article examines whether a Service layer in Java Spring projects truly requires interfaces, debunking common arguments, exploring development workflows without interfaces, discussing project structuring for single and multiple implementations, and concluding when interfaces are beneficial or unnecessary.
This article introduces Spring 6.2’s Parallel Bean Initialization feature, explains its benefits for reducing startup time, provides step‑by‑step code examples for configuring background bean initialization and a bootstrap executor, compares traditional and concurrent initialization timings, and details the underlying implementation in the Spring container.
This article explains how to design a plug‑in architecture for a data‑governance service that can start, stop, add, or upgrade individual tasks at runtime without restarting the whole service, using a custom URLClassLoader, Spring bean registration, XXL‑Job integration, dynamic configuration updates, and a clean unload process.
The article shows how to replace bulky if‑else logic in Spring Boot by using the strategy pattern together with a factory that autowires all Strategy implementations into a Map, explains the @Autowired semantics for collections, and provides concrete code examples.
This article explains the concept of Service Provider Interface (SPI), demonstrates how Java's ServiceLoader, Spring's SpringFactoriesLoader, and Dubbo's ExtensionLoader implement SPI, compares their configurations and capabilities, and discusses advanced features such as adaptive extensions, IOC/AOP integration, wrappers, and auto‑activation.
This article explains Spring's Resource abstraction, its key methods, built‑in implementations, and how to use ResourceLoader, ResourcePatternResolver, and ResourceLoaderAware for flexible resource access in Spring Boot 2.7 applications.
IntelliJ IDEA 2024.1 introduces full‑line code completion powered by a local deep‑learning model, Java 22 language support, a revamped terminal, sticky lines in the editor, enhanced Maven handling, improved debugging, richer Spring assistance, advanced HTTP client features, and new database tools, all aimed at boosting developer productivity and safety.
This article shares a detailed ByteDance backend interview experience covering three rounds, summarizing essential topics such as Java HashMap internals, Spring circular dependencies, MySQL indexing, OS process/thread concepts, networking protocols, TLS handshake, HTTP/2 features, and common design patterns, providing concise explanations and practical tips.
This article explains the Chain of Responsibility design pattern, demonstrates its use for multi‑step product validation and a reimbursement workflow in Java with Spring, provides UML diagrams, configuration handling, concrete handler implementations, client execution code, and discusses the pattern’s advantages and drawbacks.
Spring supports constructor, setter, and field injection, but field injection is discouraged; @Autowired (Spring‑specific, by‑type) and @Resource (standard, by‑name) differ in defaults and IDE warnings, so prefer constructor injection for required beans, setter injection for optional ones, and only use @Resource for unavoidable field injection to lessen container coupling.
This article introduces a Java library that simplifies file and resource download handling in Spring MVC and WebFlux by using annotations, reactive programming, customizable handlers, source factories, concurrent loading, compression, response writing, and event‑driven logging to support a wide range of download scenarios.
This article explores solutions for managing multiple data sources in a Spring application, covering dynamic routing with AbstractRoutingDataSource, configuration‑file and database‑table approaches, AOP‑based source switching, and custom multi‑transaction handling to ensure consistency across heterogeneous databases.
This guide demonstrates how to use Spring's @Resource annotation to inject collections such as Map, List, and array, as well as single beans, and explains resolution strategies like @Priority, @Primary, BeanFactory, ApplicationContext, @Qualifier, and custom qualifiers.
This guide explains how to define Spring AOP aspects with @Aspect, configure ProxyFactoryBean for fine‑grained proxy control, and create proxies programmatically using ProxyFactory, providing complete code examples and configuration details for Spring 6.1.2.
This article explains how to dynamically manage multiple data sources and ensure transaction consistency across a master and several application databases in Spring by extending AbstractRoutingDataSource, using configuration‑file and database‑table solutions, and implementing a custom multi‑database transaction manager.
This article introduces Spring's BeanWrapper, explains how to set and retrieve simple and nested properties, demonstrates indexed and key‑based access, covers automatic and custom type conversion using PropertyEditorSupport and Converter, and clarifies conversion priority and registration details for backend developers.
This article introduces a Java library that simplifies file download in Spring applications by using a @Download annotation, supporting various source types, reactive and servlet environments, concurrent loading, compression, and customizable handlers, and details its architecture, code examples, and practical considerations.
This article walks through Spring 6.1.2’s bean creation lifecycle, from the refresh entry point to property population, initialization, and disposable bean registration, illustrating each step with concise code examples and detailed explanations.
This guide demonstrates how to use Spring's UriComponentsBuilder and related classes—UriBuilderFactory, ServletUriComponentsBuilder, and MvcUriComponentsBuilder—to construct, encode, and link URIs in various scenarios, providing clear code examples for each step, including handling templates, query parameters, and servlet contexts.
This article compiles a comprehensive Java backend interview guide covering Redis fundamentals, thread creation methods, thread‑pool pitfalls, Spring ecosystem relationships, IoC/AOP principles, shallow vs deep copying, collection cloning, differences between interfaces and abstract classes, and string handling classes, providing concise explanations and code examples for each topic.
This article explains how to improve large‑file upload experiences by using instant transfer (MD5‑based deduplication), chunked upload, and resumable upload techniques, and provides complete Java backend implementations with Redis coordination and code examples using RandomAccessFile and MappedByteBuffer.
This article explains how Spring Boot's @Conditional annotations—covering class, bean, property, resource, web application, and SpEL expression conditions—can be used to conditionally load configuration and beans, with examples and guidance on custom conditions.
IntelliJ IDEA 2024.1 EAP 5 introduces a suite of enhancements—including richer Spring, Quarkus, and Micronaut support, smarter Spring Bean autocompletion, improved HTTP Client with PKCE and Netty, and advanced GitHub Actions assistance—designed to streamline backend development, debugging, and CI/CD workflows.
This article introduces Spring 6's new HTTP Interface feature, walks through building a Spring Boot project with a User entity, a REST controller, an HTTP Interface definition, and a test using WebClient, while explaining related annotations and the need for Spring Reactive Web dependencies.
The article surveys frequent Java development mistakes—such as NullPointerExceptions, unsafe object equality, improper null handling, manual mapping errors, thread‑safety and thread‑pool misuse, swallowed exceptions, Spring bean initialization problems, memory leaks, performance traps, and transaction misconfigurations—while offering practical fixes like annotations, Optional, MapStruct, concurrent utilities, immutable wrappers, bounded executors, unified logging, and proper AOP usage.
This article demonstrates how to use Spring Framework 6's new HTTP Interface feature by creating a simple Spring Boot application, defining a User entity and controller, implementing an HTTP Interface with @GetExchange, and testing the service via a WebClient proxy, while covering required dependencies and key annotations.
This article provides a comprehensive analysis of the Spring framework, covering its core concepts, main components such as IoC container, AOP, data access and web support, its modular and declarative features, and the author’s personal learning experiences and best‑practice insights.
This article showcases clever Lombok tricks—including @onConstructor, @Delegate, @Cleanup, @Singular, @Builder, and @With—demonstrating how they simplify Java code, improve readability, and integrate with Spring for dependency injection while warning against overuse.
This article provides a comprehensive guide to Spring 5.3.30 utility classes, covering resource handling, object and array utilities, number conversion, stream operations, system property resolution, collection helpers, AOP proxy tools, BeanFactory shortcuts, annotation processing, bean manipulation, validation, XML/HTML parsing, web utilities, and URI handling, all illustrated with clear code examples.
To prevent performance degradation during large MySQL data exports, this article presents a Java Spring implementation of a bounded FIFO export queue, detailing the ExportQueue class, abstract export handling with EasyExcel, concrete service and controller code, and test results demonstrating queue limits and concurrency considerations.
This guide explains how to configure and use Spring Validation (JSR‑303) in Spring Boot, covering dependency setup, @Valid vs @Validated, request body and parameter validation, group, nested and collection checks, custom constraints, programmatic validation, fail‑fast mode, and underlying implementation details.
This article compiles a comprehensive Java backend interview guide covering network protocols, HTTP characteristics, core data structures and algorithms, MySQL logging mechanisms, Elasticsearch full‑text search, Kafka reliability and deduplication, common micro‑service components, load‑balancing algorithms, and essential Spring concepts such as IoC, AOP, transactions, and MVC workflow.
This article explains how the Spring framework discovers and registers custom annotations by using @ComponentScan, ClassPathScanningCandidateComponentProvider, and TypeFilter mechanisms, guiding developers to configure package scanning, apply meta‑annotations, and optionally implement custom filters for flexible bean management.
The article presents a Java Spring solution that uses a custom URLClassLoader to dynamically load, register, and unload governance task JARs as Spring beans and XXL‑Job handlers at runtime, with configuration persistence via YAML or Nacos and Maven Shade packaging for seamless updates without service restarts.
The article explains how to execute parallel tasks with CompletableFuture, why @Async cannot guarantee transactional integrity in a multi‑threaded Spring environment, and presents a programmatic transaction approach—including copying transaction resources between threads—to achieve consistent commit or rollback across concurrent operations.
This article explains eight practical ways to control which DAO implementation Spring injects, covering @Qualifier, bean naming, custom qualifiers, manual lookup, profile‑based beans, @Primary, and @Priority, with complete code examples for each method.
This article provides a detailed overview of Spring MVC request‑mapping annotations, Spring Bean lifecycle and dependency‑injection annotations, as well as Spring Boot configuration annotations, illustrating each with explanations and code examples to help Java backend developers use these tools effectively.
This article explains the differences between DTO, BO, PO, and VO in backend development, illustrates their roles with Java code examples, and shows how to configure global settings to filter null fields in DTOs, reducing the need for separate VO objects.
This article explains how Spring's @ConfigurationProperties and @PropertySources annotations work, compares their purposes, and provides step‑by‑step examples for binding external configuration to Java beans and loading multiple property files in a Spring Boot application.
This article explains the seven Spring transaction propagation levels, shows how nested @Transactional methods interact under each level, and provides concrete code‑level examples that illustrate when transactions are merged, suspended, started anew, or rolled back, helping developers choose the right strategy for reliable enterprise applications.
This article shares hard‑won production lessons on using Spring Event, explaining why graceful service shutdown, proper startup timing, consistency requirements, and retry mechanisms are essential for reliable event publishing in Java backend systems.
This article demonstrates various Spring dependency‑injection techniques—including Optional, ObjectProvider, Provider, arrays, collections, maps, @Value literals and SpEL expressions, as well as @Lazy proxies—showing the code and resulting bean representations for each approach.
This article demonstrates advanced Lombok annotations such as @RequiredArgsConstructor, @Delegate, @Cleanup, @Builder, and @Singular, showing how they can be combined with Spring to reduce boilerplate, manage resources, and create fluent builders in Java backend projects.
This article demonstrates how to prevent API abuse in a Java Spring application by using a custom HandlerInterceptor combined with Redis to track request counts per IP and URI, covering basic implementation, configuration, custom annotations, reflection for flexible limits, and discusses potential pitfalls and improvements.
This article explains Spring's @Lookup method injection, shows how to define the annotation, register beans, run examples, and dives into the underlying CGLIB proxy mechanism and bean creation process for dynamic bean lookup.
This article walks through the fundamentals of HTTP session handling, the challenges of session sharing in clustered environments, and presents a step‑by‑step design of a Single Sign‑On solution using CAS, including concrete code examples, Redis‑based session storage, and a comparison with OAuth2.
This article introduces eight common Java asynchronous implementation techniques—including raw threads, thread pools, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, ThreadUtil, and Guava ListenableFuture—explains their use cases, advantages, and limitations, and provides concrete code examples for each method.
This article explains Spring's seven transaction propagation behaviors—REQUIRED, SUPPORTS, MANDATORY, REQUIRES_NEW, NOT_SUPPORTED, NEVER, and NESTED—detailing how nested transactional methods interact, when new transactions are created or suspended, and how exceptions influence commit and rollback across different propagation settings.
This article explains why MyBatis' default SqlSession implementation is not thread‑safe, how Spring‑MyBatis integration introduces SqlSessionTemplate and its dynamic proxy, and how transaction‑bound ThreadLocal management ensures safe SqlSession usage across multiple threads.
An in‑depth guide to Spring Expression Language (SpEL) covering its core features, evaluation contexts, parser configuration, collection handling, operators, variables, bean references, and a practical AOP case study, all illustrated with concise Java code examples.
This article explores the motivations, benefits, and step‑by‑step implementations of business operation logging, starting with a simple AOP‑annotation approach, advancing to AOP combined with Spring Expression Language for richer context, and finally leveraging MySQL binlog and time‑window techniques for low‑level, reliable change capture.
This article explains Spring's transaction mechanism, covering its reliance on database support, ACID properties, isolation levels, propagation attributes, programmatic and declarative management styles, and the underlying AOP implementation with concrete code examples.
This article shares practical lessons from real‑world production incidents, explaining why graceful shutdown, proper listener registration timing, consistency requirements, retry mechanisms, idempotency, and traffic control are essential when using Spring Event in Java backend systems.
The IntelliJ IDEA 2024.1 EAP 5 release brings powerful enhancements for Spring and other Java frameworks, richer HTTP client capabilities, improved GitHub Actions support, and various productivity tweaks such as JSON schema handling and automatic header completion, all aimed at boosting backend developers' efficiency.
Spring Boot, an evolution of the Spring framework, simplifies project setup, offers built-in web servers, provides production-ready features, and enhances development efficiency, distinguishing it from traditional Spring which requires extensive XML configuration and external servlet containers, making Boot the preferred choice for modern Java backend development.
This article explains the fundamentals of finite state machines, introduces Spring Statemachine's features, and provides a step‑by‑step guide—including code samples, persistence options, testing, and AOP‑based error handling—to implement reliable order processing flows in Java backend applications.
This article explains the classic State design pattern, demonstrates a traffic‑light example, compares Spring State Machine with COLA, and walks through building a complete order‑status workflow in Spring Boot using enums, configuration, listeners, services, and a test controller, while highlighting trade‑offs and alternatives.
This article explains why the @Transactional annotation fails in Spring when using multithreading, demonstrates a failing example, and provides a solution using manual SqlSession management to guarantee that all database changes are rolled back if any thread encounters an exception.
This article explains the fundamentals of finite state machines, demonstrates how to model order states using Spring Statemachine, shows persistence options with in‑memory and Redis stores, and provides advanced techniques such as exception handling, extended state tracking, and AOP‑based result logging for reliable state transitions.
This article explains how to guarantee transactional integrity when importing a 100,000‑row Excel file with asynchronous threads in Spring, covering double‑async optimization, Future and CompletableFuture handling, @Transactional pitfalls, manual transaction control, and a complete solution for cross‑thread transaction management.
The solution introduces a plug‑in architecture that uses a custom URLClassLoader to load governance task JARs at runtime, registers their Spring beans and @XxlJob handlers with XXL‑Job, and provides unload logic to deregister jobs, destroy beans, and update configuration via YAML or Nacos without restarting the service.
This article examines the progressive design of business operation logging—from a basic AOP‑annotation approach, through an AOP‑SpEL enhancement, to a binlog‑based time‑window solution—detailing each method's implementation steps, trade‑offs, and practical considerations for robust audit and monitoring in enterprise systems.
This article provides a comprehensive analysis of Spring's @Autowired annotation, covering its usage, the bean lifecycle stages where it operates, the core classes and methods that implement it, and a comparison with other injection annotations such as @Resource, all illustrated with runnable code examples.
This comprehensive guide walks you through the most useful Spring framework utility classes—including Assert, StringUtils, CollectionUtils, ObjectUtils, ClassUtils, BeanUtils, ReflectionUtils, Base64Utils, SerializationUtils, HttpStatus, and HtmlUtils—showing practical code examples and explaining when and how to use each to streamline Java backend development.
This article explains how to implement dynamic loading, upgrading, and unloading of data‑governance tasks in a Java Spring application using a custom URLClassLoader, integrate the tasks with the XXL‑Job scheduler, manage Spring bean registration, and persist configuration changes via local YAML or Nacos.
This article analyzes the growing risk of personal data leakage, defines data masking, compares common log‑masking techniques, and presents a comprehensive Java‑Spring solution that combines annotation‑based marking, custom Jackson serializers, and extended SLF4J methods to achieve precise, low‑overhead log masking.
This article provides an in‑depth tutorial on Spring Validation, covering simple usage, requestBody and requestParam/PathVariable validation, unified exception handling, advanced techniques such as group, nested, collection and custom validation, programmatic validation, fail‑fast mode, and the underlying implementation mechanisms within Spring MVC and Hibernate Validator.
The article details two incidents where a misconfigured Spring Bean caused thread blockage and Full GC in a Java backend, explains the step‑by‑step debugging using thread and GC dumps, and presents the code changes that finally eliminated the memory leak.
This article explores the evolution of business operation logging in a Java backend, starting from a simple AOP‑annotation approach, advancing to AOP combined with Spring Expression Language for richer context, and finally leveraging MySQL binlog with time‑window processing to achieve comprehensive, low‑intrusion audit trails.
This article explains the concept of idempotency, identifies which API requests are naturally idempotent, discusses why idempotency is essential for retries, asynchronous callbacks, and message queues, and provides a step‑by‑step Java Spring implementation using custom annotations, AOP, and Redis for token management.
Aspect-Oriented Programming (AOP) separates cross‑cutting concerns such as logging, transactions, and security from core business logic, improving modularity, maintainability, and reusability, and the article explains its concepts, benefits, implementation methods (dynamic/static proxies, dedicated languages) and provides a Spring AOP code example.
This article explains how to design a plug‑in style architecture for data‑governance tasks by creating a custom URLClassLoader, dynamically loading JARs into a Spring context, registering and deregistering XXL‑Job handlers, updating configuration via YAML or Nacos, and finally unloading resources without restarting the service.
This article demonstrates how to build a hot‑pluggable AOP solution in Spring by dynamically adding and removing Advice at runtime, covering the required concepts, core implementation code, a complete demo, and practical considerations for backend Java developers.
