This article explains how Spring AOP annotations such as @Before, @After, @Around and @AfterReturning are defined, demonstrates their usage with concrete Java code, analyzes why @Around may be invoked twice, and provides the correct implementation and execution flow of advice methods.
This article provides a comprehensive guide to Spring’s @Value annotation, covering basic usage, property naming, handling Unicode and encoding issues, default values, static fields, arrays, collections, EL expressions, bean injection, and the differences between ${} and #{} syntax, with practical code examples and solutions to common problems.
This article explains the fundamentals of Aspect‑Oriented Programming, introduces AspectJ as a standalone AOP solution, demonstrates how to implement a HelloWorld example with compile‑time weaving, compares it with Spring AOP’s runtime proxies, and shows how CGLIB can be used for proxy generation.
This article explains how to extend the Spring IoC container using custom BeanPostProcessor, BeanFactoryPostProcessor, and FactoryBean implementations, covering registration methods, ordering, interaction with AOP proxies, and practical code examples for tracing bean creation and externalizing configuration properties.
This article explains the core differences between Spring's BeanFactory and ApplicationContext, why ApplicationContext is generally preferred, and how to manually register BeanPostProcessors when using a plain DefaultListableBeanFactory.
This article explains how Spring’s @Transactional works with locks, why the transaction may commit after the unlock operation, and provides debugging techniques to trace transaction start, commit, and rollback points in high‑concurrency scenarios.
This article explains how Spring’s core container uses classic design patterns—Simple Factory via BeanFactory, Factory Method with FactoryBean, Singleton, Adapter, Decorator, Proxy, Observer, Strategy, and Template Method—illustrated with code snippets and diagrams to show their implementation and purpose within the framework.
This article explains how Spring's @Transactional annotation works by leveraging AOP and dynamic proxies, walks through the bean post‑processor and advisor setup, and details the core TransactionInterceptor code that manages transaction boundaries during method execution.
This article provides a comprehensive overview of Spring MVC request‑mapping annotations, core Spring Bean annotations, dependency‑injection and scope configurations, container setup annotations, and essential Spring Boot annotations, each illustrated with clear code examples and usage tips.
This tutorial explains Java's proxy design pattern, bytecode manipulation, static proxies using AspectJ and JDK, dynamic proxies with JDK and CGLIB, and demonstrates how Spring AOP selects between these mechanisms, providing complete code examples for each approach.
This article explains the concept of database transactions, the ACID properties, various isolation levels, and how Spring Framework implements transaction propagation, isolation, and architecture, providing both theoretical background and practical guidance for developers.
The article explains the concept of streaming queries in MyBatis, introduces the Cursor interface, demonstrates how to use it in Spring MVC controllers, and provides three practical solutions—SqlSessionFactory, TransactionTemplate, and @Transactional—to keep the database connection open during iteration.
This article walks through fourteen practical techniques for building Spring MVC controllers, covering annotation‑based definitions, interface implementation, extending abstract classes, URL mapping, request method handling, parameter binding, model handling, redirects, form validation, file uploads, autowiring services, and best practices such as single‑responsibility and domain‑specific controller design.
This comprehensive guide explores Spring's @Value annotation, covering basic usage, property name handling, encoding issues, default values, static fields, various data types, collection injection, EL expressions, bean injection, and the differences between ${} and #{} to help Java developers master configuration injection.
This article explains why Spring @Transactional may become ineffective or fail to roll back in various situations—such as wrong method visibility, final modifiers, internal calls, missing Spring bean registration, multithreading, unsupported table engines, misconfigured propagation, swallowed exceptions, and improper rollback settings—while also offering practical solutions and best‑practice recommendations.
This article explains how designing domain objects, services, and repositories as interfaces in Java enables seamless switching between different persistence technologies and deployment models, improving modularity, testability, and adaptability for micro‑service architectures.
This article explains how Spring AOP weaves aspect code using dynamic proxies, why internal calls via this bypass proxy logic, and how to correctly configure and obtain proxied beans using JDK/CGLIB proxies, @EnableAspectJAutoProxy, @Autowired injection, and AopContext.
This article provides a comprehensive guide to Spring Web MVC and Spring Bean annotations, detailing usage, attributes, and examples of @RequestMapping, @GetMapping, @PostMapping, @ControllerAdvice, @Autowired, @Scope, and various Spring Boot conditional annotations, helping developers understand and apply them effectively.
This article explains how Spring implements classic design patterns—including Simple Factory via BeanFactory, Factory Method with FactoryBean, Singleton with double‑checked locking, Adapter through HandlerAdapter, Decorator via Wrapper classes, Observer in its event model, Strategy via the Resource interface, and Template Method in JdbcTemplate—providing clear examples and code snippets for each.
This article explains how Spring Boot’s auto‑configuration mechanism operates, covering configuration files, key annotations like @EnableAutoConfiguration, the role of spring.factories, conditional annotations, and how properties are bound to beans to become effective at runtime.
This article explains the differences between system and operation logs, explores various implementation methods such as Canal, file logging, LogUtil, and method annotations, and demonstrates how to achieve clean, dynamic, and decoupled operation logging in Java Spring applications using AOP, SpEL, custom functions, and a well‑structured logging context.
A 2021 survey reveals that Spring remains the leading Java backend platform, with 75% of developers using core modules, over 80% adopting modern architectures, and growing interest in Kotlin, Spring Native, and Kubernetes integration, highlighting its extensive ecosystem and productivity benefits.
The author, a senior Java developer with ten years of experience, documents a ten‑day interview marathon across 20 companies, summarizing interview processes, outcomes, and the most frequently asked technical questions on Java fundamentals, Spring, MySQL, Redis, MQ, and micro‑service architecture to help fellow developers prepare effectively.
This article explains why Spring AOP proxies are not applied when a bean invokes its own methods via the this reference, compares JDK and CGLIB proxy mechanisms, and shows how to enable proxy exposure or use AopContext to achieve the desired AOP behavior.
This tutorial explains how implementing Spring’s *Aware interfaces lets beans obtain ApplicationContext, Environment, and BeanFactory objects, walks through the underlying processing mechanism, and provides concrete code examples with the relevant Spring classes and lifecycle hooks.
This article provides a comprehensive guide to Spring MVC request‑mapping annotations, Spring Bean lifecycle and dependency‑injection annotations, as well as Spring Boot conditional and configuration annotations, illustrating each with code examples and usage notes for Java backend development.
The article demonstrates how to implement elegant, business‑logic‑independent operation logging in Java back‑ends by using AOP‑driven annotations, SpEL dynamic templates, custom parse functions, thread‑local context, and a Spring Boot starter, offering flexible persistence and automatic operator retrieval.
This comprehensive guide explores every way to define Spring beans—from classic XML configurations and constructor or setter injection to modern @Component annotations, JavaConfig @Bean methods, and advanced @Import, ImportSelector, and post‑processor techniques—empowering developers to choose the most suitable approach for any project.
This article introduces the most frequently used Spring framework annotations—including core, MVC/REST, Spring Boot, stereotype, transaction, scheduling, and testing annotations—explaining their purposes, usage locations, and providing Java code examples to illustrate how they configure beans, handle requests, and manage application behavior.
This article provides a comprehensive overview of Spring IoC circular dependency problems, explains the three types of circular dependencies, demonstrates them with Java and XML code, and details how Spring resolves singleton setter‑based cycles using its three‑level cache mechanism.
This article explores why Spring transactions may fail, covering seven common pitfalls such as incorrect method visibility, final methods, internal calls, missing Spring management, multithreading, unsupported table engines, and misconfigured propagation, and provides practical solutions to ensure reliable transaction handling.
This article explains how Spring implements nine classic design patterns—including Simple Factory, Factory Method, Singleton, Adapter, Decorator, Proxy, Observer, Strategy, and Template Method—detailing their implementation mechanisms, core principles, key Spring interfaces, and code examples for each pattern.
This article explains the design and step‑by‑step implementation of a Redis delay queue using Java and Spring, covering the workflow, core components, task states, public APIs, container classes, timer handling, and testing procedures with complete code examples.
This article explains how to configure and inject List, Map, Set, and array values in Spring applications using @Value annotations, EL expression split functions, default values, and custom parsing methods, providing practical code examples and discussing the advantages and limitations of each approach.
This article explains how to use Spring annotations such as @Component, @Configuration, @Bean, @Autowired, and @Qualifier to inject beans via XML replacement, constructor injection, setter injection, property injection, List and Map injection, providing code examples and detailed explanations for each method.
This article explains why encrypting sensitive customer data in databases is essential, outlines common pain points, and demonstrates how Apache ShardingSphere’s data‑desensitization module can be quickly configured in Spring (XML and Boot) to provide transparent AES encryption and decryption without altering business code.
This article explains how Spring's @Async annotation enables asynchronous method execution, compares synchronous and asynchronous flows, reviews the built‑in executors, highlights the drawbacks of the default SimpleAsyncTaskExecutor, and demonstrates how to configure a custom thread pool using AsyncConfigurer or TaskExecutor beans.
This article explores comprehensive domain interface design in Java backend development, showing how to model domain objects as interfaces, implement repositories for JPA, MyBatis, and Elasticsearch, handle associations with JPA annotations, and apply these patterns in the open‑source Mallfoundry e‑commerce platform.
This article explains how to replace bulky if‑else statements with a clean, annotation‑based Strategy pattern in a Spring Boot application, covering interface definition, custom annotations, dynamic proxy handling, map injection, and the crucial hashCode/equals overrides for reliable handler lookup.
During development of the DCS_FunTester framework a custom servlet filter logged each HTTP request twice because Spring automatically registered an implicit filter with a lowercase bean name, and overriding the filterName resolved the duplicate logging issue.
This article explains how Spring's BeanUtils.copyProperties performs a shallow copy, outlines scenarios where it is appropriate, compares it with manual setters, and provides Java code examples illustrating its behavior with parent‑child classes and common pitfalls.
On August 17, Spring announced that Spring Authorization Server has left experimental status and entered the Spring Project family with a production‑ready 0.2.0 release, supporting most of OAuth 2.1 and adding OpenID Connect 1.0 support, and provided a new GitHub repository for developers.
This article explores the various ways to use Spring’s @Autowired annotation—including constructor, setter, field, and collection injection—examines its purpose, and provides a detailed analysis of its implementation in the Spring framework by dissecting the source code and related reflection mechanisms.
This article provides an in‑depth tutorial on Spring Validation, covering basic usage, requestBody and requestParam validation, group and nested validation, collection handling, custom constraints, programmatic validation, fail‑fast mode, and the underlying implementation details within Spring MVC and Hibernate Validator.
This article explains how Spring's @Autowired annotation works across constructors, methods, fields, arrays, collections, maps, optional dependencies, and special beans, providing practical code examples and important notes on required flags, ordering, and usage restrictions.
This article explains Spring's pointcut implementations, covering static and dynamic pointcuts, regular‑expression based pointcuts, the RegexpMethodPointcutAdvisor, control‑flow pointcuts, and how to create custom pointcuts by subclassing Spring’s abstract pointcut classes, with full XML and Java code examples.
This article explains the differences between stateful and stateless Spring beans, the impact of singleton and prototype scopes on thread safety, and demonstrates how ThreadLocal can be used to safely share resources in multithreaded backend applications, complete with code examples.
This article explains why a custom AOP annotation like @MyMonitor may not trigger advice in Spring Boot, analyzes the proxy‑based limitation of Spring AOP, and provides practical solutions such as self‑injection or AspectJ mode to ensure the advice executes correctly.
This guide explains how Spring's @Async annotation works, compares built-in executors, shows how to configure custom thread pools via AsyncConfigurer or AsyncConfigurerSupport, and demonstrates various async method signatures including void, Future and CompletableFuture with practical code examples.
This article explains the differences between Spring's @Autowired, @Resource, and @Inject annotations, compares field, setter, and constructor injection, shows how Spring resolves bean candidates, and outlines the framework's recommendations for choosing the appropriate injection style.
The article explains how Xianyu’s search service refactors tightly‑coupled, if‑else‑heavy code by applying the lightweight SWAK framework—defining @SwakInterface and @SwakTag annotations, registering proxy beans, using AOP and CGLIB proxies to route business logic via request‑derived tag groups, achieving clean, modular routing.
Java's ThreadPoolExecutor offers four rejection policies—AbortPolicy, DiscardPolicy, DiscardOldestPolicy, and CallerRunsPolicy—each handling task overflow differently; this article explains their behavior, default setting, code examples, and how to configure them via Spring's ThreadPoolTaskExecutor for various business scenarios.
This article outlines the ten most frequent errors developers make when using the Spring framework—ranging from over‑focusing on low‑level details to neglecting proper testing—and provides concrete best‑practice solutions with code examples to improve code quality, maintainability, and reliability.
According to Snyk’s 2021 JVM Ecosystem Report, Java 11 now powers 61.5% of production environments, while Java 8 usage declines, and the Java community overwhelmingly favors Spring, IntelliJ IDEA, Maven, and a growing mix of IDEs and languages like Kotlin.
This article explains how Spring's IoC container creates and manages beans, covering the container startup phase, bean definition loading, BeanFactoryPostProcessor and BeanPostProcessor extensions, object creation strategies, property injection, Aware interfaces, and bean lifecycle callbacks.
This page aggregates over 300 curated interview question articles covering Java backend development topics such as Spring, MySQL, Redis, concurrency, data structures, and system design, organized by issue numbers to help candidates prepare effectively for technical interviews.
This guide explains the Java 11 migration process, covering the new JDK release schedule, LTS support, OpenJDK and Amazon Corretto adoption, required tool upgrades, JPMS module changes, class‑loader differences, obsolete JVM options, and common framework compatibility problems.
This article explains how to use Apache ShardingSphere's encryption module to transparently store and query sensitive customer data such as ID numbers and bank cards by configuring encryption rules in Spring or Spring Boot, eliminating manual SQL encryption and simplifying compliance for legacy systems.
This tutorial explains why encrypting sensitive fields like ID numbers and bank cards is required, outlines common pain points, and shows how to configure ShardingSphere's data‑desensitization module using Spring namespace or Spring Boot with full code examples and configuration files.
Flyway is an open‑source database migration tool that version‑controls SQL scripts, supports many databases, and integrates with Maven and Spring to automate schema changes across environments, offering commands such as migrate, clean, info, validate, baseline, undo and repair, with detailed configuration examples.
This article introduces Aspect‑Oriented Programming in Spring, explains core concepts such as pointcut, advice, aspect, join point and weaving, and provides step‑by‑step code examples—including a simple @GetMapping logger, a custom permission annotation with multiple aspects, and detailed usage of @Pointcut, @Around, @Before, @After, @AfterReturning and @AfterThrowing annotations—illustrated with diagrams and runnable snippets.
This article explains Java's reflection mechanism, discusses its strengths and weaknesses, and demonstrates common scenarios such as JDBC connection setup and Spring framework bean loading with clear code examples, helping developers decide when to apply reflection in backend development.
This article describes how a Java backend service suffered high CPU usage and load, how the team diagnosed the problems with jtop and thread stacks, optimized JSON/Bean processing, re‑engineered Hystrix circuit‑breaker settings, reduced logging overhead, and fixed Spring data‑binding exceptions to double the QPS and achieve stable recovery after traffic spikes.
This article explains why global exception handling is needed in Spring MVC, outlines its application scenarios, compares AOP with the simpler @ControllerAdvice/@ExceptionHandler approach, and provides detailed code examples for custom response objects, validation handling, and transaction rollback strategies to improve code cleanliness and maintainability.
This article provides a detailed overview of how the Spring framework implements classic design patterns—including Simple Factory, Factory Method, Singleton, Adapter, Decorator, Proxy, Observer, Strategy, and Template Method—illustrated with code snippets and explanations of their roles in Spring's dependency injection and bean lifecycle management.
This guide explains how Spring's @Autowired annotation works across constructors, methods, fields, arrays, collections, maps, optional dependencies, and built‑in Spring components, providing code examples and tips for handling required and optional beans in a Spring 5.2.15 environment.
This article demonstrates how to use Spring's BeanUtils.copyProperties method to copy properties between objects and provides a generic utility to convert a list of source objects into a list of target objects, illustrated with Java code examples for User and Employee classes.
This article explains the purpose and inner workings of Spring's @Transactional annotation, detailing how AOP and dynamic proxies create transactional proxies, the role of BeanPostProcessor, advisors, TransactionInterceptor, and the transaction lifecycle, accompanied by code examples and diagrams for deeper insight.
This article explains the concept of streaming queries, introduces MyBatis' Cursor interface, demonstrates how to use it in Spring MVC controllers, and provides three practical solutions—using SqlSessionFactory, TransactionTemplate, or the @Transactional annotation—to keep the database connection alive during iteration.
This guide explains how to integrate Alipay’s new secure transfer API (alipay.fund.trans.uni.transfer) into a Java Spring application, covering SDK upgrade, certificate placement, configuration files, Maven dependency, bean injection, and utility classes with full code examples for payment and transfer operations.
This article explains the purpose and inner workings of Spring's @Transactional annotation, detailing how AOP creates proxy objects, the role of BeanPostProcessor, advisors, interceptors, and the TransactionInterceptor, and walks through key source code snippets that manage transaction boundaries.
Streaming queries return an iterator instead of a full result set, reducing memory usage, but require keeping the database connection open; this guide explains MyBatis’s Cursor interface, its methods, and three practical ways—using SqlSessionFactory, TransactionTemplate, or @Transactional—to safely perform MyBatis streaming queries in Spring.
This article explains the differences between Spring's @Autowired, @Resource, and @Inject annotations, describes the injection order and rules, shows code examples for each approach, and discusses why constructor‑based injection is recommended over field injection for cleaner, more maintainable applications.
This article explains why sensitive customer data must be encrypted at rest, outlines the drawbacks of manual SQL encryption and retrofitting existing systems, and provides step‑by‑step Spring and Spring Boot configurations using ShardingSphere's encryption module with full code examples.
This article explains the @Autowired annotation in Spring, covering its various usage forms such as constructor, setter, method, field, and collection injection, and delves into the underlying implementation details within Spring's AutowiredAnnotationBeanPostProcessor, including metadata handling, reflection-based injection, and common pitfalls.
A detailed recount of four interview rounds for a Java backend position at Alibaba Cainiao, covering the breadth of topics from JVM and garbage collection to Spring, MySQL indexing, Kafka, and project design, plus personal reflections and next‑step plans.
This article explains the Service Provider Interface (SPI) concept, demonstrates its use in plain JDK, Dubbo, and Spring frameworks with code examples, compares their strengths and limitations, and shows how SPI enhances extensibility and modularity in Java applications.
This article explains the inner workings of Spring Cloud's RefreshScope, detailing its source code, registration process, refresh endpoint activation, event-driven refresh mechanism, and how beans annotated with @RefreshScope or @ConfigurationProperties are dynamically reloaded without restarting the application.
This article demonstrates how to use Spring AOP to create a request‑logging aspect that captures request parameters, response data, execution time, and error information, while also addressing high‑concurrency logging issues and integrating trace‑ID tracking for easier debugging.
This article demystifies MyBatis transaction handling by explaining the true JDBC methods—setAutoCommit, commit, rollback—and clarifying common misconceptions about create, begin, close, and suspend, while exploring MyBatis’s Transaction, TransactionFactory, and practical code examples that illustrate how commits, rollbacks, and connection closing behave in various scenarios.
This article explains why IntelliJ IDEA reports errors when injecting MyBatis @Mapper beans with @Autowired despite successful execution, and provides four practical solutions—including disabling inspections, adding Spring stereotypes, allowing null injection, and using @Resource—to eliminate the warnings.
This article explains why a caught javax.validation.ConstraintViolationException in a Spring @Transactional method does not stop the transaction from rolling back, and shows how to debug the flow with logs and breakpoints to understand the underlying commit process.
This article explains the concept of MyBatis streaming queries, why keeping the database connection open is essential, and provides three concrete approaches—using SqlSessionFactory, TransactionTemplate, or @Transactional—to ensure cursors remain usable without premature closure.
The 2021 JVM ecosystem report, based on responses from over 2,000 Java developers worldwide, shows OpenJDK now dominates with 77% market share, Java 11 surpasses Java 8 in production, Kotlin gains traction, IntelliJ IDEA leads IDE usage, and Maven remains the top build tool.
This article explains how to use Spring's built‑in StopWatch utility to record the start and end times of multiple code sections, generate a clear performance summary, and compares it with similar tools from Apache Commons and Guava.
The article explains how to abstract remote data location logic using an RPC framework built on Spring and Dubbo, demonstrates proxy injection and service registration, and shows how similar principles are applied to Redis Cluster to reduce request redirection and improve scalability.
This article explains the difference between shallow and deep copying in Java, demonstrates how Apache Commons BeanUtils and Spring Framework BeanUtils perform property copying with code examples, highlights performance concerns, and recommends more efficient alternatives for backend development.
This guide explains how Spring's @Scope annotation determines bean lifecycles, shows the underlying source code handling singleton and prototype scopes, demonstrates creating and registering a custom scope, and provides practical examples of using custom and prototype-scoped beans with proper proxy configuration in Spring Boot.
This article introduces Spring Cache as a framework‑agnostic caching abstraction that eliminates manual cache code, explains its core concepts, annotations, configuration options, and demonstrates practical usage with Redis and custom key, condition, and eviction strategies in Spring Boot applications.
This article examines four Spring Boot @Transactional test cases using a MySQL InnoDB database to determine whether each method rolls back or commits when exceptions are thrown or caught, providing code examples and inviting readers to vote on the outcomes.
This article explains the various ways to use Spring's @Autowired annotation, examines its underlying implementation via reflection, and provides detailed code examples illustrating field, constructor, setter, and collection injection, while also discussing annotation lifecycle and best practices.
This article explains the various ways to use Spring's @Autowired annotation, explores its underlying implementation using reflection, analyzes the core processing classes in the Spring framework, and answers common questions about its lifecycle, bean relationships, and why static injection is discouraged.
This article explains how Spring 5.3.3 creates AOP proxy objects using Advisors, details the internal methods for locating and applying both bean-defined and @Aspect advisors, and demonstrates how to implement a custom Advisor to intercept methods annotated with @DS, including common pitfalls and solutions.
The article explains how Spring's automatic dependency injection initializes beans to avoid NullPointerExceptions, contrasting it with manual object creation using new, and provides example code demonstrating proper @Autowired usage versus manual instantiation.
Spring remains a leading cloud‑native platform because of rapid JDK evolution, a thriving JVM language ecosystem, mature Spring Boot and Spring Cloud for service‑oriented architectures, and Spring Reactive’s support for event‑driven designs, all of which address cost, performance, and modern development needs.
This article walks through Spring’s AOP proxy creation process, detailing how enabling @EnableAspectJAutoProxy registers AnnotationAwareAspectJAutoProxyCreator, how it decides whether to wrap a bean, and the internal methods—wrapIfNecessary, isInfrastructureClass, shouldSkip, and advisor discovery—that together generate the dynamic proxies used at runtime.
This article explains why Spring’s default singleton beans can handle circular references, describes the three‑level cache mechanism that makes it possible, shows prototype limitations, provides a minimal implementation example, and even relates the solution to the classic two‑sum algorithm.
This article examines why Spring remains a top cloud‑native platform by exploring Java and JDK evolution, the competitive JVM language ecosystem, the maturity of Spring Boot and Spring Cloud for service‑oriented architectures, and Spring Reactive’s support for event‑driven designs.
Understanding Java web backend requires grasping how Tomcat parses HTTP requests, dispatches them through servlets, JSPs, listeners and filters, and then leverages Spring’s IoC, AOP, MVC, Boot’s auto‑configuration, and Cloud’s micro‑service tools to build robust, industrial‑grade applications.
This article explains how to store and inject collection types such as List, Map, Set, and arrays from Spring configuration files using @Value, @ConfigurationProperties, and Spring Expression Language, while handling missing keys and reducing code‑configuration coupling.
