This article explains why cross‑origin issues occur, presents common solutions such as @CrossOrigin, HttpClient and Spring Cloud Gateway, and provides detailed code examples for configuring CORS, building a gateway module, and making HTTP requests in a Java backend project.
This article explains traditional HTTP session handling, the problems of session sharing in clustered and multi‑service environments, and presents practical SSO solutions—including session replication, centralized Redis storage, and a complete CAS‑based single sign‑on implementation with Java code examples.
This article provides a comprehensive tutorial on using Spring annotations for pure annotation‑based development, defining beans, managing bean scopes, performing various injection techniques, reading configuration properties, and integrating Spring with MyBatis, complete with code examples and best‑practice tips.
This guide explains how to upgrade to Alipay’s new transfer interface, alipay.fund.trans.uni.transfer, by updating the SDK, configuring certificates, adding Maven dependencies, and implementing Java Spring beans and utility classes for secure fund transfers.
This article compares Spring's @Autowired and @Resource annotations, explains their injection semantics, outlines practical differences, and dives into the internal implementation classes and processing steps that Spring uses to resolve and inject beans.
This article reveals ten common Spring transaction pitfalls—including private methods, final modifiers, self‑invocation, missing @Service, wrong propagation, non‑transactional databases, swallowed or wrong exceptions, multi‑threaded calls, and nested transaction rollbacks—that can silently disable transaction management in Java backend projects.
This article walks through the eleven most commonly used Spring extension points—including custom interceptors, bean retrieval methods, global exception handling, type converters, import configurations, startup runners, bean definition tweaks, post‑processing, initialization and destruction callbacks, and custom scopes—providing clear explanations and code samples for each.
This article explains six common techniques for adding beans to the Spring IoC container, including @Configuration with @Bean, @Component with @ComponentScan, various @Import approaches, FactoryBean, and BeanDefinitionRegistryPostProcessor, providing code examples and usage details for each method.
Explore the 11 most commonly used Spring extension points—from custom interceptors and bean factories to global exception handling, type converters, import mechanisms, startup runners, bean lifecycle processors, and custom scopes—complete with clear code examples and practical guidance for enhancing Java backend applications.
This article compares JWT and session authentication, explains their differences, outlines the authentication flows, evaluates advantages, disadvantages, security, performance and one‑time use issues, and provides a complete Java implementation with JWT, Redis, interceptor and utility classes.
This article introduces RobustDB, a client‑side read‑write splitting framework that replaces the problematic Atlas proxy by routing SQL statements to master or slave databases based on DML/DQL detection, using Spring, AspectJ, thread‑local context, and dynamic data‑source management.
This article provides a step‑by‑step tutorial on using Spring annotations for bean definition, component scanning, scope management, autowiring, qualifier usage, simple value injection, property file loading, and finally demonstrates how to integrate Spring with MyBatis for streamlined data access in Java backend projects.
This article compiles a large set of interview questions frequently asked by top tech companies, covering Java fundamentals, multithreading, Spring framework, MyBatis, Redis, and related concepts, and provides a free QR‑code link for downloading the complete question set with answers.
This article explains how MyBatis‑Plus maps Mapper interface methods to executable SQL statements, detailing the auto‑configuration of SqlSessionFactory, XML parsing, mapper registration, SQL injection, and the dynamic proxy mechanism used at runtime.
This article explains the complete Spring Bean lifecycle—including IoC fundamentals, bean creation, property injection, initialization callbacks, custom init/destroy methods, and post‑processor hooks—by walking through detailed source‑code examples and step‑by‑step execution traces for a sample bean.
This article explains the IDEA warning for @Autowired field injection, compares @Autowired and @Resource, outlines the pros and cons of constructor, setter, and field injection in Spring, and clarifies why only @Autowired triggers the warning due to its tighter framework coupling.
The article investigates MySQL InnoDB lock‑wait timeouts caused by hanging transactions that lack proper commit or rollback, explains ACID and lock mechanisms, shows how stale ThreadLocal bindings let pooled threads reuse unfinished transactions, and recommends using @Transactional with robust try‑catch handling to prevent such deadlocks.
This article explains why Spring singleton beans can be unsafe in concurrent scenarios, demonstrates the issue with a controller example, and presents multiple solutions including changing bean scope, using ThreadLocal, avoiding member variables, employing concurrent collections, and leveraging distributed caches.
This article explains the Strategy design pattern in Java, demonstrates its integration with Spring using custom annotations, enums, and a context manager, provides complete code examples, discusses its advantages over traditional conditional logic, and shows how to easily add new strategies.
This article explains how Spring treats @Component and @Configuration annotations, distinguishes their LITE and FULL modes, demonstrates the proxy behavior with concrete code examples, and details the role of ConfigurationClassPostProcessor and CGLIB enhancement in implementing FULL configuration.
This article compares Spring’s @Autowired and Java’s @Resource annotations, detailing five key differences—including their origins, lookup order, supported parameters, injection styles, and IDE warnings—while providing code examples and diagrams to help developers choose the appropriate annotation.
This article explains how to create a web‑based chat application similar to WeChat using Netty as the core server, WebSocket for real‑time communication, and Spring MVC for HTTP handling, covering architecture, required tools, core code, and deployment steps.
Explore the complete lifecycle of graceful shutdown in Java backend systems, covering kernel signal handling, JVM shutdown hooks, Spring’s ContextClosedEvent, Dubbo’s integration and bug fix, and Netty’s Reactor shutdown process, with detailed code examples and state transition diagrams.
This article explains why IntelliJ IDEA warns about @Autowired field injection but not @Resource, compares the two annotations, outlines Spring's common DI methods, discusses the pros and cons of constructor, setter, and field injection, and provides guidance on choosing the appropriate approach.
This article explains why IntelliJ IDEA warns about field injection with @Autowired but not with @Resource, compares the two annotations, outlines common Spring DI methods, and discusses the advantages and drawbacks of each injection style.
This article explains how to improve Spring MVC controller logic by separating responsibilities, introducing a unified response structure, handling String return types with ResponseBodyAdvice, applying JSR‑303 validation, creating custom validators, and using custom exceptions with global exception handling to produce concise and maintainable backend code.
This article provides a comprehensive overview of the most frequently used Spring and Spring Boot annotations, explaining their purposes, usage scenarios, and includes practical Java code examples for core, MVC/REST, stereotype, data access, scheduling, asynchronous, and testing annotations.
This article explains how to refactor Spring MVC controller code by introducing a unified response structure, handling String response issues with ResponseBodyAdvice, applying JSR‑303 validation, creating custom validation annotations, and implementing custom exceptions with global exception handling to produce cleaner, more maintainable backend services.
This article explains Spring's core features such as IoC, DI, and AOP, demonstrates a simple Hello World application with Spring Boot, then shows how to implement the same functionality using raw Servlets and a handcrafted mini‑Spring framework, complete with code examples and deployment steps.
This article demonstrates how Spring's @Transactional annotation rolls back only for RuntimeException subclasses, explains why checked exceptions like Exception do not trigger rollback by default, and shows how to configure rollbackFor to handle custom exceptions, illustrated with SQL updates and Java code examples.
This article explains the Spring Bean lifecycle in depth, covering IoC fundamentals, each lifecycle stage, extension points such as Aware interfaces and BeanPostProcessor, and provides a step‑by‑step code walkthrough that maps the execution flow from bean creation to destruction.
This article explains why manual timestamp logging is cumbersome, introduces Spring's org.springframework.util.StopWatch and Apache Commons Lang's StopWatch, provides Maven dependencies, detailed usage examples, key methods, and important cautions for accurate performance measurement in Java applications.
This comprehensive guide explores ten practical Java scheduling techniques—from Linux crontab and JDK Thread/Timer to Spring Task, Quartz, and distributed solutions like XXL‑Job and Elastic‑Job—detailing their usage, code examples, advantages, and drawbacks for robust backend automation.
The article explains why IntelliJ IDEA shows a warning for Spring's @Autowired field injection but not for @Resource, compares the two annotations, outlines common DI methods, and discusses the advantages and drawbacks of constructor, setter, and field injection in Spring applications.
This article explains various methods to add beans to the Spring IoC container, including @Configuration with @Bean, component scanning, @Import with selectors or registrars, FactoryBean usage, and BeanDefinitionRegistryPostProcessor, providing code examples and detailed explanations for each approach.
This article explains the concept and usage of Service Provider Interface (SPI) in Java, demonstrating how JDK’s ServiceLoader, Dubbo’s enhanced SPI, and Spring’s SPI mechanisms enable flexible extension of logging frameworks and other components, while comparing their features, configuration files, and limitations.
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.
