This article demonstrates how to create a simple custom annotation that mimics Spring's @Autowired functionality by defining a new annotation, a BeanPostProcessor, configuring beans in XML, and wiring everything together in a test class to show the injection working at runtime.
This article explains the causes of Spring circular dependency exceptions, details how Spring's three‑level cache and AOP proxy mechanisms contribute to the problem, and provides practical solutions such as using @Lazy, refactoring code, and ensuring a single AutoProxyCreator to prevent bean creation failures.
This article explains five ways to add a bean to the Spring IoC container—including @Configuration + @Bean, @Component + @ComponentScan, various @Import techniques, FactoryBean, and BeanDefinitionRegistryPostProcessor—provides complete code examples for each, and concludes with a summary and related promotional notes.
This article explains Spring's transaction propagation behaviors, rollback mechanisms, common pitfalls such as self-invocation, and provides solutions using AOP proxies and @EnableAspectJAutoProxy, supplemented with code examples and a brief promotion of a related community.
This guide explains how to use Spring's @Bean annotation to declare beans, configure dependencies, control lifecycle callbacks, set custom scopes, assign names, aliases, and descriptions, providing Java code examples that parallel equivalent XML configurations.
This article explains Spring's transaction propagation options, rollback mechanisms, the limitations of self‑invocation within @Transactional methods, and how to correctly use AOP proxies such as AopContext.currentProxy() and @EnableAspectJAutoProxy to ensure transactional behavior in Java backend applications.
This article explains how to redesign Spring MVC controllers by introducing a unified Result wrapper, using ResponseBodyAdvice for automatic response packaging, applying JSR‑303 validation on DTOs and method parameters, and handling custom exceptions globally to produce consistent API outputs.
This article explains why traditional Spring MVC Controllers become cumbersome, demonstrates how to unify response structures with a Result wrapper, leverages ResponseBodyAdvice for automatic packaging, resolves String conversion issues, and shows best‑practice parameter validation using JSR‑303, custom validators, and global exception handling to keep controller code clean and maintainable.
This article explores Java multithreading concepts, JVM safety tools, thread creation methods, coordination mechanisms, and practical scenarios such as parallel data aggregation, for‑loop conversion, map‑based processing, and multi‑threaded transaction handling, providing code examples and performance tips for backend developers.
This article explores how Spring implements classic design patterns—Proxy, Strategy, Decorator, Singleton, Simple Factory, Factory Method, Observer, Template, and Adapter—detailing their purpose, core code snippets, and the way Spring leverages them to provide flexible, extensible, and maintainable backend functionality.
This article explains how to refactor a Spring MVC Controller by introducing a unified response wrapper, leveraging ResponseBodyAdvice for automatic packaging, applying JSR‑303 validation for @RequestBody, @PathVariable and @RequestParam parameters, creating custom validation annotations, and handling business and system exceptions consistently.
This article explains the complete lifecycle of a Spring bean—including creation, merged BeanDefinition processing, factory exposure, property population, initialization, and destruction—while illustrating the underlying source‑code mechanisms and how Spring resolves constructors, handles circular dependencies, and integrates AOP and post‑processors.
This article walks through building a Spring @EventListener demo, explains how to decouple registration logic, shows step‑by‑step debugging of the event‑listener infrastructure, and explores the internal mechanisms that register and invoke listeners during application startup and runtime.
This article provides a detailed tutorial on Spring Validation, covering basic dependency setup, requestBody and requestParam/PathVariable validation, advanced techniques such as group, nested, collection and custom validation, programmatic validation, fail‑fast mode, the difference between @Valid and @Validated, and the underlying implementation mechanisms within Spring MVC.
This article explains how to protect time‑consuming business operations using a Redis‑based distributed lock implemented with custom annotations, Spring AOP, and a scheduled thread pool that automatically extends lock expiration to avoid premature release.
This article demonstrates a step‑by‑step implementation of API request throttling in a Spring backend using an Interceptor and Redis, covering the underlying principle, configurable limits, custom annotations, reflection‑based flexibility, and practical considerations such as path parameters and real‑IP handling.
This article introduces Robustdb, a compact open‑source read‑write separation framework built with about ten classes and two thousand lines of code, explains its architecture, routing logic, method‑level transaction handling, dynamic data‑source management, and performance advantages over existing solutions like Atlas.
This article explains how to use Spring's profile‑specific configuration files, package a multi‑module Java project with Maven or IDEA, and deploy the resulting JAR on a Linux server by installing JDK, setting environment variables, and starting the application in foreground or background.
This article explains the complete Spring bean lifecycle—including creation, property filling, initialization, usage, and destruction—detailing how Spring manages object creation, dependency injection, AOP proxy generation, and lifecycle callbacks through various internal phases and extension points.
This article explains how to dynamically manage multiple Spring data sources, switch them at runtime using AbstractRoutingDataSource, and ensure transactional consistency across databases by implementing custom AOP, connection proxies, and multi‑transaction annotations.
This article explains how to build a clean, maintainable backend API response format by defining a standard JSON wrapper, categorizing status codes, using a Result class with static helpers, and automatically applying the wrapper through a custom @ResponseResult annotation, interceptor, and ResponseBodyAdvice in a Spring‑based service.
This article explains how to dynamically manage multiple Spring data sources, switch between them at runtime, and implement custom multi‑database transaction handling, covering both configuration‑file and database‑table approaches, with code examples and AOP techniques for seamless integration.
This article explains how to refactor a Spring MVC Controller layer by defining its responsibilities, introducing a unified response format, using ResponseBodyAdvice for automatic wrapping, applying JSR‑303 validation for request parameters, and implementing custom exceptions with centralized handling to achieve cleaner, more maintainable backend code.
This article dissects the core bean creation logic of Spring's AbstractAutowireCapableBeanFactory, detailing how createBeanInstance delegates to obtainFromSupplier, instantiateUsingFactoryMethod, autowireConstructor, and fallback default constructors, while explaining the role of Supplier, ConstructorResolver, argument resolution, and caching mechanisms.
This article explains how to replace scattered try‑catch blocks in Java services with a clean, unified exception handling approach using Spring’s @ControllerAdvice, custom Assert interfaces, enum‑based error codes, and standardized response objects to improve readability, maintainability, and internationalized error reporting.
This article explains how to dynamically manage multiple data sources and ensure transactional consistency in Spring applications by extending AbstractRoutingDataSource, using configuration‑file or database‑table approaches, applying AOP for datasource switching, and implementing custom multi‑database transaction management.
This article demonstrates how to prevent abusive API calls in a Spring Boot application by using an Interceptor together with Redis for counting requests, and extends the solution with configurable custom annotations and reflection to allow per‑endpoint rate‑limit settings.
This article explains the concept of finite state machines, outlines scenarios where they are beneficial, compares Spring Statemachine and Squirrel-foundation implementations, and provides detailed configuration, guard/action code, persistence, testing, and practical usage tips for managing complex business workflows in Java backend services.
This article explains the design and implementation of JD's JSF RPC framework, detailing the architecture, XML configuration of providers and consumers, Spring namespace handling, service registration, server startup, client initialization, load balancing, and the overall workflow from provider exposure to consumer invocation.
The article explains how to dynamically manage multiple data sources and ensure transaction consistency in Spring applications by extending AbstractRoutingDataSource, using configuration‑file or database‑table approaches, and applying AOP‑based switching with custom transaction management.
This article explains the principles and differences of the SPI mechanisms in Java, Spring, and Dubbo, covering ServiceLoader, SpringFactoriesLoader, and Dubbo's ExtensionLoader, with detailed demos, core implementation details, advantages, drawbacks, and typical usage scenarios for each framework.
The article explains Spring's three dependency injection methods, highlights the drawbacks of field injection, recommends constructor injection, and demonstrates how Lombok's @RequiredArgsConstructor can generate the required constructor to eliminate @Autowired and @Resource annotations, simplifying code and preventing NullPointerExceptions.
This article explains Spring's three dependency injection methods—field, constructor, and setter injection—highlights the advantages of constructor injection for avoiding null pointers and circular dependencies, and demonstrates how Lombok's @RequiredArgsConstructor can simplify bean wiring in Java backend development.
This article explains how to dynamically manage multiple data sources and ensure transaction consistency across them in Spring applications, covering both configuration‑file and database‑table approaches, custom AOP switching, and a bespoke multi‑database transaction mechanism.
This article explains that while Spring's Validator handles simple parameter validation, it cannot validate relationships between parameters and business data, and demonstrates how using org.springframework.util.Assert provides a more concise, readable way to perform such checks, including exception handling examples.
This article explains how to implement interface rate limiting in a Spring application by creating custom annotations, using AOP for method interception, and leveraging a Redis‑like ConcurrentMap cache to control request counts within a fixed time window.
This article shares fourteen practical Java backend development habits—including using @ConfigurationProperties, replacing @Autowired with @RequiredArgsConstructor, modularizing code, throwing exceptions instead of returning error flags, minimizing unnecessary database calls, avoiding null returns, reducing if‑else chains, and leveraging IDE features—to help developers write cleaner, more robust, and easier‑to‑maintain code.
This article introduces MapStruct, a compile‑time Java bean‑mapping code generator, explains its core concepts, shows step‑by‑step examples—including Maven dependencies, entity and DTO definitions, mapper interfaces, custom conversions, and advanced configurations—while comparing its performance to other copy utilities and highlighting deep‑copy behavior.
Learn how to implement multi‑tenant isolation in a SaaS application using MyBatis‑Plus, covering database schema design, Maven dependencies, configuration of pagination interceptors, tenant handler logic, request‑header propagation, async thread handling, selective filtering, and common pitfalls with bean copying and join queries.
This article walks through Alibaba's evolution from single‑machine scheduled jobs to a customized three‑layer distributed task framework, detailing classifications, Spring scheduling examples, batch processing integration, cluster distribution mechanics, and optimization techniques that maximize resource utilization and achieve smooth, balanced task execution.
Spring Native beta lets developers compile Spring Boot applications into GraalVM native images, delivering sub‑100 ms startup, peak performance and reduced resource usage, while providing Maven/Gradle plugins, AOT conversion, and seamless integration with start.spring.io for both Java and Kotlin projects.
This article explains eight bean types that Spring's @Autowired can inject—including single beans, collections, arrays, maps, lazy proxies, Optional, ObjectFactory/ObjectProvider, and JSR‑330 Provider—showing how each works and when to use them.
This article explains Spring's transaction abstraction, detailing the roles of PlatformTransactionManager and ReactiveTransactionManager, the TransactionDefinition attributes, TransactionStatus interface, resource synchronization techniques, declarative transaction management with AOP, rollback rules, and provides XML and Java configuration examples for both JDBC and Hibernate environments.
The article explains how to process a batch of overdue unpaid orders in a Spring scheduled task by wrapping each order's business logic in a separate REQUIRES_NEW transaction, catching exceptions, and manually rolling back only the failing transaction so that other orders remain unaffected.
This article explores Spring’s @Autowired annotation in depth, covering default wiring, handling multiple beans, using @Qualifier and @Primary, various injection targets, advanced collection injection, common pitfalls, and differences from @Resource, providing practical code examples and solutions for real‑world projects.
The article explains common problems with Spring's @Autowired injection, compares it with @Resource, and presents alternative injection methods—including setter, constructor, and Lombok-based approaches—while providing code examples and best‑practice recommendations for reliable bean initialization.
The article explains common pitfalls of using Spring's @Autowired, compares it with the standard @Resource annotation, and demonstrates various injection techniques—including field, setter, constructor, and Lombok-based constructor injection—through detailed code examples and best‑practice recommendations.
This article explains why asynchronous execution is essential for tasks like sending SMS or emails, defines async concepts, and walks through eight practical Java implementations—including Thread, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, ThreadUtil, and Guava ListenableFuture—complete with code examples and usage tips.
This article introduces eight common methods for implementing asynchronous execution in Java, including threads, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, Hutool ThreadUtil, and Guava ListenableFuture, and provides code examples and usage considerations.
The author inherited a poorly engineered Java backend project riddled with massive methods, missing abstractions, unsafe async handling with Thread.sleep, ineffective @Async annotations, and a broken distributed lock implementation, highlighting how such technical debt creates a maintenance nightmare.
The article explains how Spring's @Async annotation works, compares synchronous and asynchronous calls, reviews the built‑in executors such as SimpleAsyncTaskExecutor, discusses their drawbacks, and provides detailed guidance on creating custom thread pools via AsyncConfigurer, AsyncConfigurerSupport, or a TaskExecutor bean, including code examples.
This article explains the concept and purpose of caching, compares local and centralized cache approaches, introduces Spring's cache support and various CacheManager implementations, details GuavaCacheManager configuration and expiration strategies, demonstrates @Cacheable usage, and discusses common pitfalls such as cache miss due to internal method calls.
This article explains the Java Service Provider Interface (SPI) concept, demonstrates how to implement and test SPI with ServiceLoader, compares its limitations, and shows how Spring extends SPI using spring.factories for more flexible and efficient service loading.
This article provides a comprehensive guide to Spring’s extension mechanisms, covering FactoryBean, @Import, bean lifecycle callbacks, BeanPostProcessor, BeanFactoryPostProcessor, the SPI system, Spring Boot startup hooks, event publishing, and custom XML namespaces, complete with runnable code examples and diagrams.
This article explores web pagination across database, backend, and frontend layers, detailing MySQL LIMIT syntax, Java pagination implementations with PageHelper and Spring Data JDBC, and UI approaches using Thymeleaf and Element UI, providing code examples and comparative insights for developers.
This article explains how to design and implement a business risk‑control component using Redis + Lua scripts and Spring AOP annotations in Kotlin, covering rule definitions, counting strategies, annotation handling, and testing procedures.
This article explains how Spring enables transaction management through @EnableTransactionManagement, details the underlying proxy mechanism, outlines the basic and detailed execution flow, describes transaction propagation types and their classifications, and shows how to force rollback and use TransactionSynchronization for custom callbacks.
This article explains how to use Spring's ProxyFactoryBean to create AOP proxies, covering its properties, the choice between JDK and CGLIB proxies, bean configuration examples, global advisors, and practical considerations for proxying classes versus interfaces.
This article explains why simple System.currentTimeMillis() timing is often insufficient, introduces Spring's org.springframework.util.StopWatch and Apache Commons' org.apache.commons.lang3.time.StopWatch, provides Maven dependencies and complete Java examples, and discusses important usage notes such as thread‑safety and task management.
This article provides an in‑depth overview of scheduled task processing, covering common business scenarios, fundamental principles, single‑machine algorithms such as min‑heap and time‑wheel, Java utilities like Timer, DelayQueue, ScheduledExecutorService, Spring Task, Quartz, and distributed approaches using Redis, Elastic‑Job, and XXL‑Job.
This article explores eight Java asynchronous programming techniques—from raw threads and Future to CompletableFuture, Spring @Async, event-driven approaches, message queues, Hutool ThreadUtil, and Guava ListenableFuture—detailing their concepts, advantages, limitations, and providing complete code examples for each.
This article explains why asynchronous execution improves latency in common scenarios like sending SMS or emails, and presents eight Java techniques—including threads, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, third‑party utilities, and Guava—to implement robust asynchronous programming.
This article explains how to replace repetitive try‑catch blocks in Spring Boot applications with a unified exception handling mechanism that leverages @ControllerAdvice, custom Assert utilities, and enum‑based error codes to produce clean, maintainable backend code.
This guide walks through deploying a Spring application using Docker Compose, Jenkins, GitLab, and Maven, covering password retrieval, plugin installation, GitLab host configuration, access token creation, Jenkins setup, Maven build commands, and verification of the generated JAR file.
This article analyzes the performance and implementation differences of various Java object‑copy utilities—including Apache BeanUtils, PropertyUtils, Spring BeanCopier, and Spring BeanUtils—by examining source code, benchmarking copy operations, and recommending alternatives to avoid the inefficiencies of Apache BeanUtils.
This article provides an in‑depth walkthrough of how Spring resolves circular dependencies using its three‑level cache mechanism, complete with code examples, step‑by‑step execution flow, and a deep dive into why each cache level is essential.
This article explains the complete user login process, including mobile verification, token generation, token expiration policies, request‑rate limiting with Redis, anonymous request handling, blacklist management, and provides full Java Spring code examples for implementing these backend authentication mechanisms.
This article explains how to replace repetitive getter/setter code with MapStruct by showing dependency setup, defining source and target classes, creating mapper interfaces with @Mapping annotations, testing the conversion, and handling common integration issues such as Swagger conflicts.
The article explains the classic three‑layer MVC pattern, its shortcomings in complex Java projects, and proposes adding a Manager layer to separate generic business processing, reduce transaction scope, and improve code organization, illustrated with Spring‑based code examples.
This article explains how Spring 5.3.23 uses ApplicationEvent and ApplicationListener for event handling, details the standard lifecycle events, shows how to create and publish custom events, and demonstrates annotation‑based, asynchronous, and ordered listeners for robust backend development.
The article humorously deconstructs an overly complex Java enterprise setup, illustrating how excessive use of interfaces, abstract classes, factories, dependency injection, XML configuration, and heavyweight IDE tooling leads to bloated, hard‑to‑maintain code that ultimately fails in production.
The article demonstrates how to use Spring's HandlerMethodArgumentResolver to automatically convert Kafka messages into typed method parameters, eliminating repetitive JSON parsing code and showing a complete implementation, usage example, and notes on version support and performance considerations.
This article explores Spring's eleven most commonly used extension points—including custom interceptors, bean factory access, global exception handling, type converters, configuration imports, startup runners, bean definition tweaks, bean post‑processing, initialization methods, shutdown hooks, and custom scopes—providing code examples and practical guidance for Java backend developers.
This article explains the Spring AOP advice lifecycle, distinguishes shared and per‑instance advice beans, and details each advice type—around, before, throws, after‑returning, and introduction—along with practical Java code snippets for implementation.
This article explains how to replace tightly‑coupled if‑else or switch‑case logic for selecting file parsers (JSON, CSV, XML) with a Service Locator Pattern using Spring's ServiceLocatorFactoryBean, demonstrating a clean, extensible solution that follows the Open/Closed principle.
This article explains how to enable @AspectJ support in Spring (both via annotations and XML), defines custom AspectJ pointcuts and advice, and dives into Spring AOP APIs such as Pointcut, ClassFilter, MethodMatcher, and utility classes for composing pointcuts.
This article comprehensively reviews the various techniques for injecting beans into the Spring container—including XML and properties configuration files, annotation-based declarations, manual BeanDefinition registration, direct singleton registration, and FactoryBean usage—providing code examples, underlying principles, and practical guidance for each method.
This article explains the Java SPI mechanism, demonstrates how to create service interfaces and implementations, shows how to configure META-INF/services and spring.factories files, and compares Java's built‑in SPI with Spring's optimized SPI approach, providing complete code samples and analysis.
This article analyzes the limitations of traditional HTTP session mechanisms in single‑server and clustered environments, explains why session sharing is essential for multi‑system products, and presents practical solutions such as session replication and centralized Redis storage, followed by a detailed walkthrough of CAS‑based single sign‑on implementation with Java Spring code examples and a comparison to OAuth2.
This article introduces eight practical techniques for achieving asynchronous processing in Java—including raw threads, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, Hutool ThreadUtil, and Guava ListenableFuture—complete with code examples and discussion of their advantages and limitations.
This article explains why short-lived JWT tokens need automatic renewal, outlines a Redis‑based solution, and provides complete Spring interceptor and utility code to create, verify, and refresh tokens without forcing users to re‑login frequently.
This article examines why duplicate code harms maintainability, then demonstrates three practical techniques—using factory and template method patterns, leveraging custom annotations with reflection, and applying bean‑copy utilities—to refactor Java business logic and dramatically reduce redundancy.
This article provides an in‑depth overview of Java's ThreadPoolExecutor, covering why thread pools are needed, various creation methods via Executors, core parameters, internal workflow, source‑code analysis, monitoring, shutdown procedures, and real‑world applications such as Spring @Async and Dubbo integration.
This article explains how to let users upload a JAR that implements a predefined Java interface, then dynamically load, register, and switch the implementation at runtime using both reflection‑based and Spring‑annotation‑based hot‑deployment techniques, complete with code examples and utility methods.
This article explains how to design a flexible logging solution in Java by creating a custom @Log annotation, using meta‑annotations such as Retention and Target, and applying Spring AOP with various advice types to capture method parameters, return values, and notes without polluting service code.
This article explains why a custom business rate‑limiting (risk‑control) component is needed for AI‑driven services, compares open‑source solutions, and provides a complete implementation using Redis+Lua scripts, Kotlin code, and Spring AOP annotations, including testing and deployment tips.
This article explains why a business needs its own risk‑control (rate‑limit) component, compares open‑source options, and provides a complete Kotlin/Spring implementation using Redis Lua scripts, annotations, and AOP to enforce real‑time adjustable limits.
The article provides a hands‑on migration guide for moving an internal gateway service from Java 8 to JDK 11 with the G1 garbage collector, detailing a checklist of tool and dependency updates, showcasing up to 105 % performance gains, outlining new language features, virtual‑thread usage, and best‑practice recommendations for a smooth, cost‑effective upgrade.
Learn how to use Spring's RestTemplate and WebClient for calling REST endpoints, explore their core methods, initialization options, URI handling, header and body processing, multipart support, and underlying HttpMessageConverters, with practical code examples and migration guidance for modern Spring applications.
This article explains Spring's TaskExecutor and TaskScheduler abstractions, their various implementations, how they decouple threading and scheduling from the deployment environment, and provides practical code examples for configuring and using them in Java applications.
This article explains the Chain of Responsibility design pattern, demonstrates its use in multi‑step product creation validation and expense‑approval workflows with concrete Java/Spring code, and discusses configuration, dynamic composition, advantages, drawbacks, and testing scenarios.
This article explains the importance of data safety, defines the ACID properties of transactions, details how InnoDB implements them, and shows how Spring's @Transactional annotation works with AOP, including default rollback behavior, configuration options, and common pitfalls that can cause transaction failures.
This article explains how to replace numerous static Feign client interfaces with a single dynamic Feign client in Spring, showing the generic service definition, a client factory, and usage examples that streamline inter‑service HTTP calls while keeping code reusable and maintainable.
This article explains nine widely used design patterns—Singleton, Builder, Factory, Strategy, Template Method, Chain of Responsibility, Proxy, Adapter, and Observer—detailing their concepts, typical use‑cases, and concrete Java code examples drawn from popular open‑source projects such as Spring, Dubbo, MyBatis and Guava.
PowerJob is a third‑generation distributed job scheduler that adds workflow orchestration, map‑reduce style computation and rich execution modes to traditional CRON‑based scheduling, and this guide explains its advantages, core features, architecture, and provides step‑by‑step instructions with code samples to get started quickly.
This guide explains Spring 5.3’s built‑in servlet filters—including FormContentFilter for handling form data in PUT/PATCH/DELETE, ForwardedHeaderFilter for adjusting request URLs behind proxies, ShallowEtagHeaderFilter for lightweight caching, the CORS filter for cross‑origin requests, and CharacterEncodingFilter for enforcing request/response encoding—along with configuration tips and security considerations.
This article shares common pitfalls of Java candidates, emphasizes building a solid Java foundation, and provides a curated collection of over 100 interview questions covering Spring, Redis, MyBatis, and multithreading, with a QR code for accessing the full answer set.
This article explains how Spring's @EnableTransactionManagement activates transaction support by registering advisors and proxy beans, details the core execution flow of transactional methods, explores various propagation scenarios with code examples, and demonstrates forced rollback and transaction synchronization techniques.
This article introduces asynchronous programming concepts in Java, explaining the shift from synchronous to asynchronous execution, and demonstrates practical implementations using raw threads, ThreadPoolExecutor, Future, FutureTask, CompletableFuture, and Spring's @Async annotation, along with event handling and message queue integration for high‑throughput systems.
This article explains how Aspect‑Oriented Programming (AOP) was introduced into a data construction platform to address high development effort, strong business coupling, and maintenance difficulty by isolating cross‑cutting concerns such as logging, thereby improving modularity, development speed, and code maintainability.
