This article explains the fundamentals of finite state machines, demonstrates how to model order lifecycle states and transitions in Java using Spring StateMachine, and provides detailed code examples for persistence, event handling, and advanced error‑handling techniques such as AOP and Redis storage.
This article explains how to configure transaction timeout in Spring 5.3.23 using annotations and programmatic approaches, demonstrates four test scenarios with a large table, analyzes the resulting timeout exceptions, and delves into the underlying mechanisms in DataSourceTransactionManager, JdbcTemplate, and related utility classes.
This article enumerates and explains sixteen Spring and SpringBoot extension interfaces, illustrates their positions in the bean lifecycle with a call‑order diagram, and provides concrete usage scenarios and code samples so developers can harness these hooks to write more elegant and maintainable applications.
This article explains how improper use of Java's ThreadLocal in a Spring backend can cause user data leakage across requests, demonstrates the issue with concrete code examples, analyzes the root cause in thread‑pool reuse, and provides a simple fix by invoking remove() after each use.
This article explains Spring's transaction core, showing how TransactionInterceptor and TransactionAspectSupport use AOP to bind a Connection to ThreadLocal, walks through key code snippets for creating, committing, and rolling back transactions, and demonstrates a JUC‑based solution for maintaining transaction consistency across multiple threads.
This article walks through Spring's three‑level cache mechanism and source‑code flow that break circular dependencies, illustrating each step with a concrete demo, explaining the role of AOP, and showing why each cache level is necessary.
This article explains the fundamentals of finite‑state machines, introduces Spring Statemachine, demonstrates how to model an order lifecycle, configure persistence with in‑memory and Redis stores, and provides complete Java code for enums, configuration, services, controllers, listeners, testing, and exception‑handling improvements.
This article explains why RestTemplate is deprecated in Spring 5+, introduces the reactive WebClient as its replacement, outlines its advantages such as non‑blocking I/O and functional style, and provides detailed code examples for creating a client, performing synchronous and asynchronous requests, handling errors, and configuring timeouts.
This article explains why rate limiting is essential for high‑traffic Java services, compares common strategies such as Hystrix, Sentinel, token‑bucket algorithms, and Redis‑based counters, and provides concrete Spring‑Boot code examples for implementing both local and distributed throttling.
This article reviews common Java bean‑copy utilities—including Apache BeanUtils, Spring BeanUtils, cglib BeanCopier, Hutool BeanUtil, MapStruct, and Dozer—explaining their dependencies, usage examples, shallow versus deep copy behavior, and how to choose the right tool for backend development.
This article explains the initialization order of Java classes, the pitfalls of using @Autowired for dependency injection, compares it with @Resource, and demonstrates setter, constructor, and Lombok-based injection methods with code examples to help avoid null‑pointer exceptions and improve coupling.
This article explores how to design module interfaces using Aspect‑Oriented Programming in Java, covering AOP background, definition, pointcut identification, joinpoint interface design, advice abstraction, and both static and dynamic weaving techniques, with practical code examples and diagrams.
This article explains the fundamentals of database transactions, introduces Spring's @Transactional annotation, and enumerates nine typical situations—such as incorrect method visibility, final methods, self‑invocation, unmanaged beans, multithreading, wrong propagation, swallowed exceptions, unsupported exception types, and non‑transactional storage engines—where transactions may not work as expected, offering guidance to prevent these pitfalls.
This article examines how executing an UPDATE before a slow SELECT within a @Transactional method in Spring can prolong MySQL write locks, and demonstrates code refactoring techniques—reordering operations and separating transactional boundaries—to improve overall system performance.
This article provides a detailed overview of Spring MVC and Spring Boot annotations such as @RequestMapping, @GetMapping, @PostMapping, @RequestBody, @ControllerAdvice, @Component, @Bean, @Scope, @Autowired, and others, explaining their purposes, attributes, usage patterns, and offering practical code examples for each.
Spring's @Async annotation enables asynchronous method execution, but its default SimpleAsyncTaskExecutor creates a new thread per task, leading to resource issues; the article explains built‑in executors, their drawbacks, and how to implement custom thread pools via AsyncConfigurer, AsyncConfigurerSupport, or a custom TaskExecutor for better control.
This article introduces Spring 6's new HTTP Interface feature, walks through building a Spring Boot demo with a User entity, a controller, an HTTP Interface annotated with @GetExchange, and a test using WebClient and HttpServiceProxyFactory, and explains related annotations and reactive dependencies.
Spring’s @Autowired field injection often shows an IDE warning, prompting developers to compare field, constructor, and setter injection; this article explains each method’s implementation, evaluates reliability, maintainability, testability, flexibility, circular‑dependency detection, and performance, and recommends constructor injection as the preferred approach.
Spring developers often wonder whether to use @Autowired or @Resource for dependency injection; this article explains their origins, supported injection styles, configurable attributes, bean lookup strategies, and why constructor injection is generally preferred despite IDE warnings about field injection.
This article examines why IntelliJ IDEA flags field injection with @Autowired but not with @Resource, compares Spring’s @Autowired and JSR‑250’s @Resource, outlines the various DI approaches—constructor, setter, and field injection—and discusses their advantages, drawbacks, and best‑practice usage scenarios.
This article explains how Spring 5.3.23 uses web.xml to configure a ContextLoaderListener that creates and refreshes the parent WebApplicationContext, and how DispatcherServlet initializes the child container, detailing the configuration parameters, default locations, and the refresh process.
This article explains how to replace repetitive try‑catch blocks in Java Spring applications with a unified exception handling mechanism that leverages @ControllerAdvice, custom Assert utilities, enum‑based error codes, and standardized response objects to improve code readability, maintainability, and internationalization.
The article explains common pitfalls in Java backend interface design, proposes a unified ResultBean response format, outlines controller coding standards, and demonstrates how to use Spring AOP for logging and exception handling, providing complete code examples and configuration snippets.
Spring determines the type of an injected property, resolves collection or single-bean dependencies, and then locates matching bean instances, handling Optional, ObjectFactory, ObjectProvider, and JSR‑330 providers, while supporting @Lazy proxies and various collection descriptors.
This article explains how to generate, store, and validate login tokens across PC and mobile clients in a distributed microservice architecture, covering Redis storage, custom token entities, Spring service implementation, exception handling, client‑side storage utilities, and a custom annotation with an AOP aspect for request verification.
This article explains how to parallelize business steps with CompletableFuture, why Spring's @Async and @Transactional annotations cannot guarantee transaction consistency across threads, and presents a programmatic transaction approach—including copying Spring's transaction resources between threads—to achieve reliable multi‑threaded commits or rollbacks.
This article explains the differences between Spring's ObjectFactory and FactoryBean interfaces, shows how they are applied in bean creation, servlet API injection, and custom implementations, and provides code examples and best‑practice tips for resolving bean ambiguities in a Spring backend.
This article walks through the twelve essential steps Spring performs during application startup, explaining each method—from prepareRefresh to finishRefresh—including bean factory preparation, post‑processor registration, and the final context refresh, all illustrated with diagrams and code snippets.
This comprehensive guide explains the purpose and usage of Spring MVC, Bean, Dependency Injection, container‑configuration, and Spring Boot annotations, providing clear examples and code snippets that help Java developers master annotation‑driven configuration for backend applications.
This article explains how a Java download library uses a @Download annotation, reactive programming, handler chains, source abstractions, compression, and event logging to simplify downloading various resources—including files, HTTP URLs, and custom objects—while supporting both Spring MVC and WebFlux with concurrent processing and customizable pipelines.
This guide explains how to use Spring 6.1's new RestClient for synchronous HTTP calls, covering setup, request building, response handling, data conversion, error processing, and advanced exchange methods with full code examples.
This article explains how Spring's @Scope annotation determines bean lifecycles, demonstrates creating and registering a custom scope, and shows how to correctly inject prototype-scoped beans into singleton components using scoped proxies.
This article explains why transaction management is essential, how Spring abstracts resource handling, supports nested transactions and propagation behaviors, and compares declarative (annotation) and programmatic approaches, providing practical code examples and a deep dive into the underlying TransactionManager model.
This article provides a detailed exploration of Spring and Spring Boot's extensible interfaces, illustrating the complete bean lifecycle, presenting an invocation order diagram, and offering practical code examples for each extension point such as ApplicationContextInitializer, BeanFactoryPostProcessor, SmartInstantiationAwareBeanPostProcessor, and more, enabling developers to customize container behavior effectively.
This article analyzes AOP’s origins, defines join points and cross‑cutting logic, designs interfaces based on the AOP Alliance specifications, and compares static versus dynamic weaving approaches, illustrating each step with Java code examples and diagrams to show how Spring implements AOP.
This article introduces the Concept-Download library, explains how a single @Download annotation can handle various download sources—including files, HTTP URLs, and custom objects—by leveraging reactive programming, handler chains, source factories, concurrent loading, compression, and unified response writing for both Spring MVC and WebFlux.
This guide walks you through Spring 6.1's new RestClient, covering project setup, global client creation, data retrieval, posting, deletion, error handling, and advanced exchange methods with clear code examples for modern Java backend development.
Spring Event provides a decoupled, extensible mechanism for publishing and handling application events in Spring, covering its definition, benefits, drawbacks, practical usage with code examples, core internal classes, reserved events, asynchronous processing options, and detailed source‑code analysis of the event multicaster and listener registration.
This article introduces Spring Framework 6's new HTTP Interface feature, walks through creating a simple Spring Boot service, defining a Java interface for HTTP calls, testing it with WebClient and HttpServiceProxyFactory, and explains related annotations and dependencies.
This guide explains how to use @ControllerAdvice and @RestControllerAdvice for unified exception handling in Spring, compares their behavior, demonstrates local versus global handling, and shows advanced filtering by annotation, controller class, or package with practical code examples.
This article walks through the evolution of a Spring‑based JWT token validation solution, from passing HttpServletRequest into service methods to using a custom @NeedToken annotation, reflection, a base class, and finally ThreadLocal to ensure each request’s token is safely isolated in high‑concurrency environments.
This article explains how to manage multithreaded database insert operations in Spring Boot, demonstrates why the @Transactional annotation fails in a multithreaded context, and provides a solution using manual SqlSession transaction control with code examples and test results.
This article introduces Spring WebFlux as a reactive, non‑blocking web framework built on Reactor, explains the concepts of reactive programming, compares it with traditional Spring MVC, and provides practical code examples for building and running a WebFlux application with Spring Boot.
This article details how a legacy Dubbo service built on Spring 3.2.x with many integrated components suffered a ten‑minute startup, and how using JProfile to pinpoint costly reflection checks, disabling unnecessary Spring annotations, and fixing RabbitMQ connection issues reduced the deployment time to under two minutes.
This article demonstrates how to accelerate a one‑million‑row database query by adding indexes and using a multithreaded Java Spring controller with MyBatis, showing code examples, performance tests, and suggestions for further optimization.
This article explains the concept of idempotency, identifies which HTTP methods are naturally idempotent, and demonstrates a complete Java Spring solution—including custom annotations, AOP handling, token generation, and Redis storage—to guarantee safe retry and duplicate‑request protection.
This article explains why retry mechanisms are essential for remote service calls, compares several implementation approaches—including manual loops, static and dynamic proxies, AOP, Spring Retry annotations, and Guava‑Retry—provides complete Java code examples, and discusses the advantages and drawbacks of each method.
This article walks through seven retry implementations for Java services—manual loops, static proxy, JDK dynamic proxy, CGLib proxy, custom AOP, Spring Retry annotations, and Guava‑retry—showing code examples, analyzing their pros and cons, and recommending the best fit for different project contexts.
This article explains Spring's conditional configuration features—including @Profile, @Conditional, and various @ConditionalOn* annotations—showing how to dynamically register beans based on environment, classpath, properties, or other bean presence, with detailed code examples and usage guidelines.
This article presents a detailed collection of 31 Java‑related architecture diagrams—including class loader, JVM, Spring, Hibernate, Struts, Android, cloud computing, Linux kernel, and various enterprise frameworks—providing a visual guide for backend developers seeking a broad understanding of Java ecosystem structures.
This article explains how to enhance SpringBoot's native @Scheduled tasks with the spring-boot-starter-super-scheduled library, allowing dynamic creation, modification, and cancellation of scheduled jobs at runtime without altering existing annotations, and details the underlying implementation using BeanPostProcessor, CGLIB proxies, and a custom task manager.
This article explains three ways to inject a specific service implementation in Spring—using @Qualifier with @Autowired, using @Resource with type or name attributes, and naming @Service beans—detailing their semantics, bean‑matching rules, and providing complete code examples for each approach.
This article walks through the problem of scattered try‑catch blocks in Java back‑ends, explains the use of Spring's @ControllerAdvice together with a custom Assert‑based validation and error‑code enum, and demonstrates a complete unified exception handling solution with production‑ready response formatting and extensive code examples.
The article explains how to replace repetitive try‑catch blocks in Java Spring applications with a unified exception handling mechanism that leverages @ControllerAdvice, custom BaseException, Assert utilities, and enum‑based error codes to produce consistent, environment‑aware error responses.
This article introduces the fundamentals of state machines, explains the four core concepts, explores domain‑specific languages (DSL) and their classifications, and provides practical Java examples using Spring Statemachine and the COLA framework, ending with a comparison and adoption guidance.
This article demonstrates how to reduce repetitive Java code in business applications by applying the Template Method and Factory design patterns, leveraging Spring’s IoC for dynamic cart selection, using custom annotations with reflection to serialize API parameters, and employing bean‑mapping utilities to automate DTO‑DO conversions, thereby improving maintainability and scalability.
This article introduces Robustdb, a compact Java library that implements client‑side read‑write splitting and method‑level routing for MySQL databases, explains its architecture, core code components, dynamic read‑pool allocation strategy, and performance comparison with Atlas, while providing practical implementation details and configuration guidance.
This article reviews six theoretical approaches for maintaining MySQL‑Redis data consistency, evaluates their pros and cons, and presents a practical implementation using Java Spring, transactional updates, cache deletion, and asynchronous queue handling to achieve both real‑time and eventual consistency in high‑concurrency systems.
IntelliJ IDEA 2023.2 introduces a suite of enhancements—including a Run‑window profiler, inline return breakpoints, automatic test reruns for Gradle/Maven/JPS, WSL‑based Tomcat debugging, TLS‑enabled gRPC requests, Swagger and OpenAPI support, shared index generation, and numerous UI and code‑completion upgrades—streamlining Java development workflows.
This article explains how to achieve API idempotency in high‑concurrency scenarios by creating a custom @RepeatSubmit annotation, using AOP interception, Redis setNx for locking, and a request‑wrapper to allow repeated reading of request parameters in Spring applications.
This article explains why transaction control is essential for database‑backed applications, compares native JDBC/MyBatis handling with Spring's unified approach, details the core transaction APIs, and walks through the AOP‑based mechanism—including @EnableTransactionManagement, proxy generation, and CGLIB interception—that automatically opens, commits, and rolls back transactions at runtime.
This article explains how Spring 5.3’s @Scheduled and @Async annotations are processed, detailing the bean lookup sequence for TaskScheduler and AsyncConfigurer, the default thread pool creation mechanisms, and the configuration of web asynchronous support, with code examples for each step.
This article explains how Spring AOP integrates AspectJ using CGLIB or JDK dynamic proxies, walks through a complete logging aspect example, and details the internal registration, proxy creation, and invocation processes that enable cross‑cutting concerns without modifying business code.
This article explains how Lombok's @RequiredArgsConstructor can replace multiple @Autowired and @Resource annotations by promoting constructor injection, compares field, constructor, and setter injection in Spring, and demonstrates the resulting cleaner code with practical examples.
This article explains how to enable cross‑node WebSocket communication in a distributed Spring application by publishing messages to a Redis or Kafka topic, tracking user connections, and routing messages to the appropriate server instance, complete with full code examples and configuration details.
This article explains the ACID properties of transactions and compares various implementation approaches—including database‑level mechanisms, Spring single‑datasource transactions, and distributed transaction frameworks such as Seata and RocketMQ—while analyzing their advantages, drawbacks, and suitable scenarios.
This article curates the most valuable Spring I/O 2023 video sessions—covering the latest Java version adaptations, Spring Framework and Boot innovations, cloud‑native deployments, security, observability, and architectural best practices—providing concise Chinese summaries so developers can quickly identify which talks merit deeper viewing.
This article summarizes the key pitfalls and recommended practices for creating, configuring, monitoring, and naming Java thread pools, including proper declaration, parameter tuning for CPU‑ and I/O‑bound workloads, avoiding OOM and deadlocks, and leveraging dynamic pool frameworks.
This article introduces Spring 6.1’s new synchronous RestClient, showing how to perform basic GET and POST requests, convert responses to objects, handle errors with onStatus, and use the advanced exchange method for custom request‑response processing, positioning RestClient as a modern replacement for RestTemplate.
This article explains three practical ways to specify which Spring bean to inject in a controller, compares @Autowired and @Resource annotations, clarifies the role of @Service, and provides complete Java code examples for each approach.
The article explains why the error "Transaction rolled back because it has been marked as rollback‑only" occurs in a Java Spring service when using MyBatis‑Plus saveBatch, how hidden @Transactional annotations cause hidden nested transactions, and presents a practical workaround by replacing the batch operation with a custom mapper.
The article explains Java's ThreadLocal mechanism, detailing how each thread maintains its own ThreadLocalMap, provides practical code examples, examines the underlying source implementation—including set and get methods—and discusses potential memory‑leak pitfalls and ways to avoid them.
This article explains how to use @ControllerAdvice and @RestControllerAdvice for both local and global exception handling in Spring, demonstrates limiting handlers by annotation, controller class, or package, and clarifies the precedence rules between local and global handlers.
This article provides a comprehensive overview of Spring’s Assert utilities and a wide range of Spring Framework helper classes—including ObjectUtils, StringUtils, CollectionUtils, FileCopyUtils, ResourceUtils, StreamUtils, ReflectionUtils, and AOP utilities—detailing their purpose and key method signatures for Java backend development.
This article explains the concepts, advantages, disadvantages, and real-world use cases of four essential design patterns—Chain of Responsibility, Template Method, Publish‑Subscribe, and Strategy—providing detailed Java and Spring code examples to help developers apply them effectively.
This article walks you through building a minimal Spring Boot demo, setting breakpoints, analyzing call stacks and logs, and tracing the @Transactional rollback logic in the framework source code to understand why certain methods roll back or commit.
This article explains how to protect high‑concurrency Java applications using rate‑limiting techniques, covering basic algorithms such as counter, leaky‑bucket and token‑bucket, demonstrating a single‑node implementation with Guava’s RateLimiter and custom annotations, and showing a distributed solution based on Redis and Lua scripts.
This article demonstrates how to replace tightly‑coupled if‑else or switch‑case parser selection with the Service Locator Pattern in a Spring Java application, enabling easy addition of new file‑type parsers without modifying client code and adhering to the open‑closed principle.
This article compares Spring's @Autowired and JDK's @Resource annotations, detailing their injection mechanisms, parameter differences, default behaviors, and usage scopes with code examples, while also offering interview advice and promoting a Java interview guide.
This article explains how to execute two dependent tasks in parallel with CompletableFuture, why the usual @Transactional annotation fails in a multi‑threaded environment, and provides a programmatic transaction solution that copies Spring's transaction resources between threads to guarantee atomic commit or rollback across all parallel operations.
The article explains how Spring’s IoC container, dependency injection, singleton beans, and AOP simplify Java backend development by abstracting object creation, configuration, and cross‑cutting concerns, illustrated with code examples and practical scenarios such as conditional bean loading and Redis client selection.
This article investigates how Spring generates bean names from annotated classes, explains the default lower‑casing rule, highlights the special case when the first two characters are uppercase, and shows the underlying JDK decapitalize method through source‑code exploration.
This article introduces the fundamentals of finite state machines, explains their four core concepts, demonstrates how to model order workflows with state diagrams, and provides a comprehensive guide to implementing, configuring, persisting, and testing Spring Statemachine in a Java backend, including solutions for exception handling and AOP enhancements.
This article introduces eight practical approaches for achieving asynchronous execution in Java—including raw threads, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, Hutool ThreadUtil, and Guava ListenableFuture—providing code samples, configuration tips, and discussion of each method's advantages and drawbacks.
This article explains the concept of coupling, demonstrates how traditional object creation leads to high coupling, and shows how using interfaces, the factory pattern, and reflection—culminating in Spring IOC—can dramatically lower coupling, improve reuse, and simplify maintenance in Java backend development.
This article provides a comprehensive guide to Spring's property injection techniques, covering setter and constructor injection using both XML and Java annotations, external configuration with @PropertySource, and advanced SpEL expressions, complete with runnable code examples and output screenshots.
This article explores a real‑world scenario where a support manager faces nightly batch job interruptions, analyzes common database and environment failures, and presents a systematic redesign of the batch framework and executor to enable automatic retry, reducing manual intervention and improving operational reliability.
The article explains Spring's three‑level cache mechanism for resolving singleton circular bean dependencies, walks through bean lifecycle stages, compares field, setter and constructor injection, shows configuration to enable circular references, and details the internal code paths that expose early bean references.
This article explains why ThreadLocal can cause information loss, corruption, or OOM in Java applications and presents two practical approaches—Java agent bytecode manipulation and proxy‑based thread‑pool wrappers—along with concrete Spring Sleuth implementations and testing results to ensure safe propagation and cleanup.
This article explains how to implement the Strategy, Factory Method, and Builder design patterns within a Spring application to create a flexible reward‑distribution system, providing detailed code examples, usage guidelines, and best‑practice considerations for each pattern.
This article explains the different Spring dependency injection methods, compares @Autowired and @Resource annotations, outlines the pros and cons of each injection style, and clarifies why IntelliJ IDEA issues a warning for @Autowired but not for @Resource.
The article explains the differences between Spring's @Autowired and @Resource annotations, outlines the pros and cons of various dependency injection methods, and clarifies why IntelliJ IDEA issues a warning for field injection with @Autowired while treating @Resource as acceptable, emphasizing portability and coupling concerns.
This article explains the motivations for moving a Java 8 project to JDK 11, compares JDK 11 and JDK 17, outlines JDK 11’s key features, details Tomcat 8.5 differences, provides step‑by‑step migration instructions, and shares troubleshooting tips for common upgrade issues.
This article explains Spring's common dependency injection methods, compares @Autowired and @Resource, outlines the pros and cons of constructor, setter, and field injection, and reveals why IntelliJ IDEA flags only @Autowired while ignoring @Resource.
PowerJob is a modern distributed job scheduling framework that addresses the limitations of Quartz, XXL‑Job and SchedulerX by offering a web UI, rich scheduling strategies, DAG workflow support, lock‑free high‑performance scheduling, multiple processor types and step‑by‑step quick‑start instructions for developers.
This article provides a detailed overview of Java backend utilities, covering Spring's Assert class for logical checks, common ObjectUtils and StringUtils methods, collection helpers, file and stream utilities, as well as reflection and AOP tools with practical code examples.
This article explains what asynchronous execution is, compares it with synchronous processing, and presents eight practical Java implementations—including raw threads, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, Hutool ThreadUtil, and Guava ListenableFuture—complete with code samples and usage tips.
This article explains the fundamentals of finite state machines, introduces the four core concepts of state, event, action, and transition, and demonstrates how to model and persist order workflows using Spring Statemachine with Java code examples, database schema, and AOP-based error handling.
This article explains how improper use of AOP in Spring can cause object escape leading to concurrency safety problems, discusses issues such as asynchronous thread modifications, caching, and incorrect advice ordering with @Transaction, @Retryable, and dynamic datasource switching, and provides practical guidance to avoid these pitfalls.
This article explains the Service Provider Interface (SPI) concept and compares the implementations in Java (ServiceLoader), Spring (SpringFactoriesLoader), and Dubbo (ExtensionLoader), covering their configuration files, core mechanisms, advantages, drawbacks, and typical usage scenarios.
