This article explains how to dynamically switch between multiple service providers, such as SMS vendors, in a Spring‑based backend by using spring‑smart‑di's @AutowiredProxySPI and related annotations, covering configuration, Maven dependency, enabling the feature, and custom proxy implementations.
This article introduces Spring Framework's ResponseBodyEmitter, explains its advantages over SSE for asynchronous HTTP responses, demonstrates practical usage with a real‑time log‑streaming example, outlines core methods, working principles, best‑practice considerations, and compares it with traditional Streaming and Server‑Sent Events.
This article introduces a Java library that simplifies file download functionality in Spring MVC and WebFlux by using a single @Download annotation, handling various source types, concurrent loading, compression, and response writing through a flexible, reactive handler chain architecture.
A ConcurrentHashMap is internally thread‑safe, so a volatile declaration is only required when its reference may be reassigned (or the field is final), while Spring singleton beans with mutable fields are not thread‑safe and should be made stateless, prototype‑scoped, or synchronized for composite operations.
This article examines the three classic reasons for defining interfaces on Service and DAO layers, explains why they often fall short when using Spring's dependency injection, and offers practical structuring and workflow tips for projects that may or may not require multiple implementations.
This article discusses Meituan's spring recruitment numbers, then provides detailed Java backend interview questions and answers covering Spring MVC vs Spring Boot, MySQL MVCC, Redis Zset implementation, message queue reliability, HashMap internals, and thread pool usage, offering practical insights for candidates.
This article explains why Controllers are essential in Spring MVC, identifies common problems such as tangled validation and inconsistent responses, and demonstrates how to introduce a unified return structure, use ResponseBodyAdvice for automatic wrapping, handle String conversion issues, apply JSR‑303 validation, create custom validators, and centralize exception handling to produce cleaner, more maintainable backend code.
This article explains the purpose, usage patterns, and internal mechanics of Spring's @Import annotation, including importing regular classes, ImportSelector implementations, and ImportBeanDefinitionRegistrar implementations, with complete code examples and a discussion of how Spring processes these imports at runtime.
The article explains how automatic @Autowired injection can tightly couple domain models to the Spring container, hide dependencies, hinder testing, create circular‑dependency risks, and violate clean architecture, then demonstrates an explicit‑dependency approach with a custom SpringContext utility, compares both methods, and offers practical guidelines for layered design and testing.
The article shares DJI's impressive compensation data, details a 50‑minute Java backend interview covering concurrency tools, locks, CountDownLatch, ConcurrentHashMap, Kafka ordering, zero‑copy, Spring AOP, filters vs. interceptors, and provides code examples and explanations for each concept.
This article explains critical pitfalls, graceful shutdown requirements, startup timing issues, suitable business scenarios, and reliability techniques—including retries, idempotency, and integration with Kafka and MQ—when applying Spring Event for publish‑subscribe patterns in high‑traffic backend services.
This article explains the Chain of Responsibility design pattern, demonstrates its application in multi‑step product validation and expense‑approval workflows with detailed Java code, configuration handling, Spring bean injection, and discusses its advantages and drawbacks.
This article explains how Spring's @Value annotation can inject literal strings, file values, system properties, defaults, arrays, maps, and SpEL expressions into fields, constructors, setters, and Java records, providing practical code examples for each scenario.
This article explains RPC fundamentals, detailing a Java example that uses Spring for bean management, Netty for high‑performance network communication, and Zookeeper for service registration and discovery, and walks through both server and client implementations with code snippets and test results.
This article explores the fundamental mechanisms of the Spring container, detailing its architecture, core jars, bean factory processes, configuration parsing, bean instantiation, property population, and design patterns such as Factory, Singleton, Builder, Decorator, Observer, and Strategy, while providing extensive code examples and diagrams.
This article explains how to improve performance of massive IN‑list database queries in Java by defining custom Spring AOP annotations that automatically split the parameter list, execute the sub‑queries concurrently in a thread pool, and merge the results using a configurable return‑handling strategy.
This guide details how to integrate WeChat native payment into a Java backend, covering merchant setup, Spring configuration, QR‑code generation with the official SDK, handling HTTPS callbacks, and implementing front‑end polling using Redis and Bloom filters for reliable membership upgrades.
This article reviews Java Spring code for a coupon claim and approval workflow, identifies concurrency and transaction issues such as missing locks and inconsistent update order, and proposes optimizations including user‑level locking, simplifying lock management, and aligning transactional update sequences to prevent deadlocks.
This article introduces UniHttp, a declarative Java HTTP client framework that simplifies third‑party API integration by using annotations to generate request metadata, supports various parameter types, lifecycle hooks, custom processors, and provides practical enterprise‑level examples with full code snippets.
This article presents fifteen useful Spring techniques—including bean retrieval, event handling, custom interceptors, retry mechanisms, global exception handling, startup initialization, bean lifecycle methods, resource cleanup, dynamic configuration injection, conditional bean registration, caching, transaction management, bean loading order, AOP aspects, and conditional bean creation—each illustrated with clear Java code examples.
This article introduces MapStruct, a compile‑time Java bean mapping framework, and demonstrates advanced features such as expression‑based mappings, qualifiedByName custom converters, nullValueMappingStrategy handling, and decorator‑based post‑processing with concrete code examples for Spring‑based projects.
This article explains the fundamentals of transaction handling in Spring Boot, covering both programmatic approaches with PlatformTransactionManager and TransactionTemplate and declarative management using @Transactional, while detailing common pitfalls, propagation and isolation settings, and providing concrete code examples.
This guide explains how to create a seamless auto‑login feature by persisting a token in a cookie after the first successful login, storing the token in Redis, and validating it on subsequent visits, complete with Java Spring code examples.
This article explains three backend solutions—database polling with scheduled tasks, JDK DelayQueue, and Netty's HashedWheelTimer—for automatically cancelling unpaid orders after a timeout in a monolithic architecture, detailing their implementation steps, pros, cons, and optimization tips with Java code examples.
The article analyzes the role of Spring MVC Controllers, identifies issues with traditional implementations, and demonstrates how to create a unified response structure, automatically wrap results using ResponseBodyAdvice, resolve String conversion problems, and apply JSR‑303 validation with custom rules and global exception handling.
This article shares hard‑won lessons from production incidents and provides practical guidelines—graceful shutdown, proper startup timing, suitable business scenarios, reliability patterns, and idempotent handling—to use Spring Event safely and effectively in Java backend systems.
This article explains the Chain of Responsibility design pattern, its core concepts, characteristics, and problems it solves, then demonstrates how to combine it with the Strategy pattern in Java using Spring, complete with detailed code examples and execution flow.
This article demonstrates how Lombok’s advanced annotations such as @RequiredArgsConstructor(onConstructor=@__(@Autowired)), @Delegate, @Cleanup, and the combination of @Builder with @Singular can automatically generate Spring‑compatible constructors, delegate methods, manage resources, and build immutable objects, thereby reducing boilerplate and improving code readability in Java backend development.
This article presents a comprehensive collection of written‑test and interview questions covering Java basics, Spring MVC annotations, JVM memory, garbage collection, database design, transaction management, distributed systems, version control, and development workflow, aimed at helping candidates prepare for small‑company technical interviews.
This article explains why Spring Framework discourages field injection with @Autowired, compares constructor, setter, and field injection types, provides code examples for each, and discusses the drawbacks of field injection such as immutability issues, violation of single‑responsibility principle, tight coupling to the container, and hidden dependencies.
This article explains how to improve performance of massive IN‑list queries in PostgreSQL by splitting the parameter list, executing the sub‑queries concurrently with a custom Spring AOP annotation, and merging the results using a configurable thread pool and return‑handling strategy.
This article explains how to improve performance of massive IN‑list queries in PostgreSQL by splitting the list, executing sub‑queries in parallel using a custom Spring AOP annotation, and merging the results with a configurable handler, providing a reusable solution for Java backend services.
This article presents a comprehensive guide to Spring's utility classes—including Assert, ObjectUtils, StringUtils, CollectionUtils, FileCopyUtils, ResourceUtils, StreamUtils, ReflectionUtils, and AOP helpers—detailing their purpose, usage patterns, and code examples, while also containing promotional material for related services.
The 2024 Java trend report analyzes JDK adoption rates, AI tooling, the rise of the Commonhaus Foundation, Spring and Jakarta EE evolution, virtual thread adoption, and community insights, offering guidance for technical leaders and developers planning their future investments.
This article details how a legacy reporting module suffering from slow page loads was refactored by archiving log data, caching hourly counts in Redis, and using scheduled synchronization to dramatically improve query performance without adding new middleware.
A senior developer recounts switching from C# and Python to Java for web projects and higher pay, illustrating Java’s evolution from a “toy” language with early JVM limits to an enterprise powerhouse driven by JIT, Spring Boot, and robust performance that now rivals C++.
This article explains how to refactor the Spring MVC controller layer by introducing a unified response format, using ResponseBodyAdvice for automatic wrapping, fixing String conversion issues, applying JSR‑303 validation, creating custom validators, and handling exceptions globally to keep controller code clean and maintainable.
This article provides a comprehensive analysis of Spring's @Autowired annotation, explaining its purpose, usage in constructor, field, and method injection, and detailing the underlying bean post‑processor logic, dependency resolution, and candidate selection that enable automatic dependency injection.
This article presents a step‑by‑step guide to building a Netty‑based WebSocket server in Java, covering server initialization, channel configuration, custom handlers, push‑message services, testing procedures, and includes complete source code, while also containing promotional material for unrelated AI services.
This article explains how to make Spring AOP logging configurable at runtime by dynamically adding or removing Advice objects through custom endpoints, event listeners, and plugin management code, and demonstrates the approach with a complete example including service, controller, and aspect jar.
Fast‑Retry is a high‑throughput Java retry library that enables asynchronous, non‑blocking retries for massive task volumes, offering programmable and annotation‑based APIs, custom retry policies, and significant performance gains over traditional synchronous frameworks like Spring‑Retry and Guava‑Retry.
The article explains how the Pipeline pattern, a variant of the Chain of Responsibility, can be used to split and decouple complex business scenarios in Java backend applications such as Spring, Tomcat, and Netty, providing code examples, structural diagrams, and practical usage tips.
Explore how Lombok’s powerful annotations—@onX, @Delegate, @Cleanup, @Singular, and @Builder—can dramatically simplify Java code, enable seamless Spring dependency injection, manage resources automatically, and streamline object construction, while highlighting best practices and potential pitfalls for maintainable backend development.
This article provides a comprehensive overview of Spring and Spring Boot's extensible interfaces, detailing each extension point, its lifecycle stage, usage scenarios, and sample code, enabling developers to better understand and customize bean initialization within the backend framework.
This article demonstrates how to replace tightly‑coupled if‑else or switch‑case logic with the Service Locator Pattern in a Spring application, allowing new file‑type parsers such as XML to be added without modifying client code, thereby adhering to the Open/Closed principle.
The article introduces the Cool Request IDEA plugin, explains its tracing capabilities for arbitrary packages, automatic MyBatis function monitoring, customizable timing colors, script-based environment manipulation, and provides a Java code example for handling responses, highlighting its usefulness for backend developers.
This article explains how to implement hot‑pluggable AOP in Spring by letting users enable or disable logging advice at runtime, covering prerequisite concepts, core logic, and a complete code‑first demonstration with dynamic proxy management.
This article explains the Spring container's refresh process, details every extensible hook in a bean's lifecycle—from ApplicationContextInitializer to DisposableBean—provides usage scenarios, and includes complete Java code snippets illustrating how to implement each extension point for custom middleware and application development.
This article explains Spring's transaction management, covering ACID principles, transaction propagation types, isolation levels, timeout settings, read‑only flags, rollback behavior, and the effect of asynchronous execution, supplemented with practical code examples and common pitfalls.
This article explains how to leverage Spring's TransactionSynchronizationManager to detect active transactions, register synchronization callbacks, and asynchronously send Kafka messages only after a transaction successfully commits, illustrated with a payment‑system example and complete Java code snippets, while also noting thread‑local considerations and promotional offers.
The article explains how JDBC’s setQueryTimeout and Spring’s transaction timeout work, reveals why SQL statements can become indefinitely blocked in the socket read phase, and provides practical configuration steps—including driver URL parameters—to prevent such blocking in MySQL, SQL Server, and Oracle environments.
This article introduces a lightweight, extensible Java framework that uses custom annotations to translate relational data, dictionaries, collections, and nested objects, detailing its background, architecture, core annotation design, usage examples, advanced features, Spring Boot integration, ORM support, and provides the open‑source repository link.
This article explains how Spring's bean lifecycle uses a three‑level cache (singletonObjects, earlySingletonObjects, singletonFactories) to break circular dependencies, especially when AOP proxies are involved, and why a two‑level cache alone cannot guarantee correct singleton behavior.
This guide presents a comprehensive design for securing third‑party API calls, covering Access Key/Secret Key generation, permission granularity, timestamp and nonce based replay protection, signature creation and verification, token handling, TLS encryption, rate limiting, logging, and practical Java code examples.
This article explains how to implement runtime switching of multiple service providers in a Spring‑based backend by configuring the active implementation in a central store and using the spring‑smart‑di library's AutowiredProxySPI to inject the appropriate bean automatically.
This article explains why overusing Spring's @Autowired can lead to hidden dependencies, tight coupling, NullPointerExceptions, and testing difficulties, and demonstrates how constructor injection provides clearer, safer, and more test‑friendly dependency management.
This article explains critical pitfalls and best‑practice guidelines for employing Spring Event in Java backend applications, covering graceful shutdown requirements, event loss during startup, suitable business scenarios, reliability enhancements, retry mechanisms, idempotency, and the relationship between Spring Event and message queues.
This article explains how to automatically embed userId and orderId into log statements by defining log placeholders, storing these values in MDC via ThreadLocal, and using a custom @UserLog annotation together with Spring AOP to inject the data before method execution, complete with configuration and test examples.
This article explains how Spring AOP creates proxies using JDK dynamic proxies or CGLIB, outlines the limitations of each approach, and shows multiple ways—including XML, YAML, and annotations—to force CGLIB usage and resolve self‑invocation issues in Spring Boot applications.
An extensible asynchronous processing SDK is presented, leveraging Spring transaction events, Kafka queues, XXL‑Job scheduling, and a non‑intrusive architecture to ensure high performance, data safety, and eventual consistency while simplifying integration across Java backend services.
This article explains how to build a scalable, maintainable permission control framework in Java by defining custom annotations, designing relational database tables, and using Spring AOP to intercept method calls for organization‑level, personal, limit, and special‑role checks, while providing implementation details and best‑practice recommendations.
This article explains how to leverage Spring's TransactionSynchronizationManager to detect active transactions and register synchronization callbacks so that Kafka messages are sent asynchronously only after a transaction successfully commits, ensuring data consistency without impacting the main business flow.
This article provides a comprehensive overview of Spring's built‑in utility classes—including assertion, string, collection, object, file/resource, web, reflection, AOP, path‑matching, and ID generation helpers—illustrating their usage with code examples and highlighting how they improve development efficiency and code quality.
This article presents a detailed overview of Spring's utility classes—including Assert, ObjectUtils, StringUtils, CollectionUtils, FileCopyUtils, ResourceUtils, StreamUtils, ReflectionUtils, and AOP helpers—provides code examples for each, and also contains promotional information about ChatGPT services and a developer community.
A deep dive into Spring Event's delayed listener registration reveals how messages can be lost during the brief window between Kafka consumer initialization and EventListener setup, explaining the root cause, illustrating the startup order, and recommending safer alternatives for reliable message handling.
This article explains the Chain of Responsibility design pattern, demonstrates its application in a product creation workflow with concrete Java code, shows how to configure and assemble handlers dynamically using Spring, and discusses the pattern's advantages, drawbacks, and testing scenarios.
This article explains how to replace repetitive try‑catch blocks in Java backend development with a unified exception handling approach using Spring's @ControllerAdvice, custom Assert utilities, and enum‑based error codes, providing cleaner code, consistent error responses, and easy internationalization.
This article explains why Spring transactions may fail, demonstrates simple examples with and without the @Transactional annotation, details the annotation’s definition and attributes, and provides a step‑by‑step source‑code analysis of transaction creation, commit, rollback, and cleanup in Spring 4.3.12.
This article explains why API debouncing is crucial for backend Java services, outlines which endpoints need protection, describes how to identify duplicate requests, and provides step‑by‑step implementations using Redis shared‑cache and Redisson distributed locks with concrete code examples and test results.
This article explains Spring's three dependency injection methods—constructor‑based, setter‑based, and field‑based—illustrates each with code examples, discusses why field injection is discouraged, and recommends using constructor injection for required dependencies and setter injection for optional ones.
This article provides a detailed tutorial on the Activiti 7 workflow engine, covering workflow concepts, BPMN modeling, environment configuration, Maven dependencies, database schema creation, deployment methods, process instance management, task handling, and historical data querying, with complete code examples for Java developers.
This article explains how Spring 3.0's pure annotation mode simplifies bean configuration, demonstrates using @Component, @Scope, @Autowired, @Qualifier, @Value, and @PropertySource for dependency injection and property loading, and shows step‑by‑step integration of MyBatis with Spring, including required dependencies and configuration classes.
Fast‑Retry is a high‑performance Java framework that enables asynchronous, multi‑task retries with both programmatic and annotation‑based APIs, dramatically improving throughput for large‑scale retry scenarios compared to traditional synchronous retry libraries.
The article explains how to leverage Spring's TransactionSynchronizationManager to detect active transactions and register synchronization callbacks that asynchronously send Kafka messages after a transaction commits, ensuring reliable fund‑flow archiving in payment systems while avoiding thread‑switch issues.
Spring WebClient, the reactive replacement for the deprecated RestTemplate in Spring 5+, offers non‑blocking I/O, functional style, streaming support, and improved error handling; this article explains its benefits, demonstrates synchronous and asynchronous request patterns, timeout configuration, and comprehensive error processing with code examples.
This article explains how to use Spring's TransactionSynchronizationManager to detect active transactions and register synchronization callbacks that asynchronously send Kafka messages only after a transaction commits, illustrated with a payment‑system case and complete Java code examples.
This article explains why RestTemplate is deprecated in Spring Framework 5+, outlines the advantages of the reactive WebClient such as non‑blocking I/O, functional style, streaming and improved error handling, and provides complete Java code examples for creating, configuring, and using WebClient synchronously and asynchronously, including timeout and error management.
This article explains how to enable cross‑node WebSocket communication in a distributed Spring application by using a message queue (Redis or Kafka) to broadcast messages, tracking user connections with Redis, and providing a complete step‑by‑step implementation with code samples and configuration details.
This article demonstrates how Lombok annotations such as @RequiredArgsConstructor, @Delegate, @Cleanup, @Singular, and @Builder can be combined with Spring components to reduce boilerplate, automatically inject dependencies, manage resources, and build immutable objects, providing practical code examples and usage guidelines.
This article outlines how to correctly create, monitor, and configure Java ThreadPoolExecutor instances, explains why using the Executors factory can cause OOM, recommends separate named pools per business, provides formulas for sizing CPU‑bound and I/O‑bound workloads, and highlights real‑world pitfalls and dynamic‑configuration solutions.
This article explains why traditional programmatic HTTP clients cause duplicated, hard‑to‑maintain code in enterprise projects, introduces the UniHttp declarative framework with its annotations, shows a quick‑start guide, details lifecycle hooks for custom processing, and demonstrates an enterprise‑level weather‑service integration example.
This article presents fourteen practical Java Spring development best‑practice tips—including using @ConfigurationProperties, Lombok's @RequiredArgsConstructor, modularizing code, throwing exceptions instead of returning error codes, minimizing unnecessary database calls, avoiding null returns, reducing if‑else chains, and leveraging IDE features—to help developers write cleaner, more maintainable backend code.
This article explains how to leverage Spring's TransactionSynchronizationManager to detect active transactions, register synchronization callbacks, and asynchronously send Kafka messages only after a transaction successfully commits, providing a practical example and detailed code snippets for building a reusable Spring Boot starter library.
This article demonstrates how to build a hot‑pluggable AOP solution in Spring by dynamically adding and removing Advice, Advisor, and related components through custom endpoints, event listeners, and Spring’s bean factory APIs, enabling users to control logging at runtime.
An in‑depth guide reveals thirteen common pitfalls that cause Spring’s @Transactional annotation to malfunction—ranging from unnecessary usage and proxy limitations to propagation misconfigurations and exception handling—plus practical demos and solutions to ensure reliable transaction rollbacks in Java backend development.
This article explains how to handle time‑consuming Spring endpoints by using asynchronous streaming tools—ResponseBodyEmitter, SseEmitter, and StreamingResponseBody—detailing their use cases, code examples, and how they improve system responsiveness without blocking servlet threads.
This article, written by a senior architect, reviews Spring’s built‑in utility classes—including assertions, object and collection helpers, file/IO operations, and reflection/AOP tools—providing code snippets and usage notes to help developers replace redundant custom utilities and improve backend Java code quality.
This article analyzes the performance differences between native Java reflection and Spring Framework's ReflectionUtils by running benchmark tests, examining source code caching mechanisms, and explaining why ReflectionUtils can be faster for repeated method and field access in backend applications.
This article explains how to use Spring's TransactionSynchronizationManager to detect active transactions, register synchronization callbacks, and asynchronously publish payment‑log messages to Kafka without affecting the main business flow, complete with practical code snippets and pitfalls to avoid.
This article walks through a systematic investigation of a slow‑starting Dubbo service built on Spring 3.2, using JProfile to pinpoint costly class‑loading checks, disabling unnecessary annotation processing, and resolving thread‑waiting issues caused by RabbitMQ and other components, ultimately reducing deployment time by about 40%.
The article explains how to simplify Spring MVC controller code by introducing a unified response wrapper, handling String return types with ResponseBodyAdvice, adjusting HttpMessageConverter order, applying JSR‑303 validation for @RequestParam, @PathVariable and @RequestBody, creating custom validation annotations, and implementing global exception handling for consistent API responses.
This article explains Java's built‑in Service Provider Interface (SPI) mechanism, demonstrates how to implement and test SPI with sample code, analyzes its internal workings and limitations, and then shows how Spring extends SPI using spring.factories with comparable examples and source‑code insights.
This article dissects the exact moment a Spring @Transactional method commits relative to a surrounding lock, explains why committing after unlock can cause overselling, and provides source‑level debugging techniques to verify transaction start, commit, and rollback behavior in MySQL under high concurrency.
This article explains how to implement runtime switching of multiple service providers, such as SMS vendors, in a Spring-based backend using the spring‑smart‑di library, @EnvironmentProxySPI, and @AutowiredProxySPI annotations, with configuration stored in Nacos, databases, or environment variables.
This article explains how to design and implement a fixed-size FIFO export queue in a Java backend using Spring components and EasyExcel, covering business requirements, class definitions, code examples, testing results, and considerations for further enhancements such as Redis queues and high‑concurrency scenarios.
This article explains how to automatically include userId and orderId in log messages by storing them in MDC, defining a custom @UserLog annotation, and using Spring AOP to inject the values at runtime, eliminating manual log parameter handling.
This article explains the State design pattern, demonstrates its Java implementation with example code, introduces Spring State Machine concepts, and provides a complete step‑by‑step guide to building and testing an order status workflow using Spring State Machine, including configuration, listeners, services, and a controller.
The article describes a Java‑based FIFO export queue that limits concurrent MySQL export operations, outlines the related classes (ExportQueue, AbstractExport, ExportImpl, and a test controller), provides full source code, and presents test results showing how the queue manages up to ten simultaneous export requests.
This article walks through the eight critical phases of a Spring bean's lifecycle—from instantiation and property population to initialization, post‑processor hooks, usage, and destruction—detailing how Spring creates, configures, enhances, and finally disposes of beans, with code snippets and diagrams for clarity.
The article recounts a production incident where Spring Event caused bean‑lookup failures during service shutdown, explains the three‑step usage of Spring Event with code examples, and presents three mitigation strategies—abandoning Spring Event, handling exceptions with MQ retries, and implementing graceful shutdown—ultimately opting to drop Spring Event.
