This article explains Java object pooling using Commons Pool 2 and HikariCP, covering their core classes, configuration parameters, practical examples with Redis and JDBC, interview questions, and JMH performance benchmarks that demonstrate significant throughput improvements.
The article explains how to avoid tangled if‑else code in a Java backend by using a process engine and a plugin‑based extension point framework, detailing interface definitions, annotations, loading mechanisms, and usage examples drawn from the open‑source MemberClub project.
The article compares Spring Boot and Quarkus for cloud‑native Java apps, showing Quarkus’s faster startup, smaller builds and lower memory usage (especially in native mode) while Spring Boot slightly leads latency, and outlines migration paths leveraging Quarkus’s Spring‑compatible extensions and native‑image advantages.
The article explains why simple code quickly becomes unmanageable in multi‑business systems, introduces workflow engines and plugin extensions as solutions, and demonstrates configuration, node definition, execution, and the underlying Java implementation to achieve clean, isolated, and extensible business logic.
Explore the newly released Spring Boot 3 case collection and dive into a practical guide on implementing API version control in Spring 7.0.0‑M3, featuring step‑by‑step configuration, Maven setup, custom version resolver, and annotated controller examples, plus a promise of ongoing updates.
This article provides a concise guide on using SpringAI to connect Java applications with the domestic large‑language model DeepSeek, covering design philosophy, configuration, code examples for chat, streaming, structured output, security hardening, performance tuning, and production best practices.
The article revises a supermarket checkout performance test by incorporating elderly customers who take twice as long to pay, demonstrates using Java's ThreadLocalRandom to randomly assign customer age groups, modifies the pay() method to double payment time for seniors, and explains why realistic scenarios improve testing accuracy.
RocketMQ’s message tracing feature records each message’s full lifecycle—including producer, broker, and consumer details such as timestamps, latency, and success flags—by enabling traceTopicEnable, creating an internal RMQ_SYS_TRACE_TOPIC, and allowing custom trace topics for fast diagnostics, end‑to‑end tracking, monitoring, and audit compliance.
This article compares Spring Boot and Quarkus across architecture, startup speed, memory usage, and native image support, presents a JMeter‑based performance test suite, shares migration tips for Spring developers, and provides concrete Java code examples for building reactive microservices on both frameworks.
This article introduces Aviator, a lightweight JVM‑based expression engine, explains its features and limitations, and demonstrates how to integrate it with Spring Boot and AOP to replace traditional if‑else validation logic using custom annotations and script files.
The article examines Java thread states—WAITING and TIMED_WAITING—through monitoring screenshots, explains their definitions, trigger conditions, and recovery mechanisms, analyzes real‑world code involving concurrent tasks, and presents flame‑graph based performance optimizations for backend services.
This article explains Java thread run states, analyzes why threads appear in WAITING or TIMED_WAITING during concurrent tasks, shows flame‑graph diagnostics, and offers concrete code‑level optimizations to reduce CPU pressure and improve overall backend performance.
This article explores eight common scenarios for using message queues in backend development, covering asynchronous processing, service decoupling, traffic shaping, delayed tasks, log aggregation, distributed transactions, remote calls, and broadcast notifications, each illustrated with Java, RocketMQ, and Kafka code examples.
This curriculum outlines a 25‑week advanced Java engineering program covering performance optimization, JVM internals, concurrency, distributed storage, MySQL and NoSQL databases, Docker, Kubernetes, microservices, Spring framework deep dives, Nginx, Elasticsearch, Redis, messaging systems, CI/CD tools, and hands‑on project implementation to build high‑performance, scalable backend systems.
This article explains how Spring's ResponseBodyEmitter, introduced in Spring 4.2, enables lightweight asynchronous HTTP streaming for use cases like real-time logs, progress updates, chat, and AI responses, and provides a complete code example with best-practice guidelines.
This article explains the CRaC (Coordinated Restore at Checkpoint) technology for Java applications, describing its principles, supported environments, practical steps for enabling it with Spring Boot, and use‑case scenarios that dramatically reduce JVM startup time.
Modern Java introduces lambda expressions and the Stream API for functional programming, while upcoming projects—Loom’s virtual threads, Panama’s foreign function and memory API, and Valhalla’s value classes and generic specialization—address concurrency, native interop, and performance, dramatically enhancing developer productivity and language capabilities.
This article introduces the advantages of Java's CompletableFuture and systematically outlines six common pitfalls—including default thread‑pool issues, exception handling, timeout management, thread‑local context loss, callback hell, and task‑ordering problems—while providing correct code examples and best‑practice recommendations.
This article introduces JDFrame/SDFrame, a Java library that provides a DataFrame‑style, semantic API for JVM‑level stream processing, demonstrates quick start with Maven dependency, and showcases extensive examples covering filtering, aggregation, distinct, grouping, sorting, joining, partitioning, ranking, and data replenishment, helping developers write concise, readable data‑processing code.
This article explains Java's two primary garbage‑collection techniques—reference counting and reachability analysis—detailing their principles, drawbacks such as circular reference issues, and why modern JVMs favor reachability analysis to safely reclaim memory.
This article introduces JavaParser, an open‑source library for parsing Java source code into an AST, and walks through practical cases covering dependency setup, basic parsing, class and method extraction, code modification, class generation, and comprehensive analysis with code snippets and output screenshots.
This article explains how Spring's declarative transaction management works, why the @Transactional annotation can unexpectedly become ineffective, and presents twelve typical scenarios—such as internal method calls, non‑public methods, final/static modifiers, proxy issues, and incorrect propagation settings—along with practical solutions to ensure reliable transaction handling.
This article introduces JSONPath as a query language for JSON, explains its core concepts and basic syntax with examples, demonstrates various practical use cases such as data extraction, API testing, and shows tool support across Python, Java, and JavaScript.
Facing the need to query multiple databases in a Spring Boot application, this guide walks through building a custom dynamic datasource solution using ThreadLocal and AbstractRoutingDataSource, covering core implementations, annotation‑based switching, dynamic datasource addition, configuration, and comprehensive test results.
This guide explains how to create a shell script to deploy a Java backend application without Docker, covering variable configuration, start/stop/restart functions, log handling, and command-line usage, along with packaging and troubleshooting steps.
This article provides a comprehensive, English-language walkthrough of MyBatis's four core components—Executor, StatementHandler, ParameterHandler, and ResultSetHandler—explaining their interfaces, default implementations, key methods, and how they collaborate to translate Java objects into SQL statements and process query results.
Discover ten validated Spring Boot 3 performance optimization techniques—including lazy initialization, JVM tuning, connection pooling, caching, async processing, virtual threads, and Actuator monitoring—complete with configuration snippets and code examples, to accelerate startup, reduce memory usage, and improve response times for Java backend services.
This article introduces Magic‑API, a Java‑based rapid API development framework, outlines its extensive feature set, and provides step‑by‑step instructions—including Maven integration, configuration, and visual UI usage—to help developers create HTTP endpoints without writing traditional controller or DAO code.
This article introduces AviatorScript, a lightweight high‑performance JVM‑based scripting language, outlines its core features and limitations, demonstrates how to add it to a Maven project, shows expression evaluation, variable handling, custom functions, script files, and provides a practical Spring Boot AOP validation example with full code snippets.
The article explains the concept of GC Roots in the JVM, detailing the four main types—stack variables, static fields, constant pool references, and JNI references—along with code examples, and describes how these roots determine object liveness during garbage collection.
This article walks through a step‑by‑step troubleshooting process for JVM Out‑Of‑Memory (OOM) incidents, covering symptom identification, monitoring tools like top, jstat, and jmap, root‑cause analysis, and actionable recommendations to prevent future memory leaks.
This article explains how Spring Boot 3's new @BindParam annotation lets developers map mismatched path and query parameters to constructor arguments, supports @ModelAttribute, and shows how to create custom name resolvers for advanced parameter binding scenarios.
This article demonstrates how to integrate Apache Tika into a Spring Boot application to automatically extract file content, detect sensitive data such as ID numbers, credit cards, and phone numbers using regex, and implement data leakage protection through RESTful file upload endpoints and optional front‑end UI.
The article explains why excessive if‑else logic harms maintainability, introduces flow‑engine and plugin‑extension techniques to isolate business code and enable flexible extensions, demonstrates their implementation in the open‑source MemberClub project with configuration, node definitions, execution flow, and source code examples.
This article demonstrates how to dramatically speed up Java data‑matching operations that use nested for‑loops by breaking early when a match is found and by converting the inner list into a HashMap for O(1) lookups, showing code examples, performance measurements, and practical tips for backend developers.
This article explains the Java BigDecimal class, its internal fields, and how its addition method scales numbers to maintain precision, illustrated with code examples and debugging insights, concluding that BigDecimal performs arithmetic using scaled long integers to avoid precision loss.
The article examines the architectural concepts behind Java's Striped64 and ConcurrentHashMap, explains how they achieve high‑performance concurrency, and discusses the memory, complexity, and scalability drawbacks that developers should consider when choosing these data structures for backend systems.
This article explains the main Java garbage collection algorithms—Mark‑Sweep, Mark‑Copying, Mark‑Compact, and Generational Collection—detailing their principles, advantages, and drawbacks, helping developers choose the appropriate strategy for efficient memory management in backend applications.
This article walks through the LeetCode 77 "Combinations" problem, explaining the backtracking approach, presenting detailed examples, constraints, and providing complete implementations in Java, C++, and Python for generating all k‑element subsets of the range [1, n].
This article examines common pitfalls in Spring Boot controller implementations—such as excessive try‑catch blocks, inline validation, and business logic—then demonstrates cleaner alternatives using @Valid, validation annotations, and global exception handling to produce concise, maintainable controllers.
This article explains how to design and implement a flexible plugin mechanism for Java applications, covering the benefits of decoupling, common implementation strategies such as ServiceLoader (SPI), custom configuration loading, and Spring Boot integration via spring.factories, with complete code examples and a real‑world case study.
This article explains LeetCode problem 77, describing how to generate every possible combination of k numbers from the range 1 to n using backtracking, and provides complete Java, C++, and Python implementations along with a brief analysis and constraints.
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 explains why force‑killing a Spring Boot process is unsafe and walks through four practical ways—using Actuator, ApplicationContext.close(), PID‑based kill commands, and SpringApplication.exit()—to achieve a graceful shutdown while preserving in‑flight tasks and releasing resources.
This tutorial demonstrates how to create an AI-driven Spring Boot application by integrating DeepSeek's large language model, covering project setup, dependency configuration, API key management, and implementing a REST controller that provides weather forecasts via a conversational interface.
This article explains the concepts, usage conditions, execution flow, internal mechanisms, and best‑practice guidelines for Java's wait() and notify() methods, illustrated with a producer‑consumer example and code snippets for safe thread coordination.
The article explains five fundamental concurrency levels—Blocking, Starvation‑Free, Obstruction‑Free, Lock‑Free, and Wait‑Free—detailing their definitions, implementation mechanisms in Java, performance trade‑offs, suitable scenarios, and practical decision guidance for building high‑performance, reliable systems.
This article explains the fundamentals of I/O in Unix and Java, covering the distinction between user and kernel space, the five Unix I/O models, the evolution from select/poll to epoll/kqueue, and how modern network frameworks like Reactor and Proactor leverage these mechanisms for high‑performance networking.
This article explains RocketMQ's message tracing feature, covering its definition, key data attributes, core benefits, configuration steps for both normal and IO‑isolated modes, the underlying implementation mechanism, supported trace topics, and provides complete Java code examples for custom TraceTopic usage and verification.
This article explains how SpringBoot’s default embedded Tomcat can be replaced with the high‑performance Undertow server, shows the necessary Maven dependencies, lists Undertow’s key features, presents benchmark results comparing QPS and memory usage, and concludes with recommendations for high‑concurrency applications while also noting related AI‑product promotions.
This article revisits Sentinel, Alibaba’s open‑source traffic‑governance component, explaining its core concepts, resource and rule definitions, step‑by‑step demos for basic and Spring integration, and a detailed walkthrough of its internal processor slots, statistics nodes, flow control, and degradation mechanisms.
This article explains the core principles of Java class loading, including the uniqueness of Class objects per ClassLoader, various loading sources such as dynamic generation, network, ZIP archives, and databases, the lifecycle stages, delegation model, isolation, and practical recommendations for safe and efficient deployment.
This article presents a continuously updated collection of over 100 Spring Boot 3 practical cases, demonstrating how to implement permission authentication using Spring AOP, custom annotations, JWT utilities, interceptors, a global exception handler, a security context, and a custom argument resolver, complete with test examples and screenshots.
This article demonstrates how to create a PDF template by first designing a Word document, converting it to PDF, inserting text, option, and image fields using a PDF editor, and then programmatically filling those fields with Java iText code, including dependency setup and image insertion.
The article explains why data desensitization is essential for enterprises, classifies common masking techniques, and provides concrete implementation guides for database, log, and output level masking in Java applications using MyBatis plugins and Fastjson filters, complete with sample code and configuration.
An extensive Spring Boot 3 case collection featuring over 100 practical examples is now available, accompanied by a detailed tutorial that demonstrates how RestTemplateAdapter and RestClientAdapter simplify HTTP request handling, improve code readability, and ensure seamless integration with third‑party APIs, with a commitment to permanent updates.
Implementing real‑time statistics in a Java performance testing engine involves adding TPS and average latency counters, creating a controllable monitoring thread, using LongAdder for high‑concurrency metrics, and gracefully shutting down the thread, enabling testers to instantly observe system load and detect bottlenecks.
The article explains how using double for monetary values can cause precision loss—turning 2.01 into 2.00—illustrates the binary representation issue, demonstrates failing code, and presents a robust solution using Java's BigDecimal with sample conversion methods and performance tests.
The article introduces DeepSeek4j 1.4, a Java Spring Boot library that overcomes existing framework limitations by preserving DeepSeek's chain‑of‑thought capabilities, adding full reactive streaming, and providing a simple one‑line API along with quick‑start instructions and code examples.
An analysis of Perforce's 2025 Java Developer Productivity Report reveals that over half of Java developers face deployment delays and tool shortages, while AI tools like ChatGPT and GitHub Copilot are increasingly adopted for code completion, refactoring, and documentation, signaling a strategic shift toward AI in Java development.
The article demonstrates how to build a dynamic Chain of Responsibility in a Spring Boot and MyBatis‑Plus application by defining an abstract handler, implementing concrete @Component beans that modify a shared Lombok‑based context, retrieving them via an ApplicationContext‑aware proxy utility, and invoking them in a client‑specified order through a REST endpoint, while suggesting LiteFlow as a production alternative.
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 Java's Service Provider Interface (SPI), demonstrates a step‑by‑step example with multiple Maven modules, explains how to create interface and implementation classes, configure META‑INF/services files, and delves into the ServiceLoader internals that enable runtime discovery and instantiation of providers.
This guide explains Java's Service Provider Interface (SPI), detailing its purpose for decoupling implementations, step-by-step project setup, code examples, configuration files, and an in-depth analysis of ServiceLoader's internal mechanisms, enabling developers to create flexible, extensible Java applications.
This article walks through the background of Spring Cloud's Feign client, explains its core concepts, shows step‑by‑step project setup with Eureka services, demonstrates remote calls and file upload extensions using Feign‑Form, and concludes with a functional microservice example.
This article examines how the misuse of Java Stream and Lambda APIs can make code harder to read and maintain, and provides practical techniques such as proper line breaks, function extraction, careful filter logic, correct Optional usage, and cautious parallel stream adoption to keep code both elegant and efficient.
This article examines the challenges of locating and diagnosing SQL statements in large systems and introduces a lightweight, non‑intrusive MyBatis plugin that injects color‑marking metadata into SELECT, INSERT, UPDATE and DELETE queries, enabling rapid business source identification and enhanced debugging.
This article explores why many developers rarely use thread pools, demonstrates a SpringBoot‑Dubbo demo to reveal hidden thread pools in web containers and RPC frameworks, and offers practical guidance on when to tune existing pools versus adding custom ones for optimal performance.
By using the JavaCompiler API to compile source files at runtime together with a custom ClassLoader that loads the generated bytecode, developers can hot‑reload changed classes instantly without restarting the JVM, enabling rapid iteration, plugin‑style extensions, and faster development cycles.
This article explains the structure, contents, and characteristics of Java's Class constant pool and runtime constant pool, detailing how literals and symbolic references are stored, how the runtime pool can be dynamically modified, and the impact on memory and JVM linking.
This article explores ten effective techniques for handling null values in Java, ranging from traditional if‑else checks to modern Optional usage, Lombok annotations, AOP interceptors, the Null Object pattern, Guava utilities, Kotlin‑style safety, and JDK 14 preview features, helping developers write cleaner, more robust code.
This article explains why large SQL IN clauses cause performance issues or errors in MySQL and Oracle, and demonstrates a Spring Boot 3 solution that uses custom annotations, an AOP aspect, multithreading, and result handlers to automatically split and process the queries in batches.
This article introduces Java 21's virtual threads, explains their lightweight and high‑concurrency advantages, demonstrates basic and delayed usage with code examples, shows how to enable them in Spring Boot, compares performance against traditional threads, and offers additional Java performance‑tuning techniques.
Java 21’s virtual threads provide lightweight, high‑concurrency execution managed by the JVM, enabling developers to create hundreds of thousands of threads with minimal overhead; this article explains their basics, demonstrates Spring Boot integration, compares performance against traditional threads, and shares additional Java optimization techniques.
This article explains why workflow orchestration is essential for isolating business logic in large systems, outlines common pitfalls of tangled if‑else code, and demonstrates how to configure and execute flow chains using a Java flow engine and plugin extensions.
This guide walks Java developers through preparing the environment, installing the CodeGPT plugin, configuring DeepSeek API keys and models, and using the AI assistant for code generation, completion, explanation, and troubleshooting directly within IntelliJ IDEA, while also showing usage statistics.
This article examines three leading Java AI frameworks—LangChain4j, Spring AI, and Agent-Flex—by comparing their architectures, core capabilities, and ideal use‑cases, helping developers choose the most suitable solution for enterprise, domestic, or rapid‑prototype projects.
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.
This article explains the evolution of Java virtual threads in AJDK, details performance improvements, examines pinning problems caused by synchronization and native code, provides migration steps, configuration tips, and code examples, and introduces diagnostic tools for troubleshooting virtual thread issues.
The CMS (Concurrent Mark Sweep) garbage collector, designed for low‑latency old‑generation reclamation, suffers from memory fragmentation, floating garbage, high CPU usage, concurrent‑mode failures, Full GC risks, and complex tuning, making it unsuitable for many production Java workloads.
This article demonstrates how to use Byteman’s DO execution module on the Chaos Mesh platform to invoke static or instance methods of external Java classes without modifying the original code, covering reflection, ClassLoader tricks, and a complete BTM rule example.
This article introduces a comprehensive Spring Boot 3 practical case collection and walks through building a reentrant, auto‑renewing distributed lock using Redis and Lua scripts, providing full code snippets and configuration guidance for robust backend concurrency control.
This article introduces Apache Tika's capabilities for parsing a wide range of file formats, automatic type detection, OCR and language detection, then demonstrates how to integrate Tika into a Spring Boot service to extract text and identify sensitive information such as ID numbers, credit cards, and phone numbers.
Java 8 enriches the Map interface with default methods such as getOrDefault, forEach, merge, putIfAbsent, compute, computeIfAbsent, computeIfPresent and replace, allowing developers to retrieve values with fallbacks, iterate entries, combine or conditionally update entries, and thus write more concise, readable code with far less boilerplate.
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 explains Java 21 virtual threads, demonstrates how to create and use them in plain Java and Spring Boot, compares their performance against traditional threads in large‑scale and HTTP workloads, and offers additional Java performance optimization tips.
This article introduces a continuously updated Spring Boot 3 case collection and provides a step‑by‑step guide to nine Java string‑formatting methods—including String.format, MessageFormat, text blocks, number grouping, rounding, zero‑padding, printf, whitespace, and concatenation—complete with runnable code examples.
This article explains the concepts, advantages, design choices, database strategies, and step‑by‑step implementation of a multi‑tenant system using Java Spring Boot and Spring Cloud, including code samples for data sources, dynamic routing, and tenant management in cloud environments.
This step‑by‑step guide shows Java developers how to prepare their environment, install the CodeGPT plugin, configure DeepSeek with an API key and model settings, and then use the assistant for code generation, completion, explanation, question answering, and usage monitoring within IntelliJ IDEA.
An in‑depth comparison of Java’s Hashtable and HashMap covers their thread‑safety mechanisms, null‑key/value policies, inheritance hierarchy, default capacities, resizing strategies, and iterator behavior, highlighting performance trade‑offs and best‑practice alternatives for concurrent applications.
This article explains how enabling Java method breakpoints in IntelliJ IDEA can increase startup time from under two seconds to over thirty seconds, why the JVM design causes the slowdown, and provides practical steps—removing method breakpoints, disabling method‑exit events, and using line breakpoints—to restore fast debugging performance.
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 introduces the Liteflow rule engine, explains its architecture and configuration, demonstrates how to define components and EL rule files, and shows a real e‑commerce workflow example, while also providing Maven dependency snippets and usage guidelines for Java Spring Boot applications.
This article demonstrates how to use the iTextPdf library in a Java SpringBoot project to create PDF templates, dynamically fill fixed and tabular invoice data, generate separate PDFs, and merge them into a single document, providing complete code examples and configuration details.
Because phone numbers are identifiers that can contain symbols and exceed the numeric range of an int, storing them as a String—despite higher memory use—is semantically correct, avoids overflow, preserves formatting, and benefits from JVM string pooling, making String the preferred type in most Java applications.
This article explains the LeetCode Combination Sum II problem, detailing how to find all unique candidate combinations that sum to a target using sorting and backtracking while eliminating duplicate results, and provides complete implementations in Java, C++, C, and Python.
This article explains the CQRS pattern, its origins, benefits, and challenges, and provides a step‑by‑step guide with Java code examples on how to implement CQRS, event sourcing, and asynchronous communication using Spring Boot, Axon, and Kafka in microservice architectures.
This article provides a comprehensive guide to Java thread pools, explaining their purpose, construction parameters, execution flow, worker reuse, task retrieval with timeout, lifecycle states, shutdown mechanisms, monitoring methods, and best practices for customizing pools in real-world projects.
This guide explains common scenarios for using custom Java annotations—such as logging, permission control, data validation, and caching—and walks through the step-by-step process of defining an annotation, applying it in Spring services, handling it with an AOP aspect, and testing the implementation in a Spring Boot application.
This guide shows how to use JSONPath within a Spring Boot 3.4.0 project to efficiently query, filter, and modify complex JSON structures, providing Maven setup, syntax overview, operator tables, and practical code examples for extracting authors, prices, books, and applying custom filters.
