This article explains what a microservice gateway is, outlines the advantages of Spring Cloud Gateway, and provides step‑by‑step instructions with code examples to create, configure, and run a reactive API gateway for Java microservices.
MaxKey is an enterprise‑grade single sign‑on solution that supports OAuth 2.x, OpenID Connect, SAML 2.0, JWT, CAS and SCIM, offering secure identity management, RBAC, multi‑tenant capabilities, robust password policies, brute‑force protection, session control, and BCrypt‑based password encryption.
This article explains why threads are essential for performance, how to create and configure Java thread pools using the Executors utility, distinguishes CPU, IO, and scheduled pool types, and demonstrates monitoring techniques for latency and deadlock detection with practical code examples.
This guide explains how Spring's @Qualifier annotation eliminates bean injection ambiguities, shows basic usage, custom qualifier creation, generic qualifiers, fully custom annotations, and advanced attribute‑based qualifiers, all illustrated with clear Java code examples for Spring 6.1.2.
After an Alibaba Cloud RDS host failure caused a HA switch, the bme‑trade‑order‑svc service experienced prolonged unavailability; this article dissects how thread‑pool saturation, HikariCP connection‑pool mechanics, and CPU load interplay, and outlines systematic investigations that pinpointed thread waiting, pod restarts, and CPU throttling as root causes.
This article introduces Groovy as a JVM‑based dynamic scripting language, explains why it suits rapidly changing business rules such as payment integration, marketing and risk‑control, and provides step‑by‑step code examples, advanced usage patterns, best practices and common pitfalls for Java backend developers.
A developer debates whether placing a try‑catch block inside a Java for‑loop impacts performance, runs JMH benchmarks comparing try‑catch inside the loop versus around it, examines bytecode differences, references Effective Java’s warnings, and concludes the overhead is minimal unless exceptions are actually thrown.
To simplify RocketMQ usage, I designed an internal SDK that abstracts complex client configurations, offering single‑call ordered message sending, per‑message consumption, unified result handling, and enforced consistent subscription settings, thereby reducing developer effort and preventing common integration errors.
This article demonstrates how to implement a hot‑pluggable AOP solution in Spring by exposing endpoints that let users dynamically add or remove Advice, covering the underlying concepts, core implementation code, a demo service, and test scenarios that show logging being enabled and disabled at runtime.
This article explains the principles and implementation of a Java RPC framework, covering service registration with Zookeeper, serialization, compression, network communication via Netty, dynamic proxy generation using reflection and Javassist, and performance considerations, providing extensive code examples for each component.
This article introduces retrofit-spring-boot-starter, a lightweight, type‑safe HTTP client starter that seamlessly integrates Retrofit into Spring Boot projects, outlines its key features, provides quick usage examples with Maven/Gradle dependencies, interface definitions, injection, configuration options, and advanced capabilities such as custom OkHttpClient injection, annotation‑based interceptors, connection‑pool management, logging, and retry mechanisms.
This article analyzes a FastJSON serialization issue where a getter method is unexpectedly invoked, explains the underlying ASM-generated serializer workflow, details which methods are considered during serialization, and provides best‑practice code annotations to prevent unwanted method execution.
This article explains how to design a clean, maintainable Spring Boot backend by applying core software principles, organizing modules such as core, common, business, and admin, and providing complete Maven pom examples to illustrate a modular multi‑module project layout.
This article examines the Matrix middle‑platform framework used at JD.com, detailing its hot‑deployment mechanism, the push‑and‑pull integration chains, class‑loader isolation based on the parent‑delegation model, and the design of business‑identity recognition, while offering best‑practice recommendations and code examples.
This article explains Redis databases, the structure of the keyspace, how to set key expiration, and the various memory reclamation and eviction policies, providing Java developers with the essential knowledge needed for advanced Redis interview questions.
After a year of using Project Lombok, the author reflects on how its annotations dramatically shrink boilerplate but also introduce version incompatibilities, hidden dependencies, reduced readability, tighter coupling, and technical debt, urging developers to weigh its benefits against long‑term maintenance risks.
The article recounts a real‑world incident where a game’s leaderboard showed absurd scores due to insecure API parameters, then explains RSA and AES fundamentals, demonstrates how to combine asymmetric and symmetric encryption for secure request handling, and provides Java code, custom annotations, and AOP logic to automate decryption on the server side.
This article explains the fundamentals of finite‑state machines, introduces Spring Statemachine’s core features, walks through a complete Java implementation with database schema, persistence (memory and Redis), REST APIs, exception handling, and an AOP‑based solution for reliable state transitions.
This guide explains the fundamentals of AES symmetric encryption, compares Java and PHP implementations, highlights their shared features and differences, provides complete code samples for encryption and decryption, and offers practical advice on key management, IV usage, and performance considerations.
This article presents a concise, beginner-friendly approach to building a Spring Boot unit testing environment using only essential Maven dependencies and test classes, covering both integration-style and pure unit test techniques, complete with annotated examples and practical testing tips.
The article explains how Java’s BigDecimal class maintains exact financial precision by storing numbers as an unscaled integer and a scale, scaling operands to a common decimal place, performing integer arithmetic—including handling differing scales—and finally reconstructing a correctly scaled result.
The article introduces retrofit-spring-boot-starter, a lightweight HTTP client library for Spring Boot that simplifies HTTP calls, offers extensive features such as custom OkHttpClient injection, annotation‑based interceptors, retry, logging, circuit‑breaker, and provides detailed usage examples, configuration options, and advanced customization techniques.
This article explains why publicly exposed APIs are vulnerable to tampering and replay attacks, outlines anti‑tampering and anti‑replay strategies such as HTTPS, request signing, timestamp and nonce mechanisms, and provides a complete Spring Boot implementation with Redis support.
The article introduces Graceful Response, a Spring Boot component that unifies response structures, centralizes exception handling, and simplifies validation, thereby reducing boilerplate code, improving readability, and enhancing development efficiency for backend services.
This article explains how to improve a Java Spring Boot contract signing workflow by combining the Strategy pattern, Chain of Responsibility, and Composite patterns, detailing the process steps, project structure, code implementations, custom annotations, and dynamic bean injection to achieve a flexible and maintainable solution.
The article explains why a locally created ThreadPoolExecutor cannot be reclaimed by Java's garbage collector, detailing GC root analysis, the role of live threads, inner‑class references, static versus non‑static nesting, and how these concepts can cause memory leaks.
Learn how to use Spring's @ControllerAdvice, @ExceptionHandler, @InitBinder, and @ModelAttribute annotations to implement global exception handling, data binding, and pre-processing, including custom exceptions, order control with @Order, and practical code examples for robust backend development.
Oracle announced its upcoming AI coding assistant, Code Assist, tailored for Java, Oracle Database, NetSuite scripts, and Oracle Cloud, offering chat-driven code suggestions, documentation generation, and security scanning across VS Code and JetBrains IDEs, while emphasizing multi‑language support and data privacy.
This article introduces Arthas, an open‑source Java diagnostic tool from Alibaba, explains its key features, shows how to install it via Maven, and provides step‑by‑step commands for entering the shell, monitoring JVM status, tracing method calls, observing system resources, dynamically redefining code, and connecting to applications using default or Telnet modes.
This article explains the timing of Spring's @Transactional commit relative to lock release, analyzes why committing after unlock can cause overselling, shows how to trace the transaction lifecycle in the source code, and offers practical solutions to ensure atomicity in high‑concurrency scenarios.
This article explains the principles of Redis Pipeline, compares Lettuce and Redisson client implementations in Spring Boot, presents performance tests showing dramatic speed gains over single commands, discusses practical usage scenarios, common pitfalls, and provides detailed source code examples for both clients.
This article recounts a leaderboard data breach caused by tampered Base64 request parameters, then details a hybrid RSA‑AES encryption strategy—using RSA to protect the AES key, IV and timestamp while AES encrypts the actual payload—along with Java implementations, key‑generation utilities, and a Spring AOP aspect for automatic decryption, providing a comprehensive guide to securing API communications.
Disruptor is an open‑source, lock‑free Java framework that uses a ring‑buffer and sequencer to achieve ultra‑high‑throughput, handling millions of events per second, and is employed by projects like LMAX, Storm, Camel, and Log4j2, with detailed concepts, wait strategies, and usage examples.
This article explains TCP packet fragmentation and aggregation (sticky/unsticky packets), demonstrates the phenomena with examples, and provides detailed solutions using Netty's built‑in decoders such as FixedLengthFrameDecoder, LineBasedFrameDecoder, DelimiterBasedFrameDecoder, and LengthFieldBasedFrameDecoder, including code samples and configuration tips.
This article explores the lesser‑known Apache Commons Lang StringUtils methods such as isAnyEmpty, isNoneEmpty, isAnyBlank and isNoneBlank, showing how they differ from the classic isEmpty/isBlank checks with clear code examples and usage guidelines.
The investigation revealed that G1GC pauses were caused by uncontrolled growth of the JVM StringTable, triggered by Jackson’s InternCache interning countless random JSON field names, and was mitigated by enlarging the young generation, disabling field‑name interning, tuning G1 parameters, and monitoring StringTable size.
This guide explains why SpringBoot JARs become bulky when many dependencies are included, shows how to inspect the packaged libraries, and provides step‑by‑step Maven configurations and runtime commands to build a leaner JAR that loads external libs only when needed, dramatically speeding up deployment.
This article demonstrates how to secure Spring Boot APIs by encrypting request and response bodies using custom ControllerAdvice, switching from FastJson to Jackson for proper enum and date serialization, and configuring ObjectMapper to produce consistent JSON output across encrypted and non‑encrypted endpoints.
This article demonstrates how to design a simple Calculator interface in Java, implement it using both Spring‑managed and reflection‑based approaches, and achieve hot deployment by loading user‑provided JAR files at runtime, including code for class loading, bean registration, and cleanup.
This article explains why servers cannot know your original password, covering the principles of password hashing, the difference between cryptographic and non‑cryptographic hash functions, the role of salts, and a Java example using SHA‑256 with salt to securely store passwords.
Learn how to enforce role‑based data permission filtering in MyBatis‑Plus by creating custom annotations, implementing an InnerInterceptor, and integrating a permission handler that dynamically builds WHERE clauses based on user roles, with both basic and advanced examples covering SQL parsing, role scopes, and plugin configuration.
This guide walks you through the fundamentals of Java Spring Boot projects, explains WAR vs JAR deployment, sets up Maven and Jenkins, configures SSH and DingTalk notifications, and provides a complete CI/CD pipeline with scripts for automated builds and releases.
This article explains the rules of platform coupons, demonstrates a concrete example, and details three generations of algorithms—from a Cartesian‑product approach to Map‑based and array‑index methods—highlighting their implementations, performance trade‑offs, and a comparative benchmark.
This article explores the default behavior of Spring's @Autowired annotation, how to resolve bean name conflicts, use @Qualifier and @Primary, apply @Autowired on constructors, methods, parameters, and collections, and troubleshoot common issues such as missing annotations, filter injection, component scanning, and circular dependencies.
This article walks through three ways to map JSON columns to Java objects in MyBatis, explains why simple String or JSONObject approaches are fragile, and provides a complete custom TypeHandler implementation, registration, and usage example for complex entity fields.
Learn how to configure Spring Boot 3.2.5 to let a single controller endpoint dynamically produce JSON, XML, or custom YAML responses using Accept headers, request parameters, path extensions, and custom HttpMessageConverters, with step‑by‑step code examples and necessary Maven dependencies.
This guide explains step‑by‑step how to configure IntelliJ IDEA’s Live Templates to automatically generate Javadoc comments for Java methods, including creating a custom template group, defining variables, setting scope, and showcasing useful Java‑8 snippets, while also noting promotional offers for activation tools.
This guide walks through implementing a complete product management module in a Java e‑commerce system, covering Snowflake distributed ID generation, database schema design for SPU and SKU tables, CRUD operations, category‑brand linking, audit workflow, status toggling, batch processing, and logical deletion, all with concrete code examples.
This article explains three common methods for implementing delayed queues with Redis—using key expiration notifications, Zset with scheduled tasks, and Redisson’s RDelayedQueue—detailing their concepts, core code examples, advantages, and limitations for backend developers.
The article walks through MyBatis’s internal execution pipeline, from loading the configuration file and building a SqlSessionFactory, to creating a SqlSession, generating a MapperProxy for the mapper interface, and finally invoking the mapped method which triggers JDBC operations, while detailing caching and executor mechanisms.
This article demonstrates three practical approaches for invoking external services in a Spring Boot application—using a raw HttpClient, the RestTemplate utility, and the Feign declarative client—complete with code examples, configuration steps, and tips for handling headers and tokens.
This article explains how using an off‑heap local cache (OHC) can dramatically lower GC pauses and cut interface latency by up to tenfold, covering the underlying principles, configuration, custom serializers, performance testing, monitoring metrics, and practical optimization recommendations for high‑traffic Java backend services.
This article introduces a powerful Java parameter‑validation library based on Spring Expression Language, explains its features, supported annotations, usage examples, configuration steps, and how to extend it with custom constraints, providing a complete guide for backend developers.
This article explains nine typical scenarios that cause the Spring @Async annotation to fail—ranging from missing @EnableAsync to improper method visibility, return types, static or final modifiers, missing @Service, manual object creation, and incorrect component scanning—providing clear explanations and code examples for each case.
This article compares common global ID generation strategies for microservice architectures, covering database‑level solutions like auto‑increment configuration and MyCat + ZooKeeper, as well as application‑level approaches such as UUID, Snowflake, Leaf (segment and Snowflake modes), Redis, and ZooKeeper, with configuration steps, code samples, and pros‑cons.
This tutorial explains RSA asymmetric encryption and signing, then walks through securing Spring Boot API endpoints by adding annotations, configuring keys, integrating JavaScript decryption, and addressing practical deployment considerations to protect data from interception and tampering.
This article explains how to achieve graceful service startup and shutdown in Java projects, covering monolithic and microservice architectures, Spring and SpringBoot mechanisms, service registration with Eureka and Nacos, Kubernetes probes, thread‑pool and MQ graceful termination, and provides practical code examples for each scenario.
This article presents a design and implementation of both static AST‑based scanning and runtime JaCoCo coverage analysis to automatically detect unused (zombie) Java methods, describing the workflow, required dependencies, code snippets, and how to visualize active versus dead code in the IDE.
MyBatis, a widely used Java ORM, embeds around ten classic design patterns—including Factory, Singleton, Builder, Adapter, Proxy, Composite, Decorator, Template Method, Strategy, and Iterator—to modularize object creation, structure, and behavior, thereby simplifying complex data access and caching mechanisms within its architecture.
This article explains how to improve Spring Boot API response speed by designing a cache‑warm‑up mechanism, hierarchical caching with local and Redis layers, and a functional‑programming template for cache‑first queries, providing complete Java code examples and integration guidelines.
This article explains how to solve Java thread‑pool priority problems by leveraging java.util.concurrent.PriorityBlockingQueue, details its thread‑safe and unbounded features, and provides a complete multi‑priority thread‑pool implementation with sample code and a test demonstrating correct task ordering.
This article walks through replacing MyBatis with MyBatis‑Plus in a legacy Java project, explains the “Conversion not supported for type java.time.LocalDateTime” error caused by MyBatis 3.5.1 and an outdated mysql‑connector‑java driver, and shows how upgrading the driver resolves the issue while offering debugging tips.
This article explains how to design and implement a fixed‑size FIFO export queue in a Java Spring application to control concurrent MySQL data exports, detailing the related entities, code implementation with EasyExcel, a test controller, and observed results.
This article analyzes common anomalies caused by the PageHelper pagination plugin in a Java backend project—such as duplicate user registration, limited query results, and password‑reset errors—traces them to ThreadLocal misuse, explains the internal workflow of startPage, getLocalPage, and clearPage, and offers practical recommendations to avoid these pitfalls.
The article examines the difficulties of applying Domain-Driven Design to a cloud‑disk file‑upload scenario, demonstrates how to simplify the code by extracting business models, introducing factories and repositories, and explains how these patterns clarify the separation between business and technical concerns.
This article describes how to achieve database environment isolation and flexible data sharing in a Java backend by adding an env field, customizing a MyBatis interceptor to rewrite SQL, and defining reusable annotations to control environment filtering across services.
This article explores Java String internals across JDK versions, explaining its memory representation, immutability, substring behavior, and how techniques like StringBuilder, intern(), and shared objects can dramatically reduce memory usage from gigabytes to megabytes in high‑scale applications.
Spring’s BeanUtils.copyProperties is error‑prone and slow due to type mismatches, primitive‑wrapper issues, null overwrites and reflection, whereas MapStruct generates compile‑time, type‑safe mapper code that avoids these pitfalls, delivers far better performance, and integrates easily with Maven and Lombok.
IDEA flags @Autowired field injection but not @Resource because Spring advises against field injection—seeing it as tightly coupled and hard to test—while @Resource is a standard JSR‑250 annotation, so the IDE applies the warning only to the Spring‑specific @Autowired usage.
This article explains how to create a custom annotation and a MyBatis‑Plus interceptor that automatically injects data‑permission WHERE clauses into SQL statements, supports role‑based scopes, and shows both basic and advanced implementations with full Java code examples.
Java's Arrays.asList method has three major pitfalls: it cannot directly convert primitive arrays like int[] because of autoboxing limits, it returns a fixed-size list that throws UnsupportedOperationException on modification, and the list shares its backing array so changes to the original array are reflected in the list; using Arrays.stream for boxing or wrapping the result in a new ArrayList avoids these issues.
The Zigzag Conversion algorithm rearranges an input string into a Z‑shaped pattern across a specified number of rows, tracks the current row while toggling direction at the top and bottom, stores characters per row, and finally concatenates the rows to produce the transformed string, with reference implementations in C++, Java, and Python.
This article explains the behavioral and performance differences of positioning a try‑catch block either outside or inside a Java for‑loop, illustrating each case with code examples, execution results, memory analysis, and practical recommendations for handling exceptions during batch processing.
This article explains why asynchronous programming improves performance, compares serial and parallel implementations of a login flow, and demonstrates how to use Java's CompletableFuture API—including supplyAsync, runAsync, callbacks, composition, and error handling—to write efficient backend code.
This article walks through the complete process of creating, training, evaluating, saving, and loading a MNIST handwritten digit recognition model using TensorFlow in Java, comparing it with the equivalent Python implementation and covering required knowledge, environment setup, and code details.
This guide walks you through setting up Jenkins to pull code from GitLab, build a SpringBoot 3 Java project with Maven, back up and copy JAR files to a remote server, and perform rolling updates of Docker Swarm services, all with step‑by‑step instructions and code snippets.
This article explains why standard ThreadLocal mechanisms fail with thread pools, introduces the design of a custom solution using YesThreadLocal and YesRunnable, and then details how Alibaba's TransmittableThreadLocal (TTL) implements context capture, replay, and restoration for seamless asynchronous execution.
This guide walks you through preparing a Dubbo test environment, creating mock providers, writing JUnit 5 test cases, configuring consumers, sending requests, validating responses, handling errors, and optionally adding performance testing, monitoring, and CI automation to ensure robust backend services.
This article details a Kafka consumer issue where the offset unexpectedly becomes a large timestamp due to a native C++ method altering JVM memory, explains the debugging steps, reproduces the bug with Java code, and highlights the risks of unsafe native interactions.
When Dubbo RPC uses Protostuff serialization, DTO fields declared with ambiguous types that contain non‑standard collections such as subList results can trigger ClassNotFound or null errors during deserialization, so converting these to regular JDK collections (or switching to a more tolerant format like Hessian2/JSON) restores stability.
This article explains how to design and implement a fixed-size FIFO export queue in a Spring Boot backend, using synchronized methods, EasyExcel for large data exports, and a test controller to simulate concurrent export requests, while discussing performance considerations and future enhancements.
The article explains the limitations of Spring's BeanUtils.copyProperties—such as type mismatches, null overwriting, and reflection overhead—and demonstrates how MapStruct provides a faster, compile‑time generated alternative for copying properties between Java objects, with usage examples and Maven setup.
The article explains how moving cache operations out of business code and into Spring Cache annotations—@Cacheable, @CachePut, and @CacheEvict—creates a clean, loosely‑coupled design, simplifies maintenance, and enables custom extensions such as breakdown protection and multi‑level caching for high‑concurrency applications.
This article introduces MyBatisX, an IDEA plugin that streamlines MyBatis development with navigation, GUI‑based code generation, customizable templates, JPA‑style method hints, and icon settings, providing step‑by‑step instructions and visual examples to enhance backend productivity.
This article explains several powerful Lombok annotations—including @onX, @Delegate, @Cleanup, @Builder with @Singular, and @With—showing how they simplify Spring‑based Java code through automatic constructor generation, method delegation, resource management, and fluent builders, while also warning against overuse.
This tutorial walks through setting up Spring AI 0.8.1 with Spring Boot 3.1.1, configuring Alibaba Tongyi model access, and implementing chat, streaming, image, and audio generation endpoints using Java code and vector database integrations.
This article explains how Spring solves circular dependencies by using a three‑level cache system, walks through the underlying source‑code execution flow, clarifies the purpose of each cache level, and discusses why the design is essential for AOP‑enabled beans.
This article analyzes a FastJSON serialization issue where a getter method is unexpectedly called, explains the underlying ASM‑generated serializer mechanism, details which methods FastJSON invokes during serialization, and proposes using @JSONField(serialize = false) to explicitly exclude methods from the serialization process.
This article walks through migrating an existing MySQL‑based Java project from MyBatis 3.5.x to MyBatis‑Plus 3.1.1, diagnosing the LocalDateTime conversion exception, upgrading mysql‑connector‑java, handling subsequent null‑pointer issues, and learning from a related file‑validation bug to emphasize thorough testing during component upgrades.
This article presents a Java Kafka consumer example, explains offset semantics (at‑most‑once, at‑least‑once, exactly‑once), details consumer rebalance mechanisms, partition assignment strategies, thread‑safety considerations, and showcases core poll, heartbeat, and auto‑commit implementations with accompanying code snippets.
This tutorial explains the basics of SpringBoot's @RequestMapping annotation, its shortcut variants, handling of HEAD and OPTIONS requests, how to create custom request annotations, and demonstrates dynamic handler registration with complete code examples.
This article explains how Spring's @Transactional and @Async annotations can be applied to the same service methods, the implications for transaction boundaries across threads, and the precautions developers must take to maintain data consistency and proper transaction management.
This article demonstrates how to implement image anti-hotlinking in a Spring Boot application by creating a configurable interceptor, registering it, and providing flexible YAML settings, while discussing limitations such as referer spoofing and potential false positives.
This article examines whether every Service and DAO class in a Spring‑based backend should implement an interface, discusses the three traditional reasons for using interfaces, explains why they often do not hold up, and proposes practical structuring alternatives for single‑ and multi‑implementation scenarios.
This comprehensive tutorial walks you through OpenFeign—its relationship to Feign, environment setup, service provider and consumer creation, various parameter passing methods, timeout handling, logging, HTTP client replacement, GZIP compression, and Sentinel-based circuit breaking—providing practical code examples and configuration snippets for Spring Cloud microservices.
This article explains why Spring MVC cannot parse multiple @RequestBody annotations on a single handler method, analyzes the internal I/O stream closure that causes the failure, and provides a practical solution using a request‑body caching wrapper and a servlet filter to allow repeated reads of the request payload.
This article presents a complete Netty TCP client demo for an IoT project, explaining the project background, architecture, modules, business flow, and detailed Java code—including a local queue, thread pool, client initialization, handler logic, and test controllers—along with deployment notes and source links.
This article provides an in-depth tutorial on Java 8 Stream API, covering stream creation, intermediate and terminal operations, filtering, mapping, reduction, collection, sorting, grouping, and practical code examples, helping developers master functional programming with streams in Java.
Fast‑Retry is a high‑performance, multi‑task asynchronous retry framework for Java that outperforms traditional synchronous retry libraries like Spring‑Retry and Guava‑Retry, offering flexible APIs, annotation support, and easy integration for massive retry workloads.
This article explains how to use Spring's TransactionSynchronizationManager to detect active transactions and register callbacks that asynchronously send Kafka messages only after a transaction successfully commits, illustrated with a payment‑system case study and complete code examples.
