A Java program that creates two alarm threads and a single shared object ends up in a deadlock because each thread holds its own lock while waiting for the other's lock, illustrating the pitfalls of careless synchronized usage.
This guide explains how to implement API rate limiting in SpringBoot 2.7.16 using custom annotations, AspectJ, and the high‑performance Caffeine cache, covering cache configuration, eviction policies, statistics, and practical code examples for annotation definition, aspect logic, and controller usage.
This tutorial explains how to switch between multiple databases in a Spring Boot application by implementing ThreadLocal and AbstractRoutingDataSource, covering code implementation, configuration, testing, annotation-based switching, and dynamic addition of data sources with detailed examples and practical guidance.
This article analyzes the CPU‑heavy routing and load‑balancing modules of Dubbo in a large‑scale microservice cluster, identifies O(n) traversal as the root cause, and presents a step‑by‑step redesign—including disabling unused routers, caching route results with epoch validation, BitMap‑based intersection, and grouped routing—that reduces CPU usage by up to 27% and doubles TPS when provider instances exceed 2,000.
This article presents a curated collection of essential open‑source Java libraries—including logging, JSON parsing, testing, utility, HTTP, XML, Excel, bytecode, database connection pooling, messaging, PDF, date‑time, collections, email, HTML parsing, encryption, embedded databases, JDBC debugging, serialization, networking, and more—to help developers boost productivity and write better code.
This article compiles 28 practical IntelliJ IDEA shortcuts, settings tweaks, and plugin recommendations that help Java developers quickly navigate code history, manage memory, customize keymaps, automate imports, visualize dependencies, and improve overall coding efficiency.
This article explains how to combine Domain‑Driven Design's four‑layer architecture with a microservice‑oriented application SDK, introduces the D3boot lightweight framework and its modular base components, and shows how the approach simplifies building SaaS and PaaS systems while keeping code reusable and maintainable.
This article examines the inner workings of Java's java.util.UUID class, detailing how UUID.randomUUID() generates version‑4 UUIDs using SecureRandom, the bitwise adjustments for version and variant fields, and the constructor logic that assembles the final 128‑bit identifier.
This article walks through the complete process of implementing a custom login authentication in Spring Boot, including custom authentication filters, success/failure handlers, a token stored in Redis, role‑based URL security, and detailed configuration of Spring Security headers and session handling.
This article provides a comprehensive guide to Java development fundamentals, covering naming conventions, comment quality, class and method definitions, object design patterns, and performance considerations such as immutable types, sealed classes, and the Valhalla project, with practical code examples and best‑practice recommendations.
This article explains why rate limiting is essential for high‑concurrency systems, defines rate limiting, introduces four common algorithms (fixed‑window, sliding‑window, leaky‑bucket, token‑bucket), provides Java code examples for each, compares their advantages and disadvantages, and shows practical usage with Guava's RateLimiter and AOP annotations.
An in‑depth comparison of popular Java in‑process caching solutions—Guava, Caffeine, and Ehcache—covers their expiration policies, capacity limits, eviction strategies, monitoring features, performance optimizations, and ideal use cases, helping developers select the most suitable cache for their applications.
This article covers Java backend architecture fundamentals, including front‑end/back‑end separation, Maven configuration, distributed lock implementations with Redis and Zookeeper, session handling in distributed systems, database locking strategies, and useful code snippets for common patterns.
This article explains what optimistic locking is, why it matters for concurrent Java applications, and details four implementation methods—version numbers, timestamps, CAS, and sequence numbers—along with their principles, usage scenarios, and practical considerations for high‑performance, distributed systems.
This guide walks through Spring 6’s new capabilities—including Java 17 baseline, Jakarta namespace migration, HTTP interface proxies with @HttpExchange, WebClient integration via JDK HttpClient, internationalized ProblemDetail handling, the RestClient API, and executing asynchronous tasks on virtual threads—all demonstrated with concise code examples.
This article explains how to implement unified, user‑friendly exception handling for Feign‑based service calls in a Spring distributed architecture by customizing ErrorDecoder, defining result objects, and using global @ControllerAdvice to return clear error codes and messages to front‑end users.
This article explains how to prevent API abuse by using a Spring Interceptor combined with Redis to count requests per IP and URI, demonstrates step‑by‑step code implementations, discusses custom annotations, mapping rules, time‑window challenges, path‑parameter handling, and real‑IP extraction for robust backend rate limiting.
This article explains the concept of distributed tracing, outlines its underlying principles in Java, details step‑by‑step implementation using popular SDKs, and describes common application scenarios such as performance monitoring, fault diagnosis, complex event handling, traffic analysis, and system optimization.
This article walks through the problem of sharing a single database across pre‑release, gray, and production environments, explains why adding an env column to dozens of tables is error‑prone, and demonstrates a MyBatis interceptor‑based solution with custom annotations that isolates data while preserving backward compatibility.
The article analyzes the inventory oversell problem caused by concurrent purchase requests and presents four backend solutions—including a Redis distributed lock, MySQL row lock, optimistic locking with version fields, and conditional SQL updates—illustrated with Java code and SQL examples to ensure data consistency.
Starting from a basic Java method that maps a sale‑type string to an integer, the article incrementally refactors the code by applying null‑safe utilities, constants, static methods, ternary/Optional expressions, enums with lookup maps, a combined relation enum, and finally a Strategy pattern with a container, illustrating how each step improves safety, readability, extensibility, and testability.
This article explains how Redisson's DelayedQueue implements a distributed delayed message queue, covering basic usage, internal data structures, the overall processing flow, and detailed code analysis of sending, receiving, and initializing delayed messages in Java.
This tutorial demonstrates how to use Spring WebFlux’s reactive streaming to create a ChatGPT‑like typing effect, covering backend setup, SSE integration, frontend Axios handling, and a comparison between Flux and traditional Server‑Sent Events.
This article explains the limitations of java.util.concurrent.Phaser for large‑scale asynchronous tasks, presents a custom FunPhaser implementation that removes the party‑count ceiling, details its design, API, and usage examples, and compares it with the original Phaser approach.
This article presents a comprehensive collection of practical IntelliJ IDEA tips for Java developers, covering code history viewing, memory settings, Eclipse keymap, case‑insensitive suggestions, disabling inspections, documentation templates, method separators, multi‑line tabs, bracket navigation, code completion, fuzzy search, class preview, call hierarchy, Maven dependency visualization, SSH tool, and more to significantly boost coding efficiency.
This article explains the concepts, architecture, and practical usage of Liteflow, a lightweight Java rule engine that integrates with Spring Boot, supports various rule file formats, multiple component types, data contexts, and configuration options for building complex workflow processes in backend applications.
This guide demonstrates how to retrieve command‑line arguments, use JSON‑encoded properties, load external configuration files, encrypt values, parse YAML, generate random properties, handle internationalization, customize the banner, and configure the application context in Spring Boot 3.0.9, providing code examples for each feature.
This article walks through eight practical ways to implement retry mechanisms for remote API calls in Java, covering simple loops, recursion, Apache HttpClient settings, Spring Retry, Resilience4j, custom utilities, asynchronous thread‑pool retries, and message‑queue based retries, while highlighting trade‑offs and best‑practice guidelines.
Kafka, an Apache‑developed distributed publish/subscribe messaging system, provides reliable, high‑throughput real‑time data streaming with producers, consumers, brokers, streams, and connectors, and the article explains its core concepts, architecture, advantages, deployment methods, use cases, and includes Java code examples for producers and consumers.
This article explains the concept of delayed tasks, compares them with scheduled tasks, and evaluates multiple implementation strategies—including database polling, JDK DelayQueue, Netty HashedWheelTimer, Redis ZSET, Redis keyspace notifications, and RabbitMQ delayed queues—highlighting their advantages and drawbacks for order‑processing scenarios.
This article introduces EasyExcel, a Java library that simplifies high‑performance Excel read/write operations, explains its core concepts, provides practical code examples for reading, writing, and filling Excel files, and discusses performance‑optimizing techniques and important usage considerations.
This article walks Java and Spring Boot developers through installing Camunda, configuring dependencies, setting up the database, creating a simple BPMN process with user and service tasks, and testing the workflow via the Camunda web interface, providing code snippets and screenshots for each step.
This article explains Java enums, their underlying class inheritance, key Enum methods, practical code examples, and advanced uses such as implementing singletons and strategy patterns, helping developers master enums for robust backend development.
This article explains two API rate‑limiting strategies—fixed‑window using Redis keys and sliding‑window using Redis sorted sets—detailing their principles, drawbacks, and providing complete Java implementations with Lua scripts, AOP annotations, and Redis configuration to enforce request limits.
This article explores Spring 5.3.23’s core utility classes—including ID generators, concurrent LRU cache, concurrency throttling, StopWatch timing, digest calculation, method invocation, reflection helpers, route matching, collection utilities, and placeholder parsing—providing code examples, usage guidelines, and best practices to boost backend development efficiency.
When Maven’s archetype plugin hangs during project generation, you can resolve it by specifying archetypeCatalog=internal or local as a command-line or VM option, placing a downloaded archetype-catalog.xml in ~/.m2, or configuring a domestic mirror in settings.xml, after which generation completes in seconds.
This article presents a comprehensive design and implementation of a customizable data permission framework for Java backend applications, detailing the requirements, rule table structure, strategy pattern handling, custom annotations, AOP integration, and practical examples with full source code snippets.
This guide walks you through setting up Spring Cloud Task on Spring Boot 2.7 with Spring Cloud 2021, covering environment requirements, Maven dependencies, configuration files, task annotations, ApplicationRunner implementation, database schema, task listeners, and advanced task configuration options.
This article explains Spring's seven transaction propagation modes, how they affect nested @Transactional method calls, and the resulting commit or rollback behavior in various scenarios, providing clear examples and diagrams for each propagation type.
This article describes how ZhaiZhai implements log desensitization for personal data protection using a reusable Java utility class, JSON serializer customizations with Jackson, and an annotation‑processing tool that automatically generates masked toString methods, while also discussing operational challenges and future plans.
The article explains why iterating an ArrayList with forEach and removing elements causes a ConcurrentModificationException, analyzes the underlying fail‑fast iterator behavior, and presents three correct ways—using Iterator.remove, removeIf, and collecting then removing—to delete elements safely.
The January 2024 TIOBE Index reveals C# winning the 2023 Programming Language of the Year award, highlights Java’s market‑share loss and pricing controversy, showcases the rise of Kotlin, Fortran and COBOL, and offers expert predictions on which languages may break into the Top 20 next year.
Compileflow is a lightweight, high‑performance Java workflow engine that converts BPMN files into compiled code, offering seamless integration, visual process design, and extensive plugin support, with quick‑start instructions, code examples, and a concise summary of its advantages and current limitations.
This article compares Java's native record feature with the Lombok library, showing how records can reduce boilerplate code, outlining scenarios where records can replace Lombok, and discussing the limitations of each approach for clean and maintainable backend development.
The 2023 TIOBE Index crowned C# as the top programming language, highlighting its rapid growth over Java, the impact of Java's new subscription pricing, and the broader shifts in language popularity that could shape development trends through 2024.
This article walks Java developers from Java 8 to Java 17 through the most widely‑adopted language enhancements—including var, switch expressions, text blocks, records, pattern‑matching, sealed classes, and helpful NullPointerExceptions—explaining each feature with concise descriptions and code snippets.
The article explains Java's PreparedStatement interface, highlighting its performance, security, and batch processing benefits, and provides a complete example of inserting multiple user records efficiently, while also discussing practical considerations such as batch size, transaction handling, error management, and optimization tips.
This article introduces PowerJob, explains its key features such as lock‑free scheduling, multiple execution modes, and workflow support, and provides step‑by‑step instructions for installing via Docker or JAR, configuring databases, setting up server and client projects, and creating and managing scheduled tasks in Java.
This article provides a step‑by‑step guide to implementing custom login authentication in a Spring Boot application, including Redis‑backed session storage, token handling, security headers, and fine‑grained role‑based URL permission checks using custom filters and handlers.
This article explains how to use Spring Boot Security for authentication and improve performance by caching user details in Redis, covering dependency setup, security configuration, Redis integration, testing endpoints, and optimization tips for a robust backend authentication solution.
This article demonstrates step‑by‑step how to prevent API abuse in a Spring MVC application by using an Interceptor combined with Redis for counting requests, customizing limits per endpoint through annotations and reflection, handling mapping rules, path‑parameter challenges, and obtaining the real client IP.
This article compares delayed tasks with scheduled tasks and presents six practical Java solutions—database polling with Quartz, JDK DelayQueue, Netty's HashedWheelTimer, Redis ZSET, Redis key‑space notifications, and RabbitMQ delayed queues—detailing their implementations, advantages, and drawbacks for handling order‑timeout scenarios.
This article explains how Android's LayoutInflater converts XML layout files into View objects, demonstrates the various ways to obtain and use a LayoutInflater, details the overloads of the inflate method, and shows how to customize view creation with Factory and Factory2 interfaces, including practical code examples.
This guide explains how to use Spring Integration's LockRegistry for distributed locking, covering both database‑based and Redis‑based implementations, complete with Maven dependencies, configuration snippets, bean definitions, and comprehensive test cases to ensure reliable synchronization across multiple nodes.
This article explains why manual property copying in Java is inefficient, compares several runtime bean‑copy utilities, and demonstrates how MapStruct provides a compile‑time, type‑safe, high‑performance solution for shallow and deep object mapping, including handling of collections and ignored fields.
The article examines the One‑Billion‑Row benchmark challenge, showcasing a GraalVM‑powered Java solution and comparing its performance against dozens of languages—from C and Rust to Python and JavaScript—highlighting stark speed differences and the impact of AOT and JIT compilation techniques.
This article explains the concept of SQL injection, demonstrates a vulnerable query example, and provides a step‑by‑step Spring Boot and MyBatis implementation—including table creation, Java controller, service, DAO, mapper, and configuration—to illustrate how proper parameter handling prevents injection attacks.
Spring developers should replace the deprecated RestTemplate with the reactive WebClient, which offers non‑blocking I/O, a fluent functional API, streaming support, richer error handling and configurable timeouts, while still allowing synchronous calls via block(), as demonstrated by practical Spring Boot 3 code examples.
This tutorial walks you through creating a Spring Boot project, configuring OpenAI credentials, building a controller, and using Spring AI's Prompt and PromptTemplate classes to integrate generative AI capabilities into your backend application.
This article explains the core concepts, architecture, and implementation details of Xxl-Job, a lightweight distributed task scheduling platform, covering the scheduler center, executor, job handling, demo setup, routing strategies, trigger mechanisms, and result callbacks.
This article explains how Spring's @Configuration annotation triggers CGLIB proxy generation to manage @Bean methods, ensuring that internal calls return the same singleton instance, and contrasts this behavior with using @Component for configuration classes.
This article explains the Snowflake ID algorithm, its 64‑bit structure, provides a complete Java implementation, discusses common issues such as clock rollback and node ID management, and compares Snowflake IDs with UUIDs while suggesting Baidu's UidGenerator as a robust improvement.
This article explains Zookeeper's session management mechanism, detailing why TCP alone is insufficient for client liveness detection, how Zookeeper implements its own heartbeat protocol, and the internal data structures and algorithms—including expiryMap and SessionTracker—that efficiently track and expire sessions.
This article explains why MQ is needed beyond in‑process event listeners, details the required dependencies for Spring Boot 3, shows how to configure RocketMQ, provides code snippets for producer, consumer, and testing, and offers practical tips for handling async, batch, and one‑way messaging.
This guide explains how to secure Spring Boot API responses using RSA asymmetric encryption, covering the theory of RSA, practical scenarios, Maven setup, annotation‑based encryption/decryption, configuration files, and a JavaScript front‑end example for encrypting request payloads.
This article explains how to use MyBatis's @MapKey annotation to map query results into a Java Map, compares common data‑retrieval approaches, provides a concrete example with mapper code, and delves into the internal parsing and result‑handling mechanisms that enable key‑value mapping.
A Chengdu software engineer shares a candid, step‑by‑step recount of his job‑hunting journey, from low‑pay outsourcing traps to tough interview questions on Java, cloud, data structures, and design patterns, culminating in a modest offer and hard‑earned lessons for future candidates.
This article analyzes whether Java lambda expressions can lead to memory leaks similar to anonymous inner classes by comparing their compiled bytecode, demonstrating that lambdas only retain a reference to the outer class when they explicitly capture its members.
This article introduces a lightweight, open‑source SMS platform built with SpringBoot and Vue, explains its server‑side architecture, provides step‑by‑step deployment instructions, and demonstrates how to send templated messages using a simple Java SDK.
This article explains how to configure Guava Cache with expiration and refresh policies, analyzes its thread model under high concurrency, and presents two implementation approaches for asynchronous refresh combined with multi‑level caching to achieve low latency and reduced GC overhead.
This article explains Spring's bean scopes—including singleton, prototype, request, session, and application—detailing their lifecycles, appropriate use cases, and how to configure them with code examples, while also covering common pitfalls and proxy solutions for web environments.
This article presents a detailed three‑step plan used by Zhezhuan to detect and eliminate zombie services, unused code methods, and obsolete component dependencies through monitoring, static analysis with Spoon, and Java‑agent based runtime tracing, achieving significant resource savings and improved code health.
This article explains how to automate repetitive unit‑conversion tasks in Java backend code by first using a map‑based reflection utility and then enhancing it with a custom annotation to declaratively specify conversion types for DTO fields.
This article explains why duplicate form submissions occur, the risks they pose, and demonstrates a Spring Boot solution that uses a custom @RequestLock annotation together with Redis SETNX to generate a unique key and block rapid repeated requests, complete with project setup, code examples, and usage instructions.
This article explains how Domain‑Driven Design (DDD) combined with Spring Data JPA enables clean, object‑oriented modeling of order workflows, introduces the Repository pattern for persistence, and demonstrates the full lifecycle—from creation to address modification and payment—through concise Java code and SQL examples.
This article provides a step‑by‑step guide to building a Spring Boot starter that abstracts Amazon S3‑compatible object storage services such as Alibaba Cloud OSS, Tencent COS, Qiniu OSS, and MinIO, covering dependency setup, configuration properties, template interfaces, implementation, auto‑configuration, packaging, and testing.
This article provides a comprehensive, step‑by‑step analysis of MyBatis, covering its core features, three‑layer architecture, configuration file parsing, dynamic proxy generation, and the detailed process of executing SQL statements within the framework.
This article explains why scheduled jobs run twice in a multi‑node deployment, shows how to isolate the timing logic into a single service, and demonstrates using ElasticJob with Zookeeper for sharding, distributed locks, and high‑availability to ensure each task executes exactly once.
This tutorial explains how Spring's internationalization (i18n) works, covering core APIs, bean initialization, configuration for both classic Spring and Spring Boot, message resource files, placeholder usage, and convenient accessor utilities, with full code examples for seamless multi‑language support.
Spring’s transaction propagation defines seven behaviors—REQUIRED, SUPPORTS, MANDATORY, REQUIRES_NEW, NOT_SUPPORTED, NEVER, and NESTED—detailing how methods join, create, suspend, or nest transactions, and the article explains each type, practical scenarios, and how proper selection ensures atomicity, consistency, and correct rollback handling.
This article explains how to implement API request rate limiting in Spring Boot by creating a custom @RequestLimit annotation, using Redis to track request counts, and configuring a HandlerInterceptor and WebMvcConfig to enforce limits on controller methods.
This article introduces the Hutool Java utility library, outlines its modules, shows how to add it to a Maven project, and provides practical code examples for HTTP requests, random codes, pinyin conversion, timing, number handling, data masking, email sending, and Bloom filters, demonstrating how Hutool can streamline backend development.
This tutorial explains why BeanUtil.copyProperties is discouraged in Java projects and shows how to install and use the Bean Converter IDEA plugin to automatically generate setter injection code, streamlining bean mapping and improving development efficiency.
This article introduces a Java virtual‑thread based asynchronous task framework, detailing its design constraints, a thread‑safe task queue, daemon thread management, and overloaded execute methods for Runnable and Groovy Closure, along with code examples and performance testing considerations.
This article explains how to execute two dependent tasks in parallel, guarantee their successful completion before a final step, and maintain transaction consistency across multiple threads in Spring by using CompletableFuture, programmatic transaction management, and a custom transaction‑resource copying mechanism.
This article walks through a real‑world performance overhaul of Apache HttpClient—using a singleton client, connection pooling, a custom keep‑alive strategy, timeout tuning, and idle‑connection monitoring—to reduce average request time from 250 ms to about 80 ms for a high‑throughput service.
This article compares placing a try‑catch block inside versus outside a Java for‑loop, showing concrete code examples, execution results, memory‑usage measurements, and practical recommendations based on how exceptions affect loop termination and performance.
This article examines the causes of slow startup in large Spring applications, presents visual analysis techniques and a toolbox—including Arthas, JVM Sandbox, Async Profiler, and Spring Startup Analyzer—and provides concrete installation, configuration, and optimization procedures that can reduce startup time by 70‑80% while improving development efficiency and resource utilization.
This guide walks developers through upgrading from Spring Boot 2.x to 3.x, covering JDK 17 migration, pom.xml changes, configuration property updates, Jakarta EE transition, security reconfiguration, Kafka template adjustments, and OpenAPI integration, with code examples for each step.
An in‑depth Spring Security guide covering custom configurations, authentication providers, user‑details services, path‑based authorization, role hierarchies, exception handling, custom filters, multiple filter chains, method security, internationalization, and session management, complete with practical code examples for Spring Boot 2.7.
The article outlines which Java technologies—such as JSP, Struts, Hibernate, Servlet, Applet, Swing, JDBC, and XML—are now largely obsolete or unnecessary to learn for modern backend development, offering criteria for judging relevance and recommending focus on current frameworks like Spring MVC and MyBatis.
This article details a step‑by‑step optimization of Apache HttpClient—including connection pooling, keep‑alive, singleton client usage, timeout tuning, and response handling—to reduce average request latency from 250 ms to about 80 ms in a high‑throughput Java service.
This article provides an in‑depth overview of Java's BigDecimal class, covering its purpose for high‑precision arithmetic, frequently used constructors, essential methods for arithmetic and conversion, techniques for formatting numbers, handling of common exceptions, and includes practical code examples and a utility class for precise calculations.
This article compiles a comprehensive set of ByteDance daily internship interview questions covering Java backend fundamentals, networking protocols, operating system concepts, Linux process management, Redis data structures and persistence, MySQL indexing and query optimization, as well as essential algorithms, providing detailed explanations and code examples for each topic.
To achieve fast bulk inserts in MyBatis, open a session with ExecutorType.BATCH and insert records individually (letting JDBC batch them), limit foreach‑generated statements to about 20‑50 rows, or use MyBatis dynamic‑SQL or plain JDBC batch, avoiding massive SQL parsing and CPU overload.
This article introduces SpringBoot 3.2's JdbcClient, explains how to add the dependency, inject it, and demonstrates fluent‑API query and insert operations—including positional, named, map‑based parameters and custom RowMapper—showing how to perform CRUD without heavyweight ORM frameworks.
This article introduces PowerJob, a Java‑based enterprise distributed task scheduler, outlines its key features, installation methods, step‑by‑step server and client setup, task creation, and detailed configuration options for robust backend job management.
This article documents how the Helios scoring service, which originally took several seconds to retrieve a day's worth of data, was optimized from hundreds of milliseconds down to tens of milliseconds by analyzing Arthas trace data and applying multiple code and algorithm improvements.
This article explains how to estimate capacity, choose appropriate garbage collectors, and configure JVM memory settings—including heap size, young generation, thread stack, and GC options—for a service that processes one million login requests per day on a node with 8 GB of RAM, providing step‑by‑step guidance and example command lines.
This guide explores the JDK command‑line utilities located in %JAVA_HOME%\bin, explaining how tools such as jps, jstat, jinfo, jmap, jhat and jstack can be used to monitor JVM processes, analyze performance bottlenecks, inspect memory usage, generate heap dumps, and adjust runtime parameters for more efficient and stable Java applications.
