This article explains the differences between placing a try‑catch block inside or outside a for loop in Java, covering usage scenarios, execution results, performance impact, and practical advice for choosing the appropriate approach during development and interviews.
This article explains Java thread pools, their advantages, internal mechanics, common pitfalls such as oversized queues, excessive threads, and data loss on crashes, and presents a persistence‑based solution using database‑stored tasks and scheduled retries to ensure no data is lost when services go down.
This article explains why Java ORM frameworks are essential for simplifying database access, outlines the critical criteria for selecting the right ORM, compares popular choices such as Hibernate, JPA, EclipseLink, and DataNucleus, and provides a step‑by‑step guide for successful implementation.
The article introduces mybatis-mate, an enterprise‑grade MyBatis module that supports sharding, multi‑datasource, data auditing, field encryption, sensitive‑data masking, automatic DDL maintenance, performance logging, and fine‑grained data‑scope control, providing code examples and configuration guidelines for Spring Boot projects.
This article explains traditional session mechanisms, challenges in clustered environments, and presents solutions such as session replication and centralized storage, then details the design and implementation of a CAS-based Single Sign-On system in Java, including code for user forms, controllers, filters, and configuration.
This article explains a real‑world incident where insecure API parameters led to leaderboard manipulation, then details how to securely combine RSA asymmetric encryption with AES symmetric encryption, covering key concepts, padding modes, implementation steps, and server‑side decryption using Java.
This article explains the concept of JavaAgent, its underlying mechanism using the JVM instrumentation API, and provides a step‑by‑step guide with code samples to build a JavaAgent that measures method execution time in a Spring application.
This course provides an in‑depth exploration of the technical challenges faced by Java architects, covering Spring bean lifecycle, AOP, transaction mechanisms, SpringBoot auto‑configuration, JVM memory models, MySQL indexing, Redis caching, microservice patterns, distributed locks, and performance optimization techniques across 99 video modules.
This article explains the motivations for upgrading to JDK21, introduces Generational ZGC, details integration steps and monitoring setup, presents performance test results comparing ZGC and Generational ZGC, and outlines future plans for Java services at Zhaozhuan.
This article explains how to use the Activiti workflow engine to design a multi‑level leave‑approval process, covering BPMN diagram creation, Spring Boot configuration, deployment, Java code for starting instances, task handling, database schema, API overview, and tips for extending the workflow without additional code.
Java virtual threads, introduced in JDK 21, decouple Java threads from OS threads by using continuations and a ForkJoinPool scheduler, allowing millions of cheap, blocking‑friendly threads that boost throughput and simplify concurrent code compared to traditional platform threads or reactive frameworks, as demonstrated by performance benchmarks.
The article shares a graduate's interview experience and provides a comprehensive technical guide covering HTTP/1.x vs HTTP/2 differences, Java socket and HTTP server code, OS I/O buffering vs direct I/O, database concurrency control, Bloom filter principles, Java reflection, annotation usage, and synchronized locking semantics.
This article introduces Java 8's Stream API, explains its declarative pipeline model for filtering, mapping, sorting, and collecting data, demonstrates each operation with a UserPo example, and provides complete runnable code including parallel streams and statistical summaries.
This article explains Java’s preview Null‑Restricted and Nullable type system, showing how the new syntax (Foo! and Foo?) lets developers explicitly declare nullability, improves compile‑time safety, integrates with existing code, and compares the approach to TypeScript’s ! and ? operators.
Learn how to simplify repetitive error-handling code in Spring Boot by creating a custom @ErrorHandler annotation that leverages Spring AOP to automatically log exceptions, with step-by-step instructions, required dependencies, annotation definition, aspect implementation, and usage examples.
This article provides a step‑by‑step guide to building a Spring Boot starter that abstracts OSS object‑storage services via the Amazon S3 protocol, covering project setup, Maven dependencies, configuration properties, template interfaces, implementation, auto‑configuration, packaging, and testing.
This article walks through SkyWalking, an open‑source APM solution, covering its architecture, server and client installation, configuration for MySQL persistence, log collection, performance profiling, and alerting, while comparing it with Spring Cloud Sleuth + Zipkin and showing practical code examples.
This article provides a detailed tutorial on Maven, covering repository configuration, basic project structure, dependency management, module inheritance, unified version control, and common build plugins such as jar, assembly, and shade, with practical XML examples and code snippets for Java backend projects.
This article explains how to use SLF4J as a facade for Logback or Log4j2, shows Maven dependencies, demonstrates logback.xml and logback‑spring.xml configurations, covers Spring Boot's default logging setup, custom log levels, profile‑based settings, and how to switch to Log4j2 for higher performance.
The article explains Java's parent delegation model for class loaders, its benefits for stability and security, how to break it by customizing loadClass or using thread‑context class loaders, and illustrates common scenarios such as JNDI, JDBC and Tomcat's own class‑loader hierarchy.
This article details the background, requirements, and evaluation of migration options for the appointment service, explains why a double‑write approach with a custom MyBatis plugin was chosen, and walks through the full‑sync, incremental sync, code refactoring, plugin implementation, switch‑over procedures, and post‑migration validation to achieve reliable data isolation and system stability.
This guide explains how to enable comprehensive request logging, use request/response wrappers, implement once‑per‑request filters, and define clean controller interfaces in Spring Boot 3.2.5, providing code examples and configuration tips for robust backend development.
The article explains how Java’s invokedynamic instruction and LambdaMetafactory create synthetic classes and MethodHandles to implement Lambda expressions, detailing compilation steps, stateless versus stateful handling, performance implications, and the requirement for captured variables to be effectively final.
This article explains how Java 8 functional interfaces such as Supplier, Consumer, Runnable and custom @FunctionalInterface types can replace verbose if‑else and exception handling code, providing clear examples, utility methods, and branch‑handling patterns for cleaner backend development.
Graceful Response is a Spring Boot component that offers one‑stop unified response packaging, global exception handling, and custom error code support, enabling developers to simplify controller code, reduce boilerplate, and improve readability and efficiency.
This article explains why exceptions thrown by tasks submitted to a Java thread pool behave differently with submit and execute, demonstrates how to capture those exceptions using Future.get, try‑catch, Thread.setDefaultUncaughtExceptionHandler, and by overriding afterExecute, and provides complete code examples for each approach.
This article provides a comprehensive guide on integrating Spring Boot with the open‑source distributed scheduler XXL‑Job, covering installation, configuration of the admin console and executor, code examples, parameter details, comparison with other schedulers, and best practices for reliable task management.
This article explains the concepts of role‑based access control (RBAC), compares RBAC models, shows how to configure permissions and user groups, and provides step‑by‑step code examples for integrating Spring Security with JWT, JSON login, password encryption and database authentication in Java backend applications.
Lock4j is a Java distributed lock library supporting Spring AOP, RedisTemplate, Redisson, and Zookeeper, offering simple usage, configurable properties, annotation-driven locking, custom executors, key generators, and failure strategies, with detailed setup, code examples, and advanced customization instructions.
This article explains the principles and source‑code flow of Nacos configuration center’s long‑polling mechanism, detailing how the client initiates periodic tasks, how the server processes listener requests, and how configuration changes are detected and propagated through various internal classes and threads.
This article introduces eight common Java asynchronous implementation techniques—including raw threads, Future, CompletableFuture, Spring @Async, ApplicationEvent, message queues, third‑party utilities like Hutool ThreadUtil and Guava ListenableFuture—explaining their usage, code examples, advantages, and drawbacks for improving performance in scenarios such as sending SMS or emails.
This article explains how to implement interface debounce in Java backend services, covering the concept, identifying suitable APIs, generating unique keys, and applying distributed locking mechanisms with Redis and Redisson, including code examples and practical testing results.
The article outlines frequent Java pitfalls—including BigDecimal precision loss, immutable lists from Arrays.asList, double division by zero returning Infinity, null values in switch statements, stream filters mutating original objects, and autoboxing nulls causing NullPointerExceptions—and provides clear explanations and practical fixes to enhance code reliability.
This article explains why the backend services were upgraded from JDK 8 to JDK 21, introduces the generational ZGC garbage collector, details its architecture, tuning parameters, integration steps, monitoring setup, and presents performance test results that demonstrate reduced allocation stalls, lower latency, higher throughput, and near‑zero GC pauses.
This article explains Java's EnumMap, covering its definition, key characteristics, how to create and use it with code examples, its efficient array‑based implementation, and practical test cases, demonstrating why EnumMap is a high‑performance map for enum keys in backend development.
This article introduces the ArthasHotSwap plugin, explains why hot‑updating a few Java classes in a test environment can save minutes compared to full redeployment, and provides step‑by‑step instructions—including downloading, compiling, uploading bytecode to OSS, and applying the changes on the server—complete with code snippets and screenshots.
This article explains how to integrate JSON Schema validation into a Spring Boot application, covering dependency setup, schema definition, bean configuration, service implementation, controller exposure, and testing with curl to ensure JSON payloads conform to the defined rules.
This article explains how Java's ConcurrentHashMap provides thread‑safe, high‑performance map operations by comparing the segmented‑lock design of JDK 7 with the fine‑grained locking and CAS approach of JDK 8, and includes a practical multithreaded code example.
This article explains why API debounce is essential, identifies the types of endpoints that need it, and provides two distributed solutions—shared Redis cache and Redisson lock—along with complete Java code examples and deployment tips for preventing duplicate submissions in a Spring Boot backend.
The article explains Java's virtual threads introduced in Java 19, compares them with traditional threads, and demonstrates how to configure Spring Boot to use virtual threads, including code samples and performance benchmarks that show dramatic latency reductions in both async services and HTTP requests.
This article provides a comprehensive overview of SpringBoot’s most commonly used annotations, covering MVC, bean, JPA, configuration, exception handling, and testing annotations, complete with clear explanations and practical code examples to help developers avoid pitfalls and write cleaner code.
Using JDK 21’s standardized Virtual Threads, this guide explains how to design and implement robust asynchronous batch processing, covering common pitfalls like CPU spikes and OOM, best‑practice concurrency controls, task queue architecture, and practical code illustrations.
This article explains how to use RocketMQ's message backtracking feature to reset consumer offsets, covering problem background, verification steps, core process analysis, code examples, and comparative evaluation of different approaches in real-world scenarios.
This article explains how to design a flexible TreeNode interface and a TreeUtil class in Java that convert flat collections into hierarchical tree structures, provides multiple static methods for object and JSON tree generation, and discusses optimization techniques for large data sets.
The article demonstrates how PowerMock can be used to unit‑test a Java FileParser class—showing basic mocks for files and streams, advanced techniques for final and static classes, and achieving full coverage—while warning that its heavy class‑loader overhead can dramatically slow large test suites and increase memory consumption.
This article surveys the most suitable programming languages for artificial intelligence, detailing why Python, R, Java, LISP, Prolog, C++, Haskell, JavaScript, and Julia each excel in AI development, and provides practical FAQs for developers choosing the right language.
This article introduces JarEditor, an open‑source IDEA plugin that lets Java developers modify classes and resources inside JAR files without extracting them, explains its main features, shows how to install and use it, and concludes with a brief recommendation.
This guide explains how to activate SpringBoot DevTools for hot deployment, integrate Lombok to reduce boilerplate code, and configure the Spring Configuration Processor for property metadata, including necessary Maven dependencies, IDE settings, and build plugin adjustments.
This article provides a comprehensive guide to using MyBatis dynamic SQL tags—including foreach, if, choose, trim, selectKey, and sql fragments—explaining their attributes, usage scenarios, and offering detailed Java and XML code examples to improve query flexibility and reduce errors.
This article introduces AviatorScript, a high‑performance, lightweight JVM‑based scripting language, covering its origins, key features, quick‑start setup, core syntax for numbers, strings, booleans, control flow, functions, and real‑world use cases such as client version control, marketing rules, and order risk management.
This tutorial walks through setting up OpenTelemetry tracing from scratch for both Java and Go microservices, covering collector and Jaeger deployment, required dependencies, configuration parameters, code examples for automatic and manual instrumentation, and how to add custom span attributes and spans.
By instrumenting each node of ZuanZuan’s push system with a Prometheus counter labeled by node name and traceId, and visualizing these metrics in a Grafana Flowcharting dashboard that dynamically highlights the trace path, developers can instantly pinpoint failures, cutting troubleshooting time from minutes to near‑zero.
This article explains the four common Redis cache pitfalls—cache penetration, avalanche, breakdown, and data inconsistency—demonstrates how they can crash high‑traffic systems, and provides practical Java/Spring Boot solutions such as empty‑object caching, Bloom filters, distributed locks, and delayed double‑delete strategies.
This article explains how to design a clean, unified API response format for backend services by defining a standard JSON wrapper, categorizing status codes, adding descriptive messages, and using custom @ResponseResult annotations together with interceptors and controller advice to automatically wrap and handle responses in a Spring‑based application.
On his first day the new Java backend developer discovered duplicated internal and external configuration files causing NullPointerExceptions, hard‑coded role strings, mixed System.out and logger calls, missing manager review leading to DB mismatches, arbitrary production database edits, and Maven pom‑type dependency errors, prompting a shift to unified application.yml settings, JVM‑specified config locations, consistent logging, and stricter coding standards.
During a recent iteration, adding a simple log statement triggered a system exception because Fastjson automatically invoked a custom getter that returned null, leading to an NPE; the article details the root cause, the serialization process, and practical solutions to prevent similar issues.
This article provides a comprehensive guide to using MyBatis dynamic SQL tags such as foreach, if, choose, trim, selectKey, and sql fragments, illustrating best practices with detailed code examples for building flexible, error‑free queries and updates in Java backend applications.
MyPerf4J is a high‑performance, non‑intrusive Java Agent that records millions of method calls per second with nanosecond precision, offering real‑time metrics, low memory overhead, and comprehensive monitoring for both development and production environments.
This article examines Netty 4.1.x’s ByteBuf reference‑counting mechanism, explains why reference counting was introduced, traces its original design, shows instruction‑level optimizations, reveals concurrency bugs in version 4.1.17, and details the clever even‑odd redesign that guarantees thread‑safe memory release while preserving high performance.
This article explains the Chain of Responsibility design pattern, demonstrates its use in multi‑step product validation and expense‑approval workflows with concrete Java examples, shows how to configure and assemble handlers dynamically, and discusses the pattern's advantages and drawbacks.
This article explains Java's HashMap implementation, covering its bucket array, linked‑list and red‑black tree handling, hash function perturbation, dynamic resizing, and thread‑safety considerations, providing code examples and diagrams for clear understanding.
This article introduces Java 8's Stream API, explains its functional style for handling collections, demonstrates common operations such as filter, map, sorted, forEach, collect, statistics, and parallelStream with concrete POJO examples, and provides a complete runnable code sample.
This article explains how to leverage Spring's TransactionSynchronizationManager to detect active transactions, register synchronization callbacks, and asynchronously send Kafka messages after transaction commit, providing a starter library design for Java backend services that need reliable transaction‑aware messaging.
This article explains how Java 8 functional interfaces such as Function, Supplier, Consumer, and Runnable can replace repetitive if‑else statements, providing code examples for exception handling, branch processing, and present‑or‑else logic to improve readability and maintainability in backend development.
This article explains how to use the Strategy pattern combined with a simple factory in a Spring‑based Java backend, showing interface definition, multiple arithmetic strategy implementations, a factory that registers them in a map, a service that selects a strategy at runtime, and a REST controller for testing.
This article explains how Spring's @Async annotation interacts with circular dependencies, why it triggers BeanCurrentlyInCreationException, and provides multiple strategies—including adjusting dependencies, using @Lazy, or tweaking bean factory settings—to solve the problem.
This tutorial walks through RBAC fundamentals, model classifications (RBAC0‑3), permission and user‑group concepts, then demonstrates practical Spring Security setups including in‑memory authentication, JWT integration, JSON‑based login, password encryption with BCrypt, and database‑backed authentication, providing complete code examples.
The article explains why adopting a message‑queue improves microservice decoupling and responsibility boundaries, then details the design of a pluggable Base‑MQ component—including @MQEventListener, MQEvent base class, configuration, and MQClient interface—followed by concrete implementations for RocketMQ, Kafka, Redis and RabbitMQ, an example event flow, and guidance for extending the framework.
The author recounts switching from Gson to Fastjson, encountering a date‑formatting bug that only appears on Linux due to an outdated Fastjson version, explores a circular‑reference $ref issue, and shares debugging steps, GitHub issue references, and practical fixes for reliable JSON serialization.
This article explains how to achieve seamless code updates for SpringBoot applications by allowing two processes to share the same port, detailing the underlying servlet container mechanics, the role of DispatcherServlet, and providing a complete Java implementation with step‑by‑step instructions and code samples.
This article explains how to implement gray (canary) release in a Spring Cloud micro‑service system using Nacos for service discovery, Spring Cloud Gateway filters, ThreadLocal gray flags, custom Ribbon load‑balancing rules, and configuration files to switch between production and gray versions.
This article walks through the One Billion Row Challenge, explaining the problem, baseline solution, and a series of performance optimizations—from JVM selection and parallel I/O to custom hash tables, unsafe memory access, and SIMD techniques—that shrink execution time from minutes to under two seconds.
This article explains the core concepts of connection‑pool technology, details the architectural choices behind HikariCP such as dual HikariPool instances, FastList, custom ConcurrentBag, ThreadLocal caching, and byte‑code generation, and walks through the key source code that makes the pool exceptionally fast.
This article demonstrates three methods for invoking external services in a Spring Boot application—using raw HttpClient, the RestTemplate utility, and Feign clients—providing code examples, configuration steps, and tips for handling headers and tokens.
This article clarifies how Inversion of Control (IoC) serves as a design pattern that hands control to an external container, while Dependency Injection (DI) is a concrete IoC implementation that automatically supplies required objects, detailing their definitions, purposes, implementations, and typical usage scenarios.
This article demonstrates how Java 8’s functional interfaces—such as Supplier, Consumer, Runnable, and Function—can replace repetitive if‑else statements for exception handling and branch logic, providing clear code examples, custom interfaces, and utility methods to simplify backend development.
JDK 23, the next non‑LTS release of the Java platform slated for September 17, introduces a suite of preview features—including scoped values, structured concurrency, flexible constructor bodies, implicit class and instance methods, module import declarations, Markdown Javadoc, vector API enhancements, and a default generational ZGC mode—while deprecating sun.misc.Unsafe memory‑access methods.
This article provides a comprehensive overview of Java's ConcurrentHashMap, explaining its purpose, underlying lock‑segmentation and CAS mechanisms in JDK 7 and JDK 8, demonstrating usage with sample code, and outlining scenarios where it delivers high‑performance thread‑safe map operations.
This article introduces JetCache, an open‑source distributed caching framework built on Spring and Redis, outlines its key features and typical scenarios, and provides step‑by‑step guidance for integrating JetCache into a SpringBoot application with configuration examples and sample code.
This article presents a detailed walkthrough of the TreeUtil class, demonstrating how to construct hierarchical tree structures from flat lists, define tree nodes in Java, perform generic and functional implementations of makeTree, traverse trees using pre‑order, level‑order and post‑order methods, flatten trees back to lists, and sort tree nodes recursively, all illustrated with complete code examples.
This article explains how SpringBoot interceptors work, demonstrates custom interceptor implementation, shows how misuse of ThreadLocal can cause memory leaks and OOM errors, and provides a fix by moving cleanup logic to afterCompletion, complete with code samples and performance screenshots.
The article explains the Disruptor—an intra‑process, lock‑free, array‑based queue that achieves millions of operations per second—by covering its core concepts, demo code, source‑code mechanics, performance optimizations such as pre‑allocation and false‑sharing avoidance, and real‑world Vivo iTheme applications with best‑practice tips.
In Spring Boot you can customize JSON request and response handling by annotating fields with @JsonSerialize/@JsonDeserialize, registering a global ObjectMapper module, adding a PropertyEditor via @ControllerAdvice, creating a custom HttpMessageConverter, or using AOP interception, selecting the approach that matches your project’s complexity.
This article explains how the LiteFlow rule engine enables Java developers to define, configure, and execute complex serial and parallel business workflows using XML/JSON/YAML rule files, various node components, data contexts, and runtime parameters, with hot‑deployment and integration examples for Spring Boot projects.
This article presents LeetCode problem 112 "Path Sum", detailing the problem statement, example inputs and outputs, constraints, a recursive analysis, and complete reference implementations in Java, C++, and Python for determining whether a root‑to‑leaf path equals a given target sum.
This article explains the different effects of placing a try‑catch block inside versus outside a for loop in Java, covering usage scenarios, performance impact, memory consumption, and practical recommendations for choosing the appropriate approach during development.
This article explains critical pitfalls, proper shutdown handling, event loss during startup, suitable business scenarios, reliability guarantees, and best‑practice patterns for employing Spring Event in high‑traffic backend systems, providing concrete code examples and operational recommendations.
This guide explains what Java Agents are, their core capabilities such as bytecode enhancement, performance monitoring, security checks, and debugging, and provides step‑by‑step instructions for implementing the premain method, creating a ClassFileTransformer, packaging the agent with Maven, and loading it both statically and dynamically.
This article introduces JarEditor, an IntelliJ IDEA plugin that lets developers modify class files and resources inside a JAR directly—eliminating the need to extract, decompile, recompile, and repackage—while detailing its features, usage steps, and underlying mechanisms.
This article explains how to implement asynchronous request handling in Spring Boot using four approaches—AsyncContext, Callable, WebAsyncTask, and DeferredResult—detailing their execution flow, configuration of thread pools, and scenarios where async processing improves throughput.
This article demonstrates how to identify long‑method and duplicated code smells in a Java curriculum‑display service and refactor the implementation using the Decorator pattern, providing clear component diagrams, full code examples, and a runnable demo that showcases flexible extensions for different course types.
The article explains the major changes in Hutool 6.0, including the shift of package names to org.dromara.hutool, extensive refactoring of utilities and the HTTP module, performance optimizations, and provides migration guidance and recommendations for developers considering the upgrade.
This article explains the concept of gray (canary) release, details the required Spring Boot, Spring Cloud and Nacos versions, describes core components such as Nacos, Spring Cloud Gateway, Ribbon and OpenFeign, and provides a complete code‑first implementation with filters, interceptors, custom load‑balancer rules and deployment instructions for demonstrating gray release scenarios.
When updating a SpringBoot application the old process must be stopped because the new one cannot bind to the same port, but by leveraging Tomcat's embedded container, ServletWebServerFactory, and dynamic port handling you can keep both processes alive and achieve zero‑downtime deployments.
The article explains that Spring no longer recommends @Autowired field injection, describes constructor‑based, setter‑based, and field‑based dependency injection types, illustrates each with code examples, and outlines the drawbacks of field injection such as immutability issues, SRP violations, and tight coupling to the container.
This article documents a production incident where multiple Spring Boot services each consumed around 12 GB of memory, explains how to diagnose the issue using jps and jmap, details default JVM heap size calculations, and provides recommendations for configuring JVM parameters to prevent excessive memory usage.
This article explains the challenges of multiple product logins, reviews traditional session mechanisms, discusses session sharing solutions in clustered environments, and presents a CAS‑based single sign‑on implementation with Java code examples, highlighting differences between CAS and OAuth2 for secure authentication.
This article shares the author's experience of redesigning a microservice using Domain‑Driven Design, detailing a standardized layered architecture, directory structure, model conversions, common pitfalls, and practical recommendations to improve code clarity and testing efficiency.
This article explains the internal architecture of Java's HashMap, covering its array of buckets, linked‑list handling of hash collisions, and the conversion to red‑black trees for high‑collision scenarios, supplemented with code examples and visual diagrams.
This article provides an in‑depth analysis of Spring Security 6.x architecture, explaining its filter‑chain design, authentication and authorization mechanisms, key components such as DelegatingFilterProxy, FilterChainProxy, SecurityFilterChain, and offers code examples and practical guidance for developers.
