本文比较了Laravel 8和9，强调了影响升级决策的主要差异。 Laravel 9需要PHP 8.1，更新的Symfony组件，并提供性能改进和新功能。 Laravel 8升级涉及P
Laravel 8和Laravel 9以及何时使用的关键区别是什么？
Laravel 9于2022年2月发行，建立在2020年9月发行的Laravel 8上。虽然跳跃似乎是渐进的，但存在几种关键区别，影响了它们之间的选择。最重要的变化围绕更新的依赖性，改善性能和新功能。
关键差异：
- PHP Version: Laravel 9 requires PHP 8.1, a significant jump from Laravel 8's PHP 8.0 requirement.这需要在升级之前检查现有代码库的兼容性和依赖性与php 8.1的兼容性。 PHP 8.1介绍了几种性能增强和新功能，例如枚举和一流的可呼叫语法，这些语法是Laravel 9的利用。
- Improved Symfony Components: Laravel 9 upgrades many of its underlying Symfony components to their latest versions.这带来了性能改进和安全补丁，但也有可能引入需要调整代码的破坏变化。
- New Features (discussed in more detail below): While not a complete overhaul, Laravel 9 incorporates new features, such as improved query builder functionality and enhancements to the testing framework.
何时使用每个：
- Laravel 8: If your project is already running smoothly on Laravel 8, and you're not experiencing performance bottlenecks or needing the specific features of Laravel 9, sticking with Laravel 8 might be the best approach.升级引入了潜在的风险（稍后讨论）。仅当您需要新的Symfony组件或PHP 8.1的特定功能时，请考虑升级。
- Laravel 9: If you're starting a new project, Laravel 9 is the recommended choice.在利用最新PHP版本的同时，它受益于性能改进和新功能。如果您需要提高性能，新功能会大大改善工作流程，或者您正在积极维护和开发应用程序，则建议现有项目升级到Laravel 9。
与Laravel 8相比，Laravel 9中最重要的性能改善是什么？
Laravel 9具有多种性能增强功能，主要源于更新的Symfony组件和PHP 8.1的使用。虽然在大多数情况下并不明显地震惊地球，但累积效应可能很明显，尤其是在较大的应用中。
- Symfony Component Upgrades: The updated Symfony components, such as the upgraded
Symfony\Component\HttpFoundation and Symfony\Component\Routing , often include internal optimizations that improve request handling and routing efficiency.这些通常是在罩上的改进下，在代码本身中不容易可见，但可以通过基准测试来证明。
- PHP 8.1 Enhancements: PHP 8.1 itself offers performance improvements, including enhanced JIT compilation and optimizations in various areas. Laravel 9利用这些改进。在某些情况下，诸如Enums之类的功能虽然在实施中与实现无直接相关，但可以导致更清洁，更有效的代码。
- Improved Query Builder (subtle): While not a massive performance overhaul, the Laravel 9 query builder might offer marginal performance gains in specific use cases due to internal optimizations and better handling of certain query types.
至关重要的是要了解性能增长是渐进的，并在很大程度上取决于应用程序的复杂性和使用模式。升级前后对您的特定应用程序进行基准测试对于准确评估性能改进至关重要。
我应该将Laravel 8项目升级到Laravel 9，涉及哪些潜在风险？
从Laravel 8升级到Laravel 9是需要仔细考虑的决定。尽管有好处，但潜在风险需要采取精心计划的方法。
升级的原因：
- Performance Improvements: As discussed earlier, performance gains are possible, though their magnitude varies.
- New Features: Access to Laravel 9's new features might significantly improve your development workflow or add crucial functionality.
- Security Patches: Upgrading ensures access to the latest security patches provided by both Laravel and its underlying components.
潜在风险：
- Breaking Changes: The updated Symfony components and the PHP 8.1 requirement might introduce breaking changes.这意味着您现有的代码可能需要进行重大修改才能与Laravel 9正确运行。
- Dependency Conflicts: Your existing third-party packages might not be compatible with Laravel 9 or PHP 8.1, requiring you to find updated versions or alternatives.
- Testing Overhead: Thorough testing is crucial after upgrading to ensure everything functions as expected.这涉及大量时间投资。
- Downtime: The upgrade process itself might require downtime, depending on your deployment strategy.
Recommendation: Before upgrading, thoroughly assess the potential benefits against the risks.创建一个测试环境来模拟升级过程并确定任何破坏变化或依赖性问题。通常建议采用逐步的，分阶段的升级方法，也许是从应用程序中较小，不太关键的部分开始的。
Laravel 9中的哪些新功能可能会显着影响我现有的Laravel 8应用程序的功能？
尽管Laravel 9没有引入根本范式变化，但一些新功能可能会影响您现有的Laravel 8应用程序的功能：
- PHP 8.1 Features: The use of PHP 8.1 features like enums might necessitate code changes if your application relies on similar functionality implemented differently.
- Improved Query Builder: While generally not breaking, changes to the query builder's behavior could require adjustments to your database interaction code, especially if you're using less common query methods.
- New or Updated Package Compatibility: Many packages have updated their code to take advantage of Laravel 9's features.这可能会引入其功能变化，并需要在代码库中进行更新。检查包装维护者提供的升级说明。
- Symfony Component Changes: Changes within the underlying Symfony components, even if subtle, might impact your application's behavior.仔细测试对于识别和解决任何意外后果至关重要。
在进行升级之前，请咨询Laravel 9官方升级指南，并仔细检查Laravel及其依赖项的Changelog至关重要。这将帮助您预期并减轻对应用程序功能的潜在影响。
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