Spring 4.2升级至5.0.5常见问题及Spring Security 4.2兼容性咨询

Hey there! Let's walk through the main hurdles you'll hit upgrading from Spring 4.2 to 5.0.5, plus clear up the Spring Security 4.2 compatibility question:

1. Non-negotiable Java Version Upgrade #

Spring 5.0.x requires Java 8 or higher — this is a hard requirement. If your project is still running on Java 7 or lower, you’ll need to upgrade your JDK first. This might also mean updating any third-party dependencies that don’t support Java 8, as well as refactoring code that uses deprecated Java 7 features (like old date/time APIs, though Spring 5 does have better Java 8+ support for things like LocalDateTime).

2. Removed Deprecated APIs #

Spring 5.0 stripped out a lot of APIs that were marked deprecated in Spring 4.x. Some common ones you’ll run into:

• WebMvcConfigurerAdapter: Since Java 8 supports default methods, you can now directly implement WebMvcConfigurer without extending this adapter — no more empty method overrides!
• Old HttpMessageConverter methods: Methods like read(Class<?>, HttpInputMessage) have been replaced with generic variants, so you’ll need to update any custom message converters.
• Deprecated ApplicationContext methods: Methods like registerBeanDefinition(String, BeanDefinition) with certain overloads are gone; you’ll need to use the newer alternatives.

3. Core Module Behavior Changes #

• Dependency Injection Strictness: Spring 5 tightened up DI rules. For example, if you have @Autowired(required = true) and no matching bean exists, the context will fail to start earlier than in 4.2 (instead of silently ignoring it in some cases).
• Conversion Service Updates: The default ConversionService implementation now includes more Java 8+ type converters, but this might break existing custom conversions if they rely on old behavior.
• Bean Factory Adjustments: Some BeanFactory methods have modified exception handling or return types — double-check any code that directly interacts with the bean factory.

4. Web & WebMvc Module Requirements #

• Servlet API Upgrade: Spring 5.0 requires Servlet 3.1 or higher. That means you’ll need to upgrade your servlet container (e.g., Tomcat 8+, Jetty 9+) if you’re still on an older version.
• RestTemplate & WebClient: Some asynchronous RestTemplate methods are deprecated in favor of the new non-blocking WebClient (introduced in Spring 5.0). While synchronous RestTemplate methods still work, you might want to start migrating to WebClient for new code.
• DispatcherServlet Changes: The initialization process for DispatcherServlet has been refactored, and some old init parameters (like contextConfigLocation in certain setups) are no longer supported.

5. Third-Party Dependency Compatibility #

• ORM Frameworks: Hibernate 4.x has limited support in Spring 5.0 — it’s recommended to upgrade to Hibernate 5.0+.
• Jackson: Spring 5.0 uses Jackson 2.9+ by default. If you’re on an older Jackson version (2.6 or lower), you’ll likely run into serialization/deserialization issues with Java 8 types or new Spring features.
• Caching: Ehcache 2.x is no longer supported; upgrade to Ehcache 3.x or switch to another caching provider like Caffeine.

Short answer: Spring Security 4.2 is not compatible with Spring 5.0.5. Here’s why:

• Spring Security 4.2 is built specifically for Spring 4.x, so it relies on many Spring APIs that have been changed, moved, or removed in Spring 5.0. This will lead to class loading errors, method signature mismatches, and runtime exceptions.
• Key areas of conflict include the web security configuration (e.g., WebSecurityConfigurerAdapter dependencies on Spring MVC APIs that have changed), authentication manager setup, and core security filter chain logic.

The Fix #

If you’re upgrading to Spring 5.0.5, you must upgrade Spring Security to 5.0.x (ideally Spring Security 5.0.5 to match your Spring version). Spring Security 5.x is designed from the ground up to work with Spring 5, fixes all compatibility issues, and adds new features like improved OAuth2.0 support and modern password storage mechanisms.

内容的提问来源于stack exchange，提问作者Chandan Ghosh