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不同的保留政策如何影响我的注释?

编程基础网 Java问题

2022-01-01

How do different retention policies affect my annotations?(不同的保留政策如何影响我的注释?)

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问题描述

任何人都可以清楚地解释 java.lang.annotation.RetentionPolicy 常量 SOURCE、CLASS 和 CLASS 之间的实际区别吗?代码>运行时间?

我也不确定保留注释"这个短语是什么意思.

解决方案

RetentionPolicy.SOURCE:丢弃期间编译.这些注释不编译后有意义已完成，因此它们不会被写入字节码.
示例:@Override、@SuppressWarnings
RetentionPolicy.CLASS:丢弃期间类负载.做的时候有用字节码级后处理.有点意外，这是默认.
RetentionPolicy.RUNTIME:不要丢弃.注释应该是可在运行时进行反射.示例:@Deprecated

来源:旧网址现已失效

~~Can anyone explain in a clear way the practical differences between the java.lang.annotation.RetentionPolicy constants SOURCE, CLASS, and RUNTIME?~~

I'm also not exactly sure what the phrase "retaining annotation" means.
解决方案

RetentionPolicy.SOURCE: Discard during the compile. These annotations don't make any sense after the compile has completed, so they aren't written to the bytecode.
Example: @Override, @SuppressWarnings

RetentionPolicy.CLASS: Discard during class load. Useful when doing bytecode-level post-processing. Somewhat surprisingly, this is the default.

RetentionPolicy.RUNTIME: Do not discard. The annotation should be available for reflection at runtime. Example: @Deprecated

Source: The old URL is dead now ~~hunter_meta~~ and replaced with hunter-meta-2-098036. In case even this goes down, I am uploading the image of the page.

Image (Right Click and Select 'Open Image in New Tab/Window')

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