记录一下 Java 注解的学习过程
快速入门
设计一个测试案例，创建一个名为 Marked 的注解类，该注解可以添加在 method 上用来表示方法是否被标记过。在测试用力中遍历被标记的类并打印信息
测试类：
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| public class Person {
private String name;
private int age;
private boolean isSelected;
@Marked
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Marked(value = true)
public int getAge() {
return age;
}
}
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自己创建的注解类：
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| @Retention(RetentionPolicy.RUNTIME)
public @interface Marked {
boolean value() default false;
}
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测试用例：
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| @Test
public void test_print_by_anno() {
Method[] methods = Person.class.getDeclaredMethods();
for (Method m : methods) {
Marked myAnno = m.getAnnotation(Marked.class);
if (myAnno != null) {
System.out.println("Method: " + m.getName() + " has marked annotation.");
System.out.println("Marked value: " + myAnno.value());
} else {
System.out.println("Method: " + m.getName() + " don't has marked annotation.");
}
}
}
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终端打印：
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| Method: getName has marked annotation.
Marked value: false
Method: setName don't has marked annotation.
Method: getAge has marked annotation.
Marked value: true
Method: setAge don't has marked annotation.
Method: isSelected don't has marked annotation.
Method: setSelected don't has marked annotation.
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从这个例子可以看出来，Annotation 都是处理 class level 的问题的，和类延伸出来的实例基本没关系了