java注解，反射实现抽象代码工作中实际运用

注解类：ApiFieldAnnotation.java

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD})
public @interface ApiFieldAnnotation {

Class fieldClassType();

boolean notNull();

int maxLength() default -1;

String fieldDesc();

int scale() default 0;

}

测试代码：
@Test
public void testMyTest() throws Exception {
MyBizPojo myBizPojo = new MyBizPojo();
myBizPojo.setAccount("1111111111");
myBizPojo.setName("CCCCCC");
List<MyReturnPojo> params = Lists.newArrayList();
java.lang.reflect.Field[] fields = myBizPojo.getClass().getDeclaredFields();
for (java.lang.reflect.Field field : fields) {
if (!field.isAnnotationPresent(ApiFieldAnnotation.class)) {
continue;
}
ApiFieldAnnotation annotation = field.getAnnotation(ApiFieldAnnotation.class);
field.setAccessible(true);
MyReturnPojo myReturnPojo =
new MyReturnPojo(field.getName(), annotation.fieldDesc(), annotation.notNull(), field.get(myBizPojo));
params.add(myReturnPojo);
}
params.forEach(p -> {
System.out.println(p);
});

}

@Data
private class MyBizPojo {
@ApiFieldAnnotation(fieldClassType = String.class, maxLength = 10, notNull = true, fieldDesc = "账号")
private String account;

@ApiFieldAnnotation(fieldClassType = String.class, maxLength = 10, notNull = true, fieldDesc = "名字")
private String name;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
private class MyReturnPojo {
private String name;
private String nameZh;
private Boolean notNullFlag;
private Object defaultValue;
}

返回结果：
JxbkComponentTest.MyReturnPojo(name=account, nameZh=账号, notNullFlag=true, defaultValue=1111111111)

JxbkComponentTest.MyReturnPojo(name=name, nameZh=名字, notNullFlag=true, defaultValue=CCCCCC)

备注：

Field[]

getDeclaredFields()             返回  Field  对象的一个数组，这些对象反映此  Class  对象所表示的类或接口所声明的所有字段。

boolean

isAnnotationPresent(Class<? extends Annotation> annotationClass)             如果指定类型的注释存在于此元素上，则返回 true，否则返回 false

<T extends Annotation>  T

getAnnotation(Class<T> annotationClass)             如果存在该元素的指定类型的注释，则返回这些注释，否则返回 null

Object

get(Object obj)             返回指定对象上此  Field  表示的字段的值