自定义注解

spring

1、先上代码（定义注解）

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@Constraint(validatedBy = DecimalValidator.class) //具体的实现
@Target( { java.lang.annotation.ElementType.METHOD,
    java.lang.annotation.ElementType.FIELD })
@Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
@Documented
public @interface IsDecimal {
	java.lang.String message() default "";
	Class<?>[] groups() default {};
	Class<? extends Payload>[] payload() default {};
}

2、实现代码

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public class DecimalValidator implements ConstraintValidator<IsDecimal, Map<String,Object>> {
	String pointPrefix = "(\\-|\\+){0,1}\\d*\\.\\d+";// 浮点数的正则表达式-小数点在中间与前面
	String pointSuffix = "(\\-|\\+){0,1}\\d+\\.";// 浮点数的正则表达式-小数点在后面
	String pointPrefixWithoutPoint = "\\-{0,1}\\d+";// 整数的正则表达式
	
	@Override
	public void initialize(IsDecimal constraintAnnotation) {
	}
	public boolean isValid(Map<String,Object> map, ConstraintValidatorContext arg1) {
		String value = (String)map.get(Constants.KEY);
		if (StringUtils.isEmpty(value) && (boolean)(map.get(Constants.REQUIRED)))
			return false;
		return value.matches(pointPrefix) || value.matches(pointSuffix) || value.matches(pointPrefixWithoutPoint);
	}
}

解析

1、

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