javax.validation：约束以字节为单位验证字符串长度
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javax.validation: Constraint to validate a string length in bytes
提问by BackSlash
I'm using javax.validationto validate some bean fields' values.
我javax.validation用来验证一些 bean 字段的值。
This is what I use normally:
这是我通常使用的：
public class Market {
@NotNull
@Size(max=4)
private String marketCode;
@Digits(integer=4, fraction=0)
private Integer stalls;
// getters/setters
}
This will make sure that every Marketinstance has a market code with a maximum length of 4characters and a number of stall with a maximum of 4 integer digits and 0 decimal digits.
这将确保每个Market实例都有一个最大4字符长度的市场代码和一个最多4 个整数位和 0 个小数位的档位。
Now, I use this bean to load/store data from/to DB.
现在，我使用这个 bean 从/向 DB 加载/存储数据。
In the DB I have table Marketsdefined like this:
在数据库中，我Markets定义了如下表：
CREATE TABLE MARKETS (
MARKET_CODE VARCHAR2(4 BYTE) NOT NULL,
STALLS NUMBER(4,0)
)
As you can see, I have MARKET_CODEwhich can be at most 4 byteslong. The @Sizeannotation will check if the string is at most 4 characterslong, which is wrong.
如您所见，我MARKET_CODE最多可以有 4个字节长。该@Size注释将检查字符串最多为4个字符长，这是错误的。
So, the question is: is there an annotation like @Sizethat will check for the string bytes instead of the characters?
所以，问题是：是否有这样的注释@Size会检查字符串字节而不是字符？
采纳答案by ptomli
Check the Hibernate Validator documentation on Creating custom constraints.
查看有关创建自定义约束的Hibernate Validator 文档。
Your validator will need to encode the Stringinto a byte[], using some default or specified Charset. I imagine you might well use UTF-8.
您的验证器将需要使用一些默认或指定的将 编码String为。我想你很可能会使用 UTF-8。byte[]Charset
Maybe something like this, which uses a hard coded UTF-8 encoding and assumes a suitable annotation, as outlined in the Hibernate documentation linked.
也许像这样，它使用硬编码的 UTF-8 编码并假定合适的注释，如链接的 Hibernate 文档中所述。
public class MaxByteLengthValidator implements ConstraintValidator<MaxByteLength, String> {
private int max;
public void initialize(MaxByteLength constraintAnnotation) {
this.max = constraintAnnotation.value();
}
public boolean isValid(String object, ConstraintValidatorContext constraintContext) {
return object == null || object.getBytes(Charsets.UTF_8).length <= this.max;
}
}
