import lombok.Data;\nimport javax.validation.constraints.Size;\n@Data\npublic class Student {\n @Size(min = 1, max = 10)\n private String name;\n private short age;\n}<\/code><\/pre>\n\u5982\u4e0a\u4ee3\u7801\u6240\u793a\uff0c\u6211\u4eec\u60f3\u9488\u5bf9\u5b66\u751f\u7684\u59d3\u540d\u8fdb\u884c\u4e00\u4e2a\u5224\u65ad\uff0c\u4e0d\u80fd\u4e3a\u7a7a\uff0c\u5e76\u4e14\u957f\u5ea6\u4e3a1-10\u3002<\/p>\n
\u7136\u540e\uff0c\u6211\u4eec\u4ee5\u4e0b\u9762\u7684 JSON Body \u505a\u6d4b\u8bd5\uff1a<\/p>\n
{\n "name": "",\n "age": 10,\n "phone": {"number":"12306"}\n}<\/code><\/pre>\n\u6d4b\u8bd5\u7ed3\u679c\u7b26\u5408\u6211\u4eec\u7684\u9884\u671f\uff0c\u4f46\u662f\u5047\u8bbe\u66f4\u8fdb\u4e00\u6b65\uff0c\u7528\u4e0b\u9762\u7684 JSON Body\uff08\u53bb\u9664 name \u5b57\u6bb5\uff09\u505a\u6d4b\u8bd5\u5462\uff1f<\/p>\n
{\n "age": 10,\n "phone": {"number":"12306"}\n}<\/code><\/pre>\n\u6211\u4eec\u4f1a\u53d1\u73b0\u6821\u9a8c\u5931\u8d25\u4e86\u3002\u8fd9\u7ed3\u679c\u96be\u514d\u8ba9\u6211\u4eec\u6709\u4e00\u4e9b\u60ca\u8bb6\uff0c\u4e5f\u500d\u611f\u56f0\u60d1\uff1a@Size(min = 1, max = 10) \u90fd\u5df2\u7ecf\u8981\u6c42\u6700\u5c0f\u957f\u5ea6\u4e3a 1 \u4e86\uff0c\u96be\u9053\u8fd8\u53ea\u80fd\u7ea6\u675f\u7a7a\u5b57\u7b26\u4e32\uff08\u5373\u201c\u201d\uff09\uff0c\u4e0d\u80fd\u7ea6\u675f null?<\/p>\n
\u6848\u4f8b\u5206\u6790<\/h3>\n
\u5982\u679c\u6211\u4eec\u7a0d\u5fae\u7559\u5fc3\u70b9\u7684\u8bdd\uff0c\u5c31\u4f1a\u53d1\u73b0\u5176\u5b9e @Size \u7684 Javadoc \u5df2\u7ecf\u660e\u786e\u4e86\u8fd9\u79cd\u60c5\u51b5\uff0c\u53c2\u8003\u4e0b\u56fe\uff1a<\/p>\n
![\"image.png\"](\"https:\/\/segmentfault.com\/img\/bVdhkI5\" "\\"image.png\\"")
<\/p>\n
\u5982\u56fe\u6240\u793a\uff0c”null elements are considered valid” \u5f88\u597d\u5730\u89e3\u91ca\u4e86\u7ea6\u675f\u4e0d\u4f4f null \u7684\u539f\u56e0\u3002\u5f53\u7136\u7eb8\u4e0a\u5f97\u6765\u7ec8\u89c9\u6d45\uff0c\u6211\u4eec\u8fd8\u9700\u8981\u4ece\u6e90\u7801\u7ea7\u522b\u89e3\u8bfb\u4e0b @Size \u7684\u6821\u9a8c\u8fc7\u7a0b\u3002<\/p>\n
\u8fd9\u91cc\u6211\u4eec\u627e\u5230\u4e86\u5b8c\u6210 @Size \u7ea6\u675f\u7684\u6267\u884c\u65b9\u6cd5\uff0c\u53c2\u8003 SizeValidatorForCharSequence#isValid \u65b9\u6cd5\uff1a<\/p>\n
public boolean isValid(CharSequence charSequence, ConstraintValidatorContext constraintValidatorContext) {\n if ( charSequence == null ) {\n return true;\n }\n int length = charSequence.length();\n return length >= min && length <= max;\n}<\/code><\/pre>\n\u5982\u4ee3\u7801\u6240\u793a\uff0c\u5f53\u5b57\u7b26\u4e32\u4e3a null \u65f6\uff0c\u76f4\u63a5\u901a\u8fc7\u4e86\u6821\u9a8c\uff0c\u800c\u4e0d\u4f1a\u505a\u4efb\u4f55\u8fdb\u4e00\u6b65\u7684\u7ea6\u675f\u68c0\u67e5\u3002<\/p>\n
\u95ee\u9898\u4fee\u6b63<\/h3>\n
\u5173\u4e8e\u8fd9\u4e2a\u95ee\u9898\u7684\u4fee\u6b63\uff0c\u5176\u5b9e\u5f88\u7b80\u5355\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u5176\u4ed6\u7684\u6ce8\u89e3\uff08@NotNull \u6216 @NotEmpty\uff09\u6765\u52a0\u5f3a\u7ea6\u675f\uff0c\u4fee\u6b63\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
@NotEmpty\n@Size(min = 1, max = 10)\nprivate String name;<\/code><\/pre>\n\u5b8c\u6210\u4ee3\u7801\u4fee\u6539\u540e\uff0c\u91cd\u65b0\u6d4b\u8bd5\uff0c\u4f60\u5c31\u4f1a\u53d1\u73b0\u7ea6\u675f\u5df2\u7ecf\u5b8c\u5168\u6ee1\u8db3\u6211\u4eec\u7684\u9700\u6c42\u4e86\u3002<\/p>\n