資訊專欄INFORMATION COLUMN
摘要：校驗(yàn)器可以通過(guò)對(duì)象報(bào)告校驗(yàn)失敗的信息接口定義示例如下，可以使用等工具測(cè)試用戶名不能為空常用注解也可以自定義注解及其校驗(yàn)規(guī)則獲取并初始化注解信息設(shè)置自定義校驗(yàn)規(guī)則人的姓名不能為空參考
Java后端常用的校驗(yàn)框架 Apache commons-validatorQ: 為什么后端需要校驗(yàn)，只交給前端校驗(yàn)行不行
A: 前后端都需要校驗(yàn)
后端校驗(yàn)防止請(qǐng)求過(guò)來(lái)的非法數(shù)據(jù)，對(duì)后端進(jìn)行破壞
http://commons.apache.org/ 這個(gè)地址apache提供了常用的工具類，包括校驗(yàn)框架
提供了大量的校驗(yàn)器，如時(shí)間、數(shù)值、正則表達(dá)式、郵箱、URL等待
以IntegerValidator為例
IntegerValidator integerValidator = new IntegerValidator();
Integer value = integerValidator.validate("10");
System.out.println(value);
value = integerValidator.validate("G");
System.out.println(value);
/**
* Validate/convert an Integer using the default
* Locale.
*
* @param value The value validation is being performed on.
* @return The parsed Integer if valid or null
* if invalid.
*/
public Integer validate(String value) {
return (Integer)parse(value, (String)null, (Locale)null);
}
在校驗(yàn)傳入的參數(shù)時(shí)，當(dāng)能夠解析成Integer類型就返回這個(gè)數(shù)字，如果不能就返回null
其它數(shù)值類型校驗(yàn)類似
Spring ValidatorSpring框架提供的用于校驗(yàn)對(duì)象的Validator接口，在校驗(yàn)過(guò)程中與Errors對(duì)象配合。校驗(yàn)器可以通過(guò)Errors對(duì)象報(bào)告校驗(yàn)失敗的信息
org.springframework.validation.Validator接口定義
public interface Validator {
/**
* Can this {@link Validator} {@link #validate(Object, Errors) validate}
* instances of the supplied {@code clazz}?
* This method is typically implemented like so:
*
return Foo.class.isAssignableFrom(clazz);
* (Where {@code Foo} is the class (or superclass) of the actual
* object instance that is to be {@link #validate(Object, Errors) validated}.)
* @param clazz the {@link Class} that this {@link Validator} is
* being asked if it can {@link #validate(Object, Errors) validate}
* @return {@code true} if this {@link Validator} can indeed
* {@link #validate(Object, Errors) validate} instances of the
* supplied {@code clazz}
*/
boolean supports(Class clazz);
/**
* Validate the supplied {@code target} object, which must be
* of a {@link Class} for which the {@link #supports(Class)} method
* typically has (or would) return {@code true}.
* The supplied {@link Errors errors} instance can be used to report
* any resulting validation errors.
* @param target the object that is to be validated (can be {@code null})
* @param errors contextual state about the validation process (never {@code null})
* @see ValidationUtils
*/
void validate(Object target, Errors errors);
示例如下，可以使用POSTMAN等工具測(cè)試
package com.adagio.domain;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
public class Person {
@NotNull
private String name;
@Min(0)
@Max(150)
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
package com.adagio.validator;
import org.springframework.util.StringUtils;
import org.springframework.validation.Errors;
import org.springframework.validation.Validator;
import com.adagio.domain.Person;
public class PersonValidator implements Validator {
@Override
public boolean supports(Class clazz) {
return Person.class.isAssignableFrom(clazz);
}
@Override
public void validate(Object target, Errors errors) {
Person person = Person.class.cast(target);
String name = person.getName();
if(!StringUtils.hasLength(name)){
errors.reject("person.name.not.null", "用戶名不能為空");
}
}
}
package com.adagio.controller;
import javax.validation.Valid;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import com.adagio.domain.Person;
@Controller
public class PersonController {
@PostMapping("/person/save")
public Person save(@Valid @RequestBody Person person){
return person;
}
}
Bean Validation 1.0（JSR-303）
常用注解：@Valid、@NotNull、@Null、@Size、@Min、@Max
也可以自定義注解及其校驗(yàn)規(guī)則
package com.adagio.validator;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import javax.validation.Constraint;
import javax.validation.Payload;
@Target({METHOD, FIELD})
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = {PersonNameConstraintValidator.class})
public @interface PersonName {
String message() default "{person.name.not.null}";
Class[] groups() default {};
Class[] payload() default {};
}
