不管是html页面表单提交的对象数据还是和第三方公司进行接口对接，都需要对接收到的数据进行校验（非空、长度、格式等等）。如果使用if一个个进行校验（字段非常多），这是让人崩溃的过程。幸好jdk或hibernate都提供了对object对象的校验，只需加上相应的注解即可。

本人喜欢学习时，都建立个maven小项目进行实践学习。

1.项目建立

pom.xml

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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.fei</groupId>
<artifactId>validation-test</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>javax.el</groupId>
<artifactId>javax.el-api</artifactId>
<version>2.2.4</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.1.3.Final</version>
</dependency>
</dependencies>
</project>

是用来练手的

2.基本校验练习

StudentInfo.java

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package com.fei.info;
import javax.validation.constraints.Pattern;
import org.hibernate.validator.constraints.NotBlank;
public class StudentInfo {
@NotBlank(message="用户名不能为空")
private String userName;
@NotBlank(message="年龄不能为空")
@Pattern(regexp="^[0-9]{1,2}$",message="年龄是整数")
private String age;
/**
* 如果是空，则不校验，如果不为空，则校验
*/
@Pattern(regexp="^[0-9]{4}-[0-9]{2}-[0-9]{2}$",message="出生日期格式不正确")
private String birthday;
@NotBlank(message="学校不能为空")
private String school;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getBirthday() {
return birthday;
}
public void setBirthday(String birthday) {
this.birthday = birthday;
}
public String getSchool() {
return school;
}
public void setSchool(String school) {
this.school = school;
}
}

ValidatorUtil.java

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package com.fei.util;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.groups.Default;
public class ValidatorUtil {
private static Validator validator = Validation.buildDefaultValidatorFactory()
.getValidator();
public static <T> Map<String,StringBuffer> validate(T obj){
Map<String,StringBuffer> errorMap = null;
Set<ConstraintViolation<T>> set = validator.validate(obj,Default.class);
if(set != null && set.size() >0 ){
errorMap = new HashMap<String,StringBuffer>();
String property = null;
for(ConstraintViolation<T> cv : set){
//这里循环获取错误信息，可以自定义格式
property = cv.getPropertyPath().toString();
if(errorMap.get(property) != null){
errorMap.get(property).append("," + cv.getMessage());
}else{
StringBuffer sb = new StringBuffer();
sb.append(cv.getMessage());
errorMap.put(property, sb);
}
}
}
return errorMap;
}
}

ValidatorTest.java

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package com.fei;
import java.util.Map;
import com.fei.info.StudentInfo;
import com.fei.util.ValidatorUtil;
public class ValidatorTest {
public static void main(String[] args) {
StudentInfo s = new StudentInfo();
long startTime = System.currentTimeMillis();
print(ValidatorUtil.validate(s));
System.out.println("===============耗时(毫秒)=" + (System.currentTimeMillis() - startTime));
s.setUserName("小明");
s.setAge("a10");
s.setBirthday("2016-9-1");
startTime = System.currentTimeMillis();
print(ValidatorUtil.validate(s));
System.out.println("===============耗时(毫秒)=" + (System.currentTimeMillis() - startTime));
}
private static void print(Map<String,StringBuffer> errorMap){
if(errorMap != null){
for(Map.Entry<String, StringBuffer> m : errorMap.entrySet()){
System.out.println(m.getKey() + ":" + m.getValue().toString());
}
}
}
}

来看看运行结果：

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十二月 12, 2016 4:02:00 下午 org.hibernate.validator.internal.util.Version <clinit>
INFO: HV000001: Hibernate Validator 5.1.3.Final
school:学校不能为空
age:年龄不能为空
userName:用户名不能为空
===============耗时(毫秒)=280
birthday:出生日期格式不正确
school:学校不能为空
age:年龄是整数
===============耗时(毫秒)=3

看到运行结果，心中一喜，达到了我们的要求。

看StudentInfo中的import发现注解的来源有来自javax和hibernate。

javax中有

hibernate中有

如果现有的校验规则都不满足，则可以自定义校验规则

3.自定义校验规则

Money.java

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package com.fei.validator;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import javax.validation.Constraint;
import javax.validation.Payload;
@Target({ElementType.FIELD, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy=MoneyValidator.class)
public @interface Money {
String message() default"不是金额形式";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}

MoneyValidator.java

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package com.fei.validator;
import java.util.regex.Pattern;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
public class MoneyValidator implements ConstraintValidator<Money, Double> {
private String moneyReg = "^\\d+(\\.\\d{1,2})?$";//表示金额的正则表达式
private Pattern moneyPattern = Pattern.compile(moneyReg);
public void initialize(Money money) {
// TODO Auto-generated method stub
}
public boolean isValid(Double value, ConstraintValidatorContext arg1) {
if (value == null)
//金额是空的，返回true，是因为如果null，则会有@NotNull进行提示
//如果这里false的话，那金额是null，@Money中的message也会进行提示
//自己可以尝试
return true;
return moneyPattern.matcher(value.toString()).matches();
}
}

StudentInfo.java

加上,注意因为money是Double，所以不能用@NotBlank，因为@NotBlank是对字符串校验的

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@NotNull(message="金额不能为空")
@Money(message="金额格式不正确")
private Double money;

ValidatorTest.java

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package com.fei;
import java.util.Map;
import com.fei.info.StudentInfo;
import com.fei.util.ValidatorUtil;
public class ValidatorTest {
public static void main(String[] args) {
StudentInfo s = new StudentInfo();
long startTime = System.currentTimeMillis();
print(ValidatorUtil.validate(s));
System.out.println("===============耗时(毫秒)=" + (System.currentTimeMillis() - startTime));
s.setUserName("小明");
s.setAge("a10");
s.setBirthday("2016-9-1");
s.setMoney(100.00001);
startTime = System.currentTimeMillis();
print(ValidatorUtil.validate(s));
System.out.println("===============耗时(毫秒)=" + (System.currentTimeMillis() - startTime));
}
private static void print(Map<String,StringBuffer> errorMap){
if(errorMap != null){
for(Map.Entry<String, StringBuffer> m : errorMap.entrySet()){
System.out.println(m.getKey() + ":" + m.getValue().toString());
}
}
}
}

运行结果：

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十二月 12, 2016 4:42:41 下午 org.hibernate.validator.internal.util.Version <clinit>
INFO: HV000001: Hibernate Validator 5.1.3.Final
school:学校不能为空
age:年龄不能为空
money:金额不能为空
userName:用户名不能为空
===============耗时(毫秒)=280
birthday:出生日期格式不正确
school:学校不能为空
age:年龄是整数
money:金额格式不正确
===============耗时(毫秒)=4

当然，如果你的项目使用springMVC或structs2，都会对应的集成方法。

4.级联校验

如果校验的对象中包含另一个对象信息时，校验也要同时校验另一个对象，则可以使用@Valid

ParentInfo.java

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package com.fei.info;
import org.hibernate.validator.constraints.NotBlank;
public class ParentInfo {
@NotBlank(message="父亲名称不能为空")
private String fatherName;
@NotBlank(message="母亲名称不能为空")
private String motherName;
public String getFatherName() {
return fatherName;
}
public void setFatherName(String fatherName) {
this.fatherName = fatherName;
}
public String getMotherName() {
return motherName;
}
public void setMotherName(String motherName) {
this.motherName = motherName;
}
}

StudentInfo.java

中加入，set,get是必须的

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/**
* 如果不加@NotNull，则prentInfo=null时，不会对ParentInfo内的字段进行校验
*/
@NotNull(message="父母信息不能为空")
@Valid
private ParentInfo parentInfo;

ValidatorTest.java

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package com.fei;
import java.util.Map;
import com.fei.info.ParentInfo;
import com.fei.info.StudentInfo;
import com.fei.util.ValidatorUtil;
public class ValidatorTest {
public static void main(String[] args) {
StudentInfo s = new StudentInfo();
long startTime = System.currentTimeMillis();
print(ValidatorUtil.validate(s));
System.out.println("===============耗时(毫秒)=" + (System.currentTimeMillis() - startTime));
s.setUserName("小明");
s.setAge("a10");
s.setBirthday("2016-9-1");
s.setMoney(100.00001);
s.setParentInfo(new ParentInfo());
startTime = System.currentTimeMillis();
print(ValidatorUtil.validate(s));
System.out.println("===============耗时(毫秒)=" + (System.currentTimeMillis() - startTime));
}
private static void print(Map<String,StringBuffer> errorMap){
if(errorMap != null){
for(Map.Entry<String, StringBuffer> m : errorMap.entrySet()){
System.out.println(m.getKey() + ":" + m.getValue().toString());
}
}
}
}