使用Javax.Validation校验字段完备性

最近在做项目过程中，发现为了检验一个类里面各个字段是否完整，需要写很多check函数，例如：

if(pLane==null){
	String errorMsg="车道的值是null";
    throw new XXXException(errorMsg);
}

这些校验的函数就写在主计算的方法中，感觉不是很好，于是尝试使用Javax.Validation模块优化一下：

首先导入包：

<dependency>
    <groupId>javax.validation</groupId>
    <artifactId>validation-api</artifactId>
    <version>1.1.0.Final</version>
</dependency>
<dependency>
	<groupId>org.hibernate</groupId>
	<artifactId>hibernate-validator</artifactId>
	<version>5.4.1.Final</version>
</dependency>

然后对需要检查的类添加注解

import org.hibernate.validator.constraints.NotBlank;
import javax.validation.constraints.DecimalMin;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;

public class User {
    @NotNull(message = "用户ID不能为空")
    private Integer id;
    /* 检查约束 (字符串) 是不是Null还有被Trim的长度是否大于0,只对字符串,且会去掉前后空格.*/
    @NotBlank(message = "用户名不能为空")
    private String username;
//    @DecimalMin("1")
    @Min(value = 1,message = "低于最小值")
    @Max(value = 10,message = "超过最大值")
    private Double salary;
	//getter setter 构造函数略
}

然后编写测试工具：ValidationUtils

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;

/**
 * 校验工具类
 *
 * @author lizhilong
 */
public class ValidationUtils {

    private static Validator validator = Validation.buildDefaultValidatorFactory().getValidator();

    public static <T> ValidationResult validateEntity(T obj) {
        ValidationResult result = new ValidationResult();
        Set<ConstraintViolation<T>> set = validator.validate(obj, Default.class);
        // if( CollectionUtils.isNotEmpty(set) ){
        if (set != null && set.size() != 0) {
            result.setHasErrors(true);
            Map<String, String> errorMsg = new HashMap<String, String>();
            for (ConstraintViolation<T> cv : set) {
                errorMsg.put(cv.getPropertyPath().toString(), cv.getMessage());
            }
            result.setErrorMsg(errorMsg);
        }
        return result;
    }

    public static <T> ValidationResult validateProperty(T obj, String propertyName) {
        ValidationResult result = new ValidationResult();
        Set<ConstraintViolation<T>> set = validator.validateProperty(obj, propertyName, Default.class);
        if (set != null && set.size() != 0) {
            result.setHasErrors(true);
            Map<String, String> errorMsg = new HashMap<String, String>();
            for (ConstraintViolation<T> cv : set) {
                errorMsg.put(propertyName, cv.getMessage());
            }
            result.setErrorMsg(errorMsg);
        }
        return result;
    }

}

以及ValidationResult

import java.util.Map;

public class ValidationResult {

    // 校验结果是否有错
    private boolean             hasErrors;

    // 校验错误信息
    private Map<String, String> errorMsg;

    public boolean isHasErrors() {
        return hasErrors;
    }

    public void setHasErrors(boolean hasErrors) {
        this.hasErrors = hasErrors;
    }

    public Map<String, String> getErrorMsg() {
        return errorMsg;
    }

    public void setErrorMsg(Map<String, String> errorMsg) {
        this.errorMsg = errorMsg;
    }

    @Override
    public String toString() {
        return "ValidationResult{" +
                "hasErrors=" + hasErrors +
                ", errorMsg=" + errorMsg +
                '}';
    }
}

（上述内容参考：https://blog.csdn.net/icannotdebug/article/details/78708202）

然后写测试样例 就可以测试了。

例如 ：

User user=new User(null,null,11.0);
ValidationResult validationResult=ValidationUtils.validateEntity(user);
if (validationResult.isHasErrors){
    throw new ....Exception
}