SpringBoot如何进行全局参数验证拦截呢?

参数验证:
    是所有程序都绕不开的话题,也是每一个方法必备的功能
	那么如何采用一种统一的方式处理参数验证呢?
	下文笔者将一一道来,如下所示

优雅验证全局参数的方法

实现思路:
    1.借助@InitBinder注解(放在需验证的controller方法上),实现参数的获取
	2.使用拦截器(@RestControllerAdvice)对参数的数据类型进行验证
如:
@InitBinder
public void initBinder(WebDataBinder webDataBinder){
  //TODO
}

pom.xml定义

<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.java265</groupId>
    <artifactId>valid-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
        <relativePath /> 
    </parent>
    <name>valid-demo</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
        </dependency>
    </dependencies>
</project>

定义VO对象

package com.java265.vo;
import java.io.Serializable;
public class BaseVo implements Serializable{

}
 
package com.java265.vo;
import javax.validation.constraints.NotEmpty;
public class UserQueryVo extends BaseVo {

    @NotEmpty(message="不能为空")
    private String query;

    public String getQuery() {
        return query;
    }

    public void setQuery(String query) {
        this.query = query;
    }
}

定义控制器

package com.java265.controller;

import java.util.HashMap;
import java.util.Map;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.java265.vo.UserQueryVo;

@RestController
public class UserController {

    @RequestMapping("/user/queryUser")
    public Map queryUser(@RequestBody @Validated UserQueryVo queryVo){
        Map result = new HashMap();
        result.put("code", 200);
        result.put("msg", "success");
        return result;
    }
}

添加参数校验统一拦截入口

package com.java265;

import java.util.HashMap;
import java.util.list;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.ObjectError;
import org.springframework.validation.Validator;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import com.java265.vo.BaseVo;

@RestControllerAdvice
public class UserControllerAdvice {

    @Autowired
    private Validator validator;

    @InitBinder
    public void initValid(WebDataBinder webDataBinder){
        Object target= webDataBinder.getTarget();
        if(target==null){
            return;
        }
        if(target instanceof BaseVo){
            BeanPropertyBindingResult result = new BeanPropertyBindingResult(target, target.getClass().getSimpleName());
            validator.validate(target, result);
            List<ObjectError> errors  = result.getAllErrors();
            if(errors==null || errors.isEmpty()){
                return;
            }
            throw new RuntimeException("参数错误");
        }
    }

    @ExceptionHandler(value = Exception.class)
    @ResponseBody
    public Map defaultErrorHandler(HttpServletRequest req, Exception e)  {
        Map result = new HashMap();
        result.put("code", 500);
        result.put("msg", e.getMessage());
        return result;
    }

}

@RestControllerAdvice注解的功能

@RestControllerAdvice注解的功能:
    对@RestController控制器拦截

initValid方法中
    使用@InitBinder标识
	该方法传入WebDataBinder对象
    此时方法中写入参数校验代码
    当验证不通过时,
	 直接抛出异常
    抛出运行时异常RuntimeException

启动SpringBoot

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application 
{
    public static void main( String[] args )
    {
        SpringApplication.run(Application.class, args);
    }
}