springboot 参数校验详解

目录

• 目标
• 一、PathVariable 校验
• 二、方法参数校验
• 三、表单对象校验
• 四、RequestBody 校验
• 五、自定义校验规则
• 六、异常拦截器
• 参考文档

目标

1. 对于几种常见的入参方式，了解如何进行校验以及该如何处理错误消息；
2. 了解springboot 内置的参数异常类型，并能利用拦截器实现自定义处理；
3. 能实现简单的自定义校验规则

一、PathVariable 校验

在定义 Restful 风格的接口时，通常会采用 PathVariable 指定关键业务参数，如下：

@GetMapping("/path/{group:[a-zA-Z0-9_]+}/{userid}")
@ResponseBody
public String path(@PathVariable("group") String group, @PathVariable("userid") Integer userid) {
    return group + ":" + userid;
}

{group:[a-zA-Z0-9_]+} 这样的表达式指定了 group 必须是以大小写字母、数字或下划线组成的字符串。
我们试着访问一个错误的路径：

GET /path/testIllegal.get/10000

此时会得到 404的响应，因此对于PathVariable 仅由正则表达式可达到校验的目的

二、方法参数校验

类似前面的例子，大多数情况下，我们都会直接将HTTP请求参数映射到方法参数上。

@GetMapping("/param")
@ResponseBody
public String param(@RequestParam("group")@Email String group, 
                    @RequestParam("userid") Integer userid) {
   return group + ":" + userid;
}

上面的代码中，@RequestParam 声明了映射，此外我们还为 group 定义了一个规则(复合Email格式)
这段代码是否能直接使用呢？答案是否定的，为了启用方法参数的校验能力，还需要完成以下步骤：

• 声明 MethodValidationPostProcessor

@Bean
public MethodValidationPostProcessor methodValidationPostProcessor() {
     return new MethodValidationPostProcessor();
}

• Controller指定@Validated注解

@Controller
@RequestMapping("/validate")
@Validated
public class ValidateController {

如此之后，方法上的@Email规则才能生效。

校验异常
如果此时我们尝试通过非法参数进行访问时，比如提供非Email格式的 group
会得到以下错误：

GET /validate/param?group=simple&userid=10000
====>
{
    "timestamp": 1530955093583,
    "status": 500,
    "error": "Internal Server Error",
    "exception": "javax.validation.ConstraintViolationException",
    "message": "No message available",
    "path": "/validate/param"
}

而如果参数类型错误，比如提供非整数的 userid，会得到：

GET /validate/param?group=simple&userid=1f
====>
{
    "timestamp": 1530954430720,
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.web.method.annotation.MethodArgumentTypeMismatchException",
    "message": "Failed to convert value of type 'java.lang.String' to required type 'java.lang.Integer'; nested exception is java.lang.NumberFormatException: For input string: "1f"",
    "path": "/validate/param"
}

当存在参数缺失时，由于定义的@RequestParam注解中，属性 required=true，也将会导致失败：

GET /validate/param?userid=10000
====>
{
    "timestamp": 1530954345877,
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.web.bind.MissingServletRequestParameterException",
    "message": "Required String parameter 'group' is not present",
    "path": "/validate/param"
}

三、表单对象校验

页面的表单通常比较复杂，此时可以将请求参数封装到表单对象中，
并指定一系列对应的规则，参考JSR-303

public static class FormRequest {
<span class="hljs-variable">@NotEmpty</span>
<span class="hljs-variable">@Email</span>
private String email;

<span class="hljs-variable">@Pattern</span>(regexp = <span class="hljs-string">"[a-zA-Z0-9_]{6,30}"</span>)
private String name;

<span class="hljs-variable">@Min</span>(<span class="hljs-number">5</span>)
<span class="hljs-variable">@Max</span>(<span class="hljs-number">199</span>)
private int age;</code></pre>

上面定义的属性中：

email必须非空、符合Email格式规则；
name必须为大小写字母、数字及下划线组成，长度在6-30个；
age必须在5-199范围内

Controller方法中的定义：
@PostMapping("/form")
@ResponseBody
public FormRequest form(@Validated FormRequest form) {
    return form;
}
@Validated指定了参数对象需要执行一系列校验。
校验异常

此时我们尝试构造一些违反规则的输入，会得到以下的结果：
{
    "timestamp": 1530955713166,
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.validation.BindException",
    "errors": [
        {
            "codes": [
                "Email.formRequest.email",
                "Email.email",
                "Email.java.lang.String",
                "Email"
            ],
            "arguments": [
                {
                    "codes": [
                        "formRequest.email",
                        "email"
                    ],
                    "arguments": null,
                    "defaultMessage": "email",
                    "code": "email"
                },
                [],
                {
                    "arguments": null,
                    "codes": [
                        ".*"
                    ],
                    "defaultMessage": ".*"
                }
            ],
            "defaultMessage": "不是一个合法的电子邮件地址",
            "objectName": "formRequest",
            "field": "email",
            "rejectedValue": "tecom",
            "bindingFailure": false,
            "code": "Email"
        },
        {
            "codes": [
                "Pattern.formRequest.name",
                "Pattern.name",
                "Pattern.java.lang.String",
                "Pattern"
            ],
            "arguments": [
                {
                    "codes": [
                        "formRequest.name",
                        "name"
                    ],
                    "arguments": null,
                    "defaultMessage": "name",
                    "code": "name"
                },
                [],
                {
                    "arguments": null,
                    "codes": [
                        "[a-zA-Z0-9_]{6,30}"
                    ],
                    "defaultMessage": "[a-zA-Z0-9_]{6,30}"
                }
            ],
            "defaultMessage": "需要匹配正则表达式"[a-zA-Z0-9_]{6,30}"",
            "objectName": "formRequest",
            "field": "name",
            "rejectedValue": "fefe",
            "bindingFailure": false,
            "code": "Pattern"
        },
        {
            "codes": [
                "Min.formRequest.age",
                "Min.age",
                "Min.int",
                "Min"
            ],
            "arguments": [
                {
                    "codes": [
                        "formRequest.age",
                        "age"
                    ],
                    "arguments": null,
                    "defaultMessage": "age",
                    "code": "age"
                },
                5
            ],
            "defaultMessage": "最小不能小于5",
            "objectName": "formRequest",
            "field": "age",
            "rejectedValue": 2,
            "bindingFailure": false,
            "code": "Min"
        }
    ],
    "message": "Validation failed for object='formRequest'. Error count: 3",
    "path": "/validate/form"
}

如果是参数类型不匹配，会得到：
{
    "timestamp": 1530955359265,
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.validation.BindException",
    "errors": [
        {
            "codes": [
                "typeMismatch.formRequest.age",
                "typeMismatch.age",
                "typeMismatch.int",
                "typeMismatch"
            ],
            "arguments": [
                {
                    "codes": [
                        "formRequest.age",
                        "age"
                    ],
                    "arguments": null,
                    "defaultMessage": "age",
                    "code": "age"
                }
            ],
            "defaultMessage": "Failed to convert property value of type 'java.lang.String' 
to required type 'int' for property 'age'; nested exception is java.lang.NumberFormatException: 
For input string: """,
            "objectName": "formRequest",
            "field": "age",
            "rejectedValue": "",
            "bindingFailure": true,
            "code": "typeMismatch"
        }
    ],
    "message": "Validation failed for object='formRequest'. Error count: 1",
    "path": "/validate/form"
}

Form表单参数上，使用@Valid注解可达到同样目的，而关于两者的区别则是：

@Valid 基于JSR303，即 Bean Validation 1.0，由Hibernate Validator实现；

@Validated 基于JSR349，是Bean Validation 1.1，由Spring框架扩展实现；
后者做了一些增强扩展，如支持分组校验，有兴趣可参考这里。
四、RequestBody 校验
对于直接Json消息体输入，同样可以定义校验规则：
@PostMapping("/json")
@ResponseBody
public JsonRequest json(@Validated @RequestBody JsonRequest request) {
<span class="hljs-selector-tag">return</span> <span class="hljs-selector-tag">request</span>;

}
...

public static class JsonRequest {
<span class="hljs-variable">@NotEmpty</span>
<span class="hljs-variable">@Email</span>
private String email;

<span class="hljs-variable">@Pattern</span>(regexp = <span class="hljs-string">"[a-zA-Z0-9_]{6,30}"</span>)
private String name;

<span class="hljs-variable">@Min</span>(<span class="hljs-number">5</span>)
<span class="hljs-variable">@Max</span>(<span class="hljs-number">199</span>)
private int age;</code></pre>

校验异常

构造一个违反规则的Json请求体进行输入，会得到：
{
    "timestamp": 1530956161314,
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.web.bind.MethodArgumentNotValidException",
    "errors": [
        {
            "codes": [
                "Min.jsonRequest.age",
                "Min.age",
                "Min.int",
                "Min"
            ],
            "arguments": [
                {
                    "codes": [
                        "jsonRequest.age",
                        "age"
                    ],
                    "arguments": null,
                    "defaultMessage": "age",
                    "code": "age"
                },
                5
            ],
            "defaultMessage": "最小不能小于5",
            "objectName": "jsonRequest",
            "field": "age",
            "rejectedValue": 1,
            "bindingFailure": false,
            "code": "Min"
        }
    ],
    "message": "Validation failed for object='jsonRequest'. Error count: 1",
    "path": "/validate/json"
}

此时与FormBinding的情况不同，我们得到了一个MethodArgumentNotValidException异常。

而如果发生参数类型不匹配，比如输入age=1f，会产生以下结果：
{
    "timestamp": 1530956206264,
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.http.converter.HttpMessageNotReadableException",
    "message": "Could not read document: Can not deserialize value of type int from String "ff": not a valid Integer value
 at [Source: java.io.PushbackInputStream@68dc9800; line: 2, column: 8] (through reference chain: org.zales.dmo.boot.controllers.ValidateController$JsonRequest["age"]); nested exception is com.fasterxml.jackson.databind.exc.InvalidFormatException: Can not deserialize value of type int from String "ff": not a valid Integer value
 at [Source: java.io.PushbackInputStream@68dc9800; line: 2, column: 8] (through reference chain: org.zales.dmo.boot.controllers.ValidateController$JsonRequest["age"])",
    "path": "/validate/json"
}
这表明在JSON转换过程中已经失败！
五、自定义校验规则
框架内预置的校验规则可以满足大多数场景使用，

但某些特殊情况下，你需要制作自己的校验规则，这需要用到ContraintValidator接口。
我们以一个密码校验的场景作为示例，比如一个注册表单上，

我们需要检查 密码输入 与 密码确认 是一致的。
**首先定义 PasswordEquals 注解
@Documented
@Constraint(validatedBy = { PasswordEqualsValidator.class })
@Target({ ElementType.METHOD, ElementType.FIELD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
public @interface PasswordEquals {
<span class="hljs-selector-tag">String</span> <span class="hljs-selector-tag">message</span>() <span class="hljs-selector-tag">default</span> "<span class="hljs-selector-tag">Password</span> <span class="hljs-selector-tag">is</span> <span class="hljs-selector-tag">not</span> <span class="hljs-selector-tag">the</span> <span class="hljs-selector-tag">same</span>";

<span class="hljs-selector-tag">Class</span>&lt;?&gt;<span class="hljs-selector-attr">[]</span> <span class="hljs-selector-tag">groups</span>() <span class="hljs-selector-tag">default</span> {};

<span class="hljs-selector-tag">Class</span>&lt;? <span class="hljs-selector-tag">extends</span> <span class="hljs-selector-tag">Payload</span>&gt;<span class="hljs-selector-attr">[]</span> <span class="hljs-selector-tag">payload</span>() <span class="hljs-selector-tag">default</span> {};

}

在表单上声明@PasswordEquals 注解
@PasswordEquals
public class RegisterForm {
<span class="hljs-variable">@NotEmpty</span>
<span class="hljs-variable">@Length</span>(min=<span class="hljs-number">5</span>,max=<span class="hljs-number">30</span>)
private String username;

<span class="hljs-variable">@NotEmpty</span>
private String password;

<span class="hljs-variable">@NotEmpty</span>
private String passwordConfirm;</code></pre>

针对@PasswordEquals实现校验逻辑
public class PasswordEqualsValidator implements ConstraintValidator<PasswordEquals, RegisterForm> {
<span class="hljs-meta">@Override</span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">initialize</span><span class="hljs-params">(PasswordEquals anno)</span> </span>{
}

<span class="hljs-meta">@Override</span>
<span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">boolean</span> <span class="hljs-title">isValid</span><span class="hljs-params">(RegisterForm form, ConstraintValidatorContext context)</span> </span>{
    String passwordConfirm = form.getPasswordConfirm();
    String password = form.getPassword();

    <span class="hljs-keyword">boolean</span> match = passwordConfirm != <span class="hljs-keyword">null</span> ? passwordConfirm.equals(password) : <span class="hljs-keyword">false</span>;
    <span class="hljs-keyword">if</span> (match) {
        <span class="hljs-keyword">return</span> <span class="hljs-keyword">true</span>;
    }

    String messageTemplate = context.getDefaultConstraintMessageTemplate();
    
    <span class="hljs-comment">// disable default violation rule</span>
    context.disableDefaultConstraintViolation();

    <span class="hljs-comment">// assign error on password Confirm field</span>
    context.buildConstraintViolationWithTemplate(messageTemplate).addPropertyNode(<span class="hljs-string">"passwordConfirm"</span>)
            .addConstraintViolation();
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">false</span>;

}

}


如此，我们已经完成了自定义的校验工作。
六、异常拦截器
SpringBoot 框架中可通过 @ControllerAdvice 实现Controller方法的拦截操作。

可以利用拦截能力实现一些公共的功能，比如权限检查、页面数据填充，以及全局的异常处理等等。
在前面的篇幅中，我们提及了各种校验失败所产生的异常，整理如下表：



异常类型
描述




ConstraintViolationException
违反约束，javax扩展定义


BindException
绑定失败，如表单对象参数违反约束


MethodArgumentNotValidException
参数无效，如JSON请求参数违反约束


MissingServletRequestParameterException
参数缺失


TypeMismatchException
参数类型不匹配



如果希望对这些异常实现统一的捕获，并返回自定义的消息，

可以参考以下的代码片段：
@ControllerAdvice
public static class CustomExceptionHandler extends ResponseEntityExceptionHandler {
<span class="hljs-meta">@ExceptionHandler</span>(value = { ConstraintViolationException.<span class="hljs-keyword">class</span> })
public ResponseEntity&lt;<span class="hljs-built_in">String</span>&gt; handle(ConstraintViolationException e) {
    <span class="hljs-built_in">Set</span>&lt;ConstraintViolation&lt;?&gt;&gt; violations = e.getConstraintViolations();
    StringBuilder strBuilder = <span class="hljs-keyword">new</span> StringBuilder();
    <span class="hljs-keyword">for</span> (ConstraintViolation&lt;?&gt; violation : violations) {
        strBuilder.append(violation.getInvalidValue() + <span class="hljs-string">" "</span> + violation.getMessage() + <span class="hljs-string">"
"</span>);
    }
    <span class="hljs-built_in">String</span> result = strBuilder.toString();
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> ResponseEntity&lt;<span class="hljs-built_in">String</span>&gt;(<span class="hljs-string">"ConstraintViolation:"</span> + result, HttpStatus.BAD_REQUEST);
}

<span class="hljs-meta">@Override</span>
protected ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt; handleBindException(BindException ex, HttpHeaders headers, HttpStatus status,
        WebRequest request) {
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt;(<span class="hljs-string">"BindException:"</span> + buildMessages(ex.getBindingResult()),
            HttpStatus.BAD_REQUEST);
}

<span class="hljs-meta">@Override</span>
protected ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt; handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
        HttpHeaders headers, HttpStatus status, WebRequest request) {
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt;(<span class="hljs-string">"MethodArgumentNotValid:"</span> + buildMessages(ex.getBindingResult()),
            HttpStatus.BAD_REQUEST);
}

<span class="hljs-meta">@Override</span>
public ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt; handleMissingServletRequestParameter(MissingServletRequestParameterException ex,
        HttpHeaders headers, HttpStatus status, WebRequest request) {
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt;(<span class="hljs-string">"ParamMissing:"</span> + ex.getMessage(), HttpStatus.BAD_REQUEST);
}

<span class="hljs-meta">@Override</span>
protected ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt; handleTypeMismatch(TypeMismatchException ex, HttpHeaders headers,
        HttpStatus status, WebRequest request) {
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> ResponseEntity&lt;<span class="hljs-built_in">Object</span>&gt;(<span class="hljs-string">"TypeMissMatch:"</span> + ex.getMessage(), HttpStatus.BAD_REQUEST);
}

private <span class="hljs-built_in">String</span> buildMessages(BindingResult result) {
    StringBuilder resultBuilder = <span class="hljs-keyword">new</span> StringBuilder();

    <span class="hljs-built_in">List</span>&lt;ObjectError&gt; errors = result.getAllErrors();
    <span class="hljs-keyword">if</span> (errors != <span class="hljs-keyword">null</span> &amp;&amp; errors.size() &gt; <span class="hljs-number">0</span>) {
        <span class="hljs-keyword">for</span> (ObjectError error : errors) {
            <span class="hljs-keyword">if</span> (error instanceof FieldError) {
                FieldError fieldError = (FieldError) error;
                <span class="hljs-built_in">String</span> fieldName = fieldError.getField();
                <span class="hljs-built_in">String</span> fieldErrMsg = fieldError.getDefaultMessage();
                resultBuilder.append(fieldName).append(<span class="hljs-string">" "</span>).append(fieldErrMsg).append(<span class="hljs-string">";"</span>);
            }
        }
    }
    <span class="hljs-keyword">return</span> resultBuilder.toString();
}

}

默认情况下，对于非法的参数输入，框架会产生 HTTP_BAD_REQUEST(status=400)  错误码，

并输出友好的提示消息，这对于一般情况来说已经足够。
更多的输入校验及提示功能应该通过客户端去完成(服务端仅做同步检查)，

客户端校验的用户体验更好，而这也符合富客户端(rich client)的发展趋势。
码云同步代码
参考文档
springmvc-validation样例

使用validation api进行操作

hibernate-validation官方文档

Bean-Validation规范
原文地址：https://www.cnblogs.com/littleatp/p/9391856.html