Table of Contents
How SpringBoot performs parameter verification
1. Integrate the Validator verification framework
1.1. Introduce dependency packages
1.2. 定义要参数校验的实体类
1.3. 定义校验类进行测试
1.7. 测试结果2
1.5. 问题
1.6. 将参数异常加入全局异常
4.1. 自定义注解
2.1. 第一步,创建自定义注解
2.2. 第二步,自定义校验逻辑
2.3. 第三步,在字段上增加注解
2.4. 第四步,体验效果
3. 分组校验
3.1. 第一步,定义分组接口
3.2. 第二步,在模型中给参数分配分组
3.3. 第三步,给需要参数校验的方法指定分组
3.4. 测试
4. 业务规则校验
4.2. 实现业务校验规则
4.3. 测试代码
Home Java javaTutorial How to use the SpringBoot parameter verification Validator framework

How to use the SpringBoot parameter verification Validator framework

May 22, 2023 pm 11:28 PM
springboot validator

How SpringBoot performs parameter verification

In daily interface development, in order to prevent illegal parameters from affecting the business, it is often necessary to verify the parameters of the interface. For example, the user name needs to be verified when logging in. Check whether the password is empty. When creating a user, you need to verify whether the email and mobile phone number formats are accurate. It would be too cumbersome to rely on code to verify interface parameters one by one, and the readability of the code would be extremely poor.

Validator framework is designed to solve the problem that developers can write less code during development and improve development efficiency; Validator is specially used to verify interface parameters, such as common required verification, email Format verification, the user name must be between 6 and 12, etc...

Validator verification framework follows the JSR-303 verification specification (parameter verification specification), JSR isJava Abbreviation for Specification Requests.

1. Integrate the Validator verification framework

1.1. Introduce dependency packages

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-validation</artifactId>
</dependency>
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Note: Starting from springboot-2.3 , the verification package is independent into a starter component, so validation and web need to be introduced, while versions before springboot-2.3 only need to introduce web dependencies.

##@AssertFalsecan be null, If it is not null, it must be false@AssertTrue can be null, if it is not null, it must be true@DecimalMaxThe setting cannot exceed the maximum value@DecimalMinThe setting cannot exceed the minimum value@DigitsThe setting must be a number and the number of digits in the integer and the number of decimal digits must be within the specified range@Future The date must be in the future of the current date@PastThe date must be in the past of the current date@MaxThe maximum value shall not exceed this maximum value@MinThe maximum value shall not be less than this minimum value@NotNull cannot be null, can be empty@Nullmust be null##@Pattern @Size@Email@Length@NotBlank@NotEmpty @Range@URL

注:此表格只是简单的对注解功能的说明,并没有对每一个注解的属性进行说明;可详见源码。

1.2. 定义要参数校验的实体类

@Data
public class ValidVO {
    private String id;

    @Length(min = 6,max = 12,message = "appId长度必须位于6到12之间")
    private String appId;

    @NotBlank(message = "名字为必填项")
    private String name;

    @Email(message = "请填写正确的邮箱地址")
    private String email;

    private String sex;

    @NotEmpty(message = "级别不能为空")
    private String level;
}
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在实际开发中对于需要校验的字段都需要设置对应的业务提示,即message属性。

1.3. 定义校验类进行测试

@RestController
@Slf4j
@Validated
public class ValidController {

    @ApiOperation("RequestBody校验")
    @PostMapping("/valid/test1")   
    public String test1(@Validated @RequestBody ValidVO validVO){
        log.info("validEntity is {}", validVO);
        return "test1 valid success";
    }

    @ApiOperation("Form校验")
    @PostMapping(value = "/valid/test2")
    public String test2(@Validated ValidVO validVO){
        log.info("validEntity is {}", validVO);
        return "test2 valid success";
    }
  
  	@ApiOperation("单参数校验")
    @PostMapping(value = "/valid/test3")
    public String test3(@Email String email){
        log.info("email is {}", email);
        return "email valid success";
    }
}
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这里我们先定义三个方法test1,test2,test3,

test1使用了@RequestBody注解,用于接受前端发送的json数据,

test2模拟表单提交,

test3模拟单参数提交。

注意,当使用单参数校验时需要在Controller上加上@Validated注解否则不生效。

1.4. 测试结果1

test1的测试结果

发送值

POST http://localhost:8080/valid/test1
Content-Type: application/json

{
  "id": 1,
  "level": "12",
  "email": "47693899",
  "appId": "ab1c"
}
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返回值

提示的是org.springframework.web.bind.MethodArgumentNotValidException异常

{
  "status": 500,
  "message": "Validation failed for argument [0] in public java.lang.String com.jianzh6.blog.valid.ValidController.test1(com.jianzh6.blog.valid.ValidVO) with 3 errors: [Field error in object &#39;validVO&#39; on field &#39;email&#39;: rejected value [47693899]; codes [Email.validVO.email,Email.email,Email.java.lang.String,Email]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [validVO.email,email]; arguments []; default message [email],[Ljavax.validation.constraints.Pattern$Flag;@26139123,.*]; default message [不是一个合法的电子邮件地址]]...",
  "data": null,
  "timestamp": 1628239624332
}
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test2的测试结果

发送值

POST http://localhost:8080/valid/test2
Content-Type: application/x-www-form-urlencoded
id=1&level=12&email=476938977&appId=ab1c
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返回值

提示的是org.springframework.validation.BindException异常

{
  "status": 500,
  "message": "org.springframework.validation.BeanPropertyBindingResult: 3 errors\nField error in object &#39;validVO&#39; on field &#39;name&#39;: rejected value [null]; codes [NotBlank.validVO.name,NotBlank.name,NotBlank.java.lang.String,NotBlank]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [validVO.name,name]; arguments []; default message [name]]; default message [名字为必填项]...",
  "data": null,
  "timestamp": 1628239301951
}
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test3的测试结果

发送值

POST http://localhost:8080/valid/test3
Content-Type: application/x-www-form-urlencoded

email=476938977
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返回值

提示的是javax.validation.ConstraintViolationException异常

{
  "status": 500,
  "message": "test3.email: 不是一个合法的电子邮件地址",
  "data": null,
  "timestamp": 1628239281022
}
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1.5. 问题

虽然我们之前定义了全局异常拦截器,也看到了拦截器确实生效了,但是Validator校验框架返回的错误提示太臃肿了,不便于阅读,为了方便前端提示,我们需要将其简化一下。

通过将参数异常加入全局异常来解决

1.6. 将参数异常加入全局异常

直接修改之前定义的RestExceptionHandler,单独拦截参数校验的三个异常:

javax.validation.ConstraintViolationException

org.springframework.validation.BindException

org.springframework.web.bind.MethodArgumentNotValidException

@Slf4j
@RestControllerAdvice
public class RestExceptionHandler {
    /**
     * 默认全局异常处理。
     * @param e the e
     * @return ResultData
     */
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    public ResultData<String> exception(Exception e) {
        log.error("全局异常信息 ex={}", e.getMessage(), e);
        return ResultData.fail(ReturnCode.RC500.getCode(),e.getMessage());
    }
    
    @ExceptionHandler(value = {BindException.class, ValidationException.class, MethodArgumentNotValidException.class})
    public ResponseEntity<ResultData<String>> handleValidatedException(Exception e) {
        ResultData<String> resp = null;

        if (e instanceof MethodArgumentNotValidException) {
            // BeanValidation exception
            MethodArgumentNotValidException ex = (MethodArgumentNotValidException) e;
            resp = ResultData.fail(HttpStatus.BAD_REQUEST.value(),
                    ex.getBindingResult().getAllErrors().stream()
                            .map(ObjectError::getDefaultMessage)
                            .collect(Collectors.joining("; "))
            );
        } else if (e instanceof ConstraintViolationException) {
            // BeanValidation GET simple param
            ConstraintViolationException ex = (ConstraintViolationException) e;
            resp = ResultData.fail(HttpStatus.BAD_REQUEST.value(),
                    ex.getConstraintViolations().stream()
                            .map(ConstraintViolation::getMessage)
                            .collect(Collectors.joining("; "))
            );
        } else if (e instanceof BindException) {
            // BeanValidation GET object param
            BindException ex = (BindException) e;
            resp = ResultData.fail(HttpStatus.BAD_REQUEST.value(),
                    ex.getAllErrors().stream()
                            .map(ObjectError::getDefaultMessage)
                            .collect(Collectors.joining("; "))
            );
        }

        return new ResponseEntity<>(resp,HttpStatus.BAD_REQUEST);
    }
    
}
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1.7. 测试结果2

test1测试结果

发送值

POST http://localhost:8080/valid/test1
Content-Type: application/json

{
  "id": 1,
  "level": "12",
  "email": "47693899",
  "appId": "ab1c"
}
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接收值

{
  "status": 400,
  "message": "名字为必填项; 不是一个合法的电子邮件地址; appId长度必须位于6到12之间",
  "data": null,
  "timestamp": 1628435116680
}
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2. 自定义注解

虽然Spring Validation 提供的注解基本上够用,但是面对复杂的定义,我们还是需要自己定义相关注解来实现自动校验。

比如上面实体类中的sex性别属性,只允许前端传递传 M,F 这2个枚举值,如何实现呢?

2.1. 第一步,创建自定义注解

@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE})
@Retention(RUNTIME)
@Repeatable(EnumString.List.class)
@Documented
@Constraint(validatedBy = EnumStringValidator.class)//标明由哪个类执行校验逻辑
public @interface EnumString {
    String message() default "value not in enum values.";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

    /**
     * @return date must in this value array
     */
    String[] value();

    /**
     * Defines several {@link EnumString} annotations on the same element.
     *
     * @see EnumString
     */
    @Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE})
    @Retention(RUNTIME)
    @Documented
    @interface List {

        EnumString[] value();
    }
}
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可以根据Validator框架定义好的注解来仿写,基本上一致

2.2. 第二步,自定义校验逻辑

public class EnumStringValidator implements ConstraintValidator<EnumString, String> {
    private List<String> enumStringList;

    @Override
    public void initialize(EnumString constraintAnnotation) {
        enumStringList = Arrays.asList(constraintAnnotation.value());
    }

    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        if(value == null){
            return true;
        }
        return enumStringList.contains(value);
    }
}
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2.3. 第三步,在字段上增加注解

@ApiModelProperty(value = "性别")
@EnumString(value = {"F","M"}, message="性别只允许为F或M")
private String sex;
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2.4. 第四步,体验效果

POST http://localhost:8080/valid/test2
Content-Type: application/x-www-form-urlencoded
id=1&name=javadaily&level=12&email=476938977@qq.com&appId=ab1cdddd&sex=N
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{
  "status": 400,
  "message": "性别只允许为F或M",
  "data": null,
  "timestamp": 1628435243723
}
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3. 分组校验

一个VO对象在新增的时候某些字段为必填,在更新的时候又非必填。如上面的ValidVO中 id 和 appId 属性在新增操作时都是非必填,而在编辑操作时都为必填,name在新增操作时为必填,面对这种场景你会怎么处理呢?

在实际开发中我见到很多同学都是建立两个VO对象,ValidCreateVOValidEditVO来处理这种场景,这样确实也能实现效果,但是会造成类膨胀。

其实Validator校验框架已经考虑到了这种场景并且提供了解决方案,就是分组校验,只不过很多同学不知道而已。

要使用分组校验,只需要三个步骤

3.1. 第一步,定义分组接口

public interface ValidGroup extends Default {
    interface Crud extends ValidGroup{
        interface Create extends Crud{
        }
        interface Update extends Crud{
        }
        interface Query extends Crud{
        }
        interface Delete extends Crud{
        }
    }
}
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这里我们定义一个分组接口ValidGroup让其继承javax.validation.groups.Default,再在分组接口中定义出多个不同的操作类型,Create,Update,Query,Delete。

3.2. 第二步,在模型中给参数分配分组

@Data
public class ValidVO {
    @Null(groups = ValidGroup.Crud.Create.class)
    @NotNull(groups = ValidGroup.Crud.Update.class, message = "应用ID不能为空")
    private String id;

    @Length(min = 6,max = 12,message = "appId长度必须位于6到12之间")
    @Null(groups = ValidGroup.Crud.Create.class)
    @NotNull(groups = ValidGroup.Crud.Update.class, message = "应用ID不能为空")
    private String appId;

    @NotBlank(message = "名字为必填项")
    @NotBlank(groups = ValidGroup.Crud.Create.class,message = "名字为必填项")
    private String name;

    @Email(message = "请填写正确的邮箱地址")
    private String email;

    @EnumString(value = {"F","M"}, message="性别只允许为F或M")
    private String sex;

    @NotEmpty(message = "级别不能为空")
    private String level;
}
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给参数指定分组,对于未指定分组的则使用的是默认分组。

3.3. 第三步,给需要参数校验的方法指定分组

    @PostMapping(value = "/valid/add")
    public String add(@Validated(value = ValidGroup.Crud.Create.class) ValidVO validVO){
        log.info("validEntity is {}", validVO);
        return "test3 valid success";
    }

    @PostMapping(value = "/valid/update")
    public String update(@Validated(value = ValidGroup.Crud.Update.class) ValidVO validVO){
        log.info("validEntity is {}", validVO);
        return "test4 valid success";
    }
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这里我们通过value属性给add()update()方法分别指定Create和Update分组

3.4. 测试

POST http://localhost:8080/valid/add
Content-Type: application/x-www-form-urlencoded

name=javadaily&level=12&email=476938977@qq.com&sex=F
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Create操作

在Create时我们没有传递id和appId参数校验通过。

{
	"status": 100,
	"message": "操作成功",
	"data": "test3 valid success",
	"timestamp": 1652186105359
}
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update操作

使用同样的参数调用update方法时则提示参数校验错误

{
	"status": 400,
	"message": "ID不能为空; 应用ID不能为空",
	"data": null,
	"timestamp": 1652186962377
}
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默认校验生效操作

由于email属于默认分组,而我们的分组接口ValidGroup已经继承了Default分组,所以也是可以对email字段作参数校验的。

故意写错email格式

POST http://localhost:8080/valid/add
Content-Type: application/x-www-form-urlencoded

/valid/update?name=javadaily&level=12&email=476938977&sex=F
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{
	"status": 400,
	"message": "请填写正确的邮箱地址; ID不能为空; 应用ID不能为空",
	"data": null,
	"timestamp": 1652187273865
}
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4. 业务规则校验

业务规则校验指接口需要满足某些特定的业务规则,举个例子:业务系统的用户需要保证其唯一性,用户属性不能与其他用户产生冲突,不允许与数据库中任何已有用户的用户名称、手机号码、邮箱产生重复。

这就要求在创建用户时需要校验用户名称、手机号码、邮箱是否被注册编辑用户时不能将信息修改成已有用户的属性

最优雅的实现方法应该是参考 Bean Validation 的标准方式,借助自定义校验注解完成业务规则校验。

4.1. 自定义注解

首先我们需要创建两个自定义注解,用于业务规则校验:

  • UniqueUser:表示一个用户是唯一的,唯一性包含:用户名,手机号码、邮箱

    @Documented
    @Retention(RUNTIME)
    @Target({FIELD, METHOD, PARAMETER, TYPE})
    @Constraint(validatedBy = UserValidation.UniqueUserValidator.class)
    public @interface UniqueUser {
    
        String message() default "用户名、手机号码、邮箱不允许与现存用户重复";
    
        Class<?>[] groups() default {};
    
        Class<? extends Payload>[] payload() default {};
    }
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  • NotConflictUser:表示一个用户的信息是无冲突的,无冲突是指该用户的敏感信息与其他用户不重合

    @Documented
    @Retention(RUNTIME)
    @Target({FIELD, METHOD, PARAMETER, TYPE})
    @Constraint(validatedBy = UserValidation.NotConflictUserValidator.class)
    public @interface NotConflictUser {
        String message() default "用户名称、邮箱、手机号码与现存用户产生重复";
    
        Class<?>[] groups() default {};
    
        Class<? extends Payload>[] payload() default {};
    }
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4.2. 实现业务校验规则

想让自定义验证注解生效,需要实现 ConstraintValidator 接口。

接口的第一个参数是 自定义注解类型,第二个参数是 被注解字段的类,因为需要校验多个参数,我们直接传入用户对象。需要提到的一点是 ConstraintValidator 接口的实现类无需添加 @Component 它在启动的时候就已经被加载到容器中了。

@Slf4j
public class UserValidation<T extends Annotation> implements ConstraintValidator<T, User> {

    protected Predicate<User> predicate = c -> true;

    @Resource
    protected UserRepository userRepository;

    @Override
    public boolean isValid(User user, ConstraintValidatorContext constraintValidatorContext) {
        return userRepository == null || predicate.test(user);
    }

    /**
     * 校验用户是否唯一
     * 即判断数据库是否存在当前新用户的信息,如用户名,手机,邮箱
     */
    public static class UniqueUserValidator extends UserValidation<UniqueUser>{
        @Override
        public void initialize(UniqueUser uniqueUser) {
            predicate = c -> !userRepository.existsByUserNameOrEmailOrTelphone(c.getUserName(),c.getEmail(),c.getTelphone());
        }
    }

    /**
     * 校验是否与其他用户冲突
     * 将用户名、邮件、电话改成与现有完全不重复的,或者只与自己重复的,就不算冲突
     */
    public static class NotConflictUserValidator extends UserValidation<NotConflictUser>{
        @Override
        public void initialize(NotConflictUser notConflictUser) {
            predicate = c -> {
                log.info("user detail is {}",c);
                Collection<User> collection = userRepository.findByUserNameOrEmailOrTelphone(c.getUserName(), c.getEmail(), c.getTelphone());
                // 将用户名、邮件、电话改成与现有完全不重复的,或者只与自己重复的,就不算冲突
                return collection.isEmpty() || (collection.size() == 1 && collection.iterator().next().getId().equals(c.getId()));
            };
        }
    }

}
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这里使用Predicate函数式接口对业务规则进行判断。

4.3. 测试代码

@RestController
@RequestMapping("/senior/user")
@Slf4j
@Validated
public class UserController {
    @Autowired
    private UserRepository userRepository;
    

    @PostMapping
    public User createUser(@UniqueUser @Valid User user){
        User savedUser = userRepository.save(user);
        log.info("save user id is {}",savedUser.getId());
        return savedUser;
    }

    @SneakyThrows
    @PutMapping
    public User updateUser(@NotConflictUser @Valid @RequestBody User user){
        User editUser = userRepository.save(user);
        log.info("update user is {}",editUser);
        return editUser;
    }
}
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使用很简单,只需要在方法上加入自定义注解即可,业务逻辑中不需要添加任何业务规则的代码。

POST http://localhost:8080/valid/add
Content-Type: application/json

/senior/user

{
    "userName" : "100001"
}
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{
	"status": 400,
	"message": "用户名、手机号码、邮箱不允许与现存用户重复",
	"data": null,
	"timestamp": 1652196524725
}
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How Springboot integrates Jasypt to implement configuration file encryption How Springboot integrates Jasypt to implement configuration file encryption Jun 01, 2023 am 08:55 AM

Introduction to Jasypt Jasypt is a java library that allows a developer to add basic encryption functionality to his/her project with minimal effort and does not require a deep understanding of how encryption works. High security for one-way and two-way encryption. , standards-based encryption technology. Encrypt passwords, text, numbers, binaries... Suitable for integration into Spring-based applications, open API, for use with any JCE provider... Add the following dependency: com.github.ulisesbocchiojasypt-spring-boot-starter2. 1.1Jasypt benefits protect our system security. Even if the code is leaked, the data source can be guaranteed.

How to use Redis to implement distributed locks in SpringBoot How to use Redis to implement distributed locks in SpringBoot Jun 03, 2023 am 08:16 AM

1. Redis implements distributed lock principle and why distributed locks are needed. Before talking about distributed locks, it is necessary to explain why distributed locks are needed. The opposite of distributed locks is stand-alone locks. When we write multi-threaded programs, we avoid data problems caused by operating a shared variable at the same time. We usually use a lock to mutually exclude the shared variables to ensure the correctness of the shared variables. Its scope of use is in the same process. If there are multiple processes that need to operate a shared resource at the same time, how can they be mutually exclusive? Today's business applications are usually microservice architecture, which also means that one application will deploy multiple processes. If multiple processes need to modify the same row of records in MySQL, in order to avoid dirty data caused by out-of-order operations, distribution needs to be introduced at this time. The style is locked. Want to achieve points

How SpringBoot integrates Redisson to implement delay queue How SpringBoot integrates Redisson to implement delay queue May 30, 2023 pm 02:40 PM

Usage scenario 1. The order was placed successfully but the payment was not made within 30 minutes. The payment timed out and the order was automatically canceled. 2. The order was signed and no evaluation was conducted for 7 days after signing. If the order times out and is not evaluated, the system defaults to a positive rating. 3. The order is placed successfully. If the merchant does not receive the order for 5 minutes, the order is cancelled. 4. The delivery times out, and push SMS reminder... For scenarios with long delays and low real-time performance, we can Use task scheduling to perform regular polling processing. For example: xxl-job Today we will pick

How to solve the problem that springboot cannot access the file after reading it into a jar package How to solve the problem that springboot cannot access the file after reading it into a jar package Jun 03, 2023 pm 04:38 PM

Springboot reads the file, but cannot access the latest development after packaging it into a jar package. There is a situation where springboot cannot read the file after packaging it into a jar package. The reason is that after packaging, the virtual path of the file is invalid and can only be accessed through the stream. Read. The file is under resources publicvoidtest(){Listnames=newArrayList();InputStreamReaderread=null;try{ClassPathResourceresource=newClassPathResource("name.txt");Input

Comparison and difference analysis between SpringBoot and SpringMVC Comparison and difference analysis between SpringBoot and SpringMVC Dec 29, 2023 am 11:02 AM

SpringBoot and SpringMVC are both commonly used frameworks in Java development, but there are some obvious differences between them. This article will explore the features and uses of these two frameworks and compare their differences. First, let's learn about SpringBoot. SpringBoot was developed by the Pivotal team to simplify the creation and deployment of applications based on the Spring framework. It provides a fast, lightweight way to build stand-alone, executable

How SpringBoot customizes Redis to implement cache serialization How SpringBoot customizes Redis to implement cache serialization Jun 03, 2023 am 11:32 AM

1. Customize RedisTemplate1.1, RedisAPI default serialization mechanism. The API-based Redis cache implementation uses the RedisTemplate template for data caching operations. Here, open the RedisTemplate class and view the source code information of the class. publicclassRedisTemplateextendsRedisAccessorimplementsRedisOperations, BeanClassLoaderAware{//Declare key, Various serialization methods of value, the initial value is empty @NullableprivateRedisSe

How to implement Springboot+Mybatis-plus without using SQL statements to add multiple tables How to implement Springboot+Mybatis-plus without using SQL statements to add multiple tables Jun 02, 2023 am 11:07 AM

When Springboot+Mybatis-plus does not use SQL statements to perform multi-table adding operations, the problems I encountered are decomposed by simulating thinking in the test environment: Create a BrandDTO object with parameters to simulate passing parameters to the background. We all know that it is extremely difficult to perform multi-table operations in Mybatis-plus. If you do not use tools such as Mybatis-plus-join, you can only configure the corresponding Mapper.xml file and configure The smelly and long ResultMap, and then write the corresponding sql statement. Although this method seems cumbersome, it is highly flexible and allows us to

How to get the value in application.yml in springboot How to get the value in application.yml in springboot Jun 03, 2023 pm 06:43 PM

In projects, some configuration information is often needed. This information may have different configurations in the test environment and the production environment, and may need to be modified later based on actual business conditions. We cannot hard-code these configurations in the code. It is best to write them in the configuration file. For example, you can write this information in the application.yml file. So, how to get or use this address in the code? There are 2 methods. Method 1: We can get the value corresponding to the key in the configuration file (application.yml) through the ${key} annotated with @Value. This method is suitable for situations where there are relatively few microservices. Method 2: In actual projects, When business is complicated, logic

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AnnotationFunction
Must satisfy the specified regular expression
The size() value of collections, arrays, maps, etc. must be within the specified range
Must be in email format
The length must be within the specified range
The string cannot be null, and the string after trim() cannot be equal to ""
cannot be null, and size() of collections, arrays, maps, etc. cannot be 0; string trim() can be equal to ""
The value must be within the specified range
must be a URL