Mastering Parameter Validation in Spring Boot: Hibernate Validator Best Practices

Controller Layer vs Service Layer

General recommendation: validation unrelated to business logic belongs in the Controller, while business‑related validation belongs in the Service.

Common Validation Tools

Using Hibernate Validator

Dependency:

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>4.3.1.Final</version>
</dependency>

Common annotations (illustrated in the image below):

Usage: apply @Validated or @Valid on controller methods; both work, but @Validated adds grouping and ordering capabilities.

Annotations are placed on entity fields.

Define an entity with validation annotations:

public class DataSetSaveVO {
    // Unique identifier must not be blank
    @NotBlank(message = "user uuid is empty")
    // User name must be alphanumeric
    @Pattern(regexp = "^[a-z0-9]+$", message = "user names can only be alphabetic and numeric")
    @Length(max = 48, message = "user uuid length over 48 byte")
    private String userUuid;

    // Data set name must be alphanumeric
    @Pattern(regexp = "^[A-Za-z0-9]+$", message = "data set names can only be letters and Numbers")
    // File name length limit
    @Length(max = 48, message = "file name too long")
    // File name must not be blank
    @NotBlank(message = "file name is empty")
    private String name;

    // Description length limit
    @Length(max = 256, message = "data set description length over 256 byte")
    // Description must not be blank
    @NotBlank(message = "data set description is null")
    private String description;
}

Controller method example:

@PostMapping
public ResponseVO createDataSet(@Valid @RequestBody DataSetSaveVO dataSetVO) {
    return ResponseUtil.success(dataSetService.saveDataSet(dataSetVO));
}

Using commons‑lang3

Dependency:

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.4</version>
</dependency>

Common utility methods demonstration:

// StringUtils.isEmpty
System.out.println(StringUtils.isEmpty(""));      // true
System.out.println(StringUtils.isEmpty("  "));    // false
// StringUtils.isBlank
System.out.println(StringUtils.isBlank(""));      // true
System.out.println(StringUtils.isBlank(" "));     // true
// CollectionUtils.isEmpty
List<Integer> emptyList = new ArrayList<>();
List<Integer> nullList = null;
System.out.println(CollectionUtils.isEmpty(emptyList)); // true
System.out.println(CollectionUtils.isEmpty(nullList));  // true

Custom Annotations

If built‑in annotations cannot satisfy specific validation requirements, you can create custom validation annotations.