java 48 lines · 6 steps

Type-safe config with Spring records

A Java record binds and validates payments.gateway.* properties at startup using Spring Boot's @ConfigurationProperties.

Explained by highlit
Spring Intermediate configuration validation records type-safety immutability
1package com.example.payments.config;
2 
3import jakarta.validation.constraints.Min;
4import jakarta.validation.constraints.NotBlank;
5import jakarta.validation.constraints.NotNull;
6import java.time.Duration;
7import java.util.List;
8import org.springframework.boot.context.properties.ConfigurationProperties;
9import org.springframework.boot.context.properties.bind.DefaultValue;
10import org.springframework.validation.annotation.Validated;
11 
12@Validated
13@ConfigurationProperties(prefix = "payments.gateway")
14public record PaymentGatewayProperties(
15 
16 @NotBlank
17 String baseUrl,
18 
19 @NotBlank
20 String apiKey,
21 
22 @NotNull
23 @DefaultValue("5s")
24 Duration connectTimeout,
25 
26 @NotNull
27 @DefaultValue("30s")
28 Duration readTimeout,
29 
30 @Min(0)
31 @DefaultValue("3")
32 int maxRetries,
33 
34 @DefaultValue("true")
35 boolean tlsVerification,
36 
37 @NotNull
38 Retry retry,
39 
40 @DefaultValue
41 List<String> supportedCurrencies
42) {
43 
44 public record Retry(
45 @Min(1) @DefaultValue("2") int attempts,
46 @NotNull @DefaultValue("500ms") Duration backoff
47 ) {}
48}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Java records make immutable configuration objects where each component is a named, typed property.
  2. 2Combining @Validated with Jakarta constraints fails fast at startup when config is missing or invalid.
  3. 3@DefaultValue lets Spring supply sensible fallbacks so only secrets and overrides need to be set.

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