Java code explainers

java

public final class IniParser {
 
    private static final Pattern SECTION = Pattern.compile("\\[(.+?)\\]");

Parsing INI files in Java

parsing regex state-machine

Intermediate 10 steps

java

@Component
public class ApiKeyRotationFilter extends OncePerRequestFilter {
 
    private static final String API_KEY_HEADER = "X-Api-Key";

Building an API key rotation filter in Spring

servlet-filter authentication caching

Intermediate 10 steps

java

@Configuration
@EnableJpaAuditing(auditorAwareRef = "auditorAware")
public class AuditingConfig {

Automatic audit trails with Spring Data JPA

jpa-auditing security-context entity-listeners

Intermediate 7 steps

java

@Service
public class WebhookDedupService {
 
    private static final Logger log = LoggerFactory.getLogger(WebhookDedupService.class);

Idempotent webhooks with Redis in Spring

idempotency redis deduplication

Intermediate 7 steps

java

@Component
public class IdempotencyFilter extends OncePerRequestFilter {
 
    private final StringRedisTemplate redis;

Building an idempotency filter with Redis in Spring

idempotency redis distributed-locking

Advanced 10 steps

java

@Configuration
public class DataLoaderConfig {
 
    @Bean

Batching GraphQL queries with DataLoaders in Spring

graphql batching n+1-problem

Advanced 8 steps

java

public enum DataSourceType {
    PRIMARY,
    REPLICA
}

Read/write datasource routing in Spring

routing threadlocal read-replica

Intermediate 8 steps

java

@ControllerAdvice
public class DeprecationHeaderAdvice implements ResponseBodyAdvice<Object> {
 
    private final Clock clock;

Adding deprecation headers in Spring

response interception http headers api deprecation

Intermediate 8 steps

java

public List<Path> expandGlob(Path baseDir, String glob) throws IOException {
    FileSystem fs = baseDir.getFileSystem();
    PathMatcher matcher = fs.getPathMatcher("glob:" + glob);
    boolean recursive = glob.contains("**");

Expanding glob patterns with NIO

glob-matching nio streams

Intermediate 5 steps

java

@Component
@RequiredArgsConstructor
@Slf4j
public class FailedJobReprocessor {

Retrying failed jobs on a Spring schedule

scheduling retry exponential-backoff

Intermediate 10 steps

java

public class AccountRepository {
 
    private final DataSource dataSource;

Optimistic locking with a version column in JDBC

optimistic-locking jdbc concurrency

Intermediate 8 steps

java

import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

Rendering ${} templates with regex in Java

regex string-templating matcher-api

Intermediate 8 steps

java

public final class SensitiveDataMasker {
 
    private static final Pattern CARD_NUMBER = Pattern.compile("\\b(?:\\d[ -]*?){13,19}\\b");
    private static final Pattern EMAIL = Pattern.compile("[A-Za-z0-9._%+-]+@([A-Za-z0-9.-]+\\.[A-Za-z]{2,})");

Masking sensitive data with regex in Java

regex data-masking luhn-algorithm

Intermediate 8 steps

java

public final class UserAgentParser {
 
    private static final Pattern OS_PATTERN = Pattern.compile(
            "(Windows NT [0-9.]+|Mac OS X [0-9_]+|Android [0-9.]+|iPhone OS [0-9_]+|Linux)");

Parsing user-agent strings with regex in Java

regex parsing pattern-matching

Intermediate 9 steps

java

public class Views {
    public interface Public {}
    public interface Internal extends Public {}
}

Filtering JSON fields with @JsonView in Spring

serialization json-view access-control

Intermediate 6 steps

java

import java.util.Arrays;
import java.util.List;
 
public final class LatencyStats {

Computing latency percentiles in Java

percentiles interpolation immutability

Intermediate 9 steps

java

@Configuration
public class WebConfig {
 
    @Bean

HTTP caching with ETags in Spring

http-caching etag servlet-filters

Intermediate 6 steps

java

package com.acme.catalog.persistence;
 
import jakarta.persistence.Column;
import jakarta.persistence.EntityListeners;

Auditing timestamps with a JPA MappedSuperclass in Spring

jpa auditing lifecycle-callbacks

Intermediate 5 steps