SpringMVC RestTemplate.getForObject metodu

Giriş

İmzası şöyle

// Without parameters
<T> T getForObject(URI url, Class<T> responseType)

// Parameter object list as var args
<T> T getForObject(String url, Class<T> responseType, Object... uriVariables)

// Parameter object list as a map
<T> T getForObject(String url, Class<T> responseType, Map<String, ?> uriVariables)

getForObject metodu - Parametresiz

XML veya Json ile nesne elde etmek için kullanılır.

Örnek - Array

Şöyle yaparız.

Computer[] computer = restTemplate.getForObject("http://...", Computer[].class);

Örnek

Şöyle yaparız

Todo[] todos = restTemplate
  .getForObject("https://jsonplaceholder.typicode.com/todos", Todo[].class);

// If we use getForEntity
ResponseEntity<Todo[]> todos = restTemplate
        .getForEntity("https://jsonplaceholder.typicode.com/todos", Todo[].class);
Todo[] todoList = todos.getBody();
System.out.println(todos.getStatusCode().name()); // OK
System.out.println(todos.getStatusCodeValue());   // 200

getForObject metodu - Var arg parametreli

XML veya Json ile nesne elde etmek için kullanılır. Son parametre ?type=Foo şeklindeki url'ye dahil olan parametrelerdir.

Örnek

Şöyle yaparız.

QuoteResponse quoteResponse=    
restTemplate.getForObject("http://quotes.rest/qod.json?category=
{param}", QuoteResponse.class, uriVariables);

Örnek

Şöyle yaparız

String completedStatus = "true";
String userId = "1";

Todo[] todosCompletedOfUser = restTemplate
.getForObject(
 "https://jsonplaceholder.typicode.com/todos?completed={completedStatus}&userId={userId}",
 Todo[].class, completedStatus, userId);

getForObject metodu - Map Parametreli
XML veya Json ile nesne elde etmek için kullanılır. Son parametre yani Map ?type=Foo şeklindeki url'ye dahil olan parametrelerdir.

Örnek - Query Parametes
Şöyle yaparız

Map<String, String> map = new HashMap<>();
map.put("completed", "true");
Todo[] todosCompleted = restTemplate
  .getForObject("https://jsonplaceholder.typicode.com/todos?completed={completed}", 
    Todo[].class, map);

Örnek - Path Parameters

Şöyle yaparız

Map<String, String> map = new HashMap<>(); Todo resource
map.put("id", "1");
Todo todo = restTemplate
    .getForObject("https://jsonplaceholder.typicode.com/todos/{id}", Todo.class, map);
System.out.println(todo);

SpringWebSocket WebSocketHandler Arayüzü

Giriş

Şu satırı dahil ederiz

import org.springframework.web.reactive.socket.WebSocketHandler;

Örnek

Şöyle yaparız

import org.springframework.stereotype.Component;
import org.springframework.web.reactive.socket.WebSocketHandler;
import org.springframework.web.reactive.socket.WebSocketMessage;
import org.springframework.web.reactive.socket.WebSocketSession;
import reactor.core.publisher.Mono;

import java.util.List;

@Component
public class ReactiveServerWebSocketHandler implements WebSocketHandler {

    @Override
    public @NotNull
    Mono<Void> handle(@NotNull WebSocketSession session) {
        return session.send(session.receive()
                .map(WebSocketMessage::getPayloadAsText)
                .map(session::textMessage)
        );
    }

    @Override
    public @NotNull
    List<String> getSubProtocols() {
        return WebSocketHandler.super.getSubProtocols();
    }
}

SpringRetry UniformRandomBackOffPolicy Sınıfı

Örnek

Şöyle yaparız

import org.springframework.retry.RetryPolicy;
import org.springframework.retry.backoff.BackOffPolicy;
import org.springframework.retry.backoff.UniformRandomBackOffPolicy;
import org.springframework.retry.support.RetryTemplate;

public class PayApiRetryTemplate extends RetryTemplate implements InitializingBean {

  @Override
  public void afterPropertiesSet() throws Exception {
    this.setBackOffPolicy(backOffPolicyWithJitter());
    this.setRetryPolicy(...);
  }

  private BackOffPolicy backOffPolicyWithJitter() {
    UniformRandomBackOffPolicy policy = new UniformRandomBackOffPolicy();
    policy.setMaxBackOffPeriod(this.prop.getRetry().getMaxBackoff());
    policy.setMinBackOffPeriod(this.prop.getRetry().getMinBackoff());
    return policy;
  }
}

SpringData Flyway application.properties

baseline-on-migrate Alanı

Eğer şu hatayı alıyorsak

Use baseline() or set baselineOnMigrate to true to initialize the schema history table

Şöyle yaparız

spring: 
 flyway: 
 baseline-on-migrate: true

baseline-version Alanı

Şöyle yaparız

spring: 
 flyway: 
 baseline-on-migrate: true 
 baseline-version: 0

Açıklaması şöyle

If not, the scripts named V1__xxxx.sql would not execute. as the baseline-version default is version 1.

callbacks Alanı

Örnek

Şöyle yaparız

spring:
  flyway:
    enabled: true
    schemas: public
    baseline-on-migrate: true
    baseline-version: 0
    clean-disabled: true
    validate-on-migrate: true
    locations: classpath:db.migration
    placeholderReplacement: false
    callbacks: com.xxx.CsvUpsertCallback

SpringData Flyway Callbacks yazısına bakınız

clean-disabled Alanı

Örnek

Şöyle yaparız

spring: 
 flyway: 
 clean-disabled: true

debug

Örnek

Şöyle yaparız

logging: 
 level: 
 root: INFO 
 org: 
 flywaydb: DEBUG

locations Alanı

Normalde classpath:db/migration dizinini taranır.  Çıktısı şöyle

ClassPathScanner : Unable to resolve location classpath:db/callback.
ClassPathScanner : Scanning for classpath resources at 'classpath:db/migration' …
...

Örnek

Şöyle yaparız. Burada flyway'in arayacağı scriptlerin dizini belirtiliyor.

flyway:
  datasources:
    default:
      enabled: true
      baseline-on-migrate: true
      locations: classpath:db/mymigration

group Alanı

Açıklaması şöyle

The property spring.flyway.group set to true indicates we want to run the pending migrations in a single transaction instead of one transaction per pending migrations. So if one migration fails, all the executed migrations before will be rollbacked.

Örnek

Şöyle yaparız

spring.flyway.enabled=true
spring.flyway.url=jdbc:mysql://localhost:3307/blog?serverTimezone=UTC&useSSL=false
spring.flyway.user=root
spring.flyway.password=secretpswd
spring.flyway.group=true

schemas Alanı

Örnek

Şöyle yaparız

# Flyway properties
spring.flyway.enabled=true
spring.flyway.url=YOUR_DB_URL
spring.flyway.password= YOUR_DB_PASSWORD
spring.flyway.user= YOUR_DB_USERNAME
spring.flyway.schemas=migrations
spring.flyway.locations=classpath:db/migration/postgresql

Örnek

Şöyle yaparız

spring: 
 flyway: 
 placeholders: 
 mySchema: yourSchema

Şöyle yaparız

CREATE TABLE ${mySchema}.template 
( 
 id bigint NOT NULL, 
 code character varying(255) NOT NULL, 
 PRIMARY KEY (id) 
);

SpringMVC @GetExchange Anotasyonu - OpenFeign Yerine Kullanılır

Giriş

Şu satırı dahil ederiz

import org.springframework.web.service.annotation.GetExchange;

Açıklaması şöyle

Why do you need Spring Reactive Web dependencies

When creating the project above, the dependency of Spring Reactive Web was introduced, and the WebClient type was used when creating the service object of the proxy. This is because HTTP Interface currently only has built-in implementation of WebClient, which belongs to the category of Reactive Web. Spring will launch a RestTemplate-based implementation in subsequent versions.

Örnek

Şöyle yaparız

interface UsersClient {
  @GetExchange("/users")
  User findByFirstName(@RequestParam("firstName") String firstName);
}

Örnek

Elimizde şöyle bir REST kodu olsun

public class User implements Serializable {
  ...
}

@GetMapping("/users")
public List<User> list() {
    return IntStream.rangeClosed(1, 10)
            .mapToObj(i -> new User(i, "User" + i))
            .collect(Collectors.toList());
}

Şöyle yaparız

public interface UserApiService {
   @GetExchange("/users")
   List<User> getUsers();
}

@Test
void getUsers() {
   WebClient client = WebClient.builder()
    .baseUrl("http://localhost:8080/")
    .build();

  HttpServiceProxyFactory factory = HttpServiceProxyFactory
    .builder(WebClientAdapter.forClient(client))
    .build();

   UserApiService service = factory.createClient(UserApiService.class);
   List<User> users = service.getUsers();
   for (User user : users) {
      System.out.println(user);
   }
}

SpringData Redis Redission Sınıfı

Giriş

Redisson için açıklama şöyle

Redisson adopts the nety framework based on NIO, which can not only be used as the underlying driver client of Redis, but also can send redis commands in synchronous, asynchronous, asynchronous stream or pipeline forms, execute and process Lua scripts, and process the returned results.

Maven

Şu satırı dahil ederiz

<dependency>
   <groupId>org.redisson</groupId>
   <artifactId>redisson</artifactId>
   <version>3.17.6</version>
</dependency>

Örnek

Şöyle yaparız

@RequiredArgsConstructor
@Configuration
public class RedissonConfig {

  @Bean
  public RedissonClient redissionClient() {
    Config config = new Config();
    config.useSingleServer().setAddress("redis://127.0.0.1:6379");
    return Redisson.create(config);
 }

  @Bean
  public RedisTemplate<String, Object> redisTemplate(
  RedisConnectionFactory redisConnectionFactory) {
    RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
    redisTemplate.setConnectionFactory(redisConnectionFactory);
    redisTemplate.setKeySerializer(new StringRedisSerializer());
    redisTemplate.setHashKeySerializer(new StringRedisSerializer());
    redisTemplate.setHashKeySerializer(new JdkSerializationRedisSerializer());
    redisTemplate.setValueSerializer(new JdkSerializationRedisSerializer());
    redisTemplate.setEnableTransactionSupport(true);
    redisTemplate.afterPropertiesSet();
    return redisTemplate;
  }
}

SpringData Redis RedisStandaloneConfiguration Sınıfı

Giriş

Şu satırı dahil ederiz

import org.springframework.data.redis.connection.RedisStandaloneConfiguration;

Eğer ayarları application.properties ile yapmak istemiyorsak bu sınıfı yaratmak gerekir. 

Hem LettuceConnectionFactory  hem de JedisConnectionFactory için bu sınıf gerekir

JedisConnectionFactory

Örnek

Şöyle yaparız. Bu kod ile artık RedisTemplate kullanabiliriz.

@Configuration
@EnableRedisRepositories
public class RedisConfig {

  @Bean
  public JedisConnectionFactory connectionFactory(){
    RedisStandaloneConfiguration configuration = new RedisStandaloneConfiguration();
    configuration.setHostName("localhost");
    configuration.setPort(6379);
    return new JedisConnectionFactory(configuration);
  }

  @Bean
  @Primary
  public RedisTemplate<String, Object> redisTemplate(){
    RedisTemplate<String, Object> template = new RedisTemplate<>();
    template.setConnectionFactory(connectionFactory());
    template.setKeySerializer(new StringRedisSerializer());
    template.setHashKeySerializer(new StringRedisSerializer());
    template.setHashKeySerializer(new JdkSerializationRedisSerializer());
    template.setHashValueSerializer(new JdkSerializationRedisSerializer());
    template.setEnableTransactionSupport(true);
    template.afterPropertiesSet();

    return template;
  }
}