IdendityHashMap Sınıfı

Giriş

Örnek ver

Logback logback.xml

Giriş

1. Appender'lar tanımlanır. Appender'larda encoder + layout bilgisi bulunur
2. paket isimleri veya sınıflar için logger ve seviyeleri tanımlanır.
3. Appender'lar root logger'a eklenir

Dosyanın Yolu

Açıklaması şöyle

The program uses a default configuration file named logback.xml or logback-test.xml, which should be located in the classpath in our case, we put the file in java/main/resources.

If neither of these files is found on the classpath, logback will default to invoking BasicConfigurator which will set up a minimal configuration. This minimal configuration consists of a ConsoleAppender attached to the root logger. The output is formatted using a PatternLayoutEncoder set to the pattern %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} -%kvp- %msg%n. Moreover, by default the root logger is assigned the DEBUG level.

Farklı Bir Yol Kullanmak

Açıklaması şöyle

If you want to use a different configuration file, you can specify its location by setting the logback.configurationFile system property to the file path, like this:

java -Dlogback.configurationFile=/path/to/logback.xml

You can set the system property programmatically in your application code, like this:

System.setProperty("logback.configurationFile", "/path/to/logback.xml");

This should be done before Logback is initialized (i.e., before any logging calls are made). Once the system property is set, Logback will use the specified configuration file instead of the default one.

Örnek

Ben logback.xml dosyasını src/main/resource/logback.xml olarak sevmiyorum. 

1. maven-resources-plugin ile bu dosyayı jar ile aynı seviyeye kopyalıyorum. 

2. Uygulamayı çalıştırırken logback.xml dosyasını belirtiyorum

java -Dlogback.configurationFile=file:logback.xml -jar myjar.jar

Dosyadaki Hatalar

Dosyadaki hataları bulmak için şöyle yaparız

-Dlogback.statusListenerClass=ch.qos.logback.core.status.OnConsoleStatusListener

configuration tag

debug="true" yaparsak, logback başlarken bazı bilgileri gösterir. Açıklaması şöyle

You can add the debug="true" attribute to the <configuration> element to enable debug of the logback configuration. It will print the configuration to the console

Örnek - scanPeriod

Şöyle yaparız. scanPeriod kaç saniyede bir xml dosyasını tekrar okuyacağını belirtir.

<configuration debug="false" scan="true", scanPeriod=20">

appender tag
name Alanı

Örnek
Şöyle yaparız.

<configuration>

  <appender name="FILE" class="ch.qos.logback.core.FileAppender">
    ...
  </appender>

  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    ...
  </appender>

  <root level="debug">
    <appender-ref ref="FILE" />
    <appender-ref ref="STDOUT" />
  </root>
</configuration>

Örnek

Şöyle yaparız.

<configuration>
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
        <layout class="com.touchcorp.touchpoint.utils.MaskingPatternLayout">
          <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </layout>
    </encoder>
  </appender>

  <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>logs/touchpoint.log</file>
      <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
        <fileNamePattern>logs/touchpoint.%i.log.zip</fileNamePattern>
        <minIndex>1</minIndex>
         <maxIndex>3</maxIndex>
      </rollingPolicy>

      <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
        <maxFileSize>10MB</maxFileSize>
      </triggeringPolicy>
      <encoder>
        ...
      </encoder>
  </appender>


  <logger name="com.touchcorp.touchpoint" level="DEBUG" />
  <logger name="org.springframework.web.servlet.mvc" level="TRACE" />

  <root level="INFO">
    <appender-ref ref="FILE" />
    <appender-ref ref="STDOUT" />
  </root>
</configuration>

Örnek

Şöyle yaparız

<configuration>
  <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
  </appender>

  <appender name="file" class="ch.qos.logback.core.FileAppender">
    <file>logback.log</file>
    <encoder>
      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
  </appender>

  <root level="INFO">
    <appender-ref ref="console" />
    <appender-ref ref="file" />
  </root>

  <logger name="com.example.javasandbox" level="WARN" />
</configuration>

encoder tag

Örnek

Şöyle yaparız

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
  </appender>

  <root level="INFO">
    <appender-ref ref="STDOUT"/>
  </root>

  <logger name="com.ning.http.client" level="WARN"/>
</configuration>

PipedInputStream Sınıfı

Giriş

Açıklaması şöyle

There are use cases where data need to be read from source to a sink without modification. In code this might look quite simple: for example in Java, you may read data from one InputStream chunk by chunk into a small buffer (typically 8KB), and feed them into the OutputStream, or even better, you could create a PipedInputStream, which is basically just a util that maintains that buffer for you. 

RecordComponent Sınıfı

getType metodu

Şöyle yaparız

List<?> componentTypes = Stream
    .of(X.class.getRecordComponents())
    .map(RecordComponent::getType)
    .toList();

for (Constructor<?> c : X.class.getDeclaredConstructors())
    if (Arrays.asList(c.getParameterTypes()).equals(componentTypes))
        System.out.println(c);

Lambda ve Yerel Değişken

Lambda Yerel Değişkene Erişebilir

Ancak bu değişken "effectively final" olmalı. Açıklaması şöyle.

Any local variable, formal parameter, or exception parameter used but not declared in a lambda expression must either be declared final or be effectively final (§4.12.4), or a compile-time error occurs where the use is attempted.

Örnek

Şu kod derlenmez. Çünkü lambda içinde yerel değişken değiştiriliyor.

int ordinal = 0;
list.forEach(s -> {
  ...
  ordinal++;
});

Örnek

Şu kod derlenmez. Çünkü lambda içinde yerel değişken değiştiriliyor.

int sum = 0;
list.forEach(e -> { sum += e.size(); });

Aynı Kısıtlama Instance Member İçin Geçerli Değil

Açıklaması şöyle

There's a simple, straightforward answer to why instance variables can always be captured: this is always effectively final. That is, there is always one known fixed object at the time of the creation of a lambda accessing an instance variable

Yerel Değişken Capture Ediliyorsa Her Seferinde Yeni Lambda Instance Yaratılır

Açıklaması şöyle

Simply said, if a lambda expression does not capture values, it will be a singleton that is re-used on every invocation.

Lombok @Singular Anotasyonu

Giriş

Şu satırı dahil ederiz

import lombok.Singular;

Açıklaması şöyle

When the @Singular annotation is placed on a collection property, Lombok creates special builder methods to individually add items to that collection, rather than adding the entire collection at once. This is particularly nice for tests as creating small collections in Java is not concise.

Örnek

Şöyle yaparız

@Value
@Builder(toBuilder = true)
public class User {
  @NonNull
  UUID userId;
  @NonNull
  String email;
  @Singular
  Set<String> favoriteFoods;
  @NonNull
  @Builder.Default
  String avatar = “default.png”;
}

User user = User.builder()
  .userId(UUID.random())
  .email(“grubhub@grubhub.com”)
  .favoriteFood(“burritos”)
  .favoriteFood(“dosas”)
  .build()

Lombok @FieldDefaults Anotasyonu - Üye Alanları Örneğin Private ve Final Yapar

Giriş

Şu satırı dahil ederiz

import lombok.experimental.FieldDefaults;

Açıklaması şöyle

This annotation provides a way to set default modifiers for the fields in a class. You can control the access level of fields and specify whether they should be final. This is particularly useful in Spring-based applications where you might want to establish consistent field-level access control without explicitly declaring it for each field.

Açıklaması şöyle

When you annotate a class with @FieldDefaults, you can specify two key elements:

Access Level: The visibility of the fields, such as PRIVATE, PROTECTED, PACKAGE, or PUBLIC. The default value is PRIVATE.

Final: A Boolean value specifying whether the fields should be final. The default is false.

makeFinal Alanı

Açıklaması şöyle. Yani @Data ile üretilecek setter metodları engelleyebilir

Setting makeFinal = true works well when you are creating immutable classes, but it does limit the functionality of other Lombok annotations like @Setter. In classes annotated with @Data, the makeFinal = true setting will essentially disable the generation of setter methods, because final fields cannot be modified once initialized.

Örnek

Şöyle yaparız

import lombok.Data;
import lombok.experimental.FieldDefaults;
import lombok.AccessLevel;

@Data
@FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
public class SecureBook {
  String title;
  String author;
  int pages;
}

Örnek

Elimizde şöyle bir kod olsun

@Slf4j
@RequiredArgsConstructor
@FieldDefaults(makeFinal=true, level=AccessLevel.PRIVATE)
public class UserService {
  @NonNull UserDao userDao;
}

Açıklaması şöyle

The @FieldDefaults annotation adds the final and private modifiers to all of the fields.