Java: Ekim 2022

31 Ekim 2022 Pazartesi

IntelliJ Idea - Editor Kısayolları

Edit/Find/Select All Occurrences

Multiple selections içindir. Windows'ta Ctrl + Alt + Shift + J

Bir açıklama burada

27 Ekim 2022 Perşembe

Lambda ve Checked Exception

Giriş

Açıklaması şöyle. Yani lambda içinde checked exception fırlatılamz. Checked Excepiton'ları RuntimeException'a çevirerek durum kurtarılabiliyor.

...it is not possible to call a method that throws a checked exception from a lambda directly.

Örnek

Elimizde şöyle bir kod olsun. Bu kod pek okunaklı değil.

Stream.of("...", "...", "...")
  .map(it -> {
    try {
      return Class.forName(it);
    } catch (ClassNotFoundException e) {
      throw new RuntimeException(e);
    }
  })
  .forEach(System.out::println);

1. Lombok SneakyThrows şu anda lambda için kullanılamıyor.

2. Apache Commons Failable kullanılabilir.

3. Vavr kullanılabilir.

4. Bu kodu şu hale çevirebiliriz

var forNamer = new ForNamer()
Stream.of("...", "...", "...")
  .map(forNamer::apply)
  .forEach(System.out::println);

record ForNamer() implements Function<String, Class<?>> {
  @Override
  public Class<?> apply(String string) {
    try {
      return Class.forName(string);
    } catch (ClassNotFoundException e) {
      return null;
    }
  }
}

Vavr Kullanımı

Maven

Şu satırı dahil ederiz

<dependency>
   <groupId>io.vavr</groupId>
   <artifactId>vavr</artifactId>
   <version>0.10.4</version>
 </dependency>

Örnek

Şöyle yaparız

var result = Stream.of("java.lang.String", "ch.frankel.blog.Dummy", "java.util.ArrayList")
  .map(CheckedFunction1.liftTry(Class::forName))
  .map(Try::toEither)
       .partition(Either::isLeft)                              // 1
        .map1(left -> left.map(Either::getLeft))                // 2
        .map2(right -> right.map(Either::get));                 // 3
result._1().forEach(
  it -> System.out.println("not found: " + it.getMessage()));   // 4
result._2().forEach(
  it -> System.out.println("class: " + it.getName()));          // 4

Açıklaması şöyle

1. Partition the Stream of Either in a tuple of two Stream
2. Flatten the left stream from a Stream of Either to a Stream of Throwable
3. Flatten the right stream from a Stream of Either to a Stream of Class
4. Do whatever we want

25 Ekim 2022 Salı

IntelliJ Idea Syntax Highlighting

Giriş

İlk defa burada gördüm. Settings > Editor > Color Scheme > Java menüsüne gittim

Renkli Comment

Açıklaması şöyle

Here is how you do it, Preferences -> Editor -> Color Scheme -> Java -> Comments -> (Block Comment + Line Comment) -> Foreground color (#FFB206).

Rainbow Brackets

Bir örnek burada

Custom Renklendirm

Dark Theme kullanıyordum. Metod'lar renklendirmedim, ama sınıfları renklendirmek büyük projelerde çok faydalı

Interface ve Abstract Sınıflar

Abstract class ve interface'leri şöyle yaptım. Interface'ler açık mavi oldu. Abstract sınıflar kestane rengi oldu ve altı gök mavi olarak çizildi

<scheme name="Orcun Darcula" version="142" parent_scheme="Darcula">
  <metaInfo>
    <property name="created">2022-10-25T10:28:42</property>
    <property name="ide">Idea</property>
    <property name="ideVersion">2022.2.0.0</property>
    <property name="modified">2022-10-25T10:28:47</property>
    <property name="originalScheme">Orcun Darcula</property>
  </metaInfo>
  <attributes>
    <option name="ABSTRACT_CLASS_NAME_ATTRIBUTES">
      <value>
        <option name="FOREGROUND" value="aa0000" />
        <option name="EFFECT_COLOR" value="aaaa" />
        <option name="EFFECT_TYPE" value="1" />
      </value>
    </option>
    <option name="INTERFACE_NAME_ATTRIBUTES">
      <value>
        <option name="FOREGROUND" value="8080" />
      </value>
    </option>
  </attributes>
</scheme>

19 Ekim 2022 Çarşamba

IllegalMonitorStateException Sınıfı

Giriş
Şu satırı dahil ederiz.

import java.lang.IllegalMonitorStateException;

Açıklaması şöyle

If you use wait and notify outside the synchronized block or method then it results in IllegalMonitorStateException

14 Ekim 2022 Cuma

Debezium Kullanımı

Giriş

Embedded bir engine yaratmak için DebeziumEngine nesnesi yaratılır ve bu nesne bir ExecutorService ile çalıştırılır. DebeziumEngine.notifying() ile de bir listener takılır

Propertyler

database.hostname
database.port
database.user

database.password

database.server.name

table.include.list

connector.class

Örnek - MySQL

Şöyle yaparız

// Define the configuration for the Debezium Engine with MySQL connector...
Properties props = config.asProperties();
props.setProperty("name", "engine");
props.setProperty("offset.storage", 
  "org.apache.kafka.connect.storage.FileOffsetBackingStore");
props.setProperty("offset.storage.file.filename", "/tmp/offsets.dat");
props.setProperty("offset.flush.interval.ms", "60000");
/* begin connector properties */
props.setProperty("database.hostname", "localhost");
props.setProperty("database.port", "3306");
props.setProperty("database.user", "mysqluser");
props.setProperty("database.password", "mysqlpw");
props.setProperty("database.server.id", "85744");
props.setProperty("database.server.name", "my-app-connector");
props.setProperty("database.history",
      "io.debezium.relational.history.FileDatabaseHistory");
props.setProperty("database.history.file.filename",
      "/path/to/storage/dbhistory.dat");

// Create the engine with this configuration ...
try (DebeziumEngine<ChangeEvent<String, String>> engine = DebeziumEngine.create(Json.class)
        .using(props)
        .notifying(record -> {
            System.out.println(record);
        }).build()
    ) {
    // Run the engine asynchronously ...
    ExecutorService executor = Executors.newSingleThreadExecutor();
    executor.execute(engine);

    // Do something else or wait for a signal or an event
}
// Engine is stopped when the main code is finished

Örnek - PostgreSQL

Şöyle yaparız

@Component
public class DebeziumConnector {

  private static final String SCHEMA_PLACEHOLDER = "<schema>";

  private final Logger log = LoggerFactory.getLogger(this.getClass());

  private ExecutorService executor = Executors.newSingleThreadExecutor();

  private DebeziumEngine<ChangeEvent<String, String>> engine;

  private String databaseHostname;

  private String databaseSchema;

  private String offsetFlushIntervalMs;

  private String heartBeatMs;

  private String pollIntervalMs;
  

  @PreDestroy
  public void shutdown() throws IOException {
    log.info("Shutting down the CDC engine");
    log.info("Please wait while the current position in the offset log is stored!");
    engine.close();
    executor.shutdown();
  }

  @PostConstruct
  public void start() {
    log.info("Starting the CDC engine");

    var properties = getDebeziumProperties();
    var offsetPolicy = offsetFlushIntervalMs.equals("0") ? 
      OffsetCommitPolicy.always() : OffsetCommitPolicy.periodic(properties);

    this.engine = DebeziumEngine.create(Json.class)
      .using(properties)
      .using(offsetPolicy)
      .notifying(eventHandler)
      .build();

    executor.execute(engine);
  }
}

Properties şöyle olsun

private Properties getDebeziumProperties() {
  var props = new Properties();
  var snapshotTables = "<schema>.table_one,<schema>.table_two,<schema>.table_three";

  var allTables = snapshotTables + ",<schema>.table_without_snapshot_need";

  if (!heartBeatMs.isBlank() && !heartBeatMs.equals("0")) {
    allTables = allTables + ",<schema>.cdc_heartbeat";
    props.setProperty("heartbeat.interval.ms", heartBeatMs);
    props.setProperty(
      "heartbeat.action.query",
      "insert into <schema>.cdc_heartbeat VALUES (B'1')"
          .replace(SCHEMA_PLACEHOLDER, databaseSchema)
    );
  }

  props.setProperty("name", "FooToBarCDC");
  props.setProperty("plugin.name", "pgoutput");
  props.setProperty("publication.autocreate.mode", "filtered");
  setOptionalProperty(s -> props.setProperty("offset.storage", s), offsetStorage);
  setOptionalProperty(s -> props.setProperty("offset.flush.interval.ms", s),
      offsetFlushIntervalMs);
  setOptionalProperty(s -> props.setProperty("snapshot.mode", s), snapshotMode);
  setOptionalProperty(s -> props.setProperty("poll.interval.ms", s), pollIntervalMs);

  if (FileOffsetBackingStore.class.getName().equals(offsetStorage)) {
      props.setProperty("offset.storage.file.filename", offsetStorageFileFilename);
  }

  props.setProperty("database.hostname", databaseHostname);
  props.setProperty("database.port", databasePort);
  props.setProperty("database.user", databaseUser);
  props.setProperty("database.password", databasePassword);
  props.setProperty("database.dbname", databaseDbname);
  props.setProperty("database.server.name", "foo");
  props.setProperty("table.include.list", allTables
      .replace(SCHEMA_PLACEHOLDER, databaseSchema));
  props.setProperty("snapshot.include.collection.list", snapshotTables
      .replace(SCHEMA_PLACEHOLDER, databaseSchema));
  props.setProperty("connector.class", 
      "io.debezium.connector.postgresql.PostgresConnector");        

  return props;
}

private void setOptionalProperty(Consumer<String> consumer, String property) {
  if (property != null && !property.isBlank()) {
    consumer.accept(property);
  }
}

Okunan JSON verisini çevireceğimiz sınıf şöyle olsun

public class CdcEvent {

  private long id;

  private String table;

}

Event handler şöyle olsun

@Component
public class SingleEventHandler implements 
  Consumer<ChangeEvent<String, String>> {

  private static final JsonPointer TABLE = JsonPointer.compile("/payload/source/table");

  private static final JsonPointer PAYLOAD = JsonPointer.compile("/payload/after/id");

  private ObjectMapper objectMapper = JacksonUtil.createObjectMapper();

  private Map<String, DataExtractor> dataExtractors;

  @Override
  public void accept(final ChangeEvent<String, String> event) {
    var cdcEvent = parseEvent(event);
    ...
  }
   

  private CdcEvent parseEvent(final ChangeEvent<String, String> event) {
    if (event == null || event.value() == null) {
      return new CdcEvent();
    }

    try {
      var json = objectMapper.readTree(event.value());
      var cdcEvent = new CdcEvent().setId(json.at(PAYLOAD).asLong())
                                   .setTable(json.at(TABLE).asText());
      return cdcEvent;
    } catch (JsonProcessingException e) {
      throw new EventParsingException(e);
    }
  }
}

CompletionException Sınıfı

Giriş

Şu satırı dahil ederiz

import java.util.concurrent.CompletionException;

- Bir CompletableFuture'a join() yaparsak ve CompletableFuture exception ile biterse, CompletionException fırlatılır.

- Bir CompletableFuture'a get() yaparsak ve CompletableFuture exception ile biterse, ExecutionException fırlatılır.

Örnek - ArithmeticException

Şöyle yaparız

CompletableFuture<Void> completableFuture = CompletableFuture
  .supplyAsync(() -> {
    System.out.println("running task");
    return 1 / 0;
  })
  .thenApply(input -> {
    System.out.println("multiplying by 2");
    return input * 2;
  })
  .thenAccept(System.out::println);

  Thread.sleep(3000);//let the stages complete
  System.out.println("-- checking exceptions --");
  try {
    completableFuture.join();
  } catch (CompletionException exception) {
    exception.printStackTrace();
  }
  //compile error
  //} catch (ExecutionException exception) {
  //    exception.printStackTrace();
  //}

printStackTrace() çıktısı şöyle. "Caused by" kısmında exception'ının hangi satırdan geldiği gösteriliyor.

java.util.concurrent.CompletionException: java.lang.ArithmeticException: / by zero
  at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)
  at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)
  at java.util.concurrent.CompletableFuture$AsyncSupply.run$$$capture(CompletableFuture.java:1606)
  at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java)
  at java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1596)
  at java.util.concurrent.ForkJoinTask.doExec$$$capture(ForkJoinTask.java:289)
  at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java)
  at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
  at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
 at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:175)
Caused by: java.lang.ArithmeticException: / by zero
  at Scratch.lambda$join$0(scratch.java:13)
  at java.util.concurrent.CompletableFuture$AsyncSupply.run$$$capture(CompletableFuture.java:1604)
  ... 7 more

Örnek - completeExceptionally

Şöyle yaparız

CompletableFuture<Double> completableFuture = CompletableFuture
  .supplyAsync(() -> {
    System.out.println("running task");
    return 2.0;
  });


completableFuture.completeExceptionally(new RuntimeException("my error"));


Thread.sleep(3000);//let the stages complete
System.out.println("-- checking exceptions --");
try {
  completableFuture.join();
} catch (CompletionException exception) {
   exception.printStackTrace();
}

printStackTrace() çıktısı şöyle. "Caused by" kısmında exception'ının hangi satırdan geldiği gösteriliyor.

java.util.concurrent.CompletionException: java.lang.RuntimeException: my error
  at java.util.concurrent.CompletableFuture.reportJoin(CompletableFuture.java:375)
  at java.util.concurrent.CompletableFuture.join(CompletableFuture.java:1947)
  at Scratch.join2(scratch_6.java:49)
  at Scratch.main(scratch_6.java:83)
Caused by: java.lang.RuntimeException: my error
  at Scratch.join2(scratch.java:43)
  ... 1 more

12 Ekim 2022 Çarşamba

ArchUnit Kullanımı

Giriş

ArchUnit unit test gibi yazılarak projedeki tüm sınıfları dolaşıyor ve belli kurallara uyup uymadıklarını test ediyor.

Maven

Eğer JUnit anotasyonlarını (@ArchTest) gibi kullanmak istersek bu bağımlılıkları eklemek gerekir. Eğer bu anotasyonlara gerek yoksa sadece Core bağımlılık yeterli

Örnek

Şöyle yaparız

// if we are using JUnit 4
<dependency>
  <groupId>com.tngtech.archunit</groupId>
  <artifactId>archunit-junit4</artifactId>
  <version>0.14.1</version>
  <scope>test</scope>
</dependency>

// if we are using JUnit 5:
<dependency>
  <groupId>com.tngtech.archunit</groupId>
  <artifactId>archunit-junit5</artifactId>
  <version>0.14.1</version>
  <scope>test</scope>
</dependency>

Örnek - Core

Şöyle yaparız

<dependency>
  <groupId>com.tngtech.archunit</groupId>
  <artifactId>archunit</artifactId>
  <version>0.23.1</version>
  <scope>test</scope>
</dependency>

Gradle

Şöyle yaparız

testImplementation 'com.tngtech.archunit:archunit:0.16.0'

Kullanım

Açıklaması şöyle

An arch unit test is made up of a few common parts:

- Target the classes you want to analyze. This can be done with something like new ClassFileImporter().importPackagesOf() if you are working outside of JUnit. Or using the annotation AnalyzeClasses such as @AnalyzeClasses(packages="com.example.application") if you are working in JUnit. This gathering of classes can and should only happen once per test class as it can be an expensive, time-consuming process.

- Then the actual tests can be performed using the ArchUnit DSL.

Yani tüm kullanım şöyle

JavaClasses classes = ...
ArchRule rule = ...
rule.check(classes);

ArchRule Sınıfı

Bu sınıfı yaratmak için

1. Hazır kurallar kullanılabilir

2. Slice API kullanılabilir

Hazır Kurallar

Örnek

Şöyle yaparız

@AnalyzeClasses(packages = "com.tngtech.archunit.example.layers")
public class CodingRulesTest {

  @ArchTest
  private final ArchRule no_generic_exceptions = 
    NO_CLASSES_SHOULD_THROW_GENERIC_EXCEPTIONS;
}

classes metodu

Örnek - Paketteki Sınıflar ve Anotasyon

Şöyle yaparız Burada belirli bir paketteki sınıfların @Entity anotasyonuna sahip olduğu kontrol ediliyor

@ArchTest
static final ArchRule entities_must_reside_in_a_model_package =
  classes().that().areAnnotatedWith(Entity.class)
    .should().resideInAPackage("..model..")
    .as("Entities should reside in a package '..model..'")
    .allowEmptyShould(true);

Benzer bir kural şöyle. Burada belirli bir paketteki sınıfların @Configuration anotasyonuna sahip olduğu kontrol ediliyor

@ArchTest
static final ArchRule configs_must_reside_in_a_config_package =
  classes().that().areAnnotatedWith(Configuration.class)
    .or().areNotNestedClasses().and().areAnnotatedWith(ConfigurationProperties.class)
    .should().resideInAPackage("..config..")
    .as("Configs should reside in a package '..config..'");

Örnek - Anotasyon ve Sınıf İsmi

Şöyle yaparız. Burada SpringBootApplication anotasyonuna sahip sınıfların isminin MainApp olması kontrol ediliyor.

@AnalyzeClasses(packages = "org.mypackage")

@ArchTest
static ArchRule app_class_name_should_be_app =
   classes().that().areAnnotatedWith(SpringBootApplication.class)
     .should().haveSimpleName("MainApp");

Örnek - Sınıf İsmi Son Ek

Şöyle yaparız Burada belirli bir paketteki sınıfların son ekinin Controller olması kontrol ediliyor. allowEmptyShould(true) ile eğer Controller sınıfı yoksa test başarısız olmuyor

@ArchTest
static ArchRule controllers_should_be_suffixed =
  classes()
    .that().resideInAPackage("..controller..")
    .or().areAnnotatedWith(RestController.class)
    .should().haveSimpleNameEndingWith("Controller")
    .allowEmptyShould(true);

fields metodu

Örnek

Şöyle yaparız

@ArchTest
private final ArchRule loggers_should_be_private_static_final =
  fields().that().haveRawType(Logger.class)
    .should().bePrivate()
    .andShould().beStatic()
    .andShould().beFinal()
    .because("we agreed on this convention");

noClasses metodu

Örnek

Şöyle yaparız

@ArchTest
static final ArchRule interfaces_should_not_have_names_ending_with_the_word_interface =
  noClasses()
  .that()
  .areInterfaces()
  .should()
  .haveNameMatching(".*Interface");

slices metodu

Örnek

Şöyle yaparız

@ArchTest
static final ArchRule no_cycles_by_method_calls_between_slices =
  slices()
  .matching("..(simplecycle).(*)..")
  .namingSlices("$2 of $1")
  .should()
  .beFreeOfCycles();

Açıklaması şöyle

This takes your code and slices it by package so the above is slicing the code by the packages directly below the simplecycle package and asserts that there are no cycles. If instead of the (*) we had (**) it would look at all sub-packages below simplecycle .

Layered Architecture Enforcement

ArchUnit Layered Architecture Enforcement Kullanımı yazısına taşıdım

Kendi Kuralımız

Bir örnek burada. Bu kurulu kullanmak için kuralın check() metodu çağrılır. Şöyle yaparız

import com.tngtech.archunit.core.domain.JavaClasses;
import com.tngtech.archunit.core.importer.ClassFileImporter;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import org.junit.runner.RunWith;

public class KinesisSerializableTest {

  @Test
  public void serializable_classes_should_have_valid_serialVersionUID() {
    String basePackage = KinesisSinks.class.getPackage().getName();
    JavaClasses classes = new ClassFileImporter()
                .withImportOption(onlyCurrentModule())
                .importPackages(basePackage);

    ArchUnitRules.SERIALIZABLE_SHOULD_HAVE_VALID_SERIAL_VERSION_UID.check(classes);
  }
}

@AnalyzeClasses Anotasyonu

importOptions Alanı

Örnek

Şöyle yaparız

// ignore tests
@AnalyzeClasses(packages = "org.mypackage", 
  importOptions = ImportOption.DoNotIncludeTests.class)

// ignore class
@AnalyzeClasses(packages = "org.mypackage", 
  importOptions = {ArchUnitTest.ExcludeControllerImportOption.class, 
                   ImportOption.DoNotIncludeTests.class})

public class ArchUnitTest {

  static class ExcludeControllerImportOption 
    implements com.tngtech.archunit.core.importer.ImportOption {
    @Override
    public boolean includes(Location location) {
      return !location.contains("SomeControllerClassThatNeedsToBeExcluded");
    }
}

Hexagonal Architecture

Örnek

Şöyle yaparız

@ArchTest
static final ArchRule onion_architecture_is_respected = onionArchitecture()
  .domainModels("..domain.model..")
  .domainServices("..domain.service..")
  .applicationServices("..application..")
  .adapter("cli", "..adapter.cli..")
  .adapter("persistence", "..adapter.persistence..")
  .adapter("rest", "..adapter.rest..");

Örnek

Kullanımı şöyle. Kaynak kod burada.

HexagonalArchitecture.boundedContext("io.reflectoring.buckpal.account")
                     .withDomainLayer("domain")
                     .withAdaptersLayer("adapter")
                     .incoming("in.web")
                     .outgoing("out.persistence")
                     .and()
                         .withApplicationLayer("application")
                         .services("service")
                         .incomingPorts("port.in")
                         .outgoingPorts("port.out")
                     .and()
                         .withConfiguration("configuration")
                         .check(new ClassFileImporter()
                         .importPackages("io.reflectoring.buckpal.."));

11 Ekim 2022 Salı

Liquibase Kullanımı

Giriş

Liquibase daha çok SpringBoot ile kullanılıyor ancak tek başına kullanım da mümkün. Bir örnek burada

Gradle

Şöyle yaparız

plugins {
  id 'org.liquibase.gradle' version '2.1.1'
}

dependencies {
  liquibaseRuntime group: 'org.liquibase', name: 'liquibase-core', version: '4.2.2'
  liquibaseRuntime group: 'com.microsoft.sqlserver', name: 'mssql-jdbc', version: '10.2.0.jre11'
}

build.gradle dosyasında şöyle yaparız

liquibase {
  activities {
    def liquibaseUrl = project.hasProperty('liquibaseUrl') ? liquibaseUrl : null
    def liquibaseUsername = project.hasProperty('liquibaseUsername') ? liquibaseUsername : null
    def liquibasePassword = project.hasProperty('liquibasePassword') ? liquibasePassword : null
    main {
      changeLogFile 'change-log.sql'
      url liquibaseUrl
      username liquibaseUsername
      password liquibasePassword
    }
  }
}

Çalıştırmak için şöyle yaparız

./gradlew update -PliquibaseUrl="<jdbc-connection-string>" -PliquibaseUsername="<jdbc-username>" -PliquibasePassword="<jdbc-password>"

ChangeLog Nedir?

Açıklaması şöyle. Yani changeset dosyalarını içeren ana dosyadır

A Liquibase changelog is typically a file that contains a list of changesets. A changeset is a group of database changes that are intended to be applied together as a unit. Each changeset includes the details of the changes to be made, such as the SQL statements to be executed or the database objects to be created or modified.

ChangeLog şu formatlarda olabilir

XML
SQL
JSON
YAML

ChangeSet Nedir?

Açıklaması şöyle. Liquibase hangi changeset'in uygulandığını takip eder. Dolayısıyla changeset geri sarılabilir.

... liquibase allows developers to define their database changes in a database-agnostic format, so that the exact changelogs can be used to update different database types, such as MySQL, Oracle, or PostgreSQL. This makes it easier to support multiple database platforms and automate the process of applying changes to a database.

XML

Örnek

Şöyle yaparız. Burada bir tablo yaratılıyor ve satır ekleniyor

<?xml version="1.0" encoding="UTF-8"?>
<databaseChangeLog
  xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog
         http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-3.8.xsd">

  <changeSet id="create-table" author="liquibase">
    <createTable tableName="my_table">
      <column name="id" type="int" autoIncrement="true"/>
      <column name="name" type="varchar(255)"/>
      <column name="description" type="varchar(255)"/>
    </createTable>
  </changeSet>

  <changeSet id="insert-row" author="liquibase">
    <insert tableName="my_table">
      <column name="name" value="Example name"/>
      <column name="description" value="Example description"/>
    </insert>
  </changeSet>
</databaseChangeLog>

Örnek

changeSet tag içinde yapılabilece tablo işlemleri şöyle.

<createTable tableName="customers">
  <column name="id" type="int" autoIncrement="true">
    <constraints primaryKey="true" nullable="false"/>
  </column>
  <column name="name" type="varchar(255)"/>
  <column name="email" type="varchar(255)"/>
  <column name="created_at" type="timestamp" defaultValueComputed="CURRENT_TIMESTAMP"/>
</createTable>

<addColumn tableName="customers">
  <column name="address" type="varchar(255)"/>
</addColumn>

<modifyDataType tableName="customers" columnName="name" newDataType="varchar(100)"/>

<insert tableName="customers">
  <column name="name" value="John Smith"/>
  <column name="email" value="john@example.com"/>
</insert>

<update tableName="customers" where="email = 'john@example.com'">
  <column name="name" value="John Doe"/>
</update>

<delete tableName="customers" where="email = 'john@example.com'"/>

changeSet tag içinde yapılabilecek view işlemleri şöyle.

<createView viewName="customer_names">
  SELECT name FROM customers;
</createView>

<dropView viewName="customer_names"/>

changeSet tag içinde yapılabilecek stored procedure ve trigger işlemleri şöyle.

<createProcedure procedureName="get_customer_by_id">
  CREATE PROCEDURE get_customer_by_id(IN customer_id INT)
  BEGIN
    SELECT * FROM customers WHERE id = customer_id;
  END
</createProcedure>

<dropProcedure procedureName="get_customer_by_id"/>

<createTrigger triggerName="customer_insert_trigger" beforeInsert="true"
  tableName="customers">

SQL

Örnek

Şöyle yaparız

--liquibase formatted sql

--changeset user1:id1
CREATE TABLE Car (
  id INT PRIMARY KEY,
  make VARCHAR(100)
);

Örnek

Şöyle yaparız. Burada bir tablo yaratılıyor ve satır ekleniyor

--liquibase formatted sql
--changeset liquibase:create-table
CREATE TABLE my_table (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(255),
  description VARCHAR(255)
);

--changeset liquibase:insert-row
INSERT INTO my_table (name, description)
VALUES ('Example name', 'Example description');

JSON

Örnek

Şöyle yaparız. Burada bir tablo yaratılıyor ve satır ekleniyor

{
  "databaseChangeLog": {
    "changeSet": [
      {
        "id": "create-table",
        "author": "liquibase",
        "createTable": {
          "tableName": "my_table",
          "column": [
            {
              "name": "id",
              "type": "int",
              "autoIncrement": true
            },
            {
              "name": "name",
              "type": "varchar(255)"
            },
            {
              "name": "description",
              "type": "varchar(255)"
            }
          ]
        }
      },
      {
        "id": "insert-row",
        "author": "liquibase",
        "insert": {
          "tableName": "my_table",
          "column": [
            {
              "name": "name",
              "value": "Example name"
            },
            {
              "name": "description",
              "value": "Example description"
            }
          ]
        }
      }
    ]
  }
}

YAML

Örnek

Şöyle yaparız. Burada bir tablo yaratılıyor ve satır ekleniyor

databaseChangeLog:
  changeSet:
  - id: create-table
    author: liquibase
    createTable:
      tableName: my_table
      column:
      - name: id
        type: int
        autoIncrement: true
      - name: name
        type: varchar(255)
      - name: description
        type: varchar(255)
  - id: insert-row
    author: liquibase
    insert:
      tableName: my_table
      column:
      - name: name
        value: Example name
      - name: description
        value: Example description

10 Ekim 2022 Pazartesi

Mockito @Captor Anotasyonu

Giriş
Şu satırı dahil ederiz

import org.mockito.Captor;

Açıklaması şöyle

It allows the creation of a field-level argument captor. It is used with the Mockito’s verify() method to get the values passed when a method is called

9 Ekim 2022 Pazar

Datafaker

Giriş

Birim testleri için test verisi üreten iki kütüphane var.

1. Datafaker

1. Javafaker

Maven

Örnek

Şu satırı dahil ederiz

<dependency>
  <groupId>net.datafaker</groupId>
  <artifactId>datafaker</artifactId>
  <version>1.6.0</version>
</dependency>

Örnek

Şu satırı dahil ederiz. Datafaker 2.0 sürümü sadece Java 17 ve üstü ile çalışıyor

<dependency>
  <groupId>net.datafaker</groupId>
  <artifactId>datafaker</artifactId>
  <version>2.0.1</version>
</dependency>

Faker Sınıfı

collection metodu

Örnek

Şöyle yaparız. 2 veya 6 eleman uzunluğunda bir liste yaratır. Listede isim veya şehir ismi bulunur

Faker faker = new Faker();

List<String> names =
  faker.collection(
    () -> faker.name().fullName(),
    () -> faker.address().city())
  .len(2, 6)
  .generate();

System.out.println(names);

lorem metodu

Örnek - words

Şöyle yaparız

Faker faker = new Faker();
faker.lorem().words(10)

number metodu

Örnek - numberBetween

Şöyle yaparız

Faker faker = new Faker();
for (int i = 0; i < 1000; i++) {
  String name = faker.name().fullName();
  String gender = faker.gender().binaryTypes().toUpperCase();
  int age = faker.number().numberBetween(18, 65);
  int externalId = faker.number().numberBetween(100000, 999999);
  ...  
}

stream metodu

Örnek

Şöyle yaparız. Stream içinde 20 - 22 değerleri arasında double bulunur

Faker faker = new Faker();

Stream<Object> objects =
  faker.<Object>stream(() -> faker.random().nextDouble(20, 22))
  .generate();

objects.forEach(System.out::println);

Örnek

Şöyle yaparız. Stream içinde 20 - 22 değerleri arasında double bulunur. Stream büyüklüğü 3 veya 5 arasındadır

Faker faker = new Faker();

Stream<Object> objects =
  faker.<Object>stream(() -> faker.random().nextDouble(20, 22))
  .len(3, 5)
  .generate();

objects.forEach(System.out::println);

CsvTransformer Sınıfı

Açıklaması şöyle

The CsvTransformer builder also gives you several parameters to use, such as:

- quote(), in case you want to change the default(") quote.

- separator(), the character which delimits columns in rows.

- header() the boolean parameter, which toggles the generation of the header in the resulting CSV.

generate metodu

Örnek

Şöyle yaparız

// Datafaker supports any locale from the Locale package
Faker faker = new Faker(Locale.GERMANY); 

// Define a schema, which we can use in any Transformer
Schema<Object, ?> schema = Schema.of( 
  field("firstName", () -> faker.name().firstName()),
  field("lastName", () -> faker.name().lastName()),
  field("phoneNumber", () -> faker.phoneNumber().phoneNumberInternational()));

// Instantiate CsvTransformer using the appropriate builder.
CsvTransformer<Object> csvTransformer = CsvTransformer.builder().build(); 

// This is where the magic happens. Call the `generate` method on the 
// transformer with your schema plus the number of records to get the result as a string.
System.out.println(csvTransformer.generate(schema, 5));

Çıktı şöyle

"firstName";"lastName";"phoneNumber"

"Jannik";"Ripken";"+49 9924 780126"

"Frederike";"Birkemeyer";"+49 2933 945975"

"Michelle";"Steuk";"+49 7033 814683"

"Ellen";"Semisch";"+49 9537 991422"

"Oskar";"Habel";"+49 3626 169891"

JavaObjectTransformer Sınıfı

apply metodu

Örnek

Şöyle yaparız

// Java Record with 3 properties
public record Client(String firstName, String lastName, String phoneNumber) {}

// provide the Schema for our class.
Faker faker = new Faker();
JavaObjectTransformer jTransformer = new JavaObjectTransformer();

Schema<Object, ?> schema = Schema.of(
  field("firstName", () -> faker.name().firstName()),
  field("lastName", () -> faker.name().lastName()),
  field("phoneNumber", () -> faker.phoneNumber().phoneNumberInternational())
);

System.out.println(jTransformer.apply(Client.class, schema));

// Output 
// Client{firstName='Elton', lastName='Conroy', phoneNumber='+1 808-239-0480'}

BaseFaker Sınıfı

populate metodu - Class + Class Üzerinde @FakeForSchema Anotasyonu

Örnek

Şöyle yaparız

// com.datafaker.DatafakerSchema class
public static Schema<Object, ?> defaultSchema() {
  var faker = new Faker(Locale.UK, new RandomService(new Random(1)));
  return Schema.of(
    field("firstName", () -> faker.name().firstName()),
    field("lastName", () -> faker.name().lastName()),
    field("phoneNumber", () -> faker.phoneNumber().phoneNumberInternational())
  );
}

@FakeForSchema("com.datafaker.DatafakerSchema#defaultSchema")
public record Client(String firstName, String lastName, String phoneNumber) { }

// Then you can use net.datafaker.providers.base.BaseFaker.populate(java.lang.Class<T>) 
// to populate the object with the default predefined schema.
Client client = BaseFaker.populate(Client.class);

populate metodu - Class + Schema

Örnek

Şöyle yaparız

// Alternatively, you can use 
// net.datafaker.providers.base.BaseFaker.populate(
//  java.lang.Class<T>, 
//   net.datafaker.schema.Schema<java.lang.Object, ?>) 
//  to populate the object with a custom schema:
Client client = BaseFaker.populate(Client.class, Schema.of(
  field("firstName", () -> faker.name().firstName()),
  field("lastName", () -> faker.name().lastName()),
  field("phoneNumber", () -> faker.phoneNumber().phoneNumberInternational())
));