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Author: AnghelLeonard

HibernateSpringBootStreamAndMySQL/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.jpa</groupId>
+    <artifactId>jpa</artifactId>
+    <version>1.0</version>
+    <packaging>jar</packaging>
+
+    <name>jpa</name>
+    <description>JPA project for Spring Boot</description>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.0.5.RELEASE</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <java.version>1.8</java.version>                
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jdbc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <scope>runtime</scope>
+        </dependency>        
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+
+</project>

HibernateSpringBootStreamAndMySQL/src/main/java/com/jpa/StreamAllApplication.java

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+package com.jpa;
+
+import java.util.logging.Logger;
+import org.springframework.boot.ApplicationRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+
+@SpringBootApplication
+public class StreamAllApplication {
+
+    private static final Logger logger = Logger.getLogger(StreamAllApplication.class.getName());
+
+    private final UserService userService;
+
+    public StreamAllApplication(UserService userService) {
+        this.userService = userService;
+    }
+
+    public static void main(String[] args) {
+        SpringApplication.run(StreamAllApplication.class, args);
+    }
+
+    @Bean
+    public ApplicationRunner init() {
+        return args -> {
+
+            logger.info("Populating database with dummy data ...");
+            userService.populateDatabase();
+            
+            logger.info("Start streaming ...");
+            userService.streamDatabase();
+        };
+    }
+}

HibernateSpringBootStreamAndMySQL/src/main/java/com/jpa/User.java

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+package com.jpa;
+
+import java.io.Serializable;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Entity
+public class User implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    private String name;
+    private String city;
+    private int age;
+    
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    public void setCity(String city) {
+        this.city = city;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    @Override
+    public String toString() {
+        return "User{" + "id=" + id + ", name=" + name + ", city=" + city + ", age=" + age + '}';
+    }    
+}

HibernateSpringBootStreamAndMySQL/src/main/java/com/jpa/UserRepository.java

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+package com.jpa;
+
+import java.util.stream.Stream;
+import javax.persistence.QueryHint;
+import static org.hibernate.jpa.QueryHints.HINT_FETCH_SIZE;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.jpa.repository.QueryHints;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface UserRepository extends JpaRepository<User, Long> {
+    
+    @Query("select u from User u")
+    @QueryHints(value = @QueryHint(name = HINT_FETCH_SIZE, value = "" + Integer.MIN_VALUE))
+    Stream<User> streamAll();
+}

HibernateSpringBootStreamAndMySQL/src/main/java/com/jpa/UserService.java

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+package com.jpa;
+
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Stream;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class UserService {
+    
+    private final UserRepository userRepository;
+    
+    public UserService(UserRepository userRepository) {
+        this.userRepository = userRepository;
+    }
+
+    public void populateDatabase() {
+        for (long i = 0; i < 1000; i++) {
+            User user = new User();            
+            user.setName("User_" + i);
+            user.setCity("City_" + i);
+
+            userRepository.save(user);
+        }
+    }
+    
+    @Transactional(readOnly = true)
+    public void streamDatabase() {
+        
+        long startTime = System.nanoTime();
+        try(Stream<User> userStream = userRepository.streamAll()) {
+            
+            userStream.forEach(System.out::println);
+        }
+        System.out.println("Total time: " + 
+                TimeUnit.MILLISECONDS.convert((System.nanoTime() - startTime), TimeUnit.NANOSECONDS) + " ms");
+    }
+
+}

HibernateSpringBootStreamAndMySQL/src/main/resources/application.properties

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+spring.datasource.url=jdbc:mysql://localhost:3306/db_users?createDatabaseIfNotExist=true
+spring.datasource.username=root
+spring.datasource.password=root
+
+spring.jpa.hibernate.ddl-auto=create
+spring.jpa.show-sql=true
+
+spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect