How to Create Your First Spring Boot Project Using Spring Initializr

Here’s a step-by-step guide for creating your first Spring Boot project using Spring Initializr:

Step 1: Go to Spring Initializr

  1. Open the Spring Initializr website: https://start.spring.io/.
  2. You will see a friendly interface that allows you to configure your new Spring Boot project.

Step 2: Configure Your Project

  1. Project Settings:
    • Project Type: Choose either Maven or Gradle (Maven is common for beginners).
    • Language: Select Java, Kotlin, or Groovy. Use Java for now to keep it simple.
    • Spring Boot Version: Select the latest stable version (e.g., 3.x.x).
  2. Project Metadata:
    • Group: Enter your domain or namespace (e.g., com.example).
    • Artifact: This is the name of your project (e.g., demo).
    • Name and Description: Optional, but you can customize these values.
    • Package Name: Auto-generated from Group and Artifact but can be edited.
    • Packaging: Choose Jar.
    • Java Version: Select the Java version installed on your machine (e.g., Java 23 for compatibility).
  3. Dependencies:
    • Click Add Dependencies and search for the necessary modules, such as:
      • Spring Web for building web applications (REST APIs, etc.).
      • Spring Data JPA if you want database integration.
      • H2 Database for testing with an in-memory database.
      • Spring Boot DevTools for automatic application reload during development.

Add any additional dependencies you need for your project.

Step 3: Download the Project

  1. After configuring your project, click on the Generate button.
  2. A .zip file containing your project will be downloaded.

Step 4: Import the Project into IntelliJ IDEA

  1. Open IntelliJ IDEA.
  2. Go to File > Open and select the folder where you extracted your project.
  3. If IntelliJ suggests importing the project as a Maven/Gradle project, confirm the selection.
  4. Upon importing the project, IntelliJ will automatically resolve and download the dependencies.

Step 5: Run the Spring Boot Application

  1. Locate the main class in the project. It is usually located in src/main/java/<package-name> and has an @SpringBootApplication annotation.
  2. Right-click on the main class and select Run .
  3. Once the application starts, you will see the Spring Boot banner in the console and a log message indicating that the application started successfully.

Example Project Structure

Here’s a high-level view of what your project structure will look like:

src
├── main
|   ├── java
|   │   └── com.example.demo
|   │       └── DemoApplication.java (Main class)
|   └── resources
|       ├── application.properties (Configuration file)
|       ├── static
|       └── templates
└── test

Next Steps

  • Open the application.properties file in the src/main/resources/ directory to specify configuration data, such as database properties.
  • Start building your business logic, controller classes, and database entities.

Congratulations! 🎉 You’ve successfully created your first Spring Boot project using Spring Initializr.

How do I show Spring transaction in log / console?

When you use the Spring framework @Transactional annotation in your service layer you might want to see what is happening in your code related to database transaction. You want to see when a transaction is started, when it is committed or rollbacked.

To activate the log for transactional message you can add the following configurations in your application properties file. For example when using the JpaTransactionManager you can set the log level to DEBUG.

logging.level.root=INFO

logging.level.org.springframework.orm.jpa=DEBUG
logging.level.org.springframework.transaction=DEBUG

Running the spring boot application with these configuration, the JpaTransactionManager will write something line these on your log file or console:

2023-03-29T23:06:52.194+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Creating new transaction with name [org.kodejava.webapp.accounting.service.impl.CalculationServiceImpl.recalculate]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
2023-03-29T23:06:52.194+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Opened new EntityManager [SessionImpl(974784570<open>)] for JPA transaction
2023-03-29T23:06:52.195+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Exposing JPA transaction as JDBC [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@4150907e]
...
...
2023-03-29T23:06:52.195+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Found thread-bound EntityManager [SessionImpl(974784570<open>)] for JPA transaction
2023-03-29T23:06:52.195+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Participating in existing transaction
...
...
2023-03-29T23:06:52.237+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Initiating transaction commit
2023-03-29T23:06:52.237+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Committing JPA transaction on EntityManager [SessionImpl(974784570<open>)]
2023-03-29T23:06:52.237+08:00 DEBUG 54056 --- [nio-9090-exec-3] o.s.orm.jpa.JpaTransactionManager        : Closing JPA EntityManager [SessionImpl(974784570<open>)] after transaction

How do I build simple search page using ZK and Spring Boot?

In this example we are going to build a simple search page using ZK framework and Spring Boot. We are going to use the latest available version of Spring Boot (3.0.0) and ZK Framework (9.6.0.2). So without taking more time let’s start by creating a new spring boot project with the following pom.xml. You can create the initial project using your IDE or spring initializr.

Create a Spring Boot project and add the following dependencies:

  • zkspringboot-starter
  • zkplus
  • spring-boot-devtools
  • spring-boot-starter-data-jpa
  • mysql-connector-j
  • lombok

The pom.xml File

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.0.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>org.kodejava</groupId>
    <artifactId>kodejava-zk-search</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>kodejava-zk-search</name>
    <description>kodejava-zk-search</description>

    <properties>
        <java.version>17</java.version>
        <zkspringboot.version>3.0.0</zkspringboot.version>
        <zk.version.jakarta>9.6.0.2-jakarta</zk.version.jakarta>
        <zk.version>9.6.0.2</zk.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.zkoss.zkspringboot</groupId>
            <artifactId>zkspringboot-starter</artifactId>
            <type>pom</type>
            <version>${zkspringboot.version}</version>
        </dependency>
        <dependency>
            <groupId>org.zkoss.zk</groupId>
            <artifactId>zkplus</artifactId>
            <version>${zk.version.jakarta}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <repositories>
        <repository>
            <id>ZK CE</id>
            <name>ZK CE Repository</name>
            <url>https://mavensync.zkoss.org/maven2</url>
        </repository>
        <repository>
            <id>ZK EVAL</id>
            <name>ZK Evaluation Repository</name>
            <url>https://mavensync.zkoss.org/eval</url>
        </repository>
    </repositories>

</project>

application.properties File

This properties file configure ZK application homepage and the prefix where the zul files are located. We also configure the datasource to our application database.

zk.homepage=label
zk.zul-view-resolver-prefix=/zul
zk.resource-uri=/zkres

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost/musicdb
spring.datasource.username=root
spring.datasource.password=

spring.jpa.properties.hibernate.hbm2ddl.auto=create

Label.java Entity Definition

An entity that represent out record label with just two property of id and name. Getters and setters are generated by Lombok library, it also generated to equals() and hashcode() method, and also the toString() method.

package org.kodejava.zk.entity;

import jakarta.persistence.*;
import lombok.Data;

@Data
@Entity
public class Label {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
}

The LabelRepository.java definition.

Create the LabelRepository which extends the JpaRepository and JpaSpecificationExecutor interfaces.

package org.kodejava.zk.repository;

import org.kodejava.zk.entity.Label;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.stereotype.Repository;

@Repository
public interface LabelRepository extends JpaRepository<Label, Long>, JpaSpecificationExecutor<Label> {
}

AbstractSearchController.java a base search controller.

A base class that we can use to implements all the search page in an application. Basically it provides the method to search our application data. It defines a couple of abstract method that need to be implemented by the search controller classes such as what repository to use and the specification for searching the data. We can also define the default sort column and the direction of the data sorting.

package org.kodejava.zk.controller;

import org.springframework.data.domain.Sort;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.zkoss.zk.ui.Component;
import org.zkoss.zk.ui.event.Event;
import org.zkoss.zk.ui.select.SelectorComposer;
import org.zkoss.zk.ui.select.annotation.Listen;
import org.zkoss.zk.ui.select.annotation.VariableResolver;
import org.zkoss.zk.ui.select.annotation.Wire;
import org.zkoss.zul.Listbox;

@VariableResolver(org.zkoss.zkplus.spring.DelegatingVariableResolver.class)
public abstract class AbstractSearchController<T> extends SelectorComposer<Component> {
    @Wire
    protected Listbox listbox;

    public abstract JpaSpecificationExecutor<T> getRepository();

    public abstract Specification<T> getSpecification();

    public abstract String getCacheKey();

    protected String getDefaultSortColumn() {
        return "id";
    }

    protected Sort.Direction getDefaultSortDirection() {
        return Sort.Direction.ASC;
    }

    protected boolean getMultiple() {
        return false;
    }

    @Override
    public void doAfterCompose(Component comp) throws Exception {
        super.doAfterCompose(comp);
        search();
    }

    @Listen("onClick=#searchButton")
    public void search() {
        listbox.setVisible(true);
        SearchListModel<T> model = new SearchListModel<>(getRepository(), getSpecification(), getCacheKey());
        model.setMultiple(getMultiple());
        model.setDefaultSortColumn(getDefaultSortColumn());
        model.setDefaultSortDirection(getDefaultSortDirection());
        listbox.setModel(model);
        listbox.setActivePage(0);
    }

    @Listen("onOK=#searchForm")
    public void onEnterPressed(Event event) {
        search();
    }

    public int getPageSize() {
        return SearchListModel.PAGE_SIZE;
    }
}

SearchListModel.java

An implementation of ListModel, this class will query the database using the provided repository and specification. It read data page-by-page and cache it so when we navigating the Listbox page it doesn’t read the data that have already been cached.

package org.kodejava.zk.controller;

import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Sort;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.zkoss.zk.ui.Execution;
import org.zkoss.zk.ui.Executions;
import org.zkoss.zul.FieldComparator;
import org.zkoss.zul.ListModelList;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

public class SearchListModel<T> extends ListModelList<T> {
    public static final int PAGE_SIZE = 5;
    private final JpaSpecificationExecutor<T> repository;
    private final String cacheKey;
    private long totalElements;

    private Comparator<T> comparator;
    private boolean ascending = false;
    private final Specification<T> specification;
    private Sort.Direction defaultSortDirection = Sort.Direction.ASC;
    private String defaultSortColumn = "id";

    public SearchListModel(JpaSpecificationExecutor<T> repository, Specification<T> specification, String cacheKey) {
        this.repository = repository;
        this.specification = specification;
        this.cacheKey = cacheKey;
        this.totalElements = repository.count(specification);
    }

    @Override
    public T getElementAt(int index) {
        Map<Integer, T> cache = getCache();

        T target = cache.get(index);
        if (target == null) {
            Sort sort = Sort.by(getDefaultSortDirection(), getDefaultSortColumn());
            if (comparator != null) {
                FieldComparator fieldComparator = (FieldComparator) comparator;
                String orderBy = fieldComparator.getRawOrderBy();
                sort = Sort.by(ascending ? Sort.Direction.ASC : Sort.Direction.DESC, orderBy);
            }
            Page<T> pageResult = repository.findAll(specification, PageRequest.of(getPage(index), PAGE_SIZE, sort));
            totalElements = pageResult.getTotalElements();
            int indexKey = index;
            for (T t : pageResult.toList()) {
                cache.put(indexKey, t);
                indexKey++;
            }
        } else {
            return target;
        }

        target = cache.get(index);
        if (target == null) {
            throw new RuntimeException("element at " + index + " cannot be found in the database.");
        } else {
            return target;
        }
    }

    @Override
    public int getSize() {
        return (int) totalElements;
    }

    @Override
    public void sort(Comparator<T> comparator, boolean ascending) {
        super.sort(comparator, ascending);
        this.comparator = comparator;
        this.ascending = ascending;
    }

    @SuppressWarnings("unchecked")
    private Map<Integer, T> getCache() {
        Execution execution = Executions.getCurrent();
        Map<Integer, T> cache = (Map<Integer, T>) execution.getAttribute(cacheKey);
        if (cache == null) {
            cache = new HashMap<>();
            execution.setAttribute(cacheKey, cache);
        }
        return cache;
    }

    private int getPage(int index) {
        if (index != 0) {
            return index / PAGE_SIZE;
        }
        return index;
    }

    public Sort.Direction getDefaultSortDirection() {
        return defaultSortDirection;
    }

    public void setDefaultSortDirection(Sort.Direction defaultSortDirection) {
        this.defaultSortDirection = defaultSortDirection;
    }

    public String getDefaultSortColumn() {
        return defaultSortColumn;
    }

    public void setDefaultSortColumn(String defaultSortColumn) {
        this.defaultSortColumn = defaultSortColumn;
    }
}

LabelSearchController.java

Our label search page controller which extends from AbstractSearchController class. We provide the LabelRepository and the Specification to filter the data.

package org.kodejava.zk.controller;

import jakarta.persistence.criteria.Predicate;
import org.kodejava.zk.entity.Label;
import org.kodejava.zk.repository.LabelRepository;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.zkoss.zk.ui.select.annotation.VariableResolver;
import org.zkoss.zk.ui.select.annotation.Wire;
import org.zkoss.zk.ui.select.annotation.WireVariable;
import org.zkoss.zul.Textbox;

import java.util.ArrayList;
import java.util.List;

@VariableResolver(org.zkoss.zkplus.spring.DelegatingVariableResolver.class)
public class LabelSearchController extends AbstractSearchController<Label> {
    @WireVariable
    private LabelRepository labelRepository;

    @Wire
    private Textbox labelNameTextbox;

    @Override
    public JpaSpecificationExecutor<Label> getRepository() {
        return labelRepository;
    }

    @Override
    public Specification<Label> getSpecification() {
        return (root, query, criteriaBuilder) -> {
            List<Predicate> predicates = new ArrayList<>();
            String labelName = labelNameTextbox.getValue();
            if (!labelName.isBlank()) {
                predicates.add(criteriaBuilder.like(root.get("name"), "%" + labelName + "%"));
            }
            return criteriaBuilder.and(predicates.toArray(new Predicate[0]));
        };
    }

    @Override
    public String getCacheKey() {
        return "LABEL_CACHE_KEY";
    }
}

label-search.zul – Label Search Page in ZUL

The search page with a label name Textfield to search by label name. The Listbox will display the data with pagination.

<zk>
    <window id="labelSearchWin" zclass="none" border="none" visible="true"
            apply="org.kodejava.zk.controller.LabelSearchController" width="100%">

        <grid id="searchForm">
            <columns>
                <column width="200px"/>
                <column/>
            </columns>
            <rows>
                <row>
                    <label value="Label Name"/>
                    <textbox id="labelNameTextbox" width="450px" maxlength="50"/>
                </row>
            </rows>
        </grid>

        <separator/>

        <hlayout>
            <button id="searchButton" label="Search"/>
        </hlayout>

        <separator/>

        <vlayout>
            <listbox id="listbox" mold="paging" pageSize="${labelSearchWin$composer.pageSize}" visible="false">
                <listhead>
                    <listheader label="No" hflex="min"/>
                    <listheader label="Label Name" sort="auto(name)"/>
                    <listheader label="Action" hflex="min"/>
                </listhead>
                <template name="model">
                    <listitem>
                        <listcell label="${forEachStatus.index + 1}" hflex="min"/>
                        <listcell label="${each.name}"/>
                        <listcell hflex="min">
                            <hlayout>
                                <button label="Edit" forward="onClick=listbox.onEdit(${each})" tooltiptext="Edit Data"/>
                            </hlayout>
                        </listcell>
                    </listitem>
                </template>
            </listbox>
        </vlayout>
    </window>
</zk>

Running the application and access it at localhost:8080 will give you a screen like the screenshot at the beginning of this post.

The complete source code can be found in the following GitHub repository kodejava-zk-search.