Spring Boot, MyBatis Multiple Datasources Example

In this section, we will show you how we can use multiple data sources in Spring Boot, MyBatis application.


In this example we will create two data source configurations for User DB(PostgreSQL) and Student DB(MySQL). 

Technologies used:

  • Spring Boot 3.0.2
  • MyBatis 3
  • Java 17
  • Maven 
  • PostgreSQL driver and database
  • MySQL driver and database

Database setup

PostgreSQL - Create database and table.

Create a database in the PostgreSQL. 
CREATE DATABASE userdb;

Then, create table users. 
CREATE TABLE IF NOT EXISTS public.users
(
    id           serial primary key,
    email        VARCHAR(40) not null,
    first_name   VARCHAR(40) not null,
    last_name    VARCHAR(40) not null
);


MySQL - Create database and table.

Create a database in the MySQL. 
CREATE DATABASE studentdb;

Then, create table students. 
CREATE TABLE IF NOT EXISTS students(
 id INT PRIMARY KEY AUTO_INCREMENT, 
 name VARCHAR (200) NOT NULL, 
 email VARCHAR (200) NOT NULL,
 school_name VARCHAR (200) NOT NULL
);

Creating a simple spring boot web application:

First, open the Spring initializr https://start.spring.io/ 

Then, Provide the Group and Artifact name. We have provided Group name com.knf.dev.demo and Artifact spring-boot-mybatis-multidatasource-mysql-postgresql. Here I selected the Maven project - language Java 17 - Spring Boot 3.0.2 and add Spring web dependency, MyBatis Framework, MySQL Driver, and PostgreSQL Driver.

Then, click on the Generate button. When we click on the Generate button, it starts packing the project in a .zip(spring-boot-mybatis-multidatasource-mysql-postgresql) file and downloads the project. Then, Extract the Zip file. 
Then, import the project on your favourite IDE.

Final Project directory:


pom.xml

<?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>3.0.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.knf.dev.demo</groupId>
    <artifactId>spring-boot-mybatis-multidatasource-mysql-postgresql</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-mybatis-multidatasource-mysql-postgresql</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>

        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</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>


application.properties

#MySQL configuration properties
spring.datasource.mysql.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.mysql.jdbc-url=jdbc:mysql://localhost:3306/studentdb
spring.datasource.mysql.username=knfuser
spring.datasource.mysql.password=root

#PostgreSQL configuration properties
spring.datasource.postgresql.driver-class-name=org.postgresql.Driver
spring.datasource.postgresql.jdbc-url=jdbc:postgresql://localhost:5432/userdb
spring.datasource.postgresql.username=postgres
spring.datasource.postgresql.password=root


Create PostgreSQLConnMapper.java

package com.knf.dev.demo.config.postgresql;

import org.springframework.stereotype.Component;
import java.lang.annotation.*;

@Target({ ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface PostgreSQLConnMapper {

    String value() default "";
}


Create PostgreSQLConfig.java

package com.knf.dev.demo.config.postgresql;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import javax.sql.DataSource;

@MapperScan(value = "com.knf.dev.demo",
        annotationClass= PostgreSQLConnMapper.class,
        sqlSessionFactoryRef="PostgreSQLSessionFactory")
@Configuration
public class PostgreSQLConfig {

    @Bean(name = "PostgreSQLDataSource")
    @ConfigurationProperties(prefix="spring.datasource.postgresql")
    public DataSource SecondDataSource() {

        return DataSourceBuilder.create().build();
    }

    @Bean(name = "PostgreSQLSessionFactory")
    public SqlSessionFactory oracleSqlSessionFactory(
            @Qualifier("PostgreSQLDataSource")
             DataSource oracleDataSource) throws Exception {

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(oracleDataSource);
        sqlSessionFactoryBean.setMapperLocations(
                new PathMatchingResourcePatternResolver().
                        getResources("mapper/postgresql/*.xml"));
        sqlSessionFactoryBean.setTypeAliasesPackage("com.knf.dev.demo.model.postgresql");
        return sqlSessionFactoryBean.getObject();
    }

    @Bean(name = "PostgreSQLSessionTemplate")
    public SqlSessionTemplate oracleSqlSessionTemplate(
            @Qualifier("PostgreSQLSessionFactory")
             SqlSessionFactory oracleSessionTemplate) {

        return new SqlSessionTemplate(oracleSessionTemplate);
    }


    @Bean(name = "PostgreSQLTransactionManager")
    public DataSourceTransactionManager PrimaryTransactionManager(
            @Qualifier("PostgreSQLDataSource")
              DataSource oracleDataSource) {

        return new DataSourceTransactionManager(oracleDataSource);
    }
}


Create MySQLConnMapper.java

package com.knf.dev.demo.config.mysql;

import org.springframework.stereotype.Component;
import java.lang.annotation.*;

@Target({ ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface MySQLConnMapper {
    String value() default "";
}


Create MySQLConfig.java

package com.knf.dev.demo.config.mysql;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import javax.sql.DataSource;


/*
When using multiDB, set the basePackages for mapper class
file scan separately for each DB, and now it doesn't
matter because you make separate annotations.
 */
@MapperScan(value = "com.knf.dev.demo",
        annotationClass= MySQLConnMapper.class,
         sqlSessionFactoryRef="MySQLSessionFactory")
@Configuration
public class MySQLConfig {

    //When there are multiple beans of the same type,
    // give those beans a higher priority
    @Primary
    @Bean(name = "MySQLDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.mysql")
    public DataSource mysqlDataSource() {
        return DataSourceBuilder
                .create()
                .build();
    }

    @Primary
    @Bean(name = "MySQLSessionFactory")
    public SqlSessionFactory mySqlSessionFactory
            (@Qualifier("MySQLDataSource") DataSource mysqlDataSource,
               ApplicationContext applicationContex) throws Exception {

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(mysqlDataSource);
        sqlSessionFactoryBean.setMapperLocations(
                new PathMatchingResourcePatternResolver().
                        getResources("mapper/mysql/*.xml"));
        sqlSessionFactoryBean.setTypeAliasesPackage("com.knf.dev.demo.model.mysql");

        return sqlSessionFactoryBean.getObject();
    }

    @Primary
    @Bean(name = "MySQLSessionTemplate")
    public SqlSessionTemplate mySqlSessionTemplate
            (@Qualifier("MySQLSessionFactory")
              SqlSessionFactory mySqlSessionFactory) {

        return new SqlSessionTemplate(mySqlSessionFactory);
    }


    @Bean(name = "MysqlTransactionManager")
    @Primary
    public DataSourceTransactionManager PrimaryTransactionManager
            (@Qualifier("MySQLDataSource") DataSource mysqlDataSource) {

        return new DataSourceTransactionManager(mysqlDataSource);
    }
}


Create User Bean

package com.knf.dev.demo.model.postgresql;

public class User {

    private Integer id;
    private String firstName;
    private String lastName;
    private String email;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}


Create Student Bean

package com.knf.dev.demo.model.mysql;

public class Student {

    private Integer id;
    private String name;
    private String schoolName;
    private String email;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSchoolName() {
        return schoolName;
    }

    public void setSchoolName(String schoolName) {
        this.schoolName = schoolName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}


Create UserMapper.java

package com.knf.dev.demo.mapper.postgresql;

import com.knf.dev.demo.config.postgresql.PostgreSQLConnMapper;
import com.knf.dev.demo.model.postgresql.User;
import java.util.List;
import java.util.Optional;

@PostgreSQLConnMapper("PostgreSQLUserMapper")
public interface UserMapper {

     List<User> findAllUser();

     Optional<User> findUserById(Integer id);

     int deleteUserById(Integer id);

     int insertUser(User user);

     int updateUser(User user);
}


Create StudentMapper.java

package com.knf.dev.demo.mapper.mysql;

import com.knf.dev.demo.config.mysql.MySQLConnMapper;
import com.knf.dev.demo.model.mysql.Student;
import java.util.List;
import java.util.Optional;

@MySQLConnMapper("MysqlStudentRepository")
public interface StudentMapper {

    List<Student> findAllStudent();

    Optional<Student> findStudentById(Integer id);

    int deleteStudentById(Integer id);

    int insertStudent(Student student);

    int updateStudent(Student student);
}


Create UserMapper.xml

Mapper XML is an important file in MyBatis, which contains a set of statements to configure various SQL statements such as select, insert, update, and delete.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.knf.dev.demo.mapper.postgresql.UserMapper">
    <resultMap type="user" id="result">
        <id property="id" column="id" />
        <result property="firstName" column="first_name" />
        <result property="lastName" column="last_name" />
        <result property="email" column="email" />
    </resultMap>

    <select id="findAllUser" resultType="user" resultMap="result">
        SELECT * FROM users
    </select>

    <insert id="insertUser" parameterType="user"
            keyProperty="id" useGeneratedKeys="true">
        INSERT INTO users(first_name, last_name, email)
        VALUES(#{firstName}, #{lastName}, #{email})
    </insert>

    <update id="updateUser" parameterType="user">
        UPDATE users SET first_name = #{firstName},
        email = #{email}, last_name = #{lastName}
        WHERE id = #{id}
    </update>

    <delete id="deleteUserById" parameterType="int">
        DELETE FROM users WHERE id = #{id}
    </delete>

    <select id="findUserById" parameterType="int"
            resultType="user" resultMap="result">
        SELECT * FROM users WHERE id = #{id}
    </select>
</mapper>


Create StudentMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.knf.dev.demo.mapper.mysql.StudentMapper">
    <resultMap type="student" id="result">
        <id property="id" column="id" />
        <result property="name" column="name" />
        <result property="schoolName" column="school_name" />
        <result property="email" column="email" />
    </resultMap>

    <select id="findAllStudent" resultType="student" resultMap="result">
        SELECT * FROM students
    </select>

    <insert id="insertStudent" parameterType="student"
            keyProperty="id" useGeneratedKeys="true">
        INSERT INTO students(name, school_name, email)
        VALUES(#{name}, #{schoolName}, #{email})
    </insert>

    <update id="updateStudent" parameterType="student">
        UPDATE students SET name = #{name},
        email = #{email}, school_name = #{schoolName}
        WHERE id = #{id}
    </update>

    <delete id="deleteStudentById" parameterType="int">
        DELETE FROM students WHERE id = #{id}
    </delete>

    <select id="findStudentById" parameterType="int"
            resultType="student" resultMap="result">
        SELECT * FROM students WHERE id = #{id}
    </select>
</mapper>


-Exception handling

Create ResourceNotFoundException

package com.knf.dev.demo.exception;

public class ResourceNotFoundException extends RuntimeException{
    private static final long serialVersionUID = 1L;

    public ResourceNotFoundException(String message) {
        super(message);
    }
}


Create GlobalExceptionHandler

Spring supports exception handling by a global Exception Handler (@ExceptionHandler) with Controller Advice (@ControllerAdvice). This enables a mechanism that makes ResponseEntity work with the type safety and flexibility of @ExceptionHandler.
package com.knf.dev.demo.exception;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.context.request.WebRequest;
import java.time.LocalDateTime;

@ControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<CustomErrorResponse> 
        globalExceptionHandler(Exception ex, WebRequest request) {
        CustomErrorResponse errors = new CustomErrorResponse();
        errors.setTimestamp(LocalDateTime.now());
        errors.setError(ex.getMessage());
        errors.setStatus(HttpStatus.NOT_FOUND.value());
        return new ResponseEntity<>(errors, HttpStatus.NOT_FOUND);
    }
}

Create CustomErrorResponse

package com.knf.dev.demo.exception;

import com.fasterxml.jackson.annotation.JsonFormat;
import java.time.LocalDateTime;

public class CustomErrorResponse {

    @JsonFormat(shape = JsonFormat.Shape.STRING, 
                       pattern = "yyyy-MM-dd hh:mm:ss")
    private LocalDateTime timestamp;
    private int status;
    private String error;
    public LocalDateTime getTimestamp()
    {
        return timestamp;
    }
    public void setTimestamp(LocalDateTime timestamp)
    {
        this.timestamp = timestamp;
    }
    public int getStatus()
    {
        return status;
    }
    public void setStatus(int status)
    {
        this.status = status;
    }
    public String getError()
    {
        return error;
    }
    public void setError(String error)
    {
        this.error = error;
    }
}


Create User Controller

package com.knf.dev.demo.controller.postgresql;

import com.knf.dev.demo.exception.ResourceNotFoundException;
import com.knf.dev.demo.mapper.postgresql.UserMapper;
import com.knf.dev.demo.model.postgresql.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/api/v1")
public class UserController {
    @Autowired
    private UserMapper userMapper;

    // get all users
    @GetMapping("/users")
    public List<User> getAllUsers()
    {
        return userMapper.findAllUser();
    }

    // create user rest API
    @PostMapping("/users")
    public Map<String, Boolean> createUser(@RequestBody User user)  {

        Map<String, Boolean> response = new HashMap<>();

        Boolean bool = userMapper.insertUser(user) > 0 ?
                response.put("created", Boolean.TRUE) :
                response.put("created", Boolean.FALSE);

        return response;

    }

    // get user by id rest api
    @GetMapping("/users/{id}")
    public User findUserById(@PathVariable Integer id) {

        User user = userMapper.findUserById(id).
                orElseThrow(() -> new ResourceNotFoundException
                ("User not exist with id :" + id));
        return user;
    }

   // update user rest api
   @PutMapping("/users/{id}")
   public Map<String, Boolean> updateUser(@PathVariable Integer id,
                                          @RequestBody User userDetails) {

      User user = userMapper.findUserById(id)
              .orElseThrow(() -> new ResourceNotFoundException
               ("User not exist with id :" + id));
       userDetails.setId(id);
       Map<String, Boolean> response = new HashMap<>();

       Boolean bool = userMapper.updateUser(userDetails) > 0 ?
               response.put("updated", Boolean.TRUE) :
               response.put("updated", Boolean.FALSE);

      return response;
    }

    // delete user rest api
    @DeleteMapping("/users/{id}")
    public Map<String, Boolean> deleteUser
               (@PathVariable Integer id) {

        User user = userMapper.findUserById(id)
                .orElseThrow(() -> new ResourceNotFoundException
                        ("User not exist with id :" + id));

        Map<String, Boolean> response = new HashMap<>();

        Boolean bool = userMapper.deleteUserById(user.getId()) > 0 ?
                response.put("deleted", Boolean.TRUE) :
                response.put("deleted", Boolean.FALSE);
        return response;
    }
}


Create Student Controller

package com.knf.dev.demo.controller.mysql;

import com.knf.dev.demo.exception.ResourceNotFoundException;
import com.knf.dev.demo.mapper.mysql.StudentMapper;
import com.knf.dev.demo.model.mysql.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/api/v1")
public class StudentController {

    @Autowired
    private StudentMapper studentMapper;

    // get all student
    @GetMapping("/students")
    public List<Student> getAllStudent()
    {
        return studentMapper.findAllStudent();
    }
    // create student rest API
    @PostMapping("/students")
    public Map<String, Boolean> createStudent(@RequestBody Student student)  {

        Map<String, Boolean> response = new HashMap<>();

        Boolean bool = studentMapper.insertStudent(student) > 0 ?
                response.put("created", Boolean.TRUE) :
                response.put("created", Boolean.FALSE);

        return response;

    }

    // get student by id rest api
    @GetMapping("/students/{id}")
    public Student findStudentById(@PathVariable Integer id) {

        Student student = studentMapper.findStudentById(id).
                orElseThrow(() -> new ResourceNotFoundException
                        ("Student not exist with id :" + id));
        return student;
    }

    // update student rest api
    @PutMapping("/students/{id}")
    public Map<String, Boolean> updateStudent(@PathVariable Integer id,
                                           @RequestBody Student studentDetails) {

        Student student = studentMapper.findStudentById(id)
                .orElseThrow(() -> new ResourceNotFoundException
                        ("Student not exist with id :" + id));
        studentDetails.setId(id);
        Map<String, Boolean> response = new HashMap<>();

        Boolean bool = studentMapper.updateStudent(studentDetails) > 0 ?
                response.put("updated", Boolean.TRUE) :
                response.put("updated", Boolean.FALSE);

        return response;
    }

    // delete student rest api
    @DeleteMapping("/students/{id}")
    public Map<String, Boolean> deleteStudent
         (@PathVariable Integer id) {

        Student student = studentMapper.findStudentById(id)
                .orElseThrow(() -> new ResourceNotFoundException
                        ("Student not exist with id :" + id));

        Map<String, Boolean> response = new HashMap<>();

        Boolean bool = studentMapper.deleteStudentById(student.getId()) > 0 ?
                response.put("deleted", Boolean.TRUE) :
                response.put("deleted", Boolean.FALSE);
        return response;
    }
}


Run the application - Application.java

package com.knf.dev.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}
Application is the entry point that sets up the Spring Boot application. The @SpringBootApplication annotation enables auto-configuration and component scanning. 

Step1: Download or clone the source code from GitHub to a local machine - Click here


Step 2: mvn clean install


Step 3: Run the Spring Boot application - mvn spring-boot:run


OR 


Run this Spring boot application from 

  • IntelliJ IDEA IDE by right click - Run 'Application.main()' 
  • Eclipse/STS - You can right click the project or the Application.java file and run as java application or Spring boot application.


Verify User APIs

Add User:


Update User:


Fetch all User:

Get User by Id:

Delete User by Id:

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Example 1: Java 8 program to print odd numbers from a List   import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; /*Java 8 Program to find Odd Numbers from a List*/ public class DriverClass { public static void main( String [] args) { List < Integer > numbers = Arrays. asList( 1 , 4 , 8 , 40 , 11 , 22 , 33 , 99 ); List < Integer > oddNumbers = numbers.stream(). filter(o -> o % 2 != 0 ). collect(Collectors.toList()); System.out.println(oddNumbers); } } 1. Initialize List using Arrays.asList() method. Java's built-in Arrays.asList() method converts an array into a list. This method takes an array as an argument and returns a List object. 2.  Java List interface provides stream() method which returns a sequential Stream with list of Integer as its source. 3. The Java stream filter() method allow
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Java Stream API - How to convert List of objects to another List of objects using Java streams?

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In this section, we will show you how to convert a List of objects to another List of objects in Java using the Java streams map(). The ‘map’ method maps each element to its corresponding result. Java Stream API   The Java Stream API provides a functional programming approach over the object oriented capabilities of Java. It is used for processing collections of objects. The Stream in Java can be defined as a sequence of elements from a source List, Set or Array. Most of the stream operations return a Stream. This avails engender a chain of stream operations(stream pipe-lining). The streams withal support the aggregate or terminal operations on the elements. for example, finding the sum or maximum element or finding the average etc...Stream operations can either be executed sequentially or parallel. when performed parallelly, it is called a parallel stream.   Stream map() Method   The Java 8 Stream map() is an intermediate operation. It converts Stream<obj1> to Stream<obj2>
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Registration and Login with Spring Boot + Spring Security + Thymeleaf

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In this section, we will learn how to create user registration and login using Spring boot, Spring security, Thymeleaf, JPA, and H2DB. The GitHub repository link is provided at the end of this tutorial. You can download the source code. Technologies used: Spring Boot 2.5.5  Spring Data JPA  Spring Security  Thymeleaf  Maven 3+  Java 17  H2 Database   User Interface User Registration Authentication Failed Authentication success Sign out Final Project Structure: Complete pom.xml: <? 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-pare
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Java, Spring Boot Mini Project - Library Management System - Download

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Hello everyone, Hope you are doing well. Here, we provide a Library Management System mini-project for beginners, it's free for download. Maybe you can build more on top of this project and create your own product, that's all about you. The source code download link is provided at the end of this post. 1. Benefit of this project You could cover the following technologies and features by learning and debugging this mini project. Java 17 Java Stream Java Lamda Expressions Java Records Functional programming Object-oriented programming var Keyword in Java Generics in Java Java Switch Spring boot 2.6.4 Spring Security Thymeleaf template engine OpenCSV Spring Data JPA Server Side Pagination H2 Database  Bootstrap HTML CSS and more... 2. Objective Of Spring Boot On Library Management System The main objective of this project is to manage the details of the books, author, category, and publisher. Only Admin/Librarian will manage all these activities. Also, they can export the data in
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ReactJS, Spring Boot JWT Authentication Example

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In this tutorial, we’ll create a user registration & login example using ReactJS, Spring Boot, Spring Security, and JWT authentication. You could download the source code from our Github repository, the download link is provided at the end of this tutorial. Technologies used Backend Technologies: Java 17 Spring Boot 2.7.0 Spring Security Spring Data JPA JWT H2 Database Frontend Technologies: React 17.0.1 Axios 0.27.2 Redux 4.0.5 Bootstrap 4.5.2 ReactJS - SpringBoot - JWT - Flow Backend Project Directory: Frontend Project Directory: Following is the screenshot of our application - User Registration: User Signin: Profile View: Access Resource: We will build two projects:  1. Backend:   spring-boot-security-jwt 2. Frontend: react-redux-jwt Project 1: spring-boot-security-jwt Pom.xml <?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"
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Spring Boot + Mockito simple application with 100% code coverage

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In this article, we will show you a simple  Spring Boot example to demonstrate test methods for Controllers, Service, and Repository, And code coverage analysis using the EclEmma plugin. Technologies used: Spring Boot 2.6.4 Mockito 3.11.2 Maven 3+ EclEmma plugin Junit 5 Java 17 A quick overview of  Spring Boot, Mockito, and EclEmma plugin Spring boot: Spring boot to develop REST web services and microservices. Spring Boot has taken the Spring framework to the next level. It has drastically reduced the configuration and setup time required for spring projects. We can set up a project with almost zero configuration and start building the things that actually matter to your application. Mockito: Mockito is a mocking framework, a JAVA-predicated library that is utilized for efficacious unit testing of JAVA applications. Mockito is utilized to mock interfaces so that a dummy functionality can be integrated into a mock interface that can be utilized in unit testing. EclEmma : E
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Top 5 Java ORM tools - 2024

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  The term ORM refers to object-relational mapping, which uses objects to adapt programming languages to database systems while allowing them to function with SQL and object-oriented programming ideas. Any kind of database management system that can accomplish object mapping to the table in the virtual system is suitable for the implementation of ORM. Java has a wide variety of ORM tools, some of which are mentioned below: 1. Hibernate Hibernate is a lightweight, open-source, non-invasive Java ORM (Object-Relational Mapping) framework that allows developers to create objects that function independently of database software and create persistence logic in any Java or JavaEE application. It offers an abstraction layer, so developers don't have to bother about implementations; Hibernate handles these tasks internally, such as connecting to databases and creating queries to carry out CRUD operations, among other things. Persistence logic development is done with it. Persistence logic r
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Java - Blowfish Encryption and decryption Example

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Blowfish is an encryption method developed by Bruce Schneier in 1993 as an alternative to the DES encryption method. It is significantly faster than DES and provides good encryption speed, although no effective cryptanalysis technique has been found to date. It is one of the first secure block ciphers that is not protected by any patents and is therefore freely available for anyone to use. This is a symmetric block cipher algorithm. Block size: 64 bits Key size: variable size from 32 to 448 bits number of subsections: 18 [P-array] number of rounds: 16 number of substitution blocks: 4 [each with 512 records of 32 bits each] develop  Example 1: Encryption and decryption using Blowfish import java.io.UnsupportedEncodingException; import java.nio.charset.Charset; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.util.Base64; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeExc
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Spring boot video streaming example-HTML5

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Hello everyone, Today we will learn how to stream MP4 video using Spring Boot and Spring Web Flux.  The Source code download link is provided at the end of this post. New, Quarkus Practice User Interface   Project Structure: G radle(build.gradle) plugins { id 'org.springframework.boot' version '2.5.4' id 'io.spring.dependency-management' version '1.0.11.RELEASE' id 'java' } group = 'com.knf.demo' version = '0.0.1-SNAPSHOT' sourceCompatibility = '11' repositories { mavenCentral() } dependencies { implementation 'org.springframework.boot:spring-boot-starter-webflux' testImplementation 'org.springframework.boot:spring-boot-starter-test' testImplementation 'io.projectreactor:reactor-test' } test { useJUnitPlatform() } Service (VideoStreamingService.java) package  com.knf.demo.service ; import org.springframework.beans.factory.annotation. Autowired ; import org.springframew
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Google Cloud Storage + Spring Boot - File Upload, Download, and Delete

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In this section, we will learn  how to  create a simple spring boot application to perform different file operations such as upload, download, list, and delete files from the Google Cloud Storage. 1.  A little bit of Background Google Cloud Storage Cloud Storage is a managed service for storing unstructured data. Store any amount of data and retrieve it as often as you like. More Info - click here! Spring Boot Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can "just run".  More Info - click here! 2. Create a GCP Project First, Sign into the Google console at  https://console.cloud.google.com . You can create a new project by first selecting the project dropdown in the top left and selecting " New Project ". Next, specify your GCP  Project name  and  Project ID . Then  Click on the " CREATE " button. Copy " Project ID " and keep it for future purposes. 3. Create a Google Cloud Storage bucket Fr
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