Spring Part 04 - Setter Injection (Class)

Spring - Dependency Injection

Dependency Injection using class

Sample Program for Dependency Injection using 'Spring Framework'

beans_di.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="car" class="com.ah.di.Car">
        <property name="engine">
            <bean class="com.ah.di.Engine"/>
        </property>
    </bean>

</beans>

package com.ah.di;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

    public static void main(String[] args) {

        ApplicationContext context = new ClassPathXmlApplicationContext("beans_di.xml");

        Car car = context.getBean("car",Car.class);

        car.checkCarEngine();

    }

}

package com.ah.di;



public class Car {

    private Engine engine;



    public void setEngine(Engine engine) {

        this.engine = engine;

    }

    public void checkCarEngine(){

        if(engine!=null){

            engine.testEngine();

        }else{

            System.out.println("Engine is dead");

        }

    }

}

package com.ah.di;

public class Engine {

    public void testEngine(){

        System.out.println("engine is working" );

    }

}

                                                                         Watch Demo

Spring Part 03 - Constructor Injection

 Spring - Construction Injection

Maven Dependency:

<dependency>

  <groupId>org.springframework</groupId>

  <artifactId>spring-context</artifactId>

  <version>5.3.16</version>

</dependency>

Sample Program for Construction Injection using 'Spring Framework' 

beans_di.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xsi:schemaLocation="http://www.springframework.org/schema/beans

        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="commonEngine" class="com.ah.di.Engine"/>


    <bean id="car1" class="com.ah.di.Car">

        <constructor-arg name="engine" ref="commonEngine"/>

    </bean>


    <bean id="car2" class="com.ah.di.Car">

        <constructor-arg name="engine" ref="commonEngine"/>

    </bean>

</beans>

package com.ah.di;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {

   /*     Engine engine = new Engine();
        Car car = new Car(engine);
        car.callEngine();*/

/*        Car car = new Car(new Engine());
        car.callEngine();*/

        ApplicationContext context = new ClassPathXmlApplicationContext("beans_di.xml");
        Car carObj1 = context.getBean("car1",Car.class);
        carObj1.callEngine();

        Car carObj2 = context.getBean("car2",Car.class);
        carObj2.callEngine();
    }
}

package com.ah.di;

public class Engine {

    public Engine() {

        System.out.println("Engine constructor.");

    }

    public void engineInfo(){

        System.out.println("engineInfo method of Engine class called.");

    }

}

package com.ah.di;

public class Car {

    private Engine engine;

    public Car(Engine engine) {

        this.engine = engine;

    }

    public void callEngine(){

        if(engine==null){

            System.out.println("Engine is dead");

        }else{

            System.out.println("Engine is working");

            engine.engineInfo();

        }

    }

}

                                                                  Watch Demo

Spring Part 02 - Dependency Injection (Primitives & String)

Spring - Dependency Injection

Dependency Injection using primitives & String

Sample Program for Dependency Injection without using 'Spring Framework'

package com.ah.di.setterdemo;

public class Test {
    public static void main(String[] args) {
        Car car = new Car();
        car.setCarName("Ford");
        car.displayCarInfo();
    }
}

package com.ah.di.setterdemo;

public class Car {

    private String carName;
    
    public void setCarName(String carName) {
        this.carName = carName;
    }

    public void displayCarInfo(){
        System.out.println("Displaying car information"+
                "\n car name : "+carName);
    }
}

Maven Dependency:

<dependency>

  <groupId>org.springframework</groupId>

  <artifactId>spring-context</artifactId>

  <version>5.3.16</version>

</dependency>

Sample Program for Dependency Injection using 'Spring Framework' 

beans_di_setter.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="car" class="com.ah.di.setterdemo.Car">
        <property name="carName" value="Ford"/>
        <property name="mileage" value="28"/>
    </bean>
</beans>

package com.ah.di.setterdemo;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans_di_setter.xml");
        Car carObj = context.getBean("car", Car.class);
        carObj.displayCarInfo();
    }
}

package com.ah.di.setterdemo;

public class Car {

    private String carName;
    private int mileage;

    public void setMileage(int mileage) {
        this.mileage = mileage;
    }

    public void setCarName(String carName) {
        this.carName = carName;
    }

    public void displayCarInfo(){
        System.out.println("Displaying car information"+
                "\n car name : "+carName+
                "\n mileage : "+mileage);
    }
}

Watch Demo

Spring Part 01 - IOC

Spring - Inversion of Control 

Sample Program to create object and call method without using 'Spring Framework'

package com.ah.ioc;

public class Test {
    public static void main(String[] args) {
        SamsungMobile sm = new SamsungMobile();
        sm.display();
    }
}

package com.ah.ioc;

public class SamsungMobile implements Mobile{
    public SamsungMobile(){
        System.out.println("Constructor of SamsungMobile class");
    }

    public void display(){
        System.out.println("display() method in SamsungMobile class");
    }
}

Maven Dependency:

<dependency>

  <groupId>org.springframework</groupId>

  <artifactId>spring-context</artifactId>

  <version>5.3.16</version>

</dependency>

Sample Program to create object and call method using 'Spring Framework' 

package com.ah.ioc;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {
        ApplicationContext context =
                new ClassPathXmlApplicationContext("beans_ioc.xml");
        SamsungMobile samsungMobile = context.getBean("sm", SamsungMobile.class);
        samsungMobile.display();
    }

} 

package com.ah.ioc;

public class SamsungMobile implements Mobile{
    public SamsungMobile(){
        System.out.println("Constructor of SamsungMobile class");
    }

    public void display(){
        System.out.println("display() method in SamsungMobile class");
    }
}

beans_ioc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="sm" class="com.ah.ioc.SamsungMobile"/>
</beans>

Sample Program using interface 'Spring Framework'

package com.ah.ioc;

public interface Mobile {
    public void display();
}

package com.ah.ioc;

public class SamsungMobile implements Mobile{
    public SamsungMobile(){
        System.out.println("Constructor of SamsungMobile class");
    }

    public void display(){
        System.out.println("display() method in SamsungMobile class");
    }
}

package com.ah.ioc;

public class NokiaMobile implements Mobile{
    public NokiaMobile(){
        System.out.println("Constructor of NokiaMobile class");
    }

    public void display(){
        System.out.println("display() method in NokiaMobile class");
    }
}

package com.ah.ioc;

public class ABCMobile implements Mobile{
    public ABCMobile(){
        System.out.println("Constructor of ABCMobile class");
    }

    public void display(){
        System.out.println("display() method in ABCMobile class");
    }
}

package com.ah.ioc;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {

        ApplicationContext context =
                new ClassPathXmlApplicationContext("beans_ioc.xml");
        Mobile mobile = context.getBean("mobile", Mobile.class);
        mobile.display();
    }
}

beans_ioc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="mobile" class="com.ah.ioc.ABCMobile"/>
</beans>

Watch Demo

Spring

Spring:

Part 1-  IOC: https://automation-home.blogspot.com/2022/05/spring-ioc.html 

Part 2-  Dependency Injection 

(Setter Injection : primitives & String) :

https://automation-home.blogspot.com/2022/05/spring-dependency-injection-primitives.html

Part 3-  Constructor Injection 

https://automation-home.blogspot.com/2022/06/spring-constructor-injection.html

Part 4- Dependency Injection 

(Setter Injection : class) :

https://automation-home.blogspot.com/2022/06/spring-setter-injection-class.html

Part 5- Autowiring

https://automation-home.blogspot.com/2022/06/Spring-Autowiring.html

Part 6- @Qualifier

https://automation-home.blogspot.com/2022/06/spring-part-06-qualifier.html

Part 7- @Component

https://automation-home.blogspot.com/2022/06/spring-part-07-component.html

Part 8- @ComponentScan & @Configuration  

https://automation-home.blogspot.com/2022/07/spring-part-08-componentscan.html

Part 9- @Bean

https://automation-home.blogspot.com/2022/07/spring-part-09-bean.html

Note: Will start with Spring core/basic annotations and move towards Spring Boot topic in upcoming demos
- Prerequisite: Basic knowledge on Java programming language
- Intended for Absolute begineers of Spring/Spring Boot Framework. 

 

Java - Reading the text content from file with out loop through

Reading the text content from file with out loop through.

Sample Program:
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Paths;

public class ReadFile {
public static void main(String[] args) throws IOException {
byte[] encoded = Files.readAllBytes(Paths.get("C:\\filename.txt"));
String fileContent = new String(encoded, Charset.defaultCharset());

System.out.println(fileContent);
}
}

Reading the text content from File using 'while' loop.

Sample Program:

import java.io.BufferedReader;

import java.io.FileReader;

public class Read2File {

public static void main(String[] args) {

try {

FileReader fileReader = new FileReader("C:\\filename.txt");

BufferedReader bufferedReader = new BufferedReader(fileReader);

String fileLine = null;

StringBuffer temp = new StringBuffer();

while((fileLine = bufferedReader.readLine()) != null) {

                              temp.append(fileLine+"\n");

                        }

System.out.println(temp);

bufferedReader.close();
   fileReader.close();

}catch (Exception e) {

e.printStackTrace();

}

}

}

Java - Reading the text content(xml/json) with out loop through 'InputStreamReader'

Reading the text content(xml/json) with out loop through 'InputStreamReader'.

Prerequisite:
Requires java 8 to execute below program

Sample Program:
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.stream.Collectors;

public class Test8WsGet {

public static void main(String[] args) {
try {

URL url = new URL("http://thomas-bayer.com/sqlrest/CUSTOMER/2/");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("Accept", "application/json");

if (connection.getResponseCode() != 200) {
throw new RuntimeException("Failed with HTTP error code : " + connection.getResponseCode());
}

String responseXml;
System.out.println("Response xml from Server .... \n");

BufferedReader bufferReader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
responseXml = bufferReader.lines().collect(Collectors.joining("\n"));

System.out.println(responseXml);

connection.disconnect();
} catch (Exception e) {
e.printStackTrace();

}
}
}

Troubleshooting :
If you are executing above program using maven(i.e. pom.xml) then add below maven-compiler-plugin
Reference: https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-source-and-target.html
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.6.1</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>


Reading the text content(xml/json) from 'InputStreamReader' using 'while' loop.

Sample Program:
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class TestWsGet {

public static void main(String[] args) {
try {

URL url = new URL("http://thomas-bayer.com/sqlrest/CUSTOMER/2/");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("Accept", "application/json");

if (connection.getResponseCode() != 200) {
throw new RuntimeException("Failed with HTTP error code : " + connection.getResponseCode());
}

String responseXml;
System.out.println("Response xml from Server .... \n");

BufferedReader br = new BufferedReader(new InputStreamReader((connection.getInputStream())));
while ((responseXml = br.readLine()) != null) {
System.out.println(responseXml);
}

connection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
}