Java toLowerCase function of string converts the given string into lower case. Return type of this function is String.
For Example if i have a string like “I Like Java Programming Language” and i want to convert this string into lower case then i will use toLowerCase function of String.
package javadream;
import java.util.Locale;
public class JavaDream {
public static void main(String[] args) {
String str = "I Like Java Programming Language";
String lowerCase = str.toLowerCase();
System.out.println(lowerCase);
}
}
Output
As toLowerCase function java also provides toUpperCase function. This function is used to convert given string into upper case.
toUpperCase Function
package javadream;
import java.util.Locale;
public class JavaDream {
public static void main(String[] args) {
String str = "I Like Java Programming Language";
String upperCase = str.toUpperCase();
System.out.println(upperCase);
}
}
In this post we will see CASE Statementin SQL. CASE Statement is like if-else block of programming language. Like in programming language we perform some task if the condition is true if not then we perform other task in else block same functionality is used for CASE statement. We use CASE when we have to perform some task based on the condition.
Syntax of Case statement in MySQL is like :
CASE
WHEN SOME_CONDITION THEN CONDITION_RESULT
WHEN SOME_CONDITION THEN CONDITION_RESULT
ELSE ELSE_CONDITION_RESULT
END
For using CASE Statementin SQL just take an Example suppose If i have a table of Student that contains two column name, course. Now i want that if the course is CSE then i will display you have exam tomorrow and for other courses i want to display Enjoy you don’t have exam tomorrow. So in this case we use CASE function.
Student Table:
Now we will use CASE function in above table. The query will be like below.
select name,course,
case
when course = "CSE" then "you have Exam tomorrow"
else "Enjoy the day you don't have exam"
end as ExamStatus
from student;
In this post we will see MySQL dates and times related examples. As we know MySQL provide some functions using which we can get date and time and related data. As we know there are many scenario when we have to get date and time and some time we have to perform some mathematics with dates and times also so MySQL inbuilt function is very helpful in all of this . Some of the inbuilt MySQL Dates and Times functions are.
now()
curdate()
curtime()
year()
month()
monthname()
day()
dayname()
dayofmonth()
dayofweek()
dayofyear()
1. now()
now() is a inbuilt function provided by MySQL. This function provide us current date and time of server.
2. curdate()
curdate() is a inbuilt function provided by MySQL. This function provide us current date of the server.
3. curtime()
curtime() is a inbuilt function provided by MySQL. This function provide us current time of the server.
4. year()
year() function is used to get the year from the current date. We can use now() and curdate() function with year() to fetch the year.
5. month()
This function is used to get the month from the current date of server.
6. monthname()
This function is used to get the name of month from the current date of server.
7. day()
This function is used to get the day from the current date of server. There are many other functions for getting details of day and that are dayname(), dayofmonth(), dayofweek(), dayofyear().
In this Post we will see how to take MySQL database backup using command line. First we have to login our MySQL using below command and enter password.
mysql -u vasu -p
Now to show all databases we use below command.
show databases
Now above command will show all the databases list that are present in your MySQL. Now it’s time to backup some database. So to take backup of any database we will use below syntax.
Syntax :
mysqldump -u {Mysql UserName} -p {databaseName} > {location where you want to save}\{Name What you want to give}.sql
Note : while you using cmd it might be possible that you get the Access is denied error, To resolve this open cmd via Run as administrator , now use command it will work .
Hi, All in this article we see how to Integrate Apache Kafka with Spring Boot. As we all know Kafka is an open-source messaging queue and it is scalable, fault-tolerant, and offers high performance.
Before Use Kafka Let’s see a live scenario example for why we use Apache Kafka
Suppose we buy a product from an online store and we want to give feedback on this product.
If our application uses synchronous calls to update the feedback then the user has to wait until we get the response from our APIs. This is a bad practice because the user does not care about the background process but he waits for a success message because of our Apis call.
what if an exception occurs while calling Apis then the user gets a message like something went wrong please try again after waiting for 4-5 second( time to get a response from Apis).
2. If our application uses an Asynchronous call to update feedback. In this case, the user gets a response message immediately and the Apis call works in the background.
What if an exception occurs while calling this Apis. And we have already shown the successful response to the user now what to do.
So both the synchronous and Asynchronous methods will not work in this scenario. So to overcome this situation we use a messaging queue. If we use message queue then when we get a request for feedback update we put this request payload on a topic and after getting acknowledgment we return a success message to the user.
Note: Getting acknowledgment from the message queue will take less time as compared to getting a response after a synchronous Apis call.
And if any exception occurs in this scenario while Apis call we can implement retry logic in the message queue.
To Integrate apache kafka with spring boot We have to install it. It is open source you can download it easily. Here i am installing it in Ubuntu.
Below are the steps to install Apache Kafka on the Ubuntu machine.
Go to the Apache Kafka website
Choose any version from Binary Downloads and download the .tgz file.
Extract this .tgz file.
Always remember you have to start zookeeper before starting your Kafka server.
Go to your bin folder and start zookeeper.
Now stay in the bin folder and run your Kafka server.
Follow Above Steps:
1- Go to Apache kafka website and download the binary version.
2- Extract this .tgz file using below command.
tar -xvf kafka_2.12-2.5.0.tgz
3- Now Go to your apache kafka bin folder and run below command to start zookeper
your Apache Kafka server has been started Now we have to create a Spring boot project and Integrate this Kafka server with that. In this example, we create a simple producer-consumer Example means we create a sender and a client. Sender Simply sends a message a client will consume this message. For creating a Spring boot application we have to follow the below steps:
Create a Spring Boot Project and add a required dependency in the pom.xml file.
Define Kafka related properties in your application.yml or application.properties file.
Producer class that writes messages on Kafka Topic.
Create a Consumer class that reds messages from Kafka Topic.
Create a Controller class and make an endPoint to send a message using postman or your frontend application.
Follow Above Steps:
1- Create a Spring Boot Project and add a required dependency in the pom.xml file. You can also copy this dependency from maven Repository
2- Define Kafka related properties in your application.yml or application.properties file.
As you know you can either create an application.yml or application.properties file. But many developers prefer applications. properties and many will prefer application.yml so I am sharing both the files use which one you like.
If you see in the above file here we simply define a server port as 8000 means my spring boot application is running on an 8000 port. And I also define Kafka as producer and consumer. Here in the producer part bootstrap is used to define the Kafka port as I have to install Kafka in my local machine so I have given the path localhost:9092. In the Producer part, there are two more keys one is key-serializer and the other is value-serializer. If you know about Kafka then you know that Kafka uses key-value for sending messages and serialized them so here we use a simple String message so we use StringSerializer.
Now discuss the consumer part here bootstrap is the same as a producer it defines my Kafka server path. Here group-id means in Kafka we have to define a topic to send and receive a message. The sender will write the message to this topic and the consumer will read the message from this topic. There is a chance that many consumers will read from the same topic so we define a group-id and assign the consumer that group-id. key-deserializer and value-deserializer are used to deserialize the message that sends by the producer.
3- Make a Producer class that writes message on Kafka Topic.
package com.vasu.SpringBootKafka.service;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Service;
@Service
public class Producer {
private static final Logger logger = LoggerFactory.getLogger(Producer.class);
private static final String TOPIC = "demo";
@Autowired
private KafkaTemplate<String, Object> kafkaTemplate;
public void sendMessage(String message) {
logger.info("vvv:: send message");
kafkaTemplate.send(TOPIC, message);
}
}
If you see the above class code here we define a topic with a name demo. And autowired the KafkaTemplate. This class simply writes the message on the demo topic using KafkaTemplate.
4- Now Make Consumer class that reds message from Kafka Topic.
package com.vasu.SpringBootKafka.service;
import java.io.IOException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Service;
import com.fasterxml.jackson.databind.ObjectMapper;
@Service
public class Consumer {
private static final Logger logger = LoggerFactory.getLogger(Consumer.class);
@Autowired
private final ObjectMapper mapper = new ObjectMapper();
@KafkaListener(topics = "demo", groupId = "group_id")
public void consume(String message) throws IOException {
logger.info(String.format("consumed message is= ", message));
}
}
In the above class code, we simply consume the message on the demo topic and print this message in the console. Here we use KafkaListener annotation to read messages from a given topic.
5- Now make a Controller class and make a endPoint to send a message using postman or your frontend application.
Here we simply define a controller class and make an endPoint. Now run your spring boot application and open postman and hit a post request with message parameter and see your eclipse console you will get the message.
You can also see all the messages of this topic in your Kafka server console. Just go to your Kafka server bin folder and run the below command.
In this post we will see Spring boot docker Integration. We often hear the word that this project work on my system perfectly i don’t know why this is not working in your system. This is the common issue between developer and tester.
And one more thing that when you develop your project and send it to DevOps team for deployment you see that this team setup the server before deploy your application like they install java version on which you develope your project, Tomcat server, Database Server then they deploy your application.
It is very old feture now days and become a headache for devops team to setup the complete server before deployment. What we can do to reduce this task so here we go here we use Docker.
Docker is a container that contain every dependency of our project and make a image and we share this image to everyone. Now we don’t need to worry about anything we just use this image and run our application. Before use docker you have to download it.
To download docker you can go to official website of docker
In above syntax see the tag <finalName> this tag is used to define the name of your spring boot jar. When you build your spring boot project you will see the jar name same as that you give in between <finalName> tag.
4- Now make a build of your project using maven install command.
5- Make a docker file with name Dockerfile
FROM java:8
EXPOSE 8080
ADD target/spring-docker.jar spring-docker.jar
ENTRYPOINT ["java","-jar","/spring-docker.jar"]
In above syntax:
From – This is used to define that our project is build on java8 and docker will install this image from dockerhub if it is not present.
EXPOSE – This is used to define that we use 8080 port in docker container.
ADD – This is used to define or jar path. we know that our jar file build inside target folder and jar name is same as that we deifine between <finalName> tag.
ENTRYPOINT – This is used to define the command that run our spring boot application. We know that to run java jar we use java -jar <jarName> command.
6- Run docker command to make docker image
Now open your project in terminal and write the below command to make a docker image.
sudo docker build -t spring-docker.jar .
If you run the above command first time it will take some time to download required images. After run the above command you see the output like.
To see the list of images in docker we use below command.
sudo docker images
7- Run this docker image.
sudo docker run -p 9090:8080 spring-docker.jar
Above command is used to run the docker Image. Here we define 9090:8080 this mean we use 8080 as a docker container port and 9090 as our application port. Means to access your application we use http://localhost:9090/ URL. After run above command you will see the output like below:
Now go to your web browser and access your endpoint.
In this post we will learn about spring cache. We know that we lose lots of users if our website take more time to load. And there are many reasons that our website take more time to load and some of them are :
Heavy traffic on website.
Using remote database.
Having a complex business logic that load data from more than one source etc.
So what we can do in this situation. We know that most of the time we load data from database and it will take time if we are using any remote database or doing some complex operation with data. So we use spring cache to solve this problem. It stores data in a cache when you fetch data from DB first time. And whenever we get request for data so we return data from cache we do not hit the DB every time.
And if we update Our database then Spring boot cache provides many useful annotation so that we can manage our cache data accordingly.
Spring boot cache provides many annotation and some of them are:
Annotation
Description
Syntax
@Cacheable
This annotation is used to tell that we are storing this method data into cache. We define a name for cache for uniquely identify cache.
To Use cache in Spring boot we have to follow the below Steps:
Add required dependency in pom.xml file.
Enable cache using @EnableCaching annotation in your main class.
Create a controller class and make some end point.
Create a service class and use Spring boot cache annotation here.
Project Description: In this Project we simply create a Student Model Class. And in this class we perform operation like add, delete, update, find student and see how we use cache for this scenario.
Now you have succesfully created a spring boot project with cache. Now run your application. After run when first time you call http://localhost:8080/ url you will get complete list of Student and check console here you will see JPA query log . Now clear log and again hit the URL now see your console you will not get any JPA log here because second time data will be received from cache not DB.
Same hit delete URL with ID http://localhost:8080/deleteById/21 and after delete Student again hit getAllUser ( http://localhost:8080/ ) URL you will again see JPA query in console because we evict cache while call delete method. Now play woth your code and see changes.
As we know Angular is a structural framework for web-apps. And it is used to perform operation on front end like parsing Json data and display in well format with help of HTML or Bootstrap Component , make http Calls to external API etc. To create a project with Angular JS you should know how to create a spring boot application with JSP for this follow my post ( Click Me ) . In this post we see how to integrate Angular JS in our Spring boot application. There are two ways you can use Angular JS in your application.
Using Angular CDN in your web page
Using Angular webjar in your pom.xml file
In this we will see how to integrate Angular JS with Spring boot using Angular webjar dependency. There are some steps that you have to follow to integrate Angular with Spring boot.
Create a Spring Boot Project.
Add Angular dependency in your pom.xml file.
Create a JSP File ( In this example we create index.jsp ).
Add Jsp Prefix in application,properties file.
Create a Angular Controller and use it in your index.jsp file.
Create a Controller class to provide end point to access your jsp Page.
Project Directory:
Now Follow above steps and create a Spring boot web porject.
If you see this index.jsp file look inside head tag we have given the path of our bootstrap, JS and Angular jar to access there feature. And also look that we have also add mycontroller.js file where we define our Angular JS controller. And in this Index.jsp file if you see html starting tag then we have added a ng-app tag that we use in Js file inside body starting tag we use ng-controller tag where we define our controller name.
5- Create a Angular Controller and use it in your index.jsp file.
var app = angular.module('myapp', []);
app.controller('myctrl', function ($scope) {
$scope.title = "Angular Two Way Binding Example";
});
If you have basic knowledge about Angular Js then you will know that we just define a simple Angular Controller in this file. Here look at module name that is myapp it is the same name that we define in html starting tag. And look at controller name myctrl that we define in body starting tag in our index.jsp file.
6- Create a Controller class to provide end point to access your jsp Page.
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package com.vasu.SpringWithAngularJs.Controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.servlet.ModelAndView;
/**
*
* @author Vasu Rajput
*/
@Controller
public class DemoController {
@GetMapping("/")
public ModelAndView myFirstModel() {
ModelAndView model = new ModelAndView("index");
return model;
}
}
In above file we simply define a controller ( / ) endPoint that return our index file.
Now Steps are over and you have successfully created a Spring boot Application with Angular JS. Now if you run your application you will get the output like .
As we know every project required some documentation so that we get some help about the project. There is two option either you write yourself in a notepad or excel file about the project like details of endPoints in the project or use some tools that do documentation for you. I think second point is better we use some tool, so spring boot provide us a open source tool named Swagger2 for documentation. To use swagger2 in our application we have to follow below steps:
Add required dependency in your pom.xml file.
Create a Bean of Docker and provide your base package name .
Create a controller class and define some end points for which you want documentation information.
As we know in every web application we define some property that we use in our code in a common file so that if we want to change the value in future we have to do changes in only one file. In Spring boot we define our property in application.properties file and to read this property from application.properties file spring boot provides two methods.
Using @Value annotation.
Using @ConfigurationProperties annotation.
In this blog we see both the methods. First we will see how to read property using @value annotation. To read the value using @Value annotaion first we define the property name in application.properties file say example we define a property name myname and value as vasu so to read myname property using @Value annotaion we use below syntax:
application.property
myname=vasu
@Value("${myname} ")
private String name;
Now Our class will look like below:
package com.example.demo.controller;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class NameController {
@Value("${myname} ")
private String name;
@GetMapping("/")
public String test() {
return "My Name is "+name;
}
}
Now if you run your application and hit the URL http://localhost:8080/ you will get the response like below:
My Name is vasu
But it is a bad practice to read property values using @Value annotation. Suppose we have 10 property so to read this 10 property we have to use @Value annotation 10 times. So to avoid this we use @ConfigurationProperties annotaion.
To use @ConfigurationProperties annotation we define a class and annotated this class with @ConfigurationProperties anotation and we use a prefix with this @ConfigurationProperties annotaion like @ConfigurationProperties(“vasu”) now in our application.properties file we define property with this prefix like below:
vasu.value=true
vasu.message= coding is fun
vasu.number=1
Now create a class that annotated with @ConfigurationProperties(“vasu”) annotaion:
package com.example.demo.model;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
@Component
@ConfigurationProperties("vasu")
public class MyModel {
private boolean value;
private String message;
private int number;
public MyModel() {
super();
}
public boolean isValue() {
return value;
}
public void setValue(boolean value) {
this.value = value;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public int getNumber() {
return number;
}
public void setNumber(int number) {
this.number = number;
}
}
Now Autowired this class in your controller and read the property file using getter method like below:
package com.example.demo.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import com.example.demo.model.MyModel;
@RestController
public class NameController {
@Value("${myname} ")
private String name;
@Autowired
private MyModel model;
@GetMapping("/")
public String test() {
return "My Name is "+name
+", i am always "+model.isValue()
+", my messgage to you is "+model.getMessage()
+", i want to be number "+model.getNumber();
}
}
Now if your run your application and hit the URL http://localhost:8080/you will get the response like below:
My Name is vasu , i am always true, my messgage to you is coding is fun, i want to be number 1
