8: spring-boot-first-app
1-- Main Method of spring boot
spring-boot-first-app --> src/main/java --> com.example.demo --> SpringBootFirstApplication.java
package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringBootFirstAppApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootFirstAppApplication.class, args);
}
}
2- A string that returns "Hello World"
When client writes" http://localhost:8080/hello-world " on browser
spring-boot-first-app --> src/main/java --> com.example.demo --> HelloWorldController.java
package com.example.demo;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloWorldController {
//GET HTTP Method
//When client writes" http://localhost:8080/hello-world " then helloWorld() method executed
@GetMapping("/hello-world")
public String helloWorld() {
return"Hello World!";
}
3- Student class for student information(Getter, Setter and Constructors)
spring-boot-first-app --> src/main/java --> com.example.demo --> Student.java
package com.example.demo;
public class Student {
private String firstName;
private String lastName;
public Student(String firstName, String lastName) {
super();
this.firstName = firstName;
this.lastName = lastName;
}
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;
}
}
4- One Student information i.e(firstName and lastName) return in json
When client writes "http://localhost:8080/student"
spring-boot-first-app --> src/main/java --> com.example.demo --> StudentController.java
package com.example.demo;
import java.util.ArrayList;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class StudentController {
// http://localhost:8080/student
// getStudent() method called
@GetMapping("/student")
public Student getStudent() {
return new Student("Zeeshan","Khan");
}
}
5- More than One Student information i.e(firstName and lastName) return
When client writes "http://localhost:8080/students" on browser
spring-boot-first-app --> src/main/java --> com.example.demo --> StudentController.java
package com.example.demo;
import java.util.ArrayList;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class StudentController {
// http://localhost:8080/student
// getStudent() method called
@GetMapping("/student")
public Student getStudent() {
return new Student("Zeeshan","Khan");
}
@GetMapping("/students")
public ArrayList<Student> getStudents(){
ArrayList<Student> students= new ArrayList<>();
students.add(new Student("Tony","Stark"));
students.add(new Student("Morgan","Stark"));
students.add(new Student("Thanos","Stark"));
return students;
}
}6- Return the student information we asked for
When client writes "http://localhost:8080/student/{firstName}/{lastName}"
spring-boot-first-app --> src/main/java --> com.example.demo --> StudentController.java
package com.example.demo;
import java.util.ArrayList;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class StudentController {
// http://localhost:8080/student
// getStudent() method called
@GetMapping("/student")
public Student getStudent() {
return new Student("Zeeshan","Khan");
}
@GetMapping("/students")
public ArrayList<Student> getStudents(){
ArrayList<Student> students= new ArrayList<>();
students.add(new Student("Tony","Stark"));
students.add(new Student("Morgan","Stark"));
students.add(new Student("Thanos","Stark"));
return students;
}
// http://localhost:8080/student/tony/stark
//Write a rest api which will handle this kind of request
/* uri template variable [@GetMapping("{firstName}/{lastName}")] is connected by methods
firstName and lastName by @PathVariable */
@GetMapping("/student/{firstName}/{lastName}")
public Student studentPathVariable(@PathVariable("firstName")String firstName,
@PathVariable("lastName")String lastName) {
return new Student(firstName, lastName);
}
}
7- A REST API with concept of Queries in it
spring-boot-first-app --> src/main/java --> com.example.demo --> StudentController.java
package com.example.demo;
import java.util.ArrayList;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class StudentController {
// http://localhost:8080/student
// getStudent() method called
@GetMapping("/student")
public Student getStudent() {
return new Student("Zeeshan","Khan");
}
@GetMapping("/students")
public ArrayList<Student> getStudents(){
ArrayList<Student> students= new ArrayList<>();
students.add(new Student("Tony","Stark"));
students.add(new Student("Morgan","Stark"));
students.add(new Student("Thanos","Stark"));
return students;
}
// http://localhost:8080/student/tony/stark
//Write a rest api which will handle this kind of request
/* uri template variable [@GetMapping("{firstName}/{lastName}")] is connected by methods
firstName and lastName by @PathVariable */
@GetMapping("/student/{firstName}/{lastName}")
public Student studentPathVariable(@PathVariable("firstName")String firstName,@PathVariable("lastName")String lastName) {
return new Student(firstName, lastName);
}
// http://localhost:8080/student/query?firstName=Tony&lastName=Stark
//Write a rest api which will handle this kind of request
/* firstName from GetMapping and from new Student are binded by @RequestParam */
@GetMapping("/student/query")
public Student studentQueryParam(
@RequestParam(name="firstName")String firstName,
@RequestParam(name="lastName")String lastName
){
return new Student(firstName,lastName);
}
}
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>2.6.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.springboot.app</groupId>
<artifactId>spring-boot-first-app</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring-boot-first-app</name>
<description>First Application created using spring boot</description>
<properties>
<java.version>11</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</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>
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