REST Template demo

ApiController.java

package com.app.demo.controller;

import com.app.demo.model.*;
import com.app.demo.service.ApiService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;

@RestController
@RequestMapping("/api/v2/users/")
public class ApiController {

    @Autowired
    private ApiService apiService;

    @GetMapping("/getData")
    public List<User> getData(){
        return apiService.getInfo();
    }

    @PostMapping("/postData")
    public User postData(@RequestBody User user){
        return apiService.saveData(user);
    }

    @PatchMapping("/patchData/{id}")
    public User getPatchData(@RequestBody User user, @PathVariable Long id){
        return apiService.patchData(user, id);
    }

    @DeleteMapping("/deleteData/{id}")
    public void deleteData(@PathVariable Long id){
        apiService.deleteData(id);
    }
}

ApiService.java

package com.app.demo.service;

import com.app.demo.model.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.core.ParameterizedTypeReference;
import org.springframework.http.*;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.util.ArrayList;
import java.util.List;

@Service
@Transactional
public class ApiService {

    @Autowired
    private RestTemplateBuilder restTemplateBuilder;

    public List<User> getInfo() {

        String url = "http://localhost:8090/api/user/users";

        ResponseEntity<List<User>> result = restTemplateBuilder.build().
                exchange(url,
                        HttpMethod.GET, null, new ParameterizedTypeReference<List<User>>() {});

        List<User> userList = new ArrayList<>();
        userList.addAll(result.getBody());

        return userList;
    }

    public User saveData(User requestUser) {

        String url = "http://localhost:8090/api/user/addUser";

        ResponseEntity<User> result = restTemplateBuilder.build().postForEntity(url, requestUser, User.class);

        User user = new User();
        user.setEmail(result.getBody().getEmail());
        user.setName(result.getBody().getName());

        return user;
    }

    public User patchData(User requestUser, Long id) {

        String url = "http://localhost:8090/api/user/patchUser/" + id;

        Object result = restTemplateBuilder.build().patchForObject(url, requestUser, User.class);

        User user = new User();

        if(result != null) {
            if (requestUser.getName() != null) {
                user.setName(((User) result).getName());
            }
            if (requestUser.getEmail() != null) {
                user.setEmail(((User) result).getEmail());
            }
        }
        return user;
    }

    public void deleteData(Long id) {

        String url = "http://localhost:8090/api/user/deleteUser/" + id;

        try{
            restTemplateBuilder.build().delete(url);
        }catch (Exception e){
            e.getMessage();
        }
    }
}

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.app</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
        </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>
            </plugin>
        </plugins>
    </build>
</project>

User.java

package com.app.demo.model;

import lombok.Data;
import java.io.Serializable;

@Data
public class User implements Serializable {
    private String name;
    private String email;
}