BAEL-1763: Get and post lists with RestTemplate (#4438)

* Code showing how to use Lists with RestTemplate

* Update URLs to work inside spring-rest project

* Refactor Employee xtor; rename EmployeeListDTO

spring-rest/src/main/java/org/baeldung/resttemplate/lists/EmployeeApplication.java

@@ -0,0 +1,16 @@
+package org.baeldung.resttemplate.lists;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * Sample application used to demonstrate working with Lists and RestTemplate.
+ */
+@SpringBootApplication
+public class EmployeeApplication
+{
+    public static void main(String[] args)
+    {
+        SpringApplication.run(EmployeeApplication.class, args);
+    }
+}

spring-rest/src/main/java/org/baeldung/resttemplate/lists/client/EmployeeClient.java

@@ -0,0 +1,100 @@
+package org.baeldung.resttemplate.lists.client;
+
+import org.baeldung.resttemplate.lists.dto.Employee;
+import org.baeldung.resttemplate.lists.dto.EmployeeList;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.*;
+import org.springframework.web.client.RestTemplate;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Application that shows how to use Lists with RestTemplate.
+ */
+public class EmployeeClient
+{
+    public static void main(String[] args)
+    {
+        EmployeeClient employeeClient = new EmployeeClient();
+
+        System.out.println("Calling GET using ParameterizedTypeReference");
+        employeeClient.getAllEmployeesUsingParameterizedTypeReference();
+
+        System.out.println("Calling GET using wrapper class");
+        employeeClient.getAllEmployeesUsingWrapperClass();
+
+        System.out.println("Calling POST using normal lists");
+        employeeClient.createEmployeesUsingLists();
+
+        System.out.println("Calling POST using wrapper class");
+        employeeClient.createEmployeesUsingWrapperClass();
+    }
+
+    public EmployeeClient()
+    {
+
+    }
+
+    public List<Employee> getAllEmployeesUsingParameterizedTypeReference()
+    {
+        RestTemplate restTemplate = new RestTemplate();
+
+        ResponseEntity<List<Employee>> response =
+                restTemplate.exchange(
+                        "http://localhost:8080/spring-rest/employees/",
+                        HttpMethod.GET,
+                        null,
+                        new ParameterizedTypeReference<List<Employee>>(){});
+
+        List<Employee> employees = response.getBody();
+
+        employees.forEach(e -> System.out.println(e));
+
+        return employees;
+    }
+
+    public List<Employee> getAllEmployeesUsingWrapperClass()
+    {
+        RestTemplate restTemplate = new RestTemplate();
+
+        EmployeeList response =
+                restTemplate.getForObject(
+                        "http://localhost:8080/spring-rest/employees/v2",
+                        EmployeeList.class);
+
+        List<Employee> employees = response.getEmployees();
+
+        employees.forEach(e -> System.out.println(e));
+
+        return employees;
+    }
+
+    public void createEmployeesUsingLists()
+    {
+        RestTemplate restTemplate = new RestTemplate();
+
+        List<Employee> newEmployees = new ArrayList<>();
+        newEmployees.add(new Employee(3, "Intern"));
+        newEmployees.add(new Employee(4, "CEO"));
+
+        restTemplate.postForObject(
+                "http://localhost:8080/spring-rest/employees/",
+                newEmployees,
+                ResponseEntity.class);
+    }
+
+    public void createEmployeesUsingWrapperClass()
+    {
+        RestTemplate restTemplate = new RestTemplate();
+
+        List<Employee> newEmployees = new ArrayList<>();
+        newEmployees.add(new Employee(3, "Intern"));
+        newEmployees.add(new Employee(4, "CEO"));
+
+        restTemplate.postForObject(
+                "http://localhost:8080/spring-rest/employees/v2/",
+                new EmployeeList(newEmployees),
+                ResponseEntity.class);
+    }
+}

spring-rest/src/main/java/org/baeldung/resttemplate/lists/controller/EmployeeResource.java

@@ -0,0 +1,45 @@
+package org.baeldung.resttemplate.lists.controller;
+
+import org.baeldung.resttemplate.lists.dto.Employee;
+import org.baeldung.resttemplate.lists.dto.EmployeeList;
+import org.baeldung.resttemplate.lists.service.EmployeeService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.List;
+
+@RestController
+@RequestMapping("/employees")
+public class EmployeeResource
+{
+    @Autowired
+    private EmployeeService employeeService;
+
+    @RequestMapping(method = RequestMethod.GET, path = "/")
+    public List<Employee> getEmployees()
+    {
+        return employeeService.getAllEmployees();
+    }
+
+    @RequestMapping(method = RequestMethod.GET, path = "/v2")
+    public EmployeeList getEmployeesUsingWrapperClass()
+    {
+        List<Employee> employees = employeeService.getAllEmployees();
+        return new EmployeeList(employees);
+    }
+
+    @RequestMapping(method = RequestMethod.POST, path = "/")
+    public void addEmployees(@RequestBody List<Employee> employees)
+    {
+        employeeService.addEmployees(employees);
+    }
+
+    @RequestMapping(method = RequestMethod.POST, path = "/v2")
+    public void addEmployeesUsingWrapperClass(@RequestBody EmployeeList employeeWrapper)
+    {
+        employeeService.addEmployees(employeeWrapper.getEmployees());
+    }
+}

spring-rest/src/main/java/org/baeldung/resttemplate/lists/dto/Employee.java

@@ -0,0 +1,40 @@
+package org.baeldung.resttemplate.lists.dto;
+
+public class Employee {
+
+    public long id;
+    public String title;
+
+    public Employee()
+    {
+
+    }
+
+    public Employee(long id, String title)
+    {
+        this.id = id;
+        this.title = title;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    @Override
+    public String toString()
+    {
+        return "Employee #" + id + "["  + title + "]";
+    }
+}

spring-rest/src/main/java/org/baeldung/resttemplate/lists/dto/EmployeeList.java

@@ -0,0 +1,29 @@
+package org.baeldung.resttemplate.lists.dto;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class EmployeeList
+{
+    public List<Employee> employees;
+
+    public EmployeeList()
+    {
+        employees = new ArrayList<>();
+    }
+
+    public EmployeeList(List<Employee> employees)
+    {
+        this.employees = employees;
+    }
+
+    public void setEmployees(List<Employee> employees)
+    {
+        this.employees = employees;
+    }
+
+    public List<Employee> getEmployees()
+    {
+        return employees;
+    }
+}

spring-rest/src/main/java/org/baeldung/resttemplate/lists/service/EmployeeService.java

@@ -0,0 +1,24 @@
+package org.baeldung.resttemplate.lists.service;
+
+import org.baeldung.resttemplate.lists.dto.Employee;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@Service
+public class EmployeeService
+{
+    public List<Employee> getAllEmployees()
+    {
+        List<Employee> employees = new ArrayList<>();
+        employees.add(new Employee(1, "Manager"));
+        employees.add(new Employee(2, "Java Developer"));
+        return employees;
+    }
+
+    public void addEmployees(List<Employee> employees)
+    {
+        employees.forEach(e -> System.out.println("Adding new employee " + e));
+    }
+}