Programación

La programación informática o programación algorítmica, acortada como programación, es el proceso de diseñar, codificar, depurar y mantener el código fuente de programas computacionales.

Algoritmo

Un algoritmo es una secuencia no ambigua, finita y ordenada de instrucciones que han de seguirse para resolver un problema. Un programa normalmente implementa (traduce a un lenguaje de programación concreto) uno o más algoritmos.

Compilación

El programa escrito en un lenguaje de programación de alto nivel (fácilmente comprensible por el programador) es llamado programa fuente y no se puede ejecutar directamente en una computadora.

Desarrollador

Para conseguirlo se hace uso de tecnologías de software del lado del servidor y del cliente que involucran una combinación de procesos de base de datos con el uso de un navegador web a fin de realizar determinadas tareas o mostrar información.

Diseño Web

Actividad que consiste en la planificación, diseño, implementación y mantenimiento de sitios web. No es simplemente la implementación del diseño convencional ya que se abarcan diferentes aspectos como el diseño gráfico web; diseño de interfaz y experiencia de usuario

miércoles, 25 de enero de 2017

Spring RESTFul Client – RestTemplate Example

After learning to build Spring REST based RESTFul APIs for XML representation and JSON representation, let’s build a RESTFul client to consume APIs which we have written. Accessing a third-party REST service inside a Spring application revolves around the use of the Spring RestTemplate class. The RestTemplate class is designed on the same principles as the many other Spring *Template classes (e.g., JdbcTemplateJmsTemplate ), providing a simplified approach with default behaviors for performing complex tasks.
Given that the RestTemplate class is designed to call REST services, it should come as no surprise that its main methods are closely tied to REST’s underpinnings, which are the HTTP protocol’s methods: HEAD, GET, POST, PUT, DELETE, and OPTIONS. E.g. it’s methods are headForHeaders()getForObject()postForObject()put() and delete() etc.

HTTP GET Method Example

1) Get XML representation of employees collection in String format
REST API Code
@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_XML_VALUE, method = RequestMethod.GET)
public String getAllEmployeesXML(Model model)
{
    model.addAttribute("employees", getEmployeesCollection());
    return "xmlTemplate";
}
REST Client Code
private static void getEmployees()
{
     
    RestTemplate restTemplate = new RestTemplate();
    String result = restTemplate.getForObject(uri, String.class);
     
    System.out.println(result);
}
2) Get JSON representation of employees collection in String format
REST API Code
@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_JSON_VALUE,  method = RequestMethod.GET)
public String getAllEmployeesJSON(Model model)
{
    model.addAttribute("employees", getEmployeesCollection());
    return "jsonTemplate";
}
REST Client Code
private static void getEmployees()
{
     
    RestTemplate restTemplate = new RestTemplate();
    String result = restTemplate.getForObject(uri, String.class);
     
    System.out.println(result);
}
3) Using custom HTTP Headers with RestTemplate
REST API Code
@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_JSON_VALUE,  method = RequestMethod.GET)
public String getAllEmployeesJSON(Model model)
{
    model.addAttribute("employees", getEmployeesCollection());
    return "jsonTemplate";
}
REST Client Code
private static void getEmployees()
{
     
    RestTemplate restTemplate = new RestTemplate();
     
    HttpHeaders headers = new HttpHeaders();
    headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
    HttpEntity<String> entity = new HttpEntity<String>("parameters", headers);
     
    ResponseEntity<String> result = restTemplate.exchange(uri, HttpMethod.GET, entity, String.class);
     
    System.out.println(result);
}
4) Get data as mapped object
REST API Code
@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_XML_VALUE, method = RequestMethod.GET)
public String getAllEmployeesXML(Model model)
{
    model.addAttribute("employees", getEmployeesCollection());
    return "xmlTemplate";
}
REST Client Code
private static void getEmployees()
{
    RestTemplate restTemplate = new RestTemplate();
     
    EmployeeListVO result = restTemplate.getForObject(uri, EmployeeListVO.class);
     
    System.out.println(result);
}
5) Passing parameters in URL
REST API Code
@RequestMapping(value = "/employees/{id}")
public ResponseEntity<EmployeeVO> getEmployeeById (@PathVariable("id") int id)
{
    if (id <= 3) {
        EmployeeVO employee = new EmployeeVO(1,"Lokesh","Gupta","howtodoinjava@gmail.com");
        return new ResponseEntity<EmployeeVO>(employee, HttpStatus.OK);
    }
    return new ResponseEntity(HttpStatus.NOT_FOUND);
}
REST Client Code
private static void getEmployeeById()
{
    final String uri = "http://localhost:8080/springrestexample/employees/{id}";
     
    Map<String, String> params = new HashMap<String, String>();
    params.put("id", "1");
     
    RestTemplate restTemplate = new RestTemplate();
    EmployeeVO result = restTemplate.getForObject(uri, EmployeeVO.class, params);
     
    System.out.println(result);
}

HTTP POST Method Example

REST API Code
@RequestMapping(value = "/employees", method = RequestMethod.POST)
public ResponseEntity<String> createEmployee(@RequestBody EmployeeVO employee)
{
    System.out.println(employee);
    return new ResponseEntity(HttpStatus.CREATED);
}
REST Client Code
private static void createEmployee()
{
    EmployeeVO newEmployee = new EmployeeVO(-1, "Adam", "Gilly", "test@email.com");
    RestTemplate restTemplate = new RestTemplate();
    EmployeeVO result = restTemplate.postForObject( uri, newEmployee, EmployeeVO.class);
    System.out.println(result);
}

HTTP PUT Method Example

REST API Code
@RequestMapping(value = "/employees/{id}", method = RequestMethod.PUT)
public ResponseEntity<EmployeeVO> updateEmployee(@PathVariable("id") int id, @RequestBody EmployeeVO employee)
{
    System.out.println(id);
    System.out.println(employee);
    return new ResponseEntity<EmployeeVO>(employee, HttpStatus.OK);
}
REST Client Code
private static void deleteEmployee()
{
    final String uri = "http://localhost:8080/springrestexample/employees/{id}";
     
    Map<String, String> params = new HashMap<String, String>();
    params.put("id", "2");
     
    EmployeeVO updatedEmployee = new EmployeeVO(2, "New Name", "Gilly", "test@email.com");
     
    RestTemplate restTemplate = new RestTemplate();
    restTemplate.put ( uri, updatedEmployee, params);
}

HTTP DELETE Method Example

REST API Code
@RequestMapping(value = "/employees/{id}", method = RequestMethod.DELETE)
public ResponseEntity<String> updateEmployee(@PathVariable("id") int id)
{
    System.out.println(id);
    return new ResponseEntity(HttpStatus.OK);
}
REST Client Code
private static void deleteEmployee()
{
    final String uri = "http://localhost:8080/springrestexample/employees/{id}";
     
    Map<String, String> params = new HashMap<String, String>();
    params.put("id", "2");
     
    RestTemplate restTemplate = new RestTemplate();
    restTemplate.delete ( uri,  params );
}