原文地址：http://howtodoinjava.com/2015/02/20/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., JdbcTemplate, JmsTemplate ), 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.
Read More and Source Code : Spring REST JSON Example
HTTP GET Method Example
1) Get XML representation of employees collection in String format
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@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_XML_VALUE, method = RequestMethod.GET)public String getAllEmployeesXML(Model model){ model.addAttribute("employees", getEmployeesCollection()); return "xmlTemplate";} |
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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
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@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_JSON_VALUE, method = RequestMethod.GET)public String getAllEmployeesJSON(Model model){ model.addAttribute("employees", getEmployeesCollection()); return "jsonTemplate";} |
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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
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@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_JSON_VALUE, method = RequestMethod.GET)public String getAllEmployeesJSON(Model model){ model.addAttribute("employees", getEmployeesCollection()); return "jsonTemplate";} |
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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.POST, entity, String.class); System.out.println(result);} |
4) Get data as mapped object
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@RequestMapping(value = "/employees", produces = MediaType.APPLICATION_XML_VALUE, method = RequestMethod.GET)public String getAllEmployeesXML(Model model){ model.addAttribute("employees", getEmployeesCollection()); return "xmlTemplate";} |
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private static void getEmployees(){ RestTemplate restTemplate = new RestTemplate(); EmployeeListVO result = restTemplate.getForObject(uri, EmployeeListVO.class); System.out.println(result);} |
5) Passing parameters in URL
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@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
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private static void getEmployeeById(){ 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
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@RequestMapping(value = "/employees", method = RequestMethod.POST)public ResponseEntity<String> createEmployee(@RequestBody EmployeeVO employee){ System.out.println(employee); return new ResponseEntity(HttpStatus.CREATED);} |
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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
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@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
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private static void deleteEmployee(){ 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
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@RequestMapping(value = "/employees/{id}", method = RequestMethod.DELETE)public ResponseEntity<String> updateEmployee(@PathVariable("id") int id){ System.out.println(id); return new ResponseEntity(HttpStatus.OK);} |
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private static void deleteEmployee(){ Map<String, String> params = new HashMap<String, String>(); params.put("id", "2"); RestTemplate restTemplate = new RestTemplate(); restTemplate.delete ( uri, params );} |
Let me know if something needs more explanation.
Happy Learning !!
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