RestTemplate使用实战（二）

2023-08-28 12:00| 来源: 网络整理| 查看: 265

在上一节的文章中，我们学习了restTemplate的基础用法。但是在日常的开发中，我们通常需要更加通用的方式来处理http远程调用。

先来回忆一下，发起一个请求需要哪些步骤：

//1、设置访问url String url = RemoteUrl + "/id"; //2、设置Http的Header HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON_UTF8); //3、设置访问参数 HashMap params = new HashMap(); params.put("name", name); //4、设置访问的Entity HttpEntity entity = new HttpEntity(params, headers); ResponseEntity result = null; try { //5、发起一个POST请求 result = restTemplate.exchange(url, HttpMethod.POST, entity, String.class); JSONObject data = JSONObject.parseObject(result.getBody()).getJSONObject("data"); return data.getString("id");

可以看到，每次发起http请求调用的时候，我们需要准备一系列的参数。如果在生产中，我们这样处理的话，那将会有很多的重复逻辑。

为了能更好的聚焦业务需求开发，我们需要提炼http远程请求的能力，提供统一的基础调用能力。

今天，就给大家带来restTemplate的使用实战进阶，restTemplate对复杂多层嵌套对象的处理和封装。

将分别通过开发中常用的两种序列化工具 fastjson和jackson来分别给交给大家。

类和对象

定义统一的返回类Result

public class Result { private String code; private T data; private String message; public String getCode() { return code; } public void setCode(String code) { this.code = code; } public T getData() { return data; } public void setData(T data) { this.data = data; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } } Fastjson

引入fastjson的依赖，建议使用1.2.68以上的版本，避免安全漏洞。

com.alibaba fastjson 1.2.73

自定义restTemplate，以post请求为例，提供统一的封装。

@Component public class MyRestTemplate { private Logger logger = LoggerFactory.getLogger(MyRestTemplate.class); private static final String HTTP_STATUS_SUCCESS = "200"; @Autowired private RestTemplate restTemplate; public T postForResult(String url, Class cls, Object body, Object... uriVariables) { ResponseEntity entity = restTemplate.exchange(url, HttpMethod.POST, new HttpEntity(body, getHeaders()), String.class, uriVariables); return getResultBody(entity, cls); } public List postForResultList(String url, Class cls, Object body, Object... uriVariables) { ResponseEntity entity = restTemplate.exchange(url, HttpMethod.POST, new HttpEntity(body, getHeaders()), String.class, uriVariables); return getListResultBody(entity, cls); } private T getResultBody(ResponseEntity responseEntity, Class cls) { Result result = JSON.parseObject(responseEntity.getBody(), new TypeReference(cls) { }.getType()); checkResultCode(result); return result.getData(); } private List getListResultBody(ResponseEntity responseEntity, Class cls) { Result result = JSON.parseObject(responseEntity.getBody(), new TypeReference(cls) { }.getType()); checkResultCode(result); return result.getData(); } private HttpHeaders getHeaders() { return getHeaders(MediaType.APPLICATION_JSON_UTF8, null); } /** * 调用微服务的默认请求头 * * @return */ private HttpHeaders getHeaders(MediaType mediaType, Map extHeaders) { HttpHeaders headers = new HttpHeaders(); headers.setContentType(mediaType); if (!CollectionUtils.isEmpty(extHeaders)) { for (Map.Entry h : extHeaders.entrySet()) { headers.add(h.getKey(), h.getValue()); } } return headers; } private void checkResultCode(Result result) { if (null == result){ throw new RuntimeException("result body is null"); } if (!isSuccess(result.getCode())) { logger.error("error, code===>{},message===>, url===>{}", result.getCode(), result.getMessage()); throw new RuntimeException(result.getMessage()); } } private boolean isSuccess(String code) { return code.equals(HTTP_STATUS_SUCCESS); } } Jackson

自定义restTemplate，以post请求为例，提供统一的封装。

@Component public class MyRestTemplate { private Logger logger = LoggerFactory.getLogger(MyRestTemplate.class); private static final String HTTP_STATUS_SUCCESS = "200"; @Autowired private RestTemplate restTemplate; public T postForResult(String url, Class cls, Object body, Object... uriVariables) { ResponseEntity entity = restTemplate.exchange(url, HttpMethod.POST, new HttpEntity(body, getHeaders()), String.class, uriVariables); return getResultBody(entity, cls); } public List postForResultList(String url, Class cls, Object body, Object... uriVariables) { ResponseEntity entity = restTemplate.exchange(url, HttpMethod.POST, new HttpEntity(body, getHeaders()), String.class, uriVariables); return getListResultBody(entity, cls); } private T getResultBody(ResponseEntity responseEntity, Class cls) { Result result = JSON.parseObject(responseEntity.getBody(), Map2ObjectUtils.constructType(cls)); checkResultCode(result); return result.getData(); } private List getListResultBody(ResponseEntity responseEntity, Class cls) { Result result = JSON.parseObject(responseEntity.getBody(), Map2ObjectUtils.constructTypeList(cls)); checkResultCode(result); return result.getData(); } private HttpHeaders getHeaders() { return getHeaders(MediaType.APPLICATION_JSON_UTF8, null); } /** * 调用微服务的默认请求头 * * @return */ private HttpHeaders getHeaders(MediaType mediaType, Map extHeaders) { HttpHeaders headers = new HttpHeaders(); headers.setContentType(mediaType); if (!CollectionUtils.isEmpty(extHeaders)) { for (Map.Entry h : extHeaders.entrySet()) { headers.add(h.getKey(), h.getValue()); } } return headers; } private void checkResultCode(Result result) { if (null == result){ throw new RuntimeException("result body is null"); } if (!isSuccess(result.getCode())) { logger.error("error, code===>{},message===>, url===>{}", result.getCode(), result.getMessage()); throw new RuntimeException(result.getMessage()); } } private boolean isSuccess(String code) { return code.equals(HTTP_STATUS_SUCCESS); } }

定义type类型转换类

public class Map2ObjectUtils { private static ObjectMapper mapper = new ObjectMapper(); static { mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")); } public static Type constructType(Class cls) { return mapper.getTypeFactory().constructParametricType( Result.class, cls); } public static Type constructTypeList(Class cls) { return mapper.getTypeFactory().constructParametricType( Result.class, mapper.getTypeFactory().constructCollectionType(List.class, cls)); } } 使用和实践

定义XiaoAMaController，通过RestTemplate远程调用可以直接获取到需要的泛型类型。

@RestController public class XiaoAMaController { private static final String HTTP_GET_URL = "http://127.0.0.1:8077/user"; private static final String HTTP_GET_LIST = "http://127.0.0.1:8077/list"; @Autowired private MyRestTemplate myRestTemplate; @GetMapping(value = "/get") public void get() { CachaUser cachaUser = myRestTemplate.postForResult(HTTP_GET_URL, CachaUser.class, new BusinessPackage() {{ setId("1"); setName("xiaoama"); }}); } @GetMapping(value = "/list") public void list() { List cachaUsers = myRestTemplate.postForResultList(HTTP_GET_LIST, CachaUser.class, new BusinessPackage() {{ setId("1"); setName("xiaoama"); }}); } }

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