一、概述
RestTemplate是Spring提供的用于访问Rest服务的客户端，RestTemplate提供了多种便捷访问远程Http服务的方法,能够大大提高客户端的编写效率。
二、配置
1、引入依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency>
2、添加配置交由spring管理
@Configuration public class RestTemplateConfig { @Bean public RestTemplate restTemplate() { SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory(); requestFactory.setConnectTimeout(30*1000); requestFactory.setReadTimeout(30*1000); return new RestTemplate(requestFactory); } }
三、快速使用
1、GET请求
1.1、无参无请求头的方式
String url="http://127.0.0.1:9999/test/restTemplateTest"; JSONObject jsonObject = restTemplate.getForObject(url,JSONObject.class);
String url="http://127.0.0.1:9999/test/restTemplateTest"; ResponseEntity<JSONObject> jsonObject = restTemplate.getForEntity(url,JSONObject.class);
1.2、无参并指定请求头的方式
paramMap 是空
Map<String, Object> paramMap = new HashMap<String, Object>(); //设置请求头 HttpHeaders headers = new HttpHeaders(); headers.add("auth","123445"); HttpEntity<Object> entity = new HttpEntity<>(paramMap,headers); ResponseEntity<JSONObject> result = restTemplate.exchange(url, HttpMethod.GET, entity, JSONObject.class, paramMap); if (result.getStatusCodeValue() == 200){ JSONObject body = result.getBody(); }
1.3、有参的方式
记得要在url中拼接参数 url + “?userId={userId}”
Map<String, String> paramMap = new HashMap<>(); paramMap.put("userId", "123456"); ResponseEntity<JSONObject> result = restTemplate.getForEntity(url + "?userId={userId}", JSONObject.class, paramMap); if (result.getStatusCodeValue() == 200){ JSONObject body = result.getBody(); }
1.4、有参并指定请求头
Map<String, Object> paramMap = new HashMap<String, Object>(); paramMap.put("userId", "123456"); //设置请求头 HttpHeaders headers = new HttpHeaders(); headers.add("auth","123445"); HttpEntity<Object> entity = new HttpEntity<>(paramMap,headers); ResponseEntity<JSONObject> result = restTemplate.exchange(url + "?userId={userId}", HttpMethod.GET, entity, JSONObject.class, paramMap); if (result.getStatusCodeValue() == 200){ JSONObject body = result.getBody(); }
1.5、优雅的拼接参数
我们发现带参数的get请求需要将参数拼接到url中，参数少好说，参数多了就很麻烦
我们使用UriComponentsBuilder来解决
MultiValueMap<String, String> paramMap = new LinkedMultiValueMap<>(); paramMap.add("userId", "123456"); UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url); URI uri = builder.queryParams(paramMap).build().encode(StandardCharsets.ISO_8859_1).toUri(); ResponseEntity<JSONObject> result = restTemplate.getForEntity(uri, JSONObject.class); if (result.getStatusCodeValue() == 200){ JSONObject body = result.getBody(); }
1.6、优雅的拼接参数并携带请求头
MultiValueMap<String, String> multiValueMap = TaskCenterDataConvert.taskSearchDTOToMultiValueMap(taskSearchDTO); UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(taskCenterListSearchUrl); URI uri = builder.queryParams(multiValueMap).build().encode(StandardCharsets.ISO_8859_1).toUri(); HttpHeaders headers = new HttpHeaders(); headers.add("Authorization","Bearer " + authorization); HttpEntity<JSONObject> httpEntity = new HttpEntity<>(null, headers); ResponseEntity<JSONObject> result = restTemplate.exchange(uri.toString(), HttpMethod.GET, httpEntity, JSONObject.class, multiValueMap); if (result.getStatusCodeValue() == 200){ JSONObject body = result.getBody(); } }
1.7、getForObject 、getForEntity和exchange 区别
post请求也是相同的道理
- getForObject 返回值直接是响应体内容转为指定的对象
- getForEntity 返回值的封装包含有响应头, 响应状态码的 ResponseEntity 对象
- exchange 可以指定为get请求或者post请求，并且返回ResponseEntity 对象
2、POST请求
2.1、application/json 的方式
其中参数可以指定为map json 或者bean的形式
Map<String, String> paramMap = new HashMap<>(); paramMap.put("userId", "123456"); // 设置请求头 HttpHeaders headers = new HttpHeaders(); headers.add("Content-Type","application/json"); headers.add("auth","12334455666"); HttpEntity<Object> entity = new HttpEntity<Object>(paramMap,headers); JSONObject result = restTemplate.postForObject(url, entity,JSONObject.class);
2.1、表单的方式
MultiValueMap<String, String> paramMap = new LinkedMultiValueMap<>(); paramMap.add("userId", "123456"); //设置请求头 HttpHeaders headers = new HttpHeaders(); headers.add("Content-Type", "application/x-www-form-urlencoded"); headers.add("auth","12334455666"); HttpEntity<Object> entity = new HttpEntity<Object>(paramMap, headers); JSONObject result = restTemplate.postForObject(url, entity, JSONObject.class);
注意：
使用 RestTemplate 提交表单时必须使用 MultiValueMap来传参
是因为是用HashMap定义的参数在使用表单方式传递的时候，最终数据是以json形式传过去的
MultiValueMap 和 Map的区别：
MultiValueMap 一个 key 可以对应多个 value
Map 一个 key 对应一个 value
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