### Java 发送 `application/x-www-form-urlencoded` POST 请求 为了发送带有 `application/x-www-form-urlencoded` 类型参数的 POST 请求，在 Java 中可以使用多种库，比如 Apache HttpClient 或者 Spring 的 RestTemplate。以下是基于这些工具的具体实现方法。 #### 使用 Apache HttpClient 实现 通过 Apache HttpClient 库能够方便地构建并执行 HTTP 请求： ```java import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; public class XWwwFormUrlencodedExample { public static void main(String[] args) throws Exception { try (CloseableHttpClient httpClient = HttpClients.createDefault()) { HttpPost postRequest = new HttpPost("http://example.com/api"); // 设置请求头部信息 postRequest.setHeader("Content-Type", "application/x-www-form-urlencoded"); // 构建表单数据字符串 String params = "title=test&sub[]=1&sub[]=2&sub[]=3"; StringEntity entity = new StringEntity(params); postRequest.setEntity(entity); try (CloseableHttpResponse response = httpClient.execute(postRequest)) { System.out.println(EntityUtils.toString(response.getEntity())); } } } } ``` 这段代码展示了如何创建一个简单的客户端程序来发起带有所需编码类型的 POST 请求[^4]。 #### 利用 Spring Framework 的 RestTemplate 进行操作 如果项目已经引入了 Spring Boot，则推荐采用更简洁的方式来完成相同的功能——RestTemplate: ```java import java.util.Collections; import org.springframework.core.ParameterizedTypeReference; import org.springframework.http.HttpEntity; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpMethod; import org.springframework.http.MediaType; import org.springframework.web.client.RestTemplate; public class SpringXWwwFormUrlencodedExample { private final RestTemplate restTemplate = new RestTemplate(); public void sendPost() { HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED); MultiValueMap<String, String> map= new LinkedMultiValueMap<>(); map.add("title", "test"); List<String> subValues = Arrays.asList("1","2","3"); for(int i=0;i<subValues.size();i++){ map.add("sub["+i+"]", subValues.get(i)); } HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers); ParameterizedTypeReference<Map<String,Object>> responseType = new ParameterizedTypeReference<>(){}; ResponseEntity<Map<String,Object>> response = restTemplate.exchange( "http://example.com/api", HttpMethod.POST, request, responseType ); System.out.println(response.getBody()); } } ``` 此段代码利用了 Spring 提供的强大功能简化了 URL 编码形式的数据提交过程，并且支持更加复杂的场景配置[^3]。