httpclient post请求如何传递list

在Apache HttpClient库中发送POST请求并传递List数据通常需要将List转换为合适的格式，如JSON或URL-encoded form data。这里我将以JSON为例说明过程：

1. 首先，你需要添加对Jackson库的支持，因为HttpClient本身并不直接支持序列化List到JSON。你可以通过Maven或Gradle添加依赖：

<!-- Maven -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.8</version>
</dependency>

// Gradle
implementation 'com.fasterxml.jackson.core:jackson-databind'

2. 创建一个`List`对象，例如List<String>:

List<String> myList = Arrays.asList("item1", "item2", "item3");

3. 使用`ObjectMapper`将List转换为JSON字符串：

import com.fasterxml.jackson.databind.ObjectMapper;

ObjectMapper mapper = new ObjectMapper();
String jsonContent = mapper.writeValueAsString(myList);

4. 设置POST请求的内容类型为application/json，并设置实际的数据：

CloseableHttpResponse response;
HttpPost post = new HttpPost("http://your-api-url.com/endpoint");
post.setHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
StringEntity entity = new StringEntity(jsonContent);
entity.setContentType(MediaType.APPLICATION_JSON);
post.setEntity(entity);

5. 发送请求并处理响应：

CloseableHttpClient httpClient = HttpClients.createDefault();
try {
    response = httpClient.execute(post);
    // ...处理响应...
} finally {
    EntityUtils.consume(response.getEntity());
    httpClient.close();
}