HttpClient添加form-data

HttpClient可以使用MultipartEntityBuilder来添加form-data。

首先需要导入以下包：

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

然后可以使用以下代码片段来添加form-data：

// 创建HttpClient对象
HttpClient httpClient = HttpClients.createDefault();
// 创建HttpPost对象
HttpPost httpPost = new HttpPost(url);
// 创建MultipartEntityBuilder对象
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
// 添加form-data参数
builder.addTextBody("key1", "value1");
builder.addTextBody("key2", "value2");
// 构建HttpEntity对象
HttpEntity entity = builder.build();
// 将HttpEntity对象设置到HttpPost对象中
httpPost.setEntity(entity);
// 发送HttpPost请求，并获取HttpResponse对象
HttpResponse httpResponse = httpClient.execute(httpPost);
// 获取响应状态码
int statusCode = httpResponse.getStatusLine().getStatusCode();
// 获取响应字符串
String responseString = EntityUtils.toString(httpResponse.getEntity());

其中，`url`为请求的URL地址，`key1`和`key2`为form-data字段名，`value1`和`value2`为form-data字段值。

需要注意的是，如果要上传文件，可以使用`addBinaryBody`方法来添加文件，具体使用方法可以参考[MultipartEntityBuilder](https://hc.apache.org/httpcomponents-client-ga/httpmime/apidocs/org/apache/http/entity/mime/MultipartEntityBuilder.html)文档。