httpclient发送post请求

使用Apache HttpComponents提供的HttpClient发送POST请求可以分为以下几个步骤：

创建 HttpClient 对象

CloseableHttpClient httpClient = HttpClients.createDefault();

创建 HttpPost 对象并设置请求 URL

HttpPost httpPost = new HttpPost("http://www.example.com/submit-form");

设置 POST 请求的参数，可以使用UrlEncodedFormEntity对Form表单进行编码

List<NameValuePair> formParams = new ArrayList<>();
formParams.add(new BasicNameValuePair("username", "user123"));
formParams.add(new BasicNameValuePair("password", "pass123"));
UrlEncodedFormEntity urlEncodedFormEntity = new UrlEncodedFormEntity(formParams, Consts.UTF_8);
httpPost.setEntity(urlEncodedFormEntity);

执行 HTTP POST 请求

CloseableHttpResponse httpResponse = httpClient.execute(httpPost);

处理结果

HttpEntity responseEntity = httpResponse.getEntity();
if (responseEntity != null) {
    // 使用 EntityUtils 将响应实体转换为字符串
    String responseString = EntityUtils.toString(responseEntity);
    // 对响应结果进行处理
    System.out.println(responseString);
}

关闭资源

httpResponse.close();
httpClient.close();

完整示例代码：

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.Consts;
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.entity.StringEntity;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.util.EntityUtils;

public class HttpClientExample {

    public static void main(String[] args) throws IOException {
        CloseableHttpClient httpClient = HttpClients.createDefault();

        try {
            HttpPost httpPost = new HttpPost("http://www.example.com/submit-form");

            List<NameValuePair> formParams = new ArrayList<>();
            formParams.add(new BasicNameValuePair("username", "user123"));
            formParams.add(new BasicNameValuePair("password", "pass123"));

            UrlEncodedFormEntity urlEncodedFormEntity = new UrlEncodedFormEntity(formParams, Consts.UTF_8);
            httpPost.setEntity(urlEncodedFormEntity);

            CloseableHttpResponse httpResponse = httpClient.execute(httpPost);

            try {
                HttpEntity responseEntity = httpResponse.getEntity();
                if (responseEntity != null) {
                    String responseString = EntityUtils.toString(responseEntity);
                    System.out.println(responseString);
                }
            } finally {
                httpResponse.close();
            }
        } finally {
            httpClient.close();
        }
    }
}

以上是使用 HttpClient 发送 POST 请求的方式。需要注意的是，其它类型的 HTTP 方法同样可以通过 HttpClient 来实现，只需使用对应的 HttpGet、HttpPut、HttpDelete等类即可。