httpclient发送POST请求 java代码

在Java中，可以使用Apache HttpClient库来发送POST请求。以下是一个简单的示例，展示了如何创建一个HttpClient实例并使用它来发送POST请求：

import org.apache.http.HttpEntity;
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 HttpPostExample {
    private static final String URL = "http://example.com/api/endpoint";

    public void sendPostRequest() {
        CloseableHttpClient httpClient = HttpClients.createDefault(); // 创建HttpClient实例

        try {
            // 创建HttpPost对象，指定请求地址
            HttpPost httpPost = new HttpPost(URL);

            // 设置POST数据，这里是一个简单的String，如果是复杂数据可以用JsonEntity
            String requestBody = "{\"key\":\"value\"}";
            httpPost.setEntity(new StringEntity(requestBody, ContentType.APPLICATION_JSON));

            // 发送请求
            CloseableHttpResponse response = httpClient.execute(httpPost);

            try {
                // 检查状态码
                int statusCode = response.getStatusLine().getStatusCode();
                if (statusCode == HttpStatus.SC_OK) {
                    // 从响应中获取实体并处理数据
                    HttpEntity entity = response.getEntity();
                    String responseBody = EntityUtils.toString(entity);
                    System.out.println("Received response: " + responseBody);
                } else {
                    throw new RuntimeException("Failed to execute request: " + response.getStatusLine());
                }
            } finally {
                // 关闭响应和客户端资源
                response.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                httpClient.close(); // 关闭HttpClient
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

在这个例子中，我们首先创建了一个`CloseableHttpClient`实例，然后创建一个`HttpPost`对象，设置请求头和POST数据。接着，我们执行请求并检查响应的状态码，最后关闭响应和客户端资源。