在安卓系统中使用Php从HttpClient接收服务器端的JSON POST请求？

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.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

public class MainActivity extends AppCompatActivity {

    private static final String SERVER_URL = "http://example.com/api";
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        // 创建HttpClient对象
        HttpClient httpClient = new DefaultHttpClient();
        
        // 创建HttpPost对象，并设置请求URL
        HttpPost httpPost = new HttpPost(SERVER_URL);
        
        try {
            // 设置请求头信息
            httpPost.setHeader("Content-Type", "application/json");
            
            // 构造请求体JSON数据
            JSONObject json = new JSONObject();
            json.put("key1", "value1");
            json.put("key2", "value2");
            
            // 设置请求体
            StringEntity entity = new StringEntity(json.toString());
            httpPost.setEntity(entity);
            
            // 发送请求并获取响应
            HttpResponse response = httpClient.execute(httpPost);
            
            // 获取响应实体
            HttpEntity httpEntity = response.getEntity();
            
            // 读取响应内容
            InputStream inputStream = httpEntity.getContent();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            StringBuilder stringBuilder = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                stringBuilder.append(line);
            }
            String responseJson = stringBuilder.toString();
            
            // 处理响应数据
            JSONObject jsonResponse = new JSONObject(responseJson);
            String result = jsonResponse.getString("result");
            
            // 关闭输入流和HttpClient
            inputStream.close();
            httpClient.getConnectionManager().shutdown();
            
            // 在此处处理服务器返回的JSON数据
            // ...
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

<?php
// 获取POST请求的JSON数据
$jsonData = file_get_contents('php://input');

// 解析JSON数据
$data = json_decode($jsonData, true);

// 在此处处理接收到的JSON数据
// ...

// 构造响应数据
$responseData = array(
    'result' => 'success'
);

// 将响应数据转换为JSON格式
$responseJson = json_encode($responseData);

// 设置响应头信息
header('Content-Type: application/json');

// 输出响应数据
echo $responseJson;
?>