Android下如何通过http协议同时向服务器发送多个文件和文本？

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;

public class FileUploader implements Runnable {
    private String filePath;
    private String serverUrl;

    public FileUploader(String filePath, String serverUrl) {
        this.filePath = filePath;
        this.serverUrl = serverUrl;
    }

    @Override
    public void run() {
        try {
            // 创建URL对象
            URL url = new URL(serverUrl);
            // 创建HttpURLConnection对象
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            // 设置请求方法为POST
            connection.setRequestMethod("POST");
            // 允许输入输出流
            connection.setDoInput(true);
            connection.setDoOutput(true);

            // 创建文件输入流
            File file = new File(filePath);
            FileInputStream fileInputStream = new FileInputStream(file);

            // 获取输出流
            DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());

            // 写入文件数据
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            // 关闭流
            fileInputStream.close();
            outputStream.flush();
            outputStream.close();

            // 获取响应码
            int responseCode = connection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                // 文件上传成功
            } else {
                // 文件上传失败
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

String serverUrl = "http://example.com/upload";
String filePath1 = "/path/to/file1";
String filePath2 = "/path/to/file2";
String text = "Hello, server!";

// 创建并启动线程
Thread thread1 = new Thread(new FileUploader(filePath1, serverUrl));
Thread thread2 = new Thread(new FileUploader(filePath2, serverUrl));
thread1.start();
thread2.start();

// 发送文本
// ...