使用Java实现批量上传文件至服务器的代码

以下是Java实现批量上传文件至服务器的代码示例：

import java.io.*;
import java.net.*;
import java.util.*;

public class FileUploader {
    private static String BOUNDARY = UUID.randomUUID().toString().substring(0, 10); //设置数据分隔线

    public static void uploadFiles(String url, Map<String, String> paramMap, List<File> fileList) throws IOException {
        URL uploadUrl = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) uploadUrl.openConnection();
        conn.setRequestMethod("POST");
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);

        OutputStream out = new DataOutputStream(conn.getOutputStream());

        //上传的表单参数部分
        StringBuilder paramSb = new StringBuilder();
        for (Map.Entry<String, String> entry : paramMap.entrySet()) {
            paramSb.append("--").append(BOUNDARY).append("\r\n");
            paramSb.append("Content-Disposition: form-data; name=\"").append(entry.getKey()).append("\"\r\n\r\n");
            paramSb.append(entry.getValue()).append("\r\n");
        }
        out.write(paramSb.toString().getBytes());

        //上传的文件部分
        for (File file : fileList) {
            String filename = file.getName();
            StringBuilder sb = new StringBuilder();
            sb.append("--").append(BOUNDARY).append("\r\n");
            sb.append("Content-Disposition: form-data; name=\"file\"; filename=\"").append(filename).append("\"\r\n");
            sb.append("Content-Type: ").append(URLConnection.guessContentTypeFromName(filename)).append("\r\n\r\n");
            out.write(sb.toString().getBytes());

            InputStream in = new FileInputStream(file);
            byte[] buffer = new byte[1024];
            int len = -1;
            while ((len = in.read(buffer)) != -1) {
                out.write(buffer, 0, len);
            }
            in.close();
            out.write("\r\n".getBytes());
        }
        out.write(("--" + BOUNDARY + "--\r\n").getBytes());

        out.flush();
        out.close();

        //读取服务器响应
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
        reader.close();

        conn.disconnect();
    }
}

调用示例：

Map<String, String> paramMap = new HashMap<String, String>();
paramMap.put("username", "testuser");
paramMap.put("password", "testpass");

List<File> fileList = new ArrayList<File>();
fileList.add(new File("D:/testfile1.txt"));
fileList.add(new File("D:/testfile2.txt"));

String url = "http://localhost:8080/upload";
FileUploader.uploadFiles(url, paramMap, fileList);