文件上传的java代码

以下是文件上传的Java代码示例：

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.UUID;

public class FileUploader {
    public static void upload(String url, String filePath) throws IOException {
        File file = new File(filePath);
        String boundary = UUID.randomUUID().toString();

        URL uploadUrl = new URL(url);
        HttpURLConnection connection = (HttpURLConnection) uploadUrl.openConnection();
        connection.setDoOutput(true);
        connection.setDoInput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);

        String lineEnd = "\r\n";
        String twoHyphens = "--";

        // 开始写入文件
        InputStream inputStream = new FileInputStream(file);
        connection.getOutputStream().write((twoHyphens + boundary + lineEnd).getBytes());
        connection.getOutputStream().write(("Content-Disposition: form-data; name=\"file\"; filename=\"" + file.getName() + "\"" + lineEnd).getBytes());
        connection.getOutputStream().write(("Content-Type: application/octet-stream" + lineEnd + lineEnd).getBytes());

        byte[] buffer = new byte[1024];
        int length;
        while ((length = inputStream.read(buffer)) != -1) {
            connection.getOutputStream().write(buffer, 0, length);
        }

        connection.getOutputStream().write((lineEnd + twoHyphens + boundary + twoHyphens + lineEnd).getBytes());
        inputStream.close();

        // 获取响应信息
        int responseCode = connection.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            InputStream responseStream = connection.getInputStream();
            byte[] responseBuffer = new byte[1024];
            int responseLength;
            while ((responseLength = responseStream.read(responseBuffer)) != -1) {
                System.out.println(new String(responseBuffer, 0, responseLength));
            }
            responseStream.close();
        } else {
            System.out.println("上传失败，错误码：" + responseCode);
        }

        connection.disconnect();
    }
}

使用示例：

public static void main(String[] args) {
    try {
        FileUploader.upload("http://localhost:8080/upload", "/path/to/file");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

其中 `http://localhost:8080/upload` 是文件上传接口的 URL，`/path/to/file` 是文件路径。