java 文件上传进度

要实现Java文件上传的进度监控，可以使用Java中的HttpURLConnection类和ProgressBar组件。以下是一个简单的实现步骤：

1. 使用HttpURLConnection类建立与服务器的连接，设置请求方法为POST，并设置文件上传参数。

2. 通过URLConnection获取输出流，将文件数据写入输出流中。

3. 在写入数据的过程中，使用ProgressBar组件更新进度条的进度。

4. 等待服务器响应，如果上传成功，则提示用户上传成功，否则提示上传失败。

以下是一个简单的示例代码，您可以根据实际情况进行修改和优化：

import java.io.*;
import java.net.*;
import javax.swing.*;

public class FileUploader {

    public static void main(String[] args) {
        JFileChooser fileChooser = new JFileChooser();
        int result = fileChooser.showOpenDialog(null);
        if (result == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            uploadFile(file);
        } else {
            JOptionPane.showMessageDialog(null, "请选择要上传的文件！");
        }
    }

    private static void uploadFile(File file) {
        String url = "http://localhost:8080/upload";
        try {
            URL uploadUrl = new URL(url);
            HttpURLConnection connection = (HttpURLConnection) uploadUrl.openConnection();
            connection.setRequestMethod("POST");
            connection.setDoOutput(true);
            connection.setRequestProperty("Content-Type", "application/octet-stream");
            connection.setRequestProperty("Content-Disposition", "attachment; filename=" + file.getName());
            OutputStream outputStream = connection.getOutputStream();
            BufferedInputStream inputStream = new BufferedInputStream(new FileInputStream(file));
            byte[] buffer = new byte[1024];
            int readLength = 0;
            int totalLength = (int) file.length();
            int uploadedLength = 0;
            while ((readLength = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, readLength);
                uploadedLength += readLength;
                int progress = (int) (uploadedLength * 100 / totalLength);
                System.out.println("已上传：" + progress + "%");
            }
            inputStream.close();
            outputStream.flush();
            outputStream.close();
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                JOptionPane.showMessageDialog(null, "上传成功！");
            } else {
                JOptionPane.showMessageDialog(null, "上传失败！");
            }
        } catch (Exception e) {
            e.printStackTrace();
            JOptionPane.showMessageDialog(null, "上传失败！");
        }
    }
}

在实际使用中，您需要将上述代码与GUI界面进行结合，以实现更好的用户体验。