ava http get请求下载文件_Java Http下载文件到本地 判断是否下载成功

好的，针对您的问题，我可以给您提供以下 Java 代码，用于使用 HTTP GET 请求下载文件并判断是否下载成功：

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

public class HttpDownloadUtility {
    private static final int BUFFER_SIZE = 4096;

    /**
     * 用 HTTP GET 请求下载文件到本地
     * @param fileURL 文件的URL地址
     * @param saveDir 文件保存的目录
     * @return 文件保存的绝对路径，如果下载失败则返回 null
     * @throws IOException
     */
    public static String downloadFile(String fileURL, String saveDir)
            throws IOException {
        URL url = new URL(fileURL);
        HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
        int responseCode = httpConn.getResponseCode();

        // 如果HTTP响应码是200，表示连接成功
        if (responseCode == HttpURLConnection.HTTP_OK) {
            String fileName = "";
            String disposition = httpConn.getHeaderField("Content-Disposition");
            String contentType = httpConn.getContentType();
            int contentLength = httpConn.getContentLength();

            if (disposition != null) {
                // 从Content-Disposition中获取文件名
                int index = disposition.indexOf("filename=");
                if (index > 0) {
                    fileName = disposition.substring(index + 10,
                            disposition.length() - 1);
                }
            } else {
                // 从URL中获取文件名
                fileName = fileURL.substring(fileURL.lastIndexOf("/") + 1,
                        fileURL.length());
            }

            System.out.println("Content-Type = " + contentType);
            System.out.println("Content-Disposition = " + disposition);
            System.out.println("Content-Length = " + contentLength);
            System.out.println("fileName = " + fileName);

            // 打开网络输入流
            InputStream inputStream = httpConn.getInputStream();
            String saveFilePath = saveDir + File.separator + fileName;

            // 打开本地文件输出流
            FileOutputStream outputStream = new FileOutputStream(saveFilePath);

            // 读取网络输入流到本地文件输出流
            int bytesRead = -1;
            byte[] buffer = new byte[BUFFER_SIZE];
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            outputStream.close();
            inputStream.close();

            System.out.println("文件下载成功");

            return saveFilePath;
        } else {
            System.out.println("文件下载失败，响应码是 " + responseCode);
            return null;
        }
    }
}

使用方法：

public static void main(String[] args) {
    String fileURL = "http://example.com/file.zip";
    String saveDir = "C:/downloads";
    try {
        HttpDownloadUtility.downloadFile(fileURL, saveDir);
    } catch (IOException ex) {
        ex.printStackTrace();
    }
}

以上代码将会把 `http://example.com/file.zip` 下载到本地的 `C:/downloads` 目录下。

希望能对您有所帮助！