java下载一张图片_java实现从网上下载图片并保存到本地

可以使用 Java 中的 HttpURLConnection 类来从网上下载图片并保存到本地。下面是一个实现示例：

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

public class DownloadImage {
    public static void main(String[] args) {
        String imageUrl = "https://example.com/image.jpg";
        String destinationFile = "image.jpg";

        try {
            URL url = new URL(imageUrl);
            HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection();
            httpConnection.setRequestMethod("GET");
            int responseCode = httpConnection.getResponseCode();

            if (responseCode == HttpURLConnection.HTTP_OK) {
                InputStream inputStream = httpConnection.getInputStream();
                FileOutputStream outputStream = new FileOutputStream(destinationFile);

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

                outputStream.close();
                inputStream.close();
                System.out.println("Image downloaded successfully.");
            } else {
                System.out.println("Image download failed. Response code: " + responseCode);
            }

        } catch (IOException ex) {
            System.out.println("Error during image download: " + ex.getMessage());
        }
    }
}

在上述代码中，`imageUrl` 变量是图片的 URL 地址，`destinationFile` 变量是下载后保存到本地的文件名及路径。该程序使用 HttpURLConnection 类的 `getInputStream()` 方法获取图片数据，然后将其写入到本地文件中。