Java通过URL类下载图片的实例代码

星空彼岸007 2023-03-20 我要评论

Java通过URL类下载图片

一、概述

URL(Uniform Resource Locator) ：统一资源定位符，它表示 Internet 上某一资源的地址。它是一种具体的 URI ，即 URL 可以用来标识一个资源，而且还指明了如何 locate 这个资源。通过 URL 我们可以访问 Internet 上的各种网络资源，比如最常见的 www ， ftp 站点。浏览器通过解析给定的 URL 可以在网络上查找相应的文件或其他资源。 URL 的基本结构由 5 部分组成： < 传输协议 >://< 主机名 >:< 端口号 >/< 文件名 ># 片段名 ? 参数列表

二、通过URL下载图片

HttpsURLConnection httpsURLConnection = null;
        InputStream is = null;
        FileOutputStream fos = null;
        try {
            //1.创建URL对象
            URL url = new URL("https://img.qb5200.com/download-x/zhongzhuanl9/jb/20230320/irxgxz4h5qv.jpg"));
            //4.输出图片
            byte[] buffer = new byte[1024];
            int len;
            while ((len = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //5.关闭资源
            try {
                if (is != null)
                    is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (fos != null)
                    fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (httpsURLConnection != null)
                httpsURLConnection.disconnect();
        }

扩展：java通过url获取图片文件

1. 根据url下载Url中的图片

import java.net.URL;
import java.io.InputStream;
import java.io.FileOutputStream;

public class ImageDownloader {
    public static void main(String[] args) throws Exception {
        // URL of the image to download
        String imageUrl = "https://example.com/image.jpg";
        
        // Create URL object and open input stream to the image
        URL url = new URL(imageUrl);
        InputStream inputStream = url.openStream();
        
        // Output stream to save the image to file
        FileOutputStream outputStream = new FileOutputStream("image.jpg");
        
        // Read bytes from the input stream and write to the output stream
        byte[] buffer = new byte[2048];
        int length;
        while ((length = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, length);
        }
        
        // Close streams
        inputStream.close();
        outputStream.close();
        
        System.out.println("Image downloaded successfully.");
    }
}

2. 根据get请求url下载Url中的图片

import java.net.URL;
import java.io.InputStream;
import java.io.FileOutputStream;

public class ImageDownloader {
    public static void main(String[] args) throws Exception {
        // URL of the image to download
        String imageUrl = "https://example.com/image.jpg";
        
        // Create URL object and open input stream to the image
        URL url = new URL(imageUrl);
        InputStream inputStream = url.openStream();
        
        // Output stream to save the image to file
        FileOutputStream outputStream = new FileOutputStream("image.jpg");
        
        // Read bytes from the input stream and write to the output stream
        byte[] buffer = new byte[2048];
        int length;
        while ((length = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, length);
        }
        
        // Close streams
        inputStream.close();
        outputStream.close();
        
        System.out.println("Image downloaded successfully.");
    }
}

3. 考虑url中携带中文，需要做转义

    imageUrl = URLEncoder.encode(imageUrl, "utf-8")
            .replaceAll("%3A", ":")
            .replaceAll("%2F", "/")
            .replaceAll("%2C", ",")
            .replaceAll("%7B", "{")
            .replaceAll("%3F","?")
            .replaceAll("%7D", "}")
            .replaceAll("%26","&")
            .replaceAll("%3D","=");
    //new一个URL对象
    URL url = new URL(imageUrl);