Java通过URL类下载图片的实例代码

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://img1.baidu.com/it/u=3009731526,373851691&fm=253&fmt=auto&app=138&f=JPEG?w=800&h=500");

            //2.与URL建立连接：首先要在一个 URL 对象上通过方法 openConnection() 生成对应的 URLConnection

            //对象。

            httpsURLConnection = (HttpsURLConnection) url.openConnection();

            httpsURLConnection.connect();

            //3.获取输入流，并创建输出流对象

            is = httpsURLConnection.getInputStream();

            fos = new FileOutputStream(new File("test.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);