URL编程

本笔记来源于：尚硅谷Java零基础全套视频教程(宋红康2023版，java入门自学必备)
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1.URL(Uniform Resource Locator)的理解:

统一资源定位符，对应着互联网的某一资源地址

2.URL的5个基本结构：

• http://localhost:8080/examples/beauty.jpg?username=Tom
• 协议 主机名 端口号 资源地址 参数列表

3.如何实例化:

URL url = new URL(“http://localhost:8080/examples/beauty.jpg?username=Tom");

4.常用方法：

5.可以读取、下载对应的url资源：

public static void main(String[] args) {

    HttpURLConnection urlConnection = null;
    InputStream is = null;
    FileOutputStream fos = null;
    try {
        URL url = new URL("http://localhost:8080/examples/beauty.jpg");

        urlConnection = (HttpURLConnection) url.openConnection();

        urlConnection.connect();

        is = urlConnection.getInputStream();
        fos = new FileOutputStream("day10\\beauty3.jpg");

        byte[] buffer = new byte[1024];
        int len;
        while((len = is.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }

        System.out.println("下载完成");
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        //关闭资源
        if(is != null){
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if(fos != null){
            try {
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if(urlConnection != null){
            urlConnection.disconnect();
        }
    }
}