使用Java从网页中提取数据？

我正在尝试用 Java 编写我的第一个程序。目标是编写一个程序来浏览网站并为我下载文件。但是，我不知道如何使用Java与互联网交互。谁能告诉我要查找/阅读哪些主题或推荐一些好的资源？

最简单的解决方案（不依赖于任何第三方库或平台）是创建一个指向要下载的网页/链接的 URL 实例，并使用流读取内容。

例如：

    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.net.URL;
    import java.net.URLConnection;
    
    
    public class DownloadPage {
    
        public static void main(String[] args) throws IOException {
            
            // Make a URL to the web page
            URL url = new URL("http://stackoverflow.com/questions/6159118/using-java-to-pull-data-from-a-webpage");
            
            // Get the input stream through URL Connection
            URLConnection con = url.openConnection();
            InputStream is = con.getInputStream();
            
            // Once you have the Input Stream, it's just plain old Java IO stuff.
            
            // For this case, since you are interested in getting plain-text web page
            // I'll use a reader and output the text content to System.out.
            
            // For binary content, it's better to directly read the bytes from stream and write
            // to the target file.          
            
            try(BufferedReader br = new BufferedReader(new InputStreamReader(is))) {
                String line = null;
            
                // read each line and write to System.out
                while ((line = br.readLine()) != null) {
                    System.out.println(line);
                }
            }
        }
    }

希望这可以帮助。