使用Java从网页中提取数据？ [英] Using Java to pull data from a webpage?

问题描述

我正在尝试用Java创建我的第一个程序。目标是编写一个浏览网站并为我下载文件的程序。但是，我不知道如何使用Java与互联网进行交互。谁能告诉我哪些主题可以查找/阅读或推荐一些好资源？

I'm attempting to make my first program in Java. The goal is to write a program that browses to a website and downloads a file for me. However, I don't know how to use Java to interact with the internet. Can anyone tell me what topics to look up/read about or recommend some good resources?

推荐答案

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

The simplest solution (without depending on any third-party library or platform) is to create a URL instance pointing to the web page / link you want to download, and read the content using streams.

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.


        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);
        }
    }
}

希望这有帮助。

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