提取/处理HTML网页的文本

1. 提取HTML网页的内容

代码如下，

import java.net.*;
import java.io.*;

public class hello {
	
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        URL oracle = new URL("https://docs.oracle.com/javase/tutorial/networking/urls/readingURL.html");
        BufferedReader in = new BufferedReader(new InputStreamReader(oracle.openStream()));
        
        String inputLine;
        while((inputLine = in.readLine()) != null) {
            System.out.println(inputLine);
        }
        in.close();
    }
}

另一种实现方法如下，

import java.net.*;
import java.io.*;

public class hello {
    
    public static String loadWebPage(String urlString) {
        byte[] buffer = new byte[1024];
        String content = new String();
        
        try {
            URL url = new URL(urlString);
            InputStream in = url.openStream();
            
            int len;
            while((len = in.read(buffer)) != -1) {
                content += new String(buffer);
            }
        } catch (IOException e) {
                content = "
Fail to download the page
" + urlString;
        }
        return content;
    }
    
    public static void main(String[] args) throws Exception {
        String url = "https://docs.oracle.com/javase/tutorial/networking/urls/readingURL.html";
        System.out.println(loadWebPage(url));
    }
}

2. ParserCallback处理HTML文本数据

ParserCallback提供了HTML文本处理的方法，如下，

import java.net.*;

import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.parser.ParserDelegator;

import java.io.*;

// ParserCallback class provides tools to handle the web content
class MyParserCallback extends HTMLEditorKit.ParserCallback {
    public String content = new String();

    @Override
    public void handleText(char[] data, int pos) {
        content += " " + new String(data);
    }
}

public class hello {
    
	// Initial the PaeserCallback class
	public static String loadPlainText(String urlString) throws IOException {
        MyParserCallback callback = new MyParserCallback();
        ParserDelegator parser = new ParserDelegator();
        
        URL url = new URL(urlString);
        InputStreamReader reader = new InputStreamReader(url.openStream());
        parser.parse(reader, callback, true);
            
        return callback.content;
    }
	
    public static String loadWebPage(String urlString) {
        byte[] buffer = new byte[1024];
        String content = new String();
        
        try {
            URL url = new URL(urlString);
            InputStream in = url.openStream();
            
            int len;
            while((len = in.read(buffer)) != -1) {
                content += new String(buffer);
            }
        } catch (IOException e) {
                content = "
Unable to download the page
" + urlString;
        }
        return content;
    }
    
    // Main function
    public static void main(String[] args) throws Exception {
        String url = "https://docs.oracle.com/javase/tutorial/networking/urls/readingURL.html";
        System.out.println(loadPlainText(url));
    } 
}

参考资料

[1. Oracle URL website] https://docs.oracle.com/javase/tutorial/networking/urls/readingURL.html