java、jsp获取网页源码内容的三种方法

一、GetURL.java
import java.io.*;
import java.net.*;

public class GetURL {
    public static void main(String[] args) {
        InputStream in = null;  
        OutputStream out = null;
        try {
            // 检查命令行参数
            if ((args.length != 1)&& (args.length != 2))
                throw new IllegalArgumentException("Wrong number of args");
    
          
            URL url = new URL(args[0]);   //创建 URL
            in = url.openStream();        // 打开到这个URL的流
            if (args.length == 2)         // 创建一个适当的输出流
                out = new FileOutputStream(args[1]);
            else out = System.out;
    
            // 复制字节到输出流
            byte[] buffer = new byte[4096];
            int bytes_read;
            while((bytes_read = in.read(buffer)) != -1)
                out.write(buffer, 0, bytes_read);
}
     
        catch (Exception e) {
            System.err.println(e);
            System.err.println("Usage: java GetURL <URL> [<filename>]");
        }
        finally { //无论如何都要关闭流
            try { in.close(); out.close(); } catch (Exception e) {}
        }
    }
}

运行方法：
C:\java>java   GetURL http://127.0.0.1:8080/kj/index.html index.html

二、geturl.jsp

<%@ page import="java.io.*" contentType="text/html;charset=gb2312" %>
<%@ page language="java" import="java.net.*"%>

<%
        String htmpath=null;
        BufferedReader in = null;
        InputStreamReader isr = null;
        InputStream is = null;
        PrintWriter pw=null;
        HttpURLConnection huc = null;
        try{
           htmpath=getServletContext().getRealPath("/")+"html\\morejava.html";
           pw=new PrintWriter(htmpath);
           URL url = new URL("http://127.0.0.1:8080/kj/morejava.jsp"); //创建 URL
              huc = (HttpURLConnection)url.openConnection();
              is = huc.getInputStream();
              isr = new InputStreamReader(is);
              in = new BufferedReader(isr);
              String line = null;
              while(((line = in.readLine()) != null)) {
                 if(line.length()==0)
                   continue;
                 pw.println(line);
               }
      
         }
     
        catch (Exception e) {
            System.err.println(e);
        }
         finally { //无论如何都要关闭流
            try { is.close(); isr.close();in.close();huc.disconnect();pw.close();   
            } catch (Exception e) {}
        }

%>
        OK--,创建文件成功

三、HttpClient.java

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

public class HttpClient {
    public static void main(String[] args) {
        try {
            // 检查命令行参数
            if ((args.length != 1) && (args.length != 2))
                throw new IllegalArgumentException("Wrong number of args");
           
            OutputStream to_file;
            if (args.length == 2)
                  to_file = new FileOutputStream(args[1]);//输出到文件
            else
                  to_file = System.out;//输出到控制台
           
          
            URL url = new URL(args[0]);
            String protocol = url.getProtocol();
            if (!protocol.equals("http"))
               throw new IllegalArgumentException("Must use 'http:' protocol");
            String host = url.getHost();
            int port = url.getPort();
            if (port == -1) port = 80;
            String filename = url.getFile();

            Socket socket = new Socket(host, port);//打开一个socket连接

            InputStream from_server = socket.getInputStream();//获取输入流
            PrintWriter to_server = new PrintWriter(socket.getOutputStream());//获取输出流
           
        
            to_server.print("GET " + filename + "\n\n");//请求服务器上的文件
            to_server.flush(); // Send it right now!
           
            byte[] buffer = new byte[4096];
            int bytes_read;

            //读服务器上的响应，并写入文件。
            while((bytes_read = from_server.read(buffer)) != -1)
                to_file.write(buffer, 0, bytes_read);
           
            socket.close();
            to_file.close();
        }
        catch (Exception e) {   
            System.err.println(e);
            System.err.println("Usage: java HttpClient <URL> [<filename>]");
        }
    }
}

运行方法：C:\java>java   HttpClient http://127.0.0.1:8080/kj/index.html index.html

 

注意中文可能会显示乱码,在得到源码后,应该做相应的转码工作,例如:

public static String GetURLstr(String strUrl)
{
   InputStream in = null;
   OutputStream out = null;
   String strdata = "";
   try
   {
    URL url = new URL(strUrl); // 创建 URL
    in = url.openStream(); // 打开到这个URL的流
    out = System.out;

    // 复制字节到输出流
    byte[] buffer = new byte[4096];
    int bytes_read;
    while ((bytes_read = in.read(buffer)) != -1)
    {
     String reads = new String(buffer, 0, bytes_read, "UTF-8");
     //System.out.print(reads);
     strdata = strdata + reads;
     // out.write(buffer, 0, bytes_read);
    }

    in.close();
    out.close();
    return strdata;
   }

   catch (Exception e)
   {
    System.err.println(e);
    System.err.println("Usage: java GetURL <URL> [<filename>]");
    return strdata;
   }
}