下载网页的基本方法

一、Java.net.URL

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

public class RetrivePage {
    public static String downloadPage(String path) throws Exception {
        URL pageURL = new URL(path);
        BufferedReader reader = new BufferedReader(new InputStreamReader(pageURL.openStream()));
        String line;
        StringBuilder pageBuffer = new StringBuilder();
        while ((line = reader.readLine()) != null) {
            pageBuffer.append(line);
        }
        return pageBuffer.toString();
    }

    public static void main(String args[]) throws Exception {
        System.out.println(RetrivePage.downloadPage("http://www.sina.com"));
    }
}

二、Scanner对象

import java.io.InputStreamReader;
import java.net.URL;
import java.util.Scanner;

public class RetrivePage {
    public static String downloadPage(String path) throws Exception {
        URL pageURL = new URL(path);
        Scanner scanner = new Scanner(new InputStreamReader(pageURL.openStream(), "utf-8"));
        scanner.useDelimiter("\\z");
        StringBuilder pageBuffer = new StringBuilder();
        while (scanner.hasNext()) {
           pageBuffer.append(scanner.next());
        }
        return pageBuffer.toString();
    }

    public static void main(String args[]) throws Exception {
        System.out.println(RetrivePage.downloadPage("http://www.sina.com"));
    }
}

三、套接字

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

public class RetrivePage {
    public static void main(String args[]) throws Exception {
        String host = "blog.csdn.net";
        String file = "/column.html";
        int port = 80;
        Socket s = new Socket(host, port);
        OutputStream out = s.getOutputStream();
        PrintWriter outw = new PrintWriter(out, false);
        outw.print("GET" + file + " HTTP/1.0\r\n");
        outw.print("Accept:text/plain,text/html,text/*\r\n");
        outw.print("\r\n");
        outw.flush();
        InputStream in = s.getInputStream();
        InputStreamReader inr = new InputStreamReader(in);
        BufferedReader bufferedReader = new BufferedReader(inr);
        String line;
        while ((line = bufferedReader.readLine()) != null) {
            System.out.println(line);
        }
    }
}

四、HttpClient

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
public class RetrivePage {
    public static void main(String args[]) throws Exception {
        HttpClient httpClient=new DefaultHttpClient();
        HttpGet httpGet=new HttpGet("http://www.sina.com");
        HttpResponse response=httpClient.execute(httpGet);
        HttpEntity entity=response.getEntity();
        if(entity!=null){
            System.out.println(EntityUtils.toString(entity,"utf-8"));
            EntityUtils.consume(entity);
        }
        httpClient.getConnectionManager().shutdown();
    }
}