对于网络,我一直处于好奇的态度。以前一直想着写个爬虫,但是一拖再拖,懒得实现,感觉这是一个很麻烦的事情,出现个小错误,就要调试很多时间,太浪费时间。
后来一想,既然早早给自己下了保证,就先实现它吧,从简单开始,慢慢增加功能,有时间就实现一个,并且随时优化代码。
下面是我简单实现爬取指定网页,并且保存的简单实现,其实有几种方式可以实现,这里慢慢添加该功能的几种实现方式。
UrlConnection爬取实现
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package html;
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
public class Spider {
public static void main(String[] args) {
String filepath = "d:/124.html" ;
String url_str = "http://www.hao123.com/" ;
URL url = null ;
try {
url = new URL(url_str);
} catch (MalformedURLException e) {
e.printStackTrace();
}
String charset = "utf-8" ;
int sec_cont = 1000 ;
try {
URLConnection url_con = url.openConnection();
url_con.setDoOutput( true );
url_con.setReadTimeout( 10 * sec_cont);
url_con.setRequestProperty( "User-Agent" , "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)" );
InputStream htm_in = url_con.getInputStream();
String htm_str = InputStream2String(htm_in,charset);
saveHtml(filepath,htm_str);
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Method: saveHtml
* Description: save String to file
* @param filepath
* file path which need to be saved
* @param str
* string saved
*/
public static void saveHtml(String filepath, String str){
try {
/*@SuppressWarnings("resource")
FileWriter fw = new FileWriter(filepath);
fw.write(str);
fw.flush();*/
OutputStreamWriter outs = new OutputStreamWriter(new FileOutputStream(filepath, true), "utf-8");
outs.write(str);
System.out.print(str);
outs.close();
} catch (IOException e) {
System.out.println("Error at save html...");
e.printStackTrace();
}
}
/**
* Method: InputStream2String
* Description: make InputStream to String
* @param in_st
* inputstream which need to be converted
* @param charset
* encoder of value
* @throws IOException
* if an error occurred
*/
public static String InputStream2String(InputStream in_st,String charset) throws IOException{
BufferedReader buff = new BufferedReader( new InputStreamReader(in_st, charset));
StringBuffer res = new StringBuffer();
String line = "" ;
while ((line = buff.readLine()) != null ){
res.append(line);
}
return res.toString();
}
}
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实现过程中,爬取的网页的中文乱码问题,是个比较麻烦的事情。
HttpClient爬取实现
HttpClient实现爬取网页时,遇到了很多问题。其一,就是存在两个版本的HttpClient,一个是sun内置的,另一个是apache开源的一个项目,似乎sun内置用的不太多,我也就没有实现,而是采用了apache开源项目(以后说的HttpClient都是指apache的开源版本);其二,在使用HttpClient时,最新的版本已经不同于以前的版本,从HttpClient4.x版本后,导入的包就已经不一样了,从网上找的很多部分都是HttpClient3.x版本的,所以如果使用最新的版本,还是看帮助文件为好。
我用的是Eclipse,需要配置环境导入引用包。
首先,下载HttpClient,地址是:http://hc.apache.org/downloads.cgi,我是用的事HttpClient4.2版本。
然后,解压缩,找到了/lib文件夹下的commons-codec-1.6.jar,commons-logging-1.1.1.jar,httpclient-4.2.5.jar,httpcore-4.2.4.jar(版本号根据下载的版本有所不同,还有其他的jar文件,我这里暂时用不到,所以先导入必须的);
最后,将上面的jar文件,加入classpath中,即右击工程文件 => Bulid Path => Configure Build Path => Add External Jar..,然后添加上面的包就可以了。
还用一种方法就是讲上面的包,直接复制到工程文件夹下的lib文件夹中。
下面是实现代码:
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package html;
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.*;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
public class SpiderHttpClient {
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
String url_str = "http://www.hao123.com" ;
String charset = "utf-8" ;
String filepath = "d:/125.html" ;
HttpClient hc = new DefaultHttpClient();
HttpGet hg = new HttpGet(url_str);
HttpResponse response = hc.execute(hg);
HttpEntity entity = response.getEntity();
InputStream htm_in = null ;
if (entity != null ){
System.out.println(entity.getContentLength());
htm_in = entity.getContent();
String htm_str = InputStream2String(htm_in,charset);
saveHtml(filepath,htm_str);
}
}
/**
* Method: saveHtml
* Description: save String to file
* @param filepath
* file path which need to be saved
* @param str
* string saved
*/
public static void saveHtml(String filepath, String str){
try {
/*@SuppressWarnings("resource")
FileWriter fw = new FileWriter(filepath);
fw.write(str);
fw.flush();*/
OutputStreamWriter outs = new OutputStreamWriter(new FileOutputStream(filepath, true), "utf-8");
outs.write(str);
outs.close();
} catch (IOException e) {
System.out.println("Error at save html...");
e.printStackTrace();
}
}
/**
* Method: InputStream2String
* Description: make InputStream to String
* @param in_st
* inputstream which need to be converted
* @param charset
* encoder of value
* @throws IOException
* if an error occurred
*/
public static String InputStream2String(InputStream in_st,String charset) throws IOException{
BufferedReader buff = new BufferedReader( new InputStreamReader(in_st, charset));
StringBuffer res = new StringBuffer();
String line = "" ;
while ((line = buff.readLine()) != null ){
res.append(line);
}
return res.toString();
}
}
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以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:http://www.cnblogs.com/ywl925/archive/2013/08/20/3270875.html