HTMLParser入门_01_网络爬虫的雏形_解析文章和处理文章中的图片
本文所用到的localHTML.html等练习文件
详见此处下载：http://download.csdn.net/detail/jadyer/5127317
package com.jadyer.httpclient;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;
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;
import org.htmlparser.Node;
import org.htmlparser.NodeFilter;
import org.htmlparser.Parser;
import org.htmlparser.filters.NodeClassFilter;
import org.htmlparser.nodes.TagNode;
import org.htmlparser.nodes.TextNode;
import org.htmlparser.tags.ImageTag;
import org.htmlparser.util.NodeList;
/**
* HTMLParser入门_01_网络爬虫的雏形_解析文章和处理文章中的图片
* @see ---------------------------------------------------------------------------------------------------------
* @see 所有jar如下
* @see commons-io-2.3.jar
* @see commons-land-2.3.jar
* @see commons-codec-1.6.jar(以下7个jar取自HttpClient官网下载的httpcomponents-client-4.2.1-bin.zip)
* @see commons-logging-1.1.1.jar
* @see fluent-hc-4.2.1.jar
* @see httpclient-4.2.1.jar
* @see httpclient-cache-4.2.1.jar
* @see httpcore-4.2.1.jar
* @see httpmime-4.2.1.jar
* @see filterbuilder.jar(以下5个jar取自HTMLParser官网下载的HTMLParser-2.0-SNAPSHOT-bin.zip)
* @see htmllexer.jar
* @see htmlparser.jar
* @see sitecapturer.jar
* @see thumbelina.jar
* @see ---------------------------------------------------------------------------------------------------------
* @see 网络爬虫的雏形
* @see 通过本文的三个方法,就可以初步实现一个网络爬虫
* @see 比如有个后台管理系统,可添加待爬虫的技术文章,输入参数为文章URL,输出参数为文章中的实际内容
* @see 并且它还会下载文章内容中的图片,并修改内容中的图片URL为本地的绝对路径,使得文章图片正常显示
* @see 接下来就是在前台显示文章了,至于怎么显示,随心所欲喽..
* @see 至于如何获取文章标题,作者,关键字,总体描述等信息,可参考我的下面这一篇文章
* @see http://blog.csdn.net/jadyer/article/details/8656477
* @see ---------------------------------------------------------------------------------------------------------
* @create Mar 10, 2013 4:05:55 PM
* @author 玄玉<http://blog.csdn/net/jadyer>
*/
public class SpiderDemo {
private static final String articleURI = "http://www.ibm.com/developerworks/cn/java/j-javaroundtable/index.html";
private static final String localHTML = "D:/Download/localHTML.html";
/**
* 下载文章
*/
private static void downloadArticle() throws Exception {
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(articleURI);
try {
HttpResponse response = httpClient.execute(httpGet);
HttpEntity entity = response.getEntity();
if(null != entity){
String responseContent = EntityUtils.toString(entity, "UTF-8");
EntityUtils.consume(entity);
//文章内容写到本地(IOUtils干完活儿会自动关闭IO流)
IOUtils.write(responseContent, new FileOutputStream(localHTML), "UTF-8");
}
}finally{
httpClient.getConnectionManager().shutdown();
}
}
/**
* 下载文章内容中的图片到本地
*/
private static void downloadArticleImage() throws Exception {
//加载文章整理
String html = IOUtils.toString(new FileInputStream(localHTML), "UTF-8");
//获取文章内容,这里是通过分析文章<body>中的特征来获取内容的
String article = StringUtils.substringBetween(html, "<!-- MAIN_COLUMN_CONTENT_BEGIN -->", "<!-- CMA");
System.out.println("文章内容:" + article);
Parser parser = new Parser();
parser.setInputHTML(article);
//提取所有的<img>标签
//这里使用了内置的NodeClassFilter,它会根据节点类型来过滤,这里过滤的是ImageTag节点类型
NodeList imageTags = parser.parse(new NodeClassFilter(ImageTag.class));
for(int i=0; i<imageTags.size(); i++){
ImageTag it = (ImageTag)imageTags.elementAt(i);
//it.getImageURL()即<img>中的src属性值
System.out.println("图片链接:" + it.getImageURL());
//合成图片的绝对路径http://www.ibm.com/developerworks/cn/java/j-javaroundtable/ + it.getImageURL()
String absoluteURL = articleURI.substring(0, articleURI.lastIndexOf("/")+1) + it.getImageURL();
System.out.println("图片地址:" + absoluteURL);
//下载文章内容中的图片
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(absoluteURL);
HttpResponse response = httpClient.execute(httpGet);
HttpEntity entity = response.getEntity();
if(null != entity){
byte[] images = EntityUtils.toByteArray(entity);
IOUtils.write(images, new FileOutputStream("D:/Download/" + FilenameUtils.getName(absoluteURL)));
System.out.println("图片[" + absoluteURL + "]下载完毕");
}
}
}
/**
* 修改文章内容中的图片链接为本地链接
*/
@SuppressWarnings("serial")
private static void modifyImageURL() throws Exception{
StringBuilder sb = new StringBuilder();
String html = IOUtils.toString(new FileInputStream(localHTML), "UTF-8");
String article = StringUtils.substringBetween(html, "<!-- MAIN_COLUMN_CONTENT_BEGIN -->", "<!-- CMA");
Parser parser = new Parser();
parser.setInputHTML(article);
//这里nodeList将包含网页中的所有内容
NodeList nodeList = parser.parse(
new NodeFilter(){
@Override
public boolean accept(Node node) {
//接受所有的标签
return true;
}
}
);
//遍历文章内容中的所有标签
for(int i=0; i<nodeList.size(); i++){
Node node = nodeList.elementAt(i);
if(node instanceof ImageTag){
ImageTag it = (ImageTag)node;
//修改文章内容中<img>图片地址为本地硬盘上的绝对路径
it.setImageURL("D:/Download/" + it.getImageURL());
//把<img>标签所有的内容放到StringBuilder
sb.append(it.toHtml());
}else if(node instanceof TextNode){
TextNode tn = (TextNode)node;
//对于文本节点,直接将其文本放到StringBuilder
sb.append(tn.getText());
}else{
TagNode tn = (TagNode)node;
//将标签原样放到StringBuilder
sb.append("<").append(tn.getText()).append(">");
}
}
System.out.println("图片链接修改后的文章内容为:" + sb);
//FileUtils的好处是,当文件所在目录不存在时,它会自动创建,省去我们判断的步骤了
FileUtils.writeStringToFile(new File("D:/Download/newHTML.html"), sb.toString());
}
}