HTMLPage类基础说明
HTMLPage类：HTMLPage类中主要也就几种用途，而从HTMLPage类中抓取图片是一个非常重要的一个功能，诚然还有超链接和表单。而在HTMLPage类的内置类Parser中，大部分工作都是由handleSimpleTag（简单标签）和和handleStartTag（起始标签方法来完成。
详细代码清单如下：
package com.heaton.bot;
import java.util.*;
import com.heaton.bot.*;
import java.net.*;
import java.io.*;
import javax.swing.text.*;
import javax.swing.text.html.*;
/**
* The HTMLPage class is used to parse an HTML page and store
* that page, in a parsed form, in memory.
* are exchanged with a webserver.
*/
public class HTMLPage {
/**
* A list of images on this page.
*/
protected Vector images = new Vector();
/**
* A list of links on this page.
*/
protected Vector links = new Vector();
/**
* A list of forms on this page.
*/
protected Vector forms = new Vector();
/**
* The underlying HTTP object for this page.
*/
protected HTTP http;
/**
* The base URL to resolve relative URL's.
*/
protected String base;
/**
* Construct an HTMLPage object.
*
* @param http The HTTP object(or subclass) to use to
* download pages.
*/
public HTMLPage(HTTP http)
{
this.http = http;
}
/**
* Called to open a page and read it in. If null
* is specified for the callback(回调）, then the other
* methods in this class may be used to look at
* images, links and forms.
* open是进入HTMLPage类的入口点。
* @param url The URL to read.
* @param callback A callback class to handle the parse, or null
* to use the built in one.
* @exception java.io.IOException
* @exception javax.swing.text.BadLocationException
*/
public void open(String url,
HTMLEditorKit.ParserCallback callback)
throws IOException,BadLocationException
{
http.send(url,null);
base = url;
processPage(callback);
}
/**
* Internal function called to start the parse.
*
* @param callback The callback object to use.
* @exception java.io.IOException
*/
protected void processPage(HTMLEditorKit.ParserCallback callback)
throws IOException
{
/*
* 创建一个字符串阅读器。
*/
StringReader r = new StringReader(http.getBody());
/*
* 创建新的解析器。
*/
HTMLEditorKit.Parser parse = new HTMLParse().getParser();
/*
* 程序检查是否提供了定制的回调类。如果提供了回调类，则
* 使用该会掉泪，从而结束了HTMLPage类的工作。如果没有提
* 供回调类，HTMLPage则使用内置的回调类，该回调类为Parser。
*/
if ( callback==null ) {
HTMLPage.Parser p=new HTMLPage.Parser();
parse.parse(r,p,true);
} else
parse.parse(r,callback,false);
}
/**
* Get the underlying HTTP object that was
* sent to the constructor.
*
* @return The underlying HTTP object.
*/
public HTTP getHTTP()
{
return http;
}
/**
* Get a list of all of the links from this page.
* If this is to be used then null must have been
* passed as the callback object to the open method.
*
* @return All links on this page.
*/
public Vector getLinks()
{
return links;
}
/**
* Get a list of all of the images from this page.
* If this is to be used then null must have been
* passed as the callback object to the open method.
*
* @return A list of all of the images on this page.
*/
public Vector getImages()
{
return images;
}
/**
* Get a list of all of the forms from this page.
* If this is to be used then null must have been
* passed as the callback object to the open method.
*
* @return A list of forms.
*/
public Vector getForms()
{
return forms;
}
/**
* Called to perform a post for the specified form.
*
* @param form The form object to post.
* @exception java.io.IOException
*/
public void post(HTMLForm form)
throws IOException
{
http.getClientHeaders().set("Content-Type",
"application/x-www-form-urlencoded");
http.send(form.getAction(),form.toString());
processPage(null);
}
/**
* Get the URL that is represented by this page.
*
* @return The URL that is represented by this page.
*/
public String getURL()
{
return http.getURL();
}
/**
* Called internally to add an image to the list.
*
* @param img The image to add.
*/
protected void addImage(String img)
{
img = URLUtility.resolveBase(base,img);
for ( int i=0;i<images.size();i ) {
String s = (String)images.elementAt(i);
if ( s.equalsIgnoreCase(img) )
return;
}
images.addElement(img);
}
/**
* A HTML parser callback used by this class to
* detect links, images and forms.
* 定义一个名为Parser的内部类，该类实现一个专门的解析器回
* 调函数，用来跟踪超链接，图像和表单。
*/
protected class Parser
extends HTMLEditorKit.ParserCallback {
/**
* Used to build up data for an HTML form.
*/
protected HTMLForm tempForm;
/**
* Used to build up options for an HTML form.
*/
protected AttributeList tempOptions;
/**
* Used to build up options for an HTML form.
*/
protected Attribute tempElement = new Attribute();
/**
* Holds the prompt text(just before or after a control.
*/
protected String tempPrompt = "";
/**
* Holds the link till the end link is found
*/
protected Link tempLink;
/**
* Called to handle comments.
*
* @param data The comment.
* @param pos The position.
*/
public void handleComment(char[] data,int pos)
{
}
/**
* Called to handle an ending tag.
*
* @param t The ending tag.
* @param pos The position.
*/
public void handleEndTag(HTML.Tag t,int pos)
{
if ( t==HTML.Tag.OPTION ) {
if ( tempElement!=null ) {
tempElement.setName(tempPrompt);
tempOptions.add(tempElement);
tempPrompt = "";
}
tempElement = null;
} else if ( t==HTML.Tag.FORM ) {
if ( tempForm!=null )
forms.addElement(tempForm);
tempPrompt = "";
} else if ( t==HTML.Tag.A ) {
if ( tempLink!=null )
tempLink.setPrompt(tempPrompt);
tempPrompt = "";
}
}
/**
* Called to handle an error. Not used.
*
* @param errorMsg The error.
* @param pos The position.
*/
public void handleError(String errorMsg,int pos)
{
}
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/**
* Called to handle a simple tag.
*
* @param t The simple tag.
* @param a The attribute list.
* @param pos The position.
*/
public void handleSimpleTag(HTML.Tag t,
MutableAttributeSet a,int pos)
{
handleStartTag(t,a,pos);
}
/**
* Called to handle a starting tag.
*
* @param t The starting tag.
* @param a The attribute list.
* @param pos The position.
*/
public void handleStartTag(HTML.Tag t,
MutableAttributeSet a,int pos)
{
String type = "";
// is it some sort of a link
String href = (String)a.getAttribute(HTML.Attribute.HREF);
if ( (href!=null) && (t!=HTML.Tag.BASE) ) {
String alt = (String)a.getAttribute(HTML.Attribute.ALT);
Link link = new Link(
alt,
URLUtility.resolveBase(base,href),
null);
links.addElement(tempLink=link);
} else if ( t==HTML.Tag.OPTION ) {
tempElement = new Attribute();
tempElement.setName("");
tempElement.setValue((String)a.getAttribute(HTML.Attribute.VALUE));
} else if ( t==HTML.Tag.SELECT ) {
if ( tempForm==null )
return;
tempOptions = new AttributeList();
tempForm.addInput(
(String)a.getAttribute(HTML.Attribute.NAME),
null,
"select",
tempPrompt,
tempOptions);
tempPrompt = "";
} else if ( t==HTML.Tag.TEXTAREA ) {
if ( tempForm==null )
return;
tempForm.addInput(
(String)a.getAttribute(HTML.Attribute.NAME),
null,
"textarea",
tempPrompt,
null);
tempPrompt = "";
}
else if ( t==HTML.Tag.FORM ) {
if ( tempForm!=null )
forms.addElement(tempForm);
String action =
(String)a.getAttribute(HTML.Attribute.ACTION);
if ( action!=null ) {
try {
URL aurl = new URL(new URL(http.getURL()),action);
action = aurl.toString();
} catch ( MalformedURLException e ) {
action = null;
}
}
tempForm = new HTMLForm(
(String)a.getAttribute(HTML.Attribute.METHOD),
action );
tempPrompt = "";
} else if ( t==HTML.Tag.INPUT ) {
if ( tempForm==null )
return;
if ( t!=HTML.Tag.INPUT ) {
type = (String)a.getAttribute(HTML.Attribute.TYPE);
if ( type==null )
return;
} else
type = "select";
if ( type.equalsIgnoreCase("text") ||
type.equalsIgnoreCase("edit") ||
type.equalsIgnoreCase("password") ||
type.equalsIgnoreCase("select") ||
type.equalsIgnoreCase("hidden") ) {
tempForm.addInput(
(String)a.getAttribute(HTML.Attribute.NAME),
(String)a.getAttribute(HTML.Attribute.VALUE),
type,
tempPrompt,
null);
tempOptions = new AttributeList();
}
} else if ( t==HTML.Tag.BASE ) {
href = (String)a.getAttribute(HTML.Attribute.HREF);
if ( href!=null )
base = href;
} else if ( t==HTML.Tag.IMG ) {
String src = (String)a.getAttribute(HTML.Attribute.SRC);
if ( src!=null )
addImage(src);
}
}
/**
* Called to handle text.
*
* @param data The text.
* @param pos The position.
*/
public void handleText(char[] data,int pos)
{
tempPrompt= new String(data) " ";
}
}
} 上一页
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