为了支持全文检索，有必要将HTML格式的文章转化为纯文本格式，因此我设计了一个基本的WebFormatter类，提供一个简单的public static String html2text(String html)，将HTML格式转化为Text：
/*
* File: WebFormatter.java
* Created on 2005-6-24
* Author: Liao Xuefeng, asklxf@163.com
* Copyright (C) 2005, Liao Xuefeng.
*/
package com.mboker.blog.web.util;
import java.util.*;
import java.text.SimpleDateFormat;
/**
* Do some format on web display.
*
* @author Xuefeng
*/
public class WebFormatter {
public static String html2text(String html) {
StringBuffer sb = new StringBuffer(html.length());
char[] data = html.toCharArray();
int start = 0;
boolean previousIsPre = false;
Token token = null;
for(;;) {
token = parse(data, start, previousIsPre);
if(token==null)
break;
previousIsPre = token.isPreTag();
sb = sb.append(token.getText());
start += token.getLength();
}
return sb.toString();
}
private static Token parse(char[] data, int start, boolean previousIsPre) {
if(start>=data.length)
return null;
// try to read next char:
char c = data[start];
if(c=='<') {
// this is a tag or comment or script:
int end_index = indexOf(data, start+1, '>');
if(end_index==(-1)) {
// the left is all text!
return new Token(Token.TOKEN_TEXT, data, start, data.length, previousIsPre);
}
String s = new String(data, start, end_index-start+1);
// now we got s="<...>":
if(s.startsWith("<!--")) { // this is a comment!
int end_comment_index = indexOf(data, start+1, "-->");
if(end_comment_index==(-1)) {
// illegal end, but treat as comment:
return new Token(Token.TOKEN_COMMENT, data, start, data.length, previousIsPre);
}
else
return new Token(Token.TOKEN_COMMENT, data, start, end_comment_index+3, previousIsPre);
}
String s_lowerCase = s.toLowerCase();
if(s_lowerCase.startsWith("<script")) { // this is a script:
int end_script_index = indexOf(data, start+1, "</script>");
if(end_script_index==(-1))
// illegal end, but treat as script:
return new Token(Token.TOKEN_SCRIPT, data, start, data.length, previousIsPre);
else
return new Token(Token.TOKEN_SCRIPT, data, start, end_script_index+9, previousIsPre);
}
else { // this is a tag:
return new Token(Token.TOKEN_TAG, data, start, start+s.length(), previousIsPre);
}
}
// this is a text:
int next_tag_index = indexOf(data, start+1, '<');
if(next_tag_index==(-1))
return new Token(Token.TOKEN_TEXT, data, start, data.length, previousIsPre);
return new Token(Token.TOKEN_TEXT, data, start, next_tag_index, previousIsPre);
}
private static int indexOf(char[] data, int start, String s) {
char[] ss = s.toCharArray();
// TODO: performance can improve!
for(int i=start; i<(data.length-ss.length); i++) {
// compare from data[i] with ss[0]:
boolean match = true;
for(int j=0; j<ss.length; j++) {
if(data[i+j]!=ss[j]) {
match = false;
break;
}
}
if(match)
&