flying saucer生成pdf实现标点符号不在行首

在项目过程中，发现了这样一个问题：利用flying saucer生成的pdf文件中，经常有中文标点符号出现在行首的现象。经过仔细分析flying saucer的源码和测试，最终解决方案如下：

首先，我们要明白这几个东西的真实含义：

 

Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS ： 4E00-9FBF：CJK 统一表意符号

Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS ：F900-FAFF：CJK 兼容象形文字 Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A ：3400-4DBF：CJK 统一表意符号扩展 A

CJK的意思是“Chinese，Japanese，Korea”的简写 ，实际上就是指中日韩三国的象形文字的Unicode编码

Character.UnicodeBlock.GENERAL_PUNCTUATION ：2000-206F：常用标点 Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION ：3000-303F：CJK 符号和标点 Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS ：FF00-FFEF：半角及全角形式

 

在flying saucer生成pdf的过程中，源代码中是按组和行宽来换行的，具体逻辑如下：

以空格为分组符，任意两个相邻空格之间的字符都是不可换行的，当该行多组字符的总长到达最接近行宽的时候，也就是再加一个字符组就会超过行宽的时候，就会换行

 

这种方式对英文是很凑效的，但是对中文是不行的，因为中文不是以空格分隔的。yye_javaeye老兄对源码做了改进，判断是否是中文字符，如果是中文字符，则把每个中文字符做一组，然后再用组+行宽来换行。他添加了两个方法：isChinese(char  c)和getStrRight(String s,int  left)， 改过后的部分源码如下：

。。。。。。
package org.xhtmlrenderer.layout;

import org.xhtmlrenderer.css.constants.IdentValue;
import org.xhtmlrenderer.css.style.CalculatedStyle;
import org.xhtmlrenderer.render.FSFont;

/**
 * A utility class that scans the text of a single inline box, looking for the 
 * next break point.
 * @author Torbj�rn Gannholm
 */
public class Breaker {

。。。。。。    
    public static void breakText(LayoutContext c, 
            LineBreakContext context, int avail, CalculatedStyle style) {
。。。。。。
        String currentString = context.getStartSubstring();
        int left = 0;
//        int right = currentString.indexOf(WhitespaceStripper.SPACE, left + 1);
        int right = getStrRight(currentString,left);
        int lastWrap = 0;
        int graphicsLength = 0;
        int lastGraphicsLength = 0;

        while (right > 0 && graphicsLength <= avail) {
            lastGraphicsLength = graphicsLength;
            graphicsLength += c.getTextRenderer().getWidth(
                    c.getFontContext(), font, currentString.substring(left, right));
            lastWrap = left;
            left = right;
//            right = currentString.indexOf(WhitespaceStripper.SPACE, left + 1);
            right = getStrRight(currentString,left+1);
        }

。。。。。。
    }

    private static boolean isChinese(char c) {
        Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
        if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
                || ub == Character.UnicodeBlock.GENERAL_PUNCTUATION
                || ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
                || ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS) {
            return true;
        }
        return false;
    }

    private static int getStrRight(String s,int left){
        if(left>=s.length())
            return -1;
        char[] ch = s.toCharArray();
        for(int i = left;i<ch.length;i++){
            if(isChinese(ch[i]) || ' ' == ch[i]){
                return i==0?i+1:i;
            }
        }
        return -1;
    }

}

 

 

 这种方法确实实现了中文汉字的换行，但是也带来了“标点符号在行首”的问题，因为他把标点符号也视作汉字了，这样标点符号也被分组被换行了，解决的方法就是把标点符号从isChinese方法中去掉。其源码如下：

/*
 * Breaker.java
 * Copyright (c) 2004, 2005 Torbj锟絩n Gannholm, 
 * Copyright (c) 2005 Wisconsin Court System
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */
package org.xhtmlrenderer.layout;

import org.xhtmlrenderer.css.constants.IdentValue;
import org.xhtmlrenderer.css.style.CalculatedStyle;
import org.xhtmlrenderer.render.FSFont;

/**
 * A utility class that scans the text of a single inline box, looking for the 
 * next break point.
 * @author Torbj锟絩n Gannholm
 */
public class Breaker {

    public static void breakFirstLetter(LayoutContext c, LineBreakContext context,
            int avail, CalculatedStyle style) {
        FSFont font = style.getFSFont(c);
        context.setEnd(getFirstLetterEnd(context.getMaster(), context.getStart()));
        context.setWidth(c.getTextRenderer().getWidth(
                c.getFontContext(), font, context.getCalculatedSubstring()));
        
        if (context.getWidth() > avail) {
            context.setNeedsNewLine(true);
            context.setUnbreakable(true);
        }
    }
    
    private static int getFirstLetterEnd(String text, int start) {
        int i = start;
        while (i < text.length()) {
            char c = text.charAt(i);
            int type = Character.getType(c);
            if (type == Character.START_PUNCTUATION || 
                    type == Character.END_PUNCTUATION ||
                    type == Character.INITIAL_QUOTE_PUNCTUATION ||
                    type == Character.FINAL_QUOTE_PUNCTUATION ||
                    type == Character.OTHER_PUNCTUATION) {
                i++;
            } else {
                break;
            }
        }
        if (i < text.length()) {
            i++;
        }
        return i;
    }    
    
    public static void breakText(LayoutContext c, 
            LineBreakContext context, int avail, CalculatedStyle style) {
        FSFont font = style.getFSFont(c);
        IdentValue whitespace = style.getWhitespace();
        
        // ====== handle nowrap
        if (whitespace == IdentValue.NOWRAP) {
        	context.setEnd(context.getLast());
        	context.setWidth(c.getTextRenderer().getWidth(
                    c.getFontContext(), font, context.getCalculatedSubstring()));
            return;
        }

        //check if we should break on the next newline
        if (whitespace == IdentValue.PRE ||
                whitespace == IdentValue.PRE_WRAP ||
                whitespace == IdentValue.PRE_LINE) {
            int n = context.getStartSubstring().indexOf(WhitespaceStripper.EOL);
            if (n > -1) {
                context.setEnd(context.getStart() + n + 1);
                context.setWidth(c.getTextRenderer().getWidth(
                        c.getFontContext(), font, context.getCalculatedSubstring()));
                context.setNeedsNewLine(true);
                context.setEndsOnNL(true);
            } else if (whitespace == IdentValue.PRE) {
            	context.setEnd(context.getLast());
                context.setWidth(c.getTextRenderer().getWidth(
                        c.getFontContext(), font, context.getCalculatedSubstring()));  
            }
        }

        //check if we may wrap
        if (whitespace == IdentValue.PRE || 
                (context.isNeedsNewLine() && context.getWidth() <= avail)) {
            return;
        }
        
        context.setEndsOnNL(false);

        String currentString = context.getStartSubstring();
        int left = 0;
//        int right = currentString.indexOf(WhitespaceStripper.SPACE, left + 1);
        int right = getStrRight(currentString,left);
        int lastWrap = 0;
        int graphicsLength = 0;
        int lastGraphicsLength = 0;

        while (right > 0 && graphicsLength <= avail) {
            lastGraphicsLength = graphicsLength;
            graphicsLength += c.getTextRenderer().getWidth(
                    c.getFontContext(), font, currentString.substring(left, right));
            lastWrap = left;
            left = right;
//            right = currentString.indexOf(WhitespaceStripper.SPACE, left + 1);
            right = getStrRight(currentString,left+1);
        }

        if (graphicsLength <= avail) {
            //try for the last bit too!
            lastWrap = left;
            lastGraphicsLength = graphicsLength;
            graphicsLength += c.getTextRenderer().getWidth(
                    c.getFontContext(), font, currentString.substring(left));
        }

        if (graphicsLength <= avail) {
            context.setWidth(graphicsLength);
            context.setEnd(context.getMaster().length());
            //It fit!
            return;
        }
        
        context.setNeedsNewLine(true);

        if (lastWrap != 0) {//found a place to wrap
            context.setEnd(context.getStart() + lastWrap);
            context.setWidth(lastGraphicsLength);
        } else {//unbreakable string
            if (left == 0) {
                left = currentString.length();
            }
            
            context.setEnd(context.getStart() + left);
            context.setUnbreakable(true);
            
            if (left == currentString.length()) {
                context.setWidth(c.getTextRenderer().getWidth(
                        c.getFontContext(), font, context.getCalculatedSubstring()));
            } else {
                context.setWidth(graphicsLength);
            }
        }
        return;
    }

    private static boolean isChinese(char c) {
        Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
        if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A) {
            return true;
        }
        return false;
    }

    private static int getStrRight(String s,int left){
        if(left>=s.length())
            return -1;
        char[] ch = s.toCharArray();
        for(int i = left;i<ch.length;i++){
            if(isChinese(ch[i]) || ' ' == ch[i]){
                return i==0?i+1:i;
            }
        }
        return -1;
    }    

}

 

对应的core-renderer.jar文件在附件中。