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itext Chunk Phrase Paragraph区别

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Java 编程

IText中有三个处理text的类com.lowagie.text.Chunk，com.lowagie.text.Phrase，com.lowagie.text.Paragraph。

它们之间有什么区别呢？

Chunk

Chunk是IText最小的文本编辑单位。不能再拆分更小的单元。其他高级的文本对象都是基于Chunk的。请看下图

（注此图，来源自http://www.cnblogs.com/LifelongLearning/archive/2011/03/30/2000072.html）

package org.study.itext.text;

import java.awt.Color;
import java.io.FileOutputStream;
import java.io.IOException;

import com.lowagie.text.Chunk;
import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.Font;
import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfWriter;
/**
 * @blog http://reymont.iteye.com/
 * @author reymont.li
 * @version create time：2011-7-14 上午11:49:01
 */
public class ChunkTest {
	public static void main(String[] args) {
		Document document = new Document();
		try {
			PdfWriter.getInstance(document, new FileOutputStream(
					"resource/ChunkTest.pdf"));
			document.open();

			BaseFont songbfChinese = BaseFont.createFont("resource/STSONG.TTF",
					BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
			Font songFont = new Font(songbfChinese, 18, Font.UNDERLINE);
			Chunk love = new Chunk("我们的爱", songFont);
			love.setTextRise(10);
			love.setBackground(Color.CYAN);

			BaseFont xingkabfChinese = BaseFont.createFont(
					"resource/STXINGKA.TTF", BaseFont.IDENTITY_H,
					BaseFont.EMBEDDED);
			Font xingkaFont = new Font(xingkabfChinese, 18, Font.ITALIC);
			Chunk simple = new Chunk("简单", xingkaFont);
			simple.setBackground(Color.BLUE);
			simple.setTextRise(-10);

			BaseFont kaibfChinese = BaseFont.createFont("resource/STKAITI.TTF",
					BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
			Font kaiFont = new Font(kaibfChinese, 18, Font.BOLD);
			Chunk song = new Chunk("如歌", kaiFont);
			song.setBackground(Color.RED);

			document.add(love);
			document.add(simple);
			document.add(song);

		} catch (DocumentException de) {
			System.err.println(de.getMessage());
		} catch (IOException ioe) {
			System.err.println(ioe.getMessage());
		}
		document.close();
	}
}

生成的文本为

在水平方向，Chunk的字符满一行，就会从头开始。请注意，这是从头开始，而不是另起一行。对于Chunk来说，行间距默认为0，那么当文档中只有Chunk时，这些字符永远只会出现再第一行。

package org.study.itext.text;

import java.awt.Color;
import java.io.FileOutputStream;
import java.io.IOException;

import com.lowagie.text.Chunk;
import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.Font;
import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfWriter;
/**
 * @blog http://reymont.iteye.com/
 * @author reymont.li
 * @version create time：2011-7-14 上午11:49:14
 */
public class ChunkTest2 {
	public static void main(String[] args) {
		Document document = new Document();
		try {
			PdfWriter.getInstance(document, new FileOutputStream(
					"resource/ChunkTest2.pdf"));
			document.open();

			BaseFont songbfChinese = BaseFont.createFont("resource/STSONG.TTF",
					BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
			Font songFont = new Font(songbfChinese, 18, Font.UNDERLINE);
			Chunk love = new Chunk("我们的爱", songFont);
			love.setTextRise(10);
			love.setBackground(Color.CYAN);

			BaseFont xingkabfChinese = BaseFont.createFont(
					"resource/STXINGKA.TTF", BaseFont.IDENTITY_H,
					BaseFont.EMBEDDED);
			Font xingkaFont = new Font(xingkabfChinese, 18, Font.ITALIC);
			Chunk simple = new Chunk("简单", xingkaFont);
			simple.setBackground(Color.BLUE);
			simple.setTextRise(-10);

			BaseFont kaibfChinese = BaseFont.createFont("resource/STKAITI.TTF",
					BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
			Font kaiFont = new Font(kaibfChinese, 18, Font.BOLD);
			Chunk song = new Chunk("如歌", kaiFont);
			song.setBackground(Color.RED);
			for (int i = 0; i < 10; i++) {
				document.add(love);
				document.add(simple);
				document.add(song);
			}
		} catch (DocumentException de) {
			System.err.println(de.getMessage());
		} catch (IOException ioe) {
			System.err.println(ioe.getMessage());
		}
		document.close();
	}
}

生成的文档为：

可以看到后面的字符串覆盖了前面的字符串。怎么才能解决这个问题呢？

Phrase

我们可以将Chunk当成固定的块，Phrase当成由Chunk组成的字符串。让我们做一些小改动。

package org.study.itext.text;

import java.awt.Color;
import java.io.FileOutputStream;
import java.io.IOException;

import com.lowagie.text.Chunk;
import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.Font;
import com.lowagie.text.Phrase;
import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfWriter;
/**
 * @blog http://reymont.iteye.com/
 * @author reymont.li
 * @version create time：2011-7-14 上午11:49:24
 */
public class PhraseTest {
	public static void main(String[] args) {
		Document document = new Document();
		try {
			PdfWriter.getInstance(document, new FileOutputStream(
					"resource/PhraseTest.pdf"));
			document.open();

			BaseFont songbfChinese = BaseFont.createFont("resource/STSONG.TTF",
					BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
			Font songFont = new Font(songbfChinese, 18, Font.UNDERLINE);
			Chunk love = new Chunk("我们的爱", songFont);
			love.setTextRise(10);
			love.setBackground(Color.CYAN);

			BaseFont xingkabfChinese = BaseFont.createFont(
					"resource/STXINGKA.TTF", BaseFont.IDENTITY_H,
					BaseFont.EMBEDDED);
			Font xingkaFont = new Font(xingkabfChinese, 18, Font.ITALIC);
			Chunk simple = new Chunk("简单", xingkaFont);
			simple.setBackground(Color.BLUE);
			simple.setTextRise(-10);

			BaseFont kaibfChinese = BaseFont.createFont("resource/STKAITI.TTF",
					BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
			Font kaiFont = new Font(kaibfChinese, 18, Font.BOLD);
			Chunk song = new Chunk("如歌", kaiFont);
			song.setBackground(Color.RED);

			
			
			Phrase phrase = new Phrase(30);
			phrase.add(love);
			phrase.add(simple);
			phrase.add(song);
			for (int i = 0; i < 10; i++)
				document.add(phrase);
			document.add(Chunk.NEWLINE);
			document.add(phrase);
			phrase.add("\n");
			for (int i = 0; i < 3; i++) {
				document.add(phrase);
			}

		} catch (DocumentException de) {
			System.err.println(de.getMessage());
		} catch (IOException ioe) {
			System.err.println(ioe.getMessage());
		}
		document.close();
	}
}

Document添加了phrase。这样，Phrase就会自动换行。

还有两种方式也可以换行 。

document.add(Chunk.NEWLINE);

和

phrase.add("\n");

貌似这样就解决了字符串换行的问题，但这些都要写一些额外的代码，有什么类封装这些动作呢？

Paragraph

Paragraph继承自Phase。

package org.study.itext.text;

import java.io.FileOutputStream;
import java.io.IOException;

import com.lowagie.text.Chunk;
import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.Element;
import com.lowagie.text.Font;
import com.lowagie.text.Paragraph;
import com.lowagie.text.Phrase;
import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfWriter;
/**
 * @blog http://reymont.iteye.com/
 * @author reymont.li
 * @version create time：2011-7-14 上午11:49:18
 */
public class ParagraphTest {

	public static void main(String[] args) {
		Document document = new Document();
		try {
			PdfWriter.getInstance(
					document,
					new FileOutputStream("resource/ParagraphTest.pdf"));
			document.open();
			String text = "我们的爱简单如歌";
			Phrase phrase1 = new Phrase(text);
			Phrase phrase2 = new Phrase(new Chunk(text, new Font(
					Font.TIMES_ROMAN)));
			
			BaseFont songbfChinese = BaseFont.createFont("resource/STSONG.TTF",
					BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
			Font font = new Font(songbfChinese, 18, Font.NORMAL);
			
			Phrase phrase3 = new Phrase(text, font);
			Paragraph paragraph = new Paragraph();
			paragraph.add(phrase1);
			paragraph.add(phrase2);
			paragraph.add(phrase3);
			document.add(paragraph);
			document.add(paragraph);
			paragraph.setAlignment(Element.ALIGN_LEFT);
			document.add(paragraph);
			paragraph.setAlignment(Element.ALIGN_CENTER);
			document.add(paragraph);
			paragraph.setAlignment(Element.ALIGN_RIGHT);
					
			document.add(paragraph);
			paragraph.setAlignment(Element.ALIGN_JUSTIFIED);
			document.add(paragraph);
			paragraph.setSpacingBefore(10);
			document.add(paragraph);
			paragraph.setSpacingBefore(0);
			paragraph.setSpacingAfter(10);
			document.add(paragraph);
			paragraph.setIndentationLeft(20);
			document.add(paragraph);
			paragraph.setIndentationRight(20);
			document.add(paragraph);
		} catch (DocumentException de) {
			System.err.println(de.getMessage());
		} catch (IOException ioe) {
			System.err.println(ioe.getMessage());
		}

		document.close();
	}
}

每段文字上面和下面的空间，可使用setSpacingBefore() 和setSpacingAfter() 来指定。

每段文字的缩进可使用setIndentationLeft()和setIndentationRight()。