insertcontent.java

疯狂Java讲义_源码(含Java设计模式CHM

import java.io.*;
import java.util.*;
/**
 * Description:
 * <br/>Copyright (C), 2005-2008, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
public class InsertContent
{
	public static void insert(String fileName , long pos , 
		String insertContent)throws IOException
	{
		RandomAccessFile raf = null;
		//创建一个临时文件来保存插入点后的数据
		File tmp = File.createTempFile("tmp" , null);
		FileOutputStream tmpOut = null;
		FileInputStream tmpIn = null;
		tmp.deleteOnExit();
		try
		{
			raf = new RandomAccessFile(fileName , "rw");
			tmpOut = new FileOutputStream(tmp);
			tmpIn = new FileInputStream(tmp);
			raf.seek(pos);
			//--------下面代码将插入点后的内容读入临时文件中保存---------
			byte[] bbuf = new byte[64];
			//用于保存实际读取的字节数
			int hasRead = 0;
			//使用循环方式读取插入点后的数据
			while ((hasRead = raf.read(bbuf)) > 0 )
			{
				//将读取的数据写入临时文件
				tmpOut.write(bbuf , 0 , hasRead);
			}
			//----------下面代码插入内容----------
			//把文件记录指针重新定位到pos位置
			raf.seek(pos);
			//追加需要插入的内容
			raf.write(insertContent.getBytes());
			//追加临时文件中的内容
			while ((hasRead = tmpIn.read(bbuf)) > 0 )
			{
				raf.write(bbuf , 0 , hasRead);
			}
		}
		finally
		{
			raf.close();
		}
	}
	public static void main(String[] args) throws IOException
	{
		insert("InsertContent.java" , 45 , "插入的内容\r\n");
	}
}