编译原理 >实验1

import java.io.*;

public class IOlianxi1 {
	public static void main(String[] args) throws IOException {
		System.out.println("the path: "+System.getProperty("user.dir"));
		CreateFile("C:/123.txt");
		
    	         readFile("C:/AbsPath.txt");
		 writeFile2("C:/RelPath.txt","abcdfdfdfdfddde");
		 readFile("C:/AbsPath.txt");
		 copy();
	}
	
	public static boolean CreateFile(String destFileName) throws IOException{
		File file = new File(destFileName);
		if(file.exists()){
			System.out.println("Fail! Here it is!");
			return false;
		}
		file.createNewFile();
		System.out.println("success!");
		return true;
	}
	
	
	public static void readFile(String fileName)throws IOException{
		File file = new File(fileName);
		BufferedReader reader = new BufferedReader(new FileReader(file));
		String br=null;
		while((br=reader.readLine())!=null){
			System.out.println(br);
		}
		reader.close();
		
	}
	public static void writeFile2(String filePath,String str)throws IOException{
	PrintWriter pw = new PrintWriter(new FileOutputStream(filePath));  
	pw.print(str);
	pw.close();
	}
	
	
	public void writeFile(String filePath,StringBuffer text)throws IOException{
		   BufferedWriter rw=new BufferedWriter(new OutputStreamWriter(new FileOutputStream(filePath)));
		   rw.write(new String(text));
		   rw.close();	  
	}
		 
	
	public static void copy_1() throws IOException
	{
		FileReader fr=new FileReader("FileReaderDemo2.java");
		
		FileWriter fw=new FileWriter("FileReaderDemo2.txt");
				
		int ch=0;
		while((ch=fr.read())!=-1)//循环读取，每次读取一个字符，到达文件尾则返回-1
		{
			fw.write(ch);//取从第一个到第num个字符，避免有数据不足3个字符的情况
		}
		fw.close();
		fr.close();
	}
	public static void copy() throws IOException
	{
		FileReader fr=new FileReader("C:/AbsPath.txt");
		
		FileWriter fw=new FileWriter("C:/out.txt");
		
		char[] buf=new char[1024];
		
		int num=0;
		while((num=fr.read(buf))!=-1)
		{
			fw.write(buf,0,num);
		}
		fr.close();
		fw.close();
	}
}