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();}}