1.字节流（FileInputStream,FileOutputStream)

package study;
import java.io.*;
public class MyFile {public static void main(String[] args){// TODO Auto-generated method stub//读入的文件必须存在，否则报错File f=new File("c:\\f.txt");//写入的文件可以自行创建，若存在，则覆盖File fo=new File("c:\\d.txt");FileInputStream fis=null;FileOutputStream fos=null;try {//因为File没有读写的能力，所以需要使用InputStream类fis=new FileInputStream(f);fos=new FileOutputStream(fo);//定义一个字节数组，相当于缓存byte []bytes=new byte[1024];int n=0;//得到实际读取到的字节数//循环读取while((n=fis.read(bytes))!=-1){//把字节转成String//String s=new String(bytes,0,n);fos.write(bytes);}}catch (Exception e) {e.printStackTrace();}finally{//关闭文件流必需放在finally语句块中try {//一定要关闭fis.close();fos.close();} catch (Exception e) {e.printStackTrace();}}}
}

2.字符流(FileReader,FileWriter)
这个try,catch真的要用那么多吗？

package study;
import java.io.*;
public class Wha {public static void main(String[] args) {FileReader fr=null;FileWriter fw=null;try {fr=new FileReader("c:\\f.txt");try {fw=new FileWriter("c:\\d.txt");} catch (IOException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}char a[]=new char[100];int n=0;try {while((n=fr.read(a))!=-1){fw.write(a);}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {fr.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}try {fw.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}