IO流之复制文件

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1.使用FileInputStream

package cn.itcast.io;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;public class CopyDemo1 {public static void main(String[] args) throws Exception {//封装数据源InputStream in=new FileInputStream("a.txt");//目的地OutputStream out=new FileOutputStream("b.txt");//复制数据byte by[]=new byte[1024];int len=0;while((len=in.read(by))!=-1){out.write(by,0,len);}//释放资源out.close();in.close();}}

2.使用转化流InputStreamReader

package cn.itcast.io;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;public class CopyDemo2 {public static void main(String[] args) throws IOException {//数据源InputStreamReader in=new InputStreamReader(new FileInputStream("a.txt"));OutputStreamWriter out=new OutputStreamWriter(new FileOutputStream("b.txt"));//这是字符流了相当于因此使用char数组char ch[]=new char[1024];int len=0;while((len=in.read(ch))!=-1){out.write(ch, 0, len);}out.close();in.close();}}

3.使用缓冲流BufferedReader读取一个字符数组

package cn.itcast.io;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;public class CopyDemo3 {public static void main(String[] args) throws Exception {BufferedReader in=new BufferedReader(new FileReader("a.txt"));BufferedWriter out=new BufferedWriter(new FileWriter("b.txt"));char ch[]=new char[1024];int len=0;while(( len=in.read(ch))!=-1){out.write(ch, 0, len);}out.close();in.close();}}

4.使用BufferedReader读取一行

package cn.itcast.io;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileNotFoundException;import java.io.FileReader;import java.io.FileWriter;public class CopyDemo4 {public static void main(String[] args) throws Exception {BufferedReader in=new BufferedReader(new FileReader("a.txt"));BufferedWriter out=new BufferedWriter(new FileWriter("b.txt"));String line=null;while((line=in.readLine())!=null){out.write(line);out.newLine();out.flush();}out.close();in.close();}}

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