如何读取一个文件并将内容写入一个新文件中

PrintWriter只能读取字符，涉及到rar这些需要用字节来读取，详细看例子2

例子1

package io;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.PrintWriter;

public class Client {
public static void main(String[] args) {
BufferedReader reader=null;
PrintWriter writer=null;
File startfile=new File("c:/test.txt");//定义一个源文件的对象
File goalfile =new File("c:/copy.txt");//定义一个接收文件的对象

try {
FileReader f=new FileReader(startfile);//读取源文件
reader=new BufferedReader(f);
writer=new PrintWriter(new FileWriter(goalfile));//定义一个写入文件的对象写入目标文件goalfile也就是"c:/copy.txt"
while(reader.ready()){
writer.println(reader.readLine());//逐行读取源文件写入目标文件
}
writer.flush();//刷新
writer.close();//关闭
reader.close();//关闭
} catch (FileNotFoundException e) {
e.printStackTrace();
System.out.println("c:/test.txt文件不存在");
System.out.println(-1);
} catch (IOException e) {
e.printStackTrace();
}

}
}

例子2    使用byte[]和BufferInputStream\BufferOutputStream

package io;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

public class ByteReadWrite {
public static void main(String[] args) {
BufferedInputStream bis=null;
BufferedOutputStream bos=null;
File startfile=new File("E:/test.rar");//定义一个源文件的对象
File goalfile =new File("C:/copy.rar");//定义一个接收文件的对象

try {
FileInputStream fis=new FileInputStream(startfile);
bis=new BufferedInputStream(fis);
bos=new BufferedOutputStream(new FileOutputStream(goalfile));
byte[] bytes=new byte[1024];
while(fis.read(bytes)!=-1){
bos.write(bytes);
}
bos.flush();
bos.close();
fis.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
System.out.println("E:/test.rar不存在");
System.out.println(-1);
} catch (IOException e) {
e.printStackTrace();
}

}

}