// 在D盘中创建文件test.txt,文件中的内容为：“hello Java”

File file = new File("D:/test.txt");

StringBuilder builder = new StringBuilder();

builder.append("hello java");

OutputStreamWriter osw = null;

try {

osw = new FileWriter(file);

osw.write(builder.toString());

} catch (IOException e) {

e.printStackTrace();

} finally { // 最后一定要关闭流

if (osw != null) {

try {

osw.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

// 利用流把该文件拷贝到E盘根目录下

InputStream ips = null;

OutputStream ops = null;

try {

ips = new FileInputStream(file);// 源文件

byte[] buffer = new byte[1024]; // 定义一个缓冲数组

ops = new FileOutputStream("E:/" + file.getName());// 目标文件

// 如果没有读到结尾就继续读，每次读指定的字节数

for (int len = 0; (len = ips.read(buffer)) != -1;) {

ops.write(buffer, 0, len); // 每次写出实际读取到长度

}

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

} finally { // 最后关闭流

if (ips != null) {

try {

ips.close();

} catch (IOException e) {

e.printStackTrace();

}

}

if (ops != null) {

try {

ops.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

简单来写：

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.FileWriter;

import java.io.IOException;

public class Change {

public static void main(String[] args) throws IOException {

FileWriter fw = new FileWriter("D:/tets.txt");

fw.write("hello java");

fw.close();

FileInputStream fis = new FileInputStream("d:/tets.txt");

FileOutputStream fos = new FileOutputStream("E:/tets.txt");

byte[] b = new byte[1024];

while(fis.read(b)!=-1)

{

fos.write(b);

}

fos.close();

fis.close();

}

}