import java.io.*;
class WriteTest
{
public static void main(String[] args)
{
FileOutputStream fos=null;
FileInputStream fis=null;
try
{
fos=new FileOutputStream("c:\\2.txt");
fis=new FileInputStream("c:\\1.txt");
byte[] buf=new byte[1024];
int len=0;
while((len=fis.read(buf))!=-1)
{
fos.write(buf,0,len); //fos.write(buf);
num++;
}
System.out.println("OK");
}
catch (IOException e)
{
throw new RuntimeException("复制文件失败");
}
finally
{
try
{
if(fis!=null)
fis.close();
}
catch (IOException e)
{
throw new RuntimeException("读取关闭失败");
}
try
{
if(fos!=null)
fos.close();
}
catch (IOException e)
{
throw new RuntimeException("写入关闭失败");
}
}
}
}
很多书上都用fos.write(buf,0,len);这样的形式,而我使用fos.write(buf);也可以实现复制,带上0和len参数有什么好处呢?
class WriteTest
{
public static void main(String[] args)
{
FileOutputStream fos=null;
FileInputStream fis=null;
try
{
fos=new FileOutputStream("c:\\2.txt");
fis=new FileInputStream("c:\\1.txt");
byte[] buf=new byte[1024];
int len=0;
while((len=fis.read(buf))!=-1)
{
fos.write(buf,0,len); //fos.write(buf);
num++;
}
System.out.println("OK");
}
catch (IOException e)
{
throw new RuntimeException("复制文件失败");
}
finally
{
try
{
if(fis!=null)
fis.close();
}
catch (IOException e)
{
throw new RuntimeException("读取关闭失败");
}
try
{
if(fos!=null)
fos.close();
}
catch (IOException e)
{
throw new RuntimeException("写入关闭失败");
}
}
}
}
很多书上都用fos.write(buf,0,len);这样的形式,而我使用fos.write(buf);也可以实现复制,带上0和len参数有什么好处呢?
package io; import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException; public class Test { /**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub byte[] b = new byte[15];
byte bnum = 110;
for (int i = 0; i < b.length; i++) {
b[i] = bnum++;
} ByteArrayInputStream bi = new ByteArrayInputStream(b);
FileOutputStream fos; try {
System.out
.println("-------------用write(byte[] b)来写入文件---------------");
fos = new FileOutputStream(new File("C:\\文件1.txt"));
int i = 0;
byte[] buffer = new byte[10];
System.out.println("写入数据如下:");
while ((i = bi.read(buffer)) > 0) {
p(buffer);
fos.write(buffer);
}
System.out
.println("-------------用write(byte[] b,int off,int len)来写入文件---------------");
bi.reset();
fos = new FileOutputStream(new File("C:\\文件1.txt"));
i = 0;
buffer = new byte[10];
System.out.println("写入数据如下:");
while ((i = bi.read(buffer)) > 0) {
p(buffer);
fos.write(buffer, 0, i);
}
fos.close(); } catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} } public static void p(byte[] arr) {
for (int i = 0; i < arr.length; i++) {
System.out.print((char) arr[i] + ",");
}
System.out.println();
} }