IO流的输入输出

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对于IO流操作无外乎三步:

1.开启流

2.操作流

3.关闭流

例：

1.输入输出字节流

//1.开启流

InputStream in=new FileInputStream("demo.txt");

OutputStream out=new FileOutputStream("demo1.txt");

//2.操作流

byte[] buffered=new byte[10];

int len=0;

while((len=in.read(buffered))!=-1){

for(int i=0;i<len;i++){

out.write(buffered[i]);

}

// out.write(buffer, 0, len);//输出写法2

}

//3.关闭流

out.close();

in.close();

2.输入输出字符流

//1.开启流

Reader read=new FileReader("demo.txt");

Writer write=new FileWriter("demo2.txt");

//2.操作流

char[] buff=new char[10];

int len=0;

while((len=read.read(buff))!=-1){

for(int i=0;i<len;i++){

write.write(buff[i]);

}

//3.关闭流

write.close();

read.close();

3.缓冲流

//1.开启流

BufferedReader read=new BufferedReader(new FileReader("demo.txt"));

BufferedWriter write=new BufferedWriter(new FileWriter("demo3.txt"));

//2.操作流

String str=null;

int i=0;

while((str=read.readLine())!=null){

if(i!=0){

write.write("\n");

}

write.write(str);

i++;

}

//3.关闭流

read.close();

write.close();

4.转换流（字节-->字符）

//1.开启流

BufferedReader in=new BufferedReader(new InputStreamReader(

new FileInputStream("demo.txt") ));

BufferedWriter out=new BufferedWriter(new OutputStreamWriter(

new FileOutputStream("demo4.txt")));

//2.操作流

int i=0;

String str=null;

while((str=in.readLine())!=null){

if(i!=0){

out.write("\n");

}

out.write(str);

}

//3.关闭流

in.close();

out.close();

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