IO流-输入输出流:字节流、字符流、缓冲流、转换流

 

字节输入输出流：

FileInputStream fis = new FileInputStream(filePath);
FileOutputStream fos = new FileOutputStream(savePath);

byte[] buffer = new byte[1024];
int length = 0;
while (-1 != (length = fis.read(buffer)))
{
 fos.write(buffer);
 /**
  * 等价于下面的写法：
  * String str = new String(buffer, 0, length);
  * fos.write(str.getBytes());
  */
}

 

字符输入输出流：

FileReader fr = new FileReader(fileName);
char[] buffer = new char[1024];//使用字符数组
int length = 0;
while (-1 != (length = fr.read(buffer)))
{
    for (int i = 0; i < length; i++)
    {
        System.out.print(buffer[i]);
    }
}


FileWriter fw = new FileWriter(fileName);
fw.write("这段字符串按字符写入good");
fw.flush();//写完清空缓存

 

转换流、缓冲流：

FileInputStream fis = new FileInputStream(fileName);
InputStreamReader isr = new InputStreamReader(fis);
BufferedReader br = new BufferedReader(isr);

FileOutputStream fos = new FileOutputStream(saveName);
OutputStreamWriter osw = new OutputStreamWriter(fos);
BufferedWriter bw = new BufferedWriter(osw);


String str = null;
while (null != (str = br.readLine()))//读取每行直到'\r'或'\t'则为空
{
    bw.write(str);//write可以写入字符串或者字符
    bw.newLine();//换行
    bw.flush();//清空缓存
}

文件拷贝方法：练习字节流、字符流、缓冲流、转换流

public class CopyMethod
{
    public static void main(String[] args)
    {
        CopyMethod cm = new CopyMethod();
        String scr = "F:/java/tt.txt";
        String dest = "F:/java/xx.txt";
        cm.copyMethod(scr, dest);
    }

    public void copyMethod(String scr,String dest)
    {
        BufferedReader fr = null;
        BufferedWriter bw = null;
        try
        {
            FileInputStream fis = new FileInputStream(scr);//文件输入流
            InputStreamReader isr = new InputStreamReader(fis);//转换流，将字节流转换为字符流
            fr = new BufferedReader(isr);//创建字符缓冲流，每次读取一行字符

            FileOutputStream fos = new FileOutputStream(dest);
            OutputStreamWriter osw = new OutputStreamWriter(fos);
            bw = new BufferedWriter(osw);

            String str = null;//缓冲流读取和写入的都是字符串
            while(null != (str = fr.readLine()))//使用readLine()，读取到\r或\n结束
            {
                bw.write(str);//写入一行字符串
                bw.newLine();//换行
                bw.flush();//清空缓存,使用writer需要flush
            }
        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        finally//关闭最外层的流
        {
            if(fr != null)
            {
                try
                {
                    fr.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            if(null != bw)
            {
                try
                {
                    bw.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
    }
}

 

 

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