以各种方式读写文件

public class ReadFormFile

{

    // 以二进制方式读取文件 常用于读取二进制文件 图片 声音 视频等

    public static void readByBytes(String fileName)

    {

        File file = new File(fileName);

        InputStream in = null;

        try

        {

            System.out.println("一次读取一个字节");

            in = new FileInputStream(file);

            int temp;// temp存放的是编码表对应的字符编码

            while ((temp = in.read()) != -1)

            {

                System.out.println(temp);

                // System.out.write(temp);

            }

            // 文件末尾输出-1

            in.close();

        } catch (IOException e)

        {

            e.printStackTrace();

            return;

        }

 

    }

 

    public static void readByteMore(String fileName)

    {

        InputStream in = null;

        File file = new File(fileName);

        try

        {

            System.out.println("一次读取多个字节");

            byte[] temp = new byte[1024];

            int buffer = 0;

            in = new FileInputStream(fileName);

            while ((buffer = in.read(temp)) != -1)

            {

                // System.out.println(buffer );

                System.out.write(temp, 0, buffer);

            }

            System.out.println(buffer);

            in.close();

        } catch (Exception e)

        {

            e.printStackTrace();

        }

    }

//以字符方式读取文件

    public static void readByChar(String fileName)

    {

        File file = new File(fileName);

        InputStreamReader reader = null;

        try

        {

            reader = new InputStreamReader(new FileInputStream(file));

            int temp = 0;

            while ((temp = reader.read()) != -1)

            {

                System.out.print((char) temp);

            }

            reader.close();

        } catch (Exception e)

        {

            // TODO: handle exception

            e.printStackTrace();

        }

    }

 

    public static void readByCharMore(String fileName)

    {

        File file = new File(fileName);

        InputStreamReader reader = null;

        try

        {

            reader = new InputStreamReader(new FileInputStream(file));

            int charLength = 0;

            char[] temp = new char[30];

            while ((charLength = reader.read(temp)) != -1)

            {

                System.out.println(temp);

 

            }

        } catch (Exception e)

        {

            // TODO: handle exception

            e.printStackTrace();

        }

    }

 

    public static void writeFileByByte(String fileName)// 以字节为单位写文件

    {

        File file = new File(fileName);

        OutputStream out = null;

        try

        {

            String wenjian = "haha";

            out = new FileOutputStream(file);

            Scanner scanner = new Scanner(System.in);

            byte[] bytes = null;

            while (!wenjian.equals("@"))

            {

                wenjian = scanner.next();

                bytes = wenjian.getBytes();// 将字符串转换成字节数组

                out.write(bytes);

            }

            out.close();

        } catch (Exception e)

        {

            e.printStackTrace();

        }

    }

 

    public static void writeByChar(String fileName)//以字符为单位写入字符串

    {

        File file = new File(fileName);

        OutputStreamWriter outputStreamWriter = null;

        try

        {

            outputStreamWriter = new OutputStreamWriter(new FileOutputStream(file));

            String string = "cui meng meng sha gua";

            outputStreamWriter.write(string);

            outputStreamWriter.close();

        } catch (Exception e)

        {

            e.printStackTrace();

        }

    }

    public static void writeByLine(String fileName)//格式化写入文件   每次写入一行

    {

        File file=new File(fileName);

        PrintWriter writer=null;

        try

        {

            writer=new PrintWriter(new FileOutputStream(file));//通常用于格式化读入

            writer.println(123);//此时的123是int型的

            writer.println("cui meng meng sha gua");//字符串

            writer.flush();//将流中的字节刷新到文件中

            writer.close();

        } catch (Exception e)

        {

            // TODO: handle exception

            e.printStackTrace();

        }

    }

    public static void main(String[] args)

    {

        String fileName = "C:/Users/Administrator/Desktop/yyy.txt";

        // ReadFormFile.readByBytes(fileName);

        // ReadFormFile.readByteMore(fileName);

        // ReadFormFile.readByChar(fileName);

        // ReadFormFile.readByCharMore(fileName);

        // ReadFormFile.writeFileByByte(fileName);

        //ReadFormFile.writeByChar(fileName);

        ReadFormFile.writeByLine(fileName);

    }

}