文件的读写操作（Java版）

IO的类型
传输方向：输入流、输出流。
传输内容：字节流、字符流：字节流可以传输任何文件，字符流只能传输文本文件。
功能上：节点流、过滤流。节点流有基本的读写功能，过滤流在节点流的基础上增加功能。

字节流的父类是InputStream（读）、OutputStream（写），
节点流：FileInputStream、FileOutputStream，
过滤流：DataInputStream、DataOutputStream。

字符流父类是Reader、Writer，
节点流：FileReader、FileWriter，
过滤流：BufferedReader、BufferedWriter，
桥转换流：InputStreamReader、OutputStreamWriter，
字符流的编码方式和解码方式需要相同。

字节流的读操作代码：

    public static void byteRead(File file) {
        try {
            InputStream inputStream = new FileInputStream(file);
            byte[] bytes = new byte[inputStream.available()];
            int n = inputStream.read(bytes);
            // 打印new String(bytes, 0, n));
            inputStream.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

字节流的写操作代码：

    public static void byteWrite(File file) {
        try {
            OutputStream outputStream = new FileOutputStream(file);
            String text = "Hello World";
            byte[] data = text.getBytes();
            outputStream.write(data);
            outputStream.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

字节流的读出再写入操作代码：

    public static void byteReadToWrite(File file,File newFile) {
        try {
            InputStream inputStream = new FileInputStream(file);
            byte[] bytes = new byte[inputStream.available()];
            OutputStream outputStream = new FileOutputStream(newFile);
            inputStream.read(bytes);
            outputStream.write(bytes);
            inputStream.close();
            outputStream.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

字符流的读操作代码：

    public static void stringRead(File file) {
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file),"GB2312"));
            String str = reader.readLine();
            // 打印str
            reader.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

字符流的写操作代码：

    public static void stringWrite(File file) {
        try {
            Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file),"GB2312"));
            String text = "Hello World 你好世界";
            writer.write(text);
            writer.flush();
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

字符流的读出再写入操作代码：

public static void stringReadToWrite(File file, File newFile) {
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file),"GB2312"));
            String str = reader.readLine();
            // 打印str
            Writer writer = new FileWriter(newFile);
            writer.write(str);
            writer.write("stringReadToWrite");
            writer.flush();
            reader.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }