Java基础-files（2）

1.使用字节流复制文件

    public static void main(String[] args) throws IOException {        // TODO Auto-generated method stub        FileInputStream fileInputStream = new FileInputStream("IODemo.java");        FileOutputStream fileOutputStream = new FileOutputStream("C:\\Eclipse\\q\\iODemo.java");        int len；        byte[] bys = new byte[1024];        while ((len = fileInputStream.read(bys)) != -1) {            fileOutputStream.write(bys, 0, len);        }        fileInputStream.close();        fileOutputStream.close();    }

2.使用字符流复制文件

public static void main(String[] args) throws IOException {        // TODO Auto-generated method stub        FileReader fileReader = new FileReader("IODemo.java");        FileWriter fileWriter = new FileWriter("C:\\Eclipse\\IOdemo.java");        /*1. 一次写入一个字符*/        /*int ch;        while ((ch = fileReader.read()) != -1 ) {            fileWriter.write(ch);            fileWriter.flush();        }*///      一次写入一个字符数组        int len;        char[] chs = new char[1024];        while ((len = fileReader.read(chs)) != -1) {            fileWriter.write(chs, 0, len);            fileWriter.flush();        }        fileWriter.close();        fileReader.close();    }

3.打印流

public static void main(String[] args) throws IOException {        // TODO Auto-generated method stub//      创建打印流对象        PrintWriter printWriter = new PrintWriter("a.txt");//      写出数据        printWriter.write("hello");        printWriter.write("world");        printWriter.write("java");        printWriter.write("i am java, i am testing");//      释放资源        printWriter.close();    }

4.打印流复制文件

public static void main(String[] args) throws IOException {        BufferedReader bufferedReader = new BufferedReader(new FileReader("copy.java"));        PrintWriter printWriter = new PrintWriter(new FileWriter("C:\\Eclipse\\copyTest.java"),true);        String line;        while ((line = bufferedReader.readLine()) != null) {            printWriter.println(line);        }        bufferedReader.close();        printWriter.close();    }

5.
* 需求：读取键盘录入的数据，并输出到项目根目录下的a.txt文件中
*
* 数据源：读取键盘录入的数据 System.in
* 目的地：项目根目录下的a.txt FileWriter
*
* 转换流：需要把字节输入流转换成字符输入流，InputStreamReader
* InputStreamReader（InputStream in）

public static void main(String[] args) throws IOException {        // TODO Auto-generated method stub//      method();        InputStream inputStream = System.in;        Reader reader = new InputStreamReader(inputStream);        FileWriter fileWriter = new FileWriter("a.txt");        char[] chs = new char[1024];        int len;        while ((len = reader.read(chs)) != -1) {            fileWriter.write(chs,0,len);            fileWriter.flush();        }        fileWriter.close();        inputStream.close();    }    private static void method() throws IOException {        InputStream inputStream = System.in;        FileWriter fileWriter = new FileWriter("a.txt");        byte[] bys = new byte[1024];        int len;        while ((len = inputStream.read(bys)) != -1) {            fileWriter.write(new String(bys,0,len));            fileWriter.flush();        }        fileWriter.close();        inputStream.close();    }