java中IO流的操作

读取转换流--读取键盘录入中键盘录入一行数据并打印其大写，发现就是读一行数据的原理。
也就是readLine方法。
能不能直接使用readLine方法来完成键盘录入一行数据的读取呢？
readLine方法是字符流BufferedReader类中的方法。
而键盘录入的read方法是字节流InputStream的方法。
那么能不能将字节流转换成字符流再去使用字符流缓冲区的readLine方法呢。

public class TransStreamDemo {

    public static void main(String[] args) {
//        获取键盘录入对象
        InputStream is = System.in;
//        将字节流对象转化为字符流对象，使用转换流InputStreamReader
        InputStreamReader isr = new InputStreamReader(is);
//        为了提高效率，将字符串送入缓冲区，使用BufferedReader
        BufferedReader br = new BufferedReader(isr);
        
        String line = null;
        try {
            while ((line =br.readLine()) !=null) {
                if("over".equals(line))
                    break;
                System.out.println(line.toUpperCase());
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

写入转换流--把字符流转换成字节流

public class TransStreamDemo2 {

    public static void main(String[] args) {
//        InputStream is=System.in;
//        InputStreamReader isr=new InputStreamReader(is);
//        BufferedReader br=new BufferedReader(isr);
//        可简化为
//        这是最常用的读取键盘录入
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
//        OutputStream os =System.out;
//        OutputStreamWriter osw = new OutputStreamWriter(os);
//        BufferedWriter bw = new BufferedWriter(osw);
//        可简化为
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        
        String line = null;
        try {
            while ((line = br.readLine()) != null) {
                if("over".equals(line))
                    break;
//                打印大写
                bw.write(line.toUpperCase());
                bw.newLine();
                bw.flush();
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

流操作规律--吧键盘录入的数据存储到一个文件中

public class TransStreamDemo3 {

    public static void main(String[] args) throws IOException {
        
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("E:/out.txt"),"utf-8"));
        
        String line = null;
        while ((line = br.readLine()) != null) {
            if("over".equals(line))
                break;
            bw.write(line);
            System.out.println("写入成功");
            bw.newLine();
            bw.flush();
        }
    }
}

将一个文件的数据打印在控制台上。

public class TransStreamDemo4 {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("E:/out.txt"),"utf-8"));
        
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        String line = null;
        while((line = br.readLine()) != null){
            bw.write(line);
            bw.newLine();
            bw.flush();
        }
    }
}