Java IO流之节点流与字符流的相关知识总结

File file = new File("路径名");

//如
File file = new File("L:\\FileTestDemo\\AAA\\aaa.txt");

 System.out.println(file.createNewFile());  //true or false表示是否创建成功

System.out.println(file.delete());

if(!file.exists()){
    System.out.println("文件不存在，创建"+ file.createNewFile());
}

System.out.println(file.getName());

System.out.println(new SimpleDateFormat().format(new Date(file.lastModified())));

public class IOTest {
    public static void main(String[] args) throws IOException {
        //选择流，建立联系
        InputStream is = new FileInputStream("L:\\FileTestDemo\\123.txt");

        //无论以何种方式 read(), read([]) 读取文件， -1,就意味着读取到文件末尾 
        //则当result的值为-1时结束
        int result = -1;
        while((result = is.read()) != -1){
            System.out.println((char)result);
        }

        //关闭
        is.close();

    }
}

public class IOTest {
    public static void main(String[] args) throws IOException {
        //选择流，建立联系
        InputStream is = new FileInputStream("L:\\FileTestDemo\\123.txt");

        //定义运输数组
        byte[] car = new byte[1024];
        int len = -1;
        //当result的值为-1时结束
        while ((len = is.read(car)) != -1){
            System.out.println(new String(car,0,len));
        }

        //关闭
        is.close();

    }
}

public class OutputStream01 {

    public static void main(String[] args) throws IOException {
        选择流，建立联系
        OutputStream os = new FileOutputStream("L:\\FileTestDemo\\abc.txt",true);
        //写入数据
        os.write('a');

        //刷出流
        os.flush();
        //关闭
        os.close();
    }
}

public class OutputStream02 {

    public static void main(String[] args) throws IOException {
        //构建输出流
        OutputStream os = new FileOutputStream("L:\\FileTestDemo\\abc.txt");

        //需要写入的数据
        String str = "我好菜啊\n" +
                "就这？\n" +
                "\t\t\t不是吧，阿sir";

        //转为字节数据存入数组
        byte[] arr = str.getBytes();

        //写入数据
        os.write(arr);

        //刷出数据
        os.flush();
        //关闭
        os.close();
    }
}

public class In_Out {
    public static void main(String[] args){
		//提升作用域范围
        InputStream is = null;
        OutputStream os = null;
        try {
            //创建输入流
            is = new FileInputStream("L:\\FileTestDemo\\aaa.txt");
            os = new FileOutputStream("L:\\FileTestDemo\\abc\\bbb.txt");

            //创建输入数组
            byte[] arr = new byte[1024];

            int len = -1;

            while ((len = is.read(arr)) != -1){
                //write(byte[] b, int off, int len) 将从偏移量 off开始的指定字节数组中的 len字节写入此输出流
                os.write(arr,0,len);
            }

            //刷出
            os.flush();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //后打开，先关闭
            //先关闭输出流
            if(os != null){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            //再关闭输入流
            if(is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

public class IOTest {
    
    public static void main(String[] args) throws IOException {
        //建立联系可能会遇到找不到文件位置(FileNotFoundException)异常
        //这时候可以抛出(throw)异常
        InputStream is = new FileInputStream("L:\\FileTestDemo\\123.txt");
    }
}

public class IOTest {
    public static void main(String[] args){
    	//通过try...carch...来抓取异常
        try {
            InputStream is = new FileInputStream("L:\\FileTestDemo\\123.txt");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

    }
}