io

字节流： FileOutputStream

public static void main(String[] args) throws IOException {
        
        //输入输出是相对程序来说 第二个参数为true是追加，不给或false是重新写
        FileOutputStream fos = new FileOutputStream(new File("a.txt")，true);
        fos.write("helloword".getBytes());
        fos.flush();
        fos.close();
    }

FileInputStream：

FileInputStream fin = new FileInputStream("a.txt");
        byte[] bs = new byte[1024];
        fin.read(bs);
        //关闭流
        fin.close();
        //创建一个字符串输出字节数组
        System.out.println(new String(bs));
    }

字符流；

public static void main(String[] args) {
        //创建读取字符流
        FileReader fr = null;
        try {
            fr = new FileReader("aa.txt");
            char[] cs = new char[1024];
            fr.read(cs);
            System.out.println((cs));
        } catch (IOException e) {
                e.printStackTrace();
        }finally {
            if(fr != null){
                try {
                    fr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

FileWriter fw = null;
        try {
            fw = new FileWriter(new File("aa.txt"));
            fw.write("Helloword this is");
            fw.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(fw != null){
                try {
                    fw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        

文件拷贝：

public static void main(String[] args) {
        InputStream is = null;
        OutputStream os = null;
        
        try {
            is = new FileInputStream("ting.jpg");
            os = new FileOutputStream("thingcop.jpg");
            /*//获得文件总共长度
            byte[] count = new byte[is.available()];
            is.read(count);
            os.write(count);
            os.flush();*/
            
            //一个一个字节拷贝
            int count;
            while((count = is.read()) != -1){
                os.write(count);
                os.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                if(is != null){
                    is.close();
                }
                if(os != null){
                    os.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

高效缓冲字节流：

public static void main(String[] args) {
        
        BufferedOutputStream bos = null;
        OutputStream os = null;
        
        try {
            os = new FileOutputStream("a.txt");
            bos = new BufferedOutputStream(os);
            bos.write("门前大桥下，啦啦啦啦".getBytes());
            bos.flush();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                if(bos != null){
                    bos.close();
                }
                if(os != null){
                    os.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

ublic static void main(String[] args) {
        
        //创建高效缓冲区流
        BufferedInputStream bis = null;
        FileInputStream fis = null;
        
        try {
            fis = new FileInputStream("ting.jpg");
            bis = new BufferedInputStream(fis);
            byte[] count = new byte[bis.available()];
            bis.read(count);
            System.out.println(new String(count));
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
                try {
                    if(bis != null){
                    bis.close();
                    }
                    if(fis != null){
                        fis.close();
                    }
                    }catch (IOException e) {
                    e.printStackTrace();
        
                }
        }