对象流

 序列化

    public static void main(String[] args) throws Exception {
        //序列化后，保存的文件格式，不是存文本，而是按照他的格式来保存
        String filePath = "e:\\data.dat";

        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filePath));

        //序列化数据到 e:\data.dat
        oos.writeInt(100);// int -> Integer (实现了 Serializable)
        oos.writeBoolean(true);// boolean -> Boolean (实现了 Serializable)
        oos.writeChar('a');// char -> Character (实现了 Serializable)
        oos.writeDouble(9.5);// double -> Double (实现了 Serializable)
        oos.writeUTF("韩顺平教育");//String
        //保存一个dog对象
        oos.writeObject(new Dog("旺财", 10, "日本", "白色"));
        oos.close();
        System.out.println("数据保存完毕(序列化形式)");


    }

反序列化

    public static void main(String[] args) throws IOException, ClassNotFoundException {

        //指定反序列化的文件
        String filePath = "e:\\data.dat";

        ObjectInputStream ois = new ObjectInputStream(new FileInputStream(filePath));

        //读取
        //老师解读
        //1. 读取(反序列化)的顺序需要和你保存数据(序列化)的顺序一致
        //2. 否则会出现异常

        System.out.println(ois.readInt());
        System.out.println(ois.readBoolean());

        System.out.println(ois.readChar());
        System.out.println(ois.readDouble());
        System.out.println(ois.readUTF());


        //dog 的编译类型是 Object , dog 的运行类型是 Dog
        Object dog = ois.readObject();
        System.out.println("运行类型=" + dog.getClass());
        System.out.println("dog信息=" + dog);//底层 Object -> Dog

        //这里是特别重要的细节:

        //1. 如果我们希望调用Dog的方法, 需要向下转型
        //2. 需要我们将Dog类的定义，放在到可以引用的位置
        Dog dog2 = (Dog)dog;
        System.out.println(dog2.getName()); //旺财..

        //关闭流, 关闭外层流即可，底层会关闭 FileInputStream 流
        ois.close();


    }

 防止读取乱码(指定编码)

    public static void main(String[] args) throws IOException {

        String filePath = "e:\\a.txt";
        //解读
        //1. 把 FileInputStream 转成 InputStreamReader
        //2. 指定编码 gbk
        //InputStreamReader isr = new InputStreamReader(new FileInputStream(filePath), "gbk");
        //3. 把 InputStreamReader 传入 BufferedReader
        //BufferedReader br = new BufferedReader(isr);

        //将2 和 3 合在一起
        BufferedReader br = new BufferedReader(new InputStreamReader(
               new FileInputStream(filePath), "gbk"));

        //4. 读取
        String s = br.readLine();
        System.out.println("读取内容=" + s);
        //5. 关闭外层流
        br.close();

    }

指定输出编码

    public static void main(String[] args) throws IOException {
        String filePath = "e:\\hsp.txt";
        String charSet = "utf-8";
        OutputStreamWriter osw = new OutputStreamWriter(
                new FileOutputStream(filePath), charSet
        );
        osw.write("hi, 韩顺平教育");
        osw.close();
        System.out.println("按照 " + charSet + " 保存文件成功~");


    }