Java 保存对象到本地

╰半夏微凉° 2022-05-19 04:26 510阅读 0赞

将对象保存在本地第一时间一般想到的都是ObjectOutput,但是我在网上无意中发现还可以将对象转为json字符串来保存,嘿,都点灯下黑了,一直在用json传输数据一时之间竟然没想到,我们在保存对象时候有时候并不需要保存信息，有时候只需要保存对这个对象来说最关键的变量即可

总结：将对象保存到本地的两种方法

1.保存成json字符串  
2.ObjectOutputStream序列化到本地

需要注意的是在使用 序列化对象的时候,该对象需要实现Serializable接口

public static void saveObjectByObjectOutput(Object o, File file) {
            try {
                ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(file));
                objectOutputStream.writeObject(o);
                objectOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
        public static Object getObjectByObjectInput(File file) {
            try {
                ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream(file));
                Object o = inputStream.readObject();
                inputStream.close();
                return o;
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }
    
        public static void saveObjectByJson(File file, Object o) {
            String json = new Gson().toJson(o);
            try {
                FileOutputStream fileOutputStream = new FileOutputStream(file);
                fileOutputStream.write(json.getBytes());
                fileOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
        public static Object getObjectByJson(File file, Class c) {
            try {
                FileInputStream fileInputStream = new FileInputStream(file);
                StringBuilder stringBuilder = new StringBuilder();
                int l = 0;
                byte[] bs = new byte[1024];
                while ((l = fileInputStream.read(bs)) != -1) {
                    stringBuilder.append(new String(bs, 0, l));
                }
                fileInputStream.close();
                return new Gson().fromJson(stringBuilder.toString(), c);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

另外送上Object和String互转的方法：

public static String ObjectToString(Object o) {
            try {
                ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
                ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
                objectOutputStream.writeObject(o);
                objectOutputStream.close();
                byteArrayOutputStream.close();
                return new BASE64Encoder().encode(byteArrayOutputStream.toByteArray());
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }
    
        public static Object StringToObject(String str) {
            try {
                byte[] bs = new BASE64Decoder().decodeBuffer(str);
    
                ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bs);
                ObjectInputStream inputStream = new ObjectInputStream(byteArrayInputStream);
                Object o = inputStream.readObject();
                inputStream.close();
                byteArrayInputStream.close();
                return o;
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }