序列化-Hessian

　　引用官网介绍：

Hessian is a dynamically-typed, binary serialization and Web Services protocol designed for object-oriented transmission.

　　Hessian 是动态类型、二进制、紧凑的，并且可跨语言移植的一种序列化框架。Hessian 协议要比 JDK、JSON 更加紧凑，性能上要比 JDK、JSON 序列化高效很多，而且生成的字节数也更小。

代码示例如下：

 1 @Data
 2 public class SimplePOJO implements Serializable {
 3     String field1;
 4     String field2;
 5     public SimplePOJO(String s1, String s2) {
 6         field1 = s1;
 7         field2 = s2;
 8     }
 9     // fastjson逆序列化时要求对象必须要有一个默认的构造函数
10     public SimplePOJO(){}
11 }
12 public static void main(String[] args) throws IOException, ClassNotFoundException {
13     SimplePOJO student = new SimplePOJO("16","张三");
14     //把student对象转化为byte数组
15     ByteArrayOutputStream bos = new ByteArrayOutputStream();
16     Hessian2Output output = new Hessian2Output(bos);
17     output.writeObject(student);
18     output.flushBuffer();
19     byte[] data = bos.toByteArray();
20     bos.close();
21
22     // 把字节流存入文件
23     FileOutputStream fos = new FileOutputStream("C:\\Users\\user\\Desktop\\student.dat");
24     fos.write(data);
25     fos.close();
26     // 从文件中读取字节流
27     FileInputStream fis = new FileInputStream( "C:\\Users\\user\\Desktop\\student.dat");
28     byte[] bytes = new byte[fis.available()];
29     fis.read(bytes);
30
31     // 转化为student对象
32     ByteArrayInputStream bis = new ByteArrayInputStream(data);
33     Hessian2Input input = new Hessian2Input(bis);
34     SimplePOJO deStudent = (SimplePOJO) input.readObject();
35     input.close();
36     System.out.println(deStudent);
37 }

　　打开保存的中间文件看看：

　　可以看到有类名以及属性名和对应值

　　具体的数据-byte类型的映射可以参考官网http://hessian.caucho.com/doc/hessian-serialization.html

　　对于上述代码，其数据类型为Object类型。Object类型转换格式为（官网）：

 1 class Car {
 2   String color;
 3   String model;
 4 }
 5
 6 out.writeObject(new Car("red", "corvette"));
 7 out.writeObject(new Car("green", "civic"));
 8
 9 ---
10
11 C                        # object definition (#0)
12   x0b example.Car        # type is example.Car
13   x92                    # two fields
14   x05 color              # color field name
15   x05 model              # model field name
16
17 O                        # object def (long form)
18   x90                    # object definition #0
19   x03 red                # color field value
20   x08 corvette           # model field value
21
22 x60                      # object def #0 (short form)
23   x05 green              # color field value
24   x05 civic              # model field value