Technical Principle Analysis and Case Analysis of Hessian Framework in Java Class Library
Technical Principle Analysis and Case Analysis of Hessian Framework in Java Class Library
Hessian is a network communication protocol based on binary serialization, developed by Caucho Technology for implementing cross language and cross platform remote procedure call (RPC). Hessian can serialize Java objects into binary streams, transmit them over the network to the other end, and then deserialize the binary streams into objects for use. Hessian has the characteristics of lightweight, fast, cross platform, and cross language, and is widely used in distributed systems.
The working principle of Hessian can be divided into the following steps:
1. Serialization: Converts Java objects into binary format data streams. Hessian provides support for various data types, including primitive types, arrays, strings, collections, and more. It dynamically obtains object type information through Java's reflection mechanism, and serializes the object's fields and attributes into binary data in a certain format.
2. Transmission: Transfer the serialized binary data to the other end through the network. Hessian uses a lightweight HTTP protocol for data transmission, which can send HTTP requests through Java's URL class or third-party libraries (such as Apache HttpClient), and send binary data as the request body to the target server.
3. Deserialization: After receiving binary data, Hessian deserializes it as a Java object on the target server. Hessian reads binary data streams and restores them to original Java objects based on their format, allowing developers to directly use these objects for business processing.
Below, we will use a simple example to demonstrate the use of Hessian in Java class libraries.
Firstly, we create a Java class called User, which contains the user's name and age.
public class User implements Serializable {
private String name;
private int age;
//Construction methods and Getter/Setter methods are omitted
}
Next, we write server-side code to serialize the User object and return it to the client as an HTTP response.
public class Server {
public static void main(String[] args) {
try {
User user = new User("Alice", 25);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
//Using Hessian's serialization method to convert the User object into a binary stream
HessianOutput out = new HessianOutput(baos);
out.writeObject(user);
byte[] data = baos.toByteArray();
//Create an HttpServerSocket and listen to the specified port
HttpServerSocket serverSocket = new HttpServerSocket(8080);
serverSocket.start();
while (true) {
//After receiving an HTTP request, send the binary data of the User object as a response to the client
HttpRequest request = serverSocket.acceptRequest();
HttpResponse response = request.getResponse();
response.setContentType("application/octet-stream");
response.getOutputStream().write(data);
response.finish();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Finally, we write client code to receive the binary data returned by the server and deserialize it into a User object.
public class Client {
public static void main(String[] args) {
try {
//Create an HttpClient and send an HTTP request
HttpClient httpClient = new HttpClient();
httpClient.open("http://localhost:8080");
HttpRequest request = httpClient.createRequest();
//After receiving the HTTP response, obtain binary data and deserialize it as a User object
HttpResponse response = request.getResponse();
byte[] data = response.getBody();
ByteArrayInputStream bais = new ByteArrayInputStream(data);
HessianInput in = new HessianInput(bais);
User user = (User) in.readObject();
System.out.println("Name: " + user.getName());
System.out.println("Age: " + user.getAge());
response.finish();
httpClient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Through the above example, we can see the usage of Hessian. The server uses Hessian's serialization method to convert Java objects into binary data and send it to the client through HTTP response. After receiving binary data, the client uses Hessian's deserialization method to restore it to the original Java object for use.
Summary: Hessian is a cross platform, cross language binary serialization protocol suitable for implementing remote procedure calls in distributed systems. It achieves data transmission and usage through serialization and deserialization of Java objects. The Hessian framework in the Java class library makes network communication more convenient for developers, providing efficient, flexible, and scalable solutions.
