Java Design Patterns Rookie series (19) model and implementation of Memo mode

Reprint Please specify source: http://blog.csdn.net/lhy_ycu/article/details/40018967

Memo Mode (Memento): The primary purpose is to save a state of an object so that it can be restored at the appropriate time.

First, UML modeling:

Second, the Code implementation

/** * Memo Mode (MEMENTO): The main purpose is to save a state of an object so that the object can be restored at the appropriate time * Example: Original class--Create, Restore Memo */class Original {private String State;publi C Original (String state) {this.state = state;} Public String GetState () {return state;} public void SetState (String state) {this.state = state;} /** * Create Memo */public Memento Creatememento () {return new Memento (state); /** * Recovery Memo */public void Recovermemento (Memento Memento) {this.state = Memento.getstate ();}} /** * Memo */class Memento {private string State;public Memento (String state) {this.state = state;} Public String GetState () {return state;} public void SetState (String state) {this.state = state;}}  /** * Used to store memos (holding memo instances): Can only be stored, cannot modify */class Storage {private Memento memento;public Storage (Memento Memento) {This.memento = Memento;} Public Memento Getmemento () {return Memento;}} /** * Client Test class * * @author Leo */public class Test {public static void main (string[] args) {/** * Create original object */original Origina L = new Original ("daytime mode"); System.out.println ("Original initial state is:" + original.getsTate ());/** * Create notes * * Note: Original.creatememento () will pass the initial state (daylight mode) to the Memento object * * Storage.getmemento () can be called when needed To get the state (daylight mode) status * equals state (Daytime mode) This status has been delegated to the Storage object to save */storage Storage = new Storage (Original.creatememento ()) ; Original.setstate ("Night Mode"); System.out.println ("Original modified State is:" + original.getstate ());/** * Recovery Memo */original.recovermemento ( Storage.getmemento ()); System.out.println ("Original status after recovery:" + original.getstate ());}}

Iii. Summary

Memento Memo design mode is used to back up the current state of an object and, when needed, to restore the object's state at a certain point in time.

Java Design Patterns Rookie series (19) model and implementation of Memo mode