代理模式(proxy pattern) 未使用代理模式 詳解

如果需要監控(monitor)類的某些狀態, 則需要編寫一個監控類, 並同過監控類進行監控.

但僅僅局限於本地, 如果需要遠程監控, 則需要使用代理模式(proxy pattern).

具體方法:

1. 類中需要提供狀態資訊, 並提供一些get方法, 進行調用.

/**  * @time 2014年7月11日  */package proxy;        /**  * @author C.L.Wang  *  */public class GumballMachine {            String location; //位置資訊                State soldOutState;      State noQuarterState;      State hasQuarterState;      State soldState;      State winnerState;                State state = soldOutState;      int count = 0;                /**      *       */    public GumballMachine(String location, int numberGumballs) {          // TODO Auto-generated constructor stub          soldOutState = new SoldOutState(this);          noQuarterState = new NoQuarterState(this);          hasQuarterState = new HasQuarterState(this);          soldState = new SoldState(this);          winnerState = new WinnerState(this);                        this.location = location;                        this.count = numberGumballs;          if (numberGumballs > 0) {              state = noQuarterState;          }      }                public void insertQuarter() {          state.insertQuarter();      }                public void ejectQuarter() {          state.ejectQuater();      }            public void turnCrank() {          state.turnCrank();          state.dispense();      }                public void setState(State state) {          this.state = state;      }                public void releaseBall() {          System.out.println("A gumball comes rolling out the slot...");          if (count != 0)              count --;      }                public int getCount() {          return count;      }                public void refill(int count) {          this.count = count;          state = noQuarterState;      }                public State getState() {          return state;      }                public String getLocation() {          return location;      }                public State getSoldOutState() {          return soldOutState;      }                public State getNoQuarterState() {          return noQuarterState;      }                public State getHasQuarterState() {          return hasQuarterState;      }                public State getSoldState() {          return soldState;      }                public State getWinnerState() {          return winnerState;      }                public String toString() {          StringBuffer result = new StringBuffer();          result.append("\nMighty Gumball, Inc.");          result.append("\nJava-enabled Standing Gumball Model #2004\n");          result.append("Inventory: " + count + " gumball");          if (count != 1) {              result.append("s");          }          result.append("\nMachine is " + state + "\n");          return result.toString();      }  }

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2. 監控類(monitor class), 調用get方法, 進行監控輸出.

/**  * @time 2014年7月12日  */package proxy;        /**  * @author C.L.Wang  *  */public class GumballMonitor {            GumballMachine machine;                /**      *       */    public GumballMonitor(GumballMachine machine) {          // TODO Auto-generated constructor stub          this.machine = machine;      }                public void report() {          System.out.println("Gumball Machine: " + machine.getLocation());          System.out.println("Current inventory: " + machine.getCount() + " gumballs.");          System.out.println("Current state: " + machine.getState());      }        }

3. 其餘代碼參考: http://blog.csdn.net/caroline_wendy/article/details/37698747

4. 測試類別, 執行個體化具體類, 並使用監控類, 進行監控.

/**  * @time 2014年7月11日  */package proxy;        /**  * @author C.L.Wang  *  */public class GumballMachineTestDrive {            /**      * @param args      */    public static void main(String[] args) {          // TODO Auto-generated method stub          GumballMachine gumballMachine = new GumballMachine("Seattle", 115);          GumballMonitor gumballMonitor = new GumballMonitor(gumballMachine);          gumballMonitor.report();      }        }

5. 輸出:

Gumball Machine: Seattle  Current inventory: 115 gumballs.  Current state: waiting for quater