设计模式（命令模式）

命令行把请求和操作封装起来，坦白的讲，我现在还不是特别理解，也没有再具体的项目中使用过，感觉有点过于复杂。

本文参考一些材料，给出一个简单的例子。如下：



Trade

public class Trade {
public void doSell(){
System.out.println("doSell");
}

public void doBuy(){
System.out.println("doBuy");
}
}

TradeCommand

public abstract class TradeCommand {
protected Trade trade;

public TradeCommand(Trade trade){
this.trade = trade;
}

public abstract void execute();
}

BuyTradeCommand

public class BuyTradeCommand extends TradeCommand {

public BuyTradeCommand(Trade trade) {
super(trade);
}

@Override
public void execute() {
this.trade.doBuy();
}
}

SellTradeCommand

public class SellTradeCommand extends TradeCommand {

public SellTradeCommand(Trade trade) {
super(trade);
}

@Override
public void execute() {
this.trade.doSell();
}
}

Invoke

public class Invoke {
public TradeCommand command;

public void setCommand(TradeCommand command){
this.command = command;
}

public void execute(){
command.execute();
}
}

APP 测试类

public class App {

public static void main(String[] args) {
Trade trade = new Trade();
Invoke invoke = new Invoke();
invoke.setCommand(new SellTradeCommand(trade));
invoke.execute();
invoke.setCommand(new BuyTradeCommand(trade));
invoke.execute();
}
}