Java深入讲解二十三种设计模式之中的策略模式

public interface CommandStrategy {
    /**
     * 计费方式
     * @param message
     */
    void calMoney(String message);
}

public class BaiShiCommand implements CommandStrategy {
    /**
     * 百世快递计费方式
     * @param message
     */
    @Override
    public void calMoney(String message) {
        System.out.println("百世快递收费方式："+"起步20，每公斤6元");
    }
}

public class JingDongCommand implements CommandStrategy {
    /**
     * 京东快递计费方式
     * @param message
     */
    @Override
    public void calMoney(String message) {
        System.out.println("京东快递收费方式："+"起步30，每公斤5元");
    }
}

public class YuanTongCommand implements CommandStrategy {
    /**
     * 圆通快递计费方式
     * @param message
     */
    @Override
    public void calMoney(String message) {
        System.out.println("圆通快递收费方式："+"起步10，每公斤8元");
    }
}

public class CommandContext {
    public CommandStrategy getInstance(String commandType) {
        CommandStrategy commandStrategy = null;
        Map<String, String> allClazz = CommandEnum.getAllClazz();
        //拿到对应算法类对应的路径
        String clazz = allClazz.get(commandType.trim().toLowerCase());
        if (StringUtils.isNotEmpty(clazz)) {
            try {
                try {
                    //创建一个对象实例
                    commandStrategy = (CommandStrategy) Class.forName(clazz).newInstance();//调用无参构造器创建实例
                } catch (InstantiationException | IllegalAccessException e) {
                    e.printStackTrace();
                }
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
        System.out.println("commandStrategy:"+commandStrategy);
        return commandStrategy;
    }
}

public enum CommandEnum {
    JingDong("京东", "com.liubujun.design.command.JingDongCommand"), BaiShi("百世", "com.liubujun.design.command.BaishiCommand"), YuanTong("圆通", "com.liubujun.design.command.YuanTongCommand");
    private String name;
    private String clazz;
    public static Map<String, String> getAllClazz() {
        Map<String, String> map = new HashMap<>(8);
        System.out.println("==================="+Arrays.toString(CommandEnum.values())+"================");
        for (CommandEnum commandEnum : CommandEnum.values()) {
            map.put(commandEnum.getCommand(), commandEnum.getClazz());
        }
        return map;
    }
    public String getCommand() {
        return name;
    }
    CommandEnum(String command, String clazz) {
        this.name = command;
        this.clazz = clazz;
    }
    public void setCommand(String command) {
        this.name = command;
    }
    public String getClazz() {
        return clazz;
    }
    public void setClazz(String clazz) {
        this.clazz = clazz;
    }
}

public class MainStart {
    public static void main(String[] args) {
        String message = "京东";
        CommandContext commandContext = new CommandContext();
        //拿到message对应算法的对象实例
        CommandStrategy commandStrategy = commandContext.getInstance(message);
        commandStrategy.calMoney(message);
    }
}