图片
那实际开发中肯定是要用Java枚举的，那有没有什么解决办法了。答案肯定是有的，只是换成另外一种方式
/**
* Android枚举
*/
public class TestEnum {
/**
* @Retention(RetentionPolicy.SOURCE) 注解可以告知编译器不将枚举的注解数据存储在 .class 文件中
*
*/
/**
* @StringDef创建整型和字符串集的枚举注解来验证其他类型的代码引用
* 具体详细看官网{@link https://developer.android.com/studio/write/annotations.html?hl=zh-cn#adding-annotations}
*/
@Retention(RetentionPolicy.SOURCE)
@StringDef({
POWER_SERVICE,
WINDOW_SERVICE,
LAYOUT_INFLATER_SERVICE
})
//@interface这是Java用来定义一个注解类。
public @interface ServiceName {}
public static final String POWER_SERVICE = "power";
public static final String WINDOW_SERVICE = "window";
public static final String LAYOUT_INFLATER_SERVICE = "layout_inflater";
public static String getSystemService(@ServiceName String name) {
if (POWER_SERVICE.equals(name)) {
return POWER_SERVICE;
} else if (WINDOW_SERVICE.equals(name)) {
return WINDOW_SERVICE;
} else if (LAYOUT_INFLATER_SERVICE.equals(name)) {
return LAYOUT_INFLATER_SERVICE;
}
return null;
}
public static void main(String[] args) {
//使用
System.out.println(TestEnum.getSystemService(TestEnum.LAYOUT_INFLATER_SERVICE));
}
}
这就是官网的写法了。可是发现每次传参数是
TestEnum.LAYOUT_INFLATER_SERVICE
或者
TestEnum.POWER_SERVICE
而不是像我们Java枚举的传参方式
ServiceName.LAYOUT_INFLATER_SERVICE
那是不是需要改造下。查看资料可以这样写
/**
* Android枚举
*/
public class TestEnum {
/**
* @Retention(RetentionPolicy.SOURCE) 注解可以告知编译器不将枚举的注解数据存储在 .class 文件中
*
*/
/**
* @StringDef创建整型和字符串集的枚举注解来验证其他类型的代码引用 具体详细看官网{@link https://developer.android.com/studio/write/annotations.html?hl=zh-cn#adding-annotations}
*/
@Retention(RetentionPolicy.SOURCE)
@StringDef({
ServiceName.POWER_SERVICE,
ServiceName.WINDOW_SERVICE,
ServiceName.LAYOUT_INFLATER_SERVICE
})
//@interface这是Java用来定义一个注解类。
public @interface ServiceName {
String POWER_SERVICE = "power";
String WINDOW_SERVICE = "window";
String LAYOUT_INFLATER_SERVICE = "layout_inflater";
}
public static String getSystemService(@ServiceName String name) {
if (ServiceName.POWER_SERVICE.equals(name)) {
return ServiceName.POWER_SERVICE;
} else if (ServiceName.WINDOW_SERVICE.equals(name)) {
return ServiceName.WINDOW_SERVICE;
} else if (ServiceName.LAYOUT_INFLATER_SERVICE.equals(name)) {
return ServiceName.LAYOUT_INFLATER_SERVICE;
}
return null;
}
public static void main(String[] args) {
//使用
System.out.println(TestEnum.getSystemService(ServiceName.LAYOUT_INFLATER_SERVICE));
}
}
不错，就是把常量放到里面去了。这个时候差不多好了，不过怎么看
public static String getSystemService(@ServiceName String name) {
if (ServiceName.POWER_SERVICE.equals(name)) {
return ServiceName.POWER_SERVICE;
} else if (ServiceName.WINDOW_SERVICE.equals(name)) {
return ServiceName.WINDOW_SERVICE;
} else if (ServiceName.LAYOUT_INFLATER_SERVICE.equals(name)) {
return ServiceName.LAYOUT_INFLATER_SERVICE;
}
return null;
}
这个代码还是有点怪怪的，每次添加一个值都需要加一个else if太麻烦了。在Java中可以通过enum.values()获取所有enum的值那是不是有类似的方法，找了资料好像没有发现，那只能通过反射获取所有的public的参数和参数值了
public static String getSystemService(@ServiceName String name) {
Field[] fields = ServiceName.class.getDeclaredFields();
for (Field field : fields) {
//在反射对象中设置 accessible 标志允许具有足够特权的复杂应用程序（比如 Java Object Serialization 或其他持久性机制）以某种通常禁止使用的方式来操作对象
field.setAccessible(true);
String value = null;
try {
value = String.valueOf(field.get(field.getName()));
} catch (IllegalAccessException e) {
e.printStackTrace();
}
if (value != null && value.equals(name)) {
return value;
}
}
return null;
}
ok完成，代码地址
这里有几个知识点参考资料链接
网友评论