Question

Java在名为synthetic和bridge的方法上有特殊标记。

JLS 13.1.7，“Java编译器引入的任何构造都没有相应的构造源代码中的构造必须标记为合成 ...“

因此，合成方法是由编译器生成的任何内容，并且未在源代码中表示，虽然在该规范中没有提及PDF，但 bridge 方法用于类型检查泛型。（例如Animal.interactWith(Creature c)获得一个桥接方法interactWith(Object c)，它转换为生物并调用另一种方法。）

我们有一个名为Bukkit的API，它可以提供稳定的访问权限来改变Minecraft服务器的工作方式。我们几乎无法控制的API（也称为vanilla Minecraft）的底层实现的一个方面是，最近在版本1.6.1中强制将其从整数值更改为浮点值。为了避免另一次更改的困难，我们选择将所有API方法更改为double。

所以，例如：

public int getHealth();
public void setHealth(int health);
// Must now be
public double getHealth();
public void setHealth(double health);

然而，与往常一样，我们希望使用以前版本1.5.2编译的插件尽可能地工作 - 这就是API的重点。

setHealth是一个已解决的问题，只是引入了一个重载。目前，我们有一个名为_INVALID_getHealth(V)I的方法，它在实现编译时重命名（不 API编译）到getHealth(V)I，这样就可以让老插件继续运行。 / p>

但是，当有人试图扩展这些重命名方法的实现时，它们会从双重命名的方法中获得编译错误并覆盖。

有没有办法使用手动/工具插入合成或桥接方法提供int和double返回，不会导致那些尝试更改部分API实现的人会出现编译错误吗？

Answer 1

答案是是 - 如果您使用不同的返回类型标记方法，但是使用与composite和bridge相同的参数，则可以编译子类。

在这种特定情况下，创建了一个新的Maven实用程序＆＃34; Overmapper＆＃34;来执行此任务，尽管您可以在任何可以编辑Java字节码的自动化工具中执行此操作。这是配置文件：

members:
  "org/bukkit/entity/Damageable _INVALID_damage (I)V": damage
  "org/bukkit/entity/Damageable _INVALID_damage (ILorg/bukkit/entity/Entity;)V": damage
  "org/bukkit/entity/Damageable _INVALID_getHealth ()I": getHealth
  "org/bukkit/entity/Damageable _INVALID_setHealth (I)V": setHealth
  "org/bukkit/entity/Damageable _INVALID_getMaxHealth ()I": getMaxHealth
  "org/bukkit/entity/Damageable _INVALID_setMaxHealth (I)V": setMaxHealth
  "org/bukkit/entity/LivingEntity _INVALID_getLastDamage ()I": getLastDamage
  "org/bukkit/entity/LivingEntity _INVALID_setLastDamage (I)V": setLastDamage
  "org/bukkit/event/entity/EntityDamageEvent _INVALID_getDamage ()I": getDamage
  "org/bukkit/event/entity/EntityDamageEvent _INVALID_setDamage (I)V": setDamage
  "org/bukkit/event/vehicle/VehicleDamageEvent _INVALID_getDamage ()I": getDamage
  "org/bukkit/event/vehicle/VehicleDamageEvent _INVALID_setDamage (I)V": setDamage
  "org/bukkit/event/entity/EntityRegainHealthEvent _INVALID_getAmount ()I": getAmount
  "org/bukkit/event/entity/EntityRegainHealthEvent _INVALID_setAmount (I)V": setAmount
  "org/bukkit/entity/Minecart _INVALID_getDamage ()I": getDamage
  "org/bukkit/entity/Minecart _INVALID_setDamage (I)V": setDamage
  "org/bukkit/entity/Projectile _INVALID_getShooter ()Lorg/bukkit/entity/LivingEntity;": getShooter
  "org/bukkit/entity/Projectile _INVALID_setShooter (Lorg/bukkit/entity/LivingEntity;)V": setShooter
  "org/bukkit/Bukkit _INVALID_getOnlinePlayers ()[Lorg/bukkit/entity/Player;": getOnlinePlayers
  "org/bukkit/Server _INVALID_getOnlinePlayers ()[Lorg/bukkit/entity/Player;": getOnlinePlayers
flags:
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity getHealth ()I": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftEnderDragonPart getHealth ()I": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity getMaxHealth ()I": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftEnderDragonPart getMaxHealth ()I": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity setHealth (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftEnderDragonPart setHealth (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity setMaxHealth (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftEnderDragonPart setMaxHealth (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity damage (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftEnderDragonPart damage (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity damage (ILorg/bukkit/entity/Entity;)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftEnderDragonPart damage (ILorg/bukkit/entity/Entity;)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity getLastDamage ()I": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftLivingEntity setLastDamage (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftMinecart setDamage (I)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftMinecart getDamage ()I": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftProjectile getShooter ()Lorg/bukkit/entity/LivingEntity;": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftProjectile setShooter (Lorg/bukkit/entity/LivingEntity;)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftArrow getShooter ()Lorg/bukkit/entity/LivingEntity;": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftArrow setShooter (Lorg/bukkit/entity/LivingEntity;)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftFireball getShooter ()Lorg/bukkit/entity/LivingEntity;": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftFireball setShooter (Lorg/bukkit/entity/LivingEntity;)V": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftFish getShooter ()Lorg/bukkit/entity/LivingEntity;": 0x1001
  "org/bukkit/craftbukkit/v${minecraft_version}/entity/CraftFish setShooter (Lorg/bukkit/entity/LivingEntity;)V": 0x1001

您可以看到所有返回int的方法都被更改为标记为桥接和合成。

Answer 2

如果您想对实体运行状况执行某些操作，可以转换为Damageable，然后就不会出现编译错误。

Entity e = /* some entity */;
double health = ((Damageable) e).getHealth();

这应该有效。我希望它有所帮助

可以使用合成或桥接方法来平滑int - ＆gt;双API变化？

2 个答案: