[英]Are method References as method parameters thread safe in Java
i have the following scenario:我有以下情况:
interface ValueBinding<T> {
public void setValue(T input);
}
public enum FacesBinding {
VALUE;
public void bindString(ValueBinding<String> fcn, HttpServletRequest req, String param){
try {
String val = req.getParameter(param);
if( val != null )
fcn.setValue(val);
} catch (Exception e) { }
}
public void bindBoolean(ValueBinding<Boolean> fcn, HttpServletRequest req, String param){
try {
fcn.setValue(req.getParameter(param) != null);
} catch (Exception e) { }
}
public void bindInt(ValueBinding<Integer> fcn, HttpServletRequest req, String param){
try {
int val = Integer.parseInt(req.getParameter(param));
fcn.setValue(val);
} catch (Exception e) { }
}
public void bindLong(ValueBinding<Long> fcn, HttpServletRequest req, String param){
try {
long val = Long.parseLong(req.getParameter(param));
fcn.setValue(val);
} catch (Exception e) { }
}
...
...
}
and i use it in a "multithreaded" Environment like this:我在这样的“多线程”环境中使用它:
concurrent Threads are calling this method并发线程正在调用此方法
@Override // concurrent Threads are calling this method
public Category initData(FacesContext facesContext) throws Exception {
Category entity = new Category();
HttpServletRequest req = facesContext.getRequest();
FacesBinding.VALUE.bindLong(entity::setId, req, Table.Category.Field.ID.name());
FacesBinding.VALUE.bindString(entity::setName, req, Table.Category.Field.NAME.name());
FacesBinding.VALUE.bindInt(entity::setPosition, req, Table.Category.Field.POSITION.name());
FacesBinding.VALUE.bindBoolean(entity::setLocalized, req, Table.Category.Field.LOCALIZED.name());
return entity;
}
is是
FacesBinding.VALUE.bindLong(entity::setId, req, Table.Category.Field.ID.name());
100% Thread safe when i pass a method reference (interface) entity::setId
as parameter of a method in enum Object (Singleton)?当我将方法引用(接口)
entity::setId
作为枚举对象(单例)中方法的参数传递时, 100% 线程安全?
NOTE:笔记:
entity::setId
entity::setName
entity::setPosition
...etc. ...等等。 ALL these methods are standard java setter methods
所有这些方法都是标准的 java setter 方法
public void setId(long id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
....
UPDATE:更新:
to be concrete: ARE是具体的:是
Category entity = new Category();
entity.setId(5);//thread safe for sure
100% equal to 100% 等于
FacesBinding.VALUE.bindLong(entity::setId, ...);
does the fact that FacesBinding
ist Singleton and the method Reference in bindLong(entity::setId, ...)
makes it thread-unsafe?? FacesBinding
Singleton 并且bindLong(entity::setId, ...)
的方法 Reference bindLong(entity::setId, ...)
使它成为线程不安全的?
Your method reference call will be thread-safe if your setId
method is thread-safe, nothing more and nothing less.如果您的
setId
方法是线程安全的,那么您的方法引用调用将是线程安全的,仅此而已。
Method reference is a fancy shorthand for creating your ValueBinding
objects.方法引用是创建
ValueBinding
对象的一种奇特的速记。 When they are compiled, there will be a private inner class of sorts that implements your functional interface and calls the method you specified.当它们被编译时,会有一个私有的内部类来实现你的功能接口并调用你指定的方法。 Since you specified method that belongs to an object, this inner class will also be equivalent to having constructor that accepts your
Category
object, and a private field to store it (I said equivalent to because by default implementations are not limited to this behavior if they can justify and choose any other).由于您指定了属于一个对象的方法,这个内部类也相当于拥有接受您的
Category
对象的构造函数和一个私有字段来存储它(我说相当于因为默认情况下实现不限于此行为,如果它们可以证明并选择任何其他)。
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