GlassFish，CDI和构造器注射 [英] GlassFish, CDI and constructor injection
问题描述
GlassFish 3.1中是否支持构造函数注入管理bean的CDI？我有一个 @Singleton EJB，我想使用构造函数注入来注入另一个托管的bean（包含在同一个EJB模块中）。现场注射工作。但是使用构造函数注入，我从 AbstractSingletonContainer 中得到一个 NullPointerException 。
Is constructor injection supported in GlassFish 3.1's implementation of CDI for managed beans? I have a @Singleton EJB into which I want to inject another managed bean (contained in the same EJB module) using constructor injection. Field injection does work. But with constructor injection I get a NullPointerException from AbstractSingletonContainer.
这样做：
@Singleton
public class FooBean implements Foo {
@Inject private BarBean bar;
}
这不起作用：
@Singleton
public class FooBean implements Foo {
private final BarBean bar;
@Inject
public FooBean(BarBean bar) {
this.bar = bar;
}
}
推荐答案
CDI支持直接现场注入，初始化方法参数注入和构造函数参数注入。从CDI 1.0规范：
CDI does support direct field injection, initializer method parameter injection and constructor parameter injection. From the CDI 1.0 specification:
3.7。 Bean构造函数
当容器实例化一个bean
类时，它调用了
构造函数。 bean构造函数是
bean类的构造函数。
3.7. Bean constructors
When the container instantiates a bean class, it calls the bean constructor. The bean constructor is a constructor of the bean class.
应用程序可以直接调用bean
构造函数。但是，如果
应用程序直接实例化
bean，则不会通过容器将参数传递给
构造函数;
返回的对象不绑定到任何
上下文;没有依赖关系由容器注入
;并且
的生命周期新的实例不由
容器管理。
The application may call bean constructors directly. However, if the application directly instantiates the bean, no parameters are passed to the constructor by the container; the returned object is not bound to any context; no dependencies are injected by the container; and the lifecycle of the new instance is not managed by the container.
可以通过注释构造函数
@Inject c>。
The bean constructor may be identified
by annotating the constructor
@Inject.
@SessionScoped
public class ShoppingCart implements Serializable {
private User customer;
@Inject
public ShoppingCart(User customer) {
this.customer = customer;
}
public ShoppingCart(ShoppingCart original) {
this.customer = original.customer;
}
ShoppingCart() {}
...
}
@ConversationScoped
public class Order {
private Product product;
private User customer;
@Inject
public Order(@Selected Product product, User customer) {
this.product = product;
this.customer = customer;
}
public Order(Order original) {
this.product = original.product;
this.customer = original.customer;
}
Order() {}
...
}
如果一个bean类没有显式地
使用 @Inject 声明一个构造函数，
构造函数它不接受
参数是bean构造函数。
If a bean class does not explicitly
declare a constructor using @Inject,
the constructor that accepts no
parameters is the bean constructor.
如果一个bean类有多个
构造函数注释 @Inject ，
容器自动检测
问题，并将其视为定义
错误。
If a bean class has more than one
constructor annotated @Inject, the
container automatically detects the
problem and treats it as a definition
error.
如果一个bean构造函数有一个参数
注释 @Dispose 或 @Observes ，
容器自动检测
的问题，并将其视为
定义错误。
If a bean constructor has a parameter
annotated @Disposes, or @Observes,
the container automatically detects
the problem and treats it as a
definition error.
一个bean构造函数可能有任何数字
的参数。
bean构造函数的所有参数都是注入点。
A bean constructor may have any number of parameters. All parameters of a bean constructor are injection points.
我想知道你的问题是否可以与 WELD-141 。
I wonder if your problem could be related to WELD-141 though.
- CDI 1.0规范
- 第3.7节。 Bean构造函数
- 4.1. Injection points
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