Spring 3 Dependency injection - JAVA

[html]
DI exists in two major variants, Constructor-based dependency injection and Setter-based dependency injection.
1. 基于构造方法的DI （Constructor-based dependency injection）

构造方法中的参数可以是原生数据类型，也可以是引用类型

引用类型：

[html]
public class SimpleMovieLister {

// the SimpleMovieLister has a dependency on a MovieFinder
private MovieFinder movieFinder;

// a constructor so that the Spring container can 'inject' a MovieFinder
public SimpleMovieLister(MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}

// business logic that actually 'uses' the injected MovieFinder is omitted...
}
[html]
package x.y;
public class Foo {
public Foo(Bar bar, Baz baz) {
// ...
}

}
[html]

简单类型:

[html]
package examples;

public class ExampleBean {

// No. of years to the calculate the Ultimate Answer
private int years;

// The Answer to Life, the Universe, and Everything
private String ultimateAnswer;

public ExampleBean(int years, String ultimateAnswer) {
this.years = years;
this.ultimateAnswer = ultimateAnswer;
}
}

方式一通过类型：
[html]

方式二通过索引:

[html]

在Spring3.0后，还提供了@ConstructorProperties注解的方法对构造方法的参数进行注入

[html]

[html]
package examples;

public class ExampleBean {

// Fields omitted

@ConstructorProperties({"years", "ultimateAnswer"})
public ExampleBean(int years, String ultimateAnswer) {
this.years = years;
this.ultimateAnswer = ultimateAnswer;
}
}

2. 基于Setter方法的DI （Constructor-based dependency injection）
Setter-based DI: 通过setter方法完成注入

[html]

[html]
public class ExampleBean {

private AnotherBean beanOne;
private YetAnotherBean beanTwo;
private int i;

public void setBeanOne(AnotherBean beanOne) {
this.beanOne = beanOne;
}

public void setBeanTwo(YetAnotherBean beanTwo) {
this.beanTwo = beanTwo;
}

public void setIntegerProperty(int i) {
this.i = i;
}
}

constructor-based DI:

[html]

[html]
public class ExampleBean {
private AnotherBean beanOne;
private YetAnotherBean beanTwo;
private int i;
public ExampleBean(AnotherBean anotherBean, YetAnotherBean yetAnotherBean, int i) {
this.beanOne = anotherBean;
this.beanTwo = yetAnotherBean;
this.i = i;
}
}

通过静态工厂方法进行注入
[html]

[html]
public class ExampleBean {

// a private constructor
private ExampleBean(...) {
...
}

// a static factory method; the arguments to this method can be
// considered the dependencies of the bean that is returned,
// regardless of how those arguments are actually used.
public static ExampleBean createInstance (
AnotherBean anotherBean, YetAnotherBean yetAnotherBean, int i) {

ExampleBean eb = new ExampleBean (...);
// some other operations...
return eb;
}
}

Arguments to the static factory method are supplied via elements, exactly the same as if a constructor had actually been used. The type of the class being returned by the factory method does not have to be of the same type as the class that contains the static factory method, although in this example it is. An instance (non-static) factory method would be used in an essentially identical fashion (aside from the use of the factory-bean attribute instead of the class attribute), so details will not be discussed here.

Dependency resoluti

Spring 3 Dependency injection(一)