以下示例使用基于 XML 的配置元数据进行基于 setter 的 DI。Spring XML 配置文件的一小部分如下指定了一些 bean 定义：
以下示例显示了相应的 ExampleBean 类：
Java
Kotlin
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;
}
}
class ExampleBean {
lateinit var beanOne: AnotherBean
lateinit var beanTwo: YetAnotherBean
var i: Int = 0
}
在前面的例子中，声明了 setter 来匹配 XML 文件中指定的属性。以下例子使用基于构造函数的 DI：
以下示例显示了相应的 ExampleBean 类：
Java
Kotlin
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;
}
}
class ExampleBean(
private val beanOne: AnotherBean,
private val beanTwo: YetAnotherBean,
private val i: Int)
bean 定义中指定的构造函数参数用作 ExampleBean 构造函数的参数。
现在考虑此示例的一个变体，其中 Spring 被告知调用 static 工厂方法而不是使用构造函数来返回对象实例：
以下示例显示了相应的 ExampleBean 类：
Java
Kotlin
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;
}
}
class ExampleBean private constructor() {
companion object {
// 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.
@JvmStatic
fun createInstance(anotherBean: AnotherBean, yetAnotherBean: YetAnotherBean, i: Int): ExampleBean {
val eb = ExampleBean (...)
// some other operations...
return eb
}
}
}
static 工厂方法的参数由