面对 spring 构造函数中的歧义，第二个构造函数被调用

Question

我遇到了一个问题，即生成的输出不完全符合规范。我读过，如果构造函数不明确，则会调用第一个构造函数。但我面临着一个完全不同的问题。

我的class-

public class Addition {
    private int a;
    private int b;
    public Addition() {
        super();
        // TODO Auto-generated constructor stub
    }
    
    public Addition(int a, int b) {
        super();
        this.a = a;
        this.b = b;
        System.out.println("Constructor : int, int");
    }
    
    public Addition(double a, double b) {
        super();
        this.a = (int)a;
        this.b = (int)b;
        System.out.println("Constructor : double, double");
    }
    
    public void doSum() {
        System.out.println("Sum is -> "+(this.a+this.b));
    }

    @Override
    public String toString() {
        return "Addition [a=" + a + ", b=" + b + "]";
    }
    
}

XML 文件 -

<bean class="com.spring.Addition" name="addition1">
    <constructor-arg>
    <value>12</value>
    </constructor-arg>
    <constructor-arg>
    <value>34</value>
    </constructor-arg>
    </bean>

主要代码-

Addition addition = (Addition)applicationContext.getBean("addition1");
System.out.println(addition);

输出-

Constructor : double, double
Addition [a=12, b=34]

我唯一关心的是，当 (int,int) 构造函数定义在 (double,double) 构造函数之前时，为什么会在这里调用第二个构造函数？

Answer 1

您可以通过 type 属性为构造函数指定确切的数据类型来避免这种歧义，如下所示：

<bean class="com.spring.Addition" name="addition1">
    <constructor-arg type="int">
        <value>12</value>
    </constructor-arg>
    <constructor-arg type="int">
        <value>34</value>
    </constructor-arg>
</bean>

面对 spring 构造函数中的歧义，第二个构造函数被调用

Facing ambiguity in spring constructors, second constructor is getting called

java

spring

constructor-injection