java如何通过spring有条件地初始化类

Question

如何通过spring有条件地初始化类？ 如果某个条件为真，那么我希望将一个参数传递给另一个参数 论据

<bean id="myFactory" class="Factory">

  if something then
   <constructor-arg>
      <util:map>
        <!-- configure your map here, or reference it as a separate bean -->
        <entry key="java.lang.String" value="key">....</entry>
      </util:map>
   </constructor-arg>
  else
    <constructor-arg>
      <util:map>
        <!-- configure your map here, or reference it as a separate bean -->
        <entry key="java.lang.String" value="key">....</entry>
      </util:map>
   </constructor-arg>
</bean>

怎么做

Answer 1

你可以完全按照你指定的方式来做。以这种方式定义FactoryBean，例如，用于生成客户Bean：

public class CustomFactoryBean implements FactoryBean<Customer>{

    private int customProperty;

    public int getCustomProperty() {
        return customProperty;
    }

    public void setCustomProperty(int customProperty) {
        this.customProperty = customProperty;
    }

    @Override
    public Customer getObject() throws Exception {
        if (customProperty==1)
            return new Customer("1", "One");        
        return new Customer("999", "Generic");
    }

    @Override
    public Class<?> getObjectType() {
        return Customer.class;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

基本上就是这样，现在根据您如何注入工厂bean的属性，可以在上面的getObject方法中控制实际的bean实例化

Answer 2

Spring表达式语言可能会对您有所帮助link