Question

创建弹出启动ConfigurationProperties Map时，我收到空指针异常。属性类是

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    var DestViewController : CreatePostScrollViewController = segue.destinationViewController as! CreatePostScrollViewController

    if dateText != "" {

        DestViewController.startTimeDateButton.setTitle(dateText, forState: .Normal)// Error Here

    } else if dateText == "" {

        DestViewController.startTimeDateButton.setTitle(currentDate, forState: .Normal)// Error Here
    }
}

ThingLayout是一个简单的pojo，具有属性文件指定的正确属性：

@Component
@ConfigurationProperties(prefix = "thing")
public class ThingProperties {

 private Map<String, ThingLayout> layouts;

 public Map<String, ThingLayout> getLayouts() {
     return layouts == null ? new HashMap<>() : layouts;
 }

 public void setLayouts(final Map<String, ThingLayout> layouts) {
     this.layouts = new HashMap(layouts);
 }
}

意图是绑定属性，我将能够执行

之类的操作

things.layouts:
 3042:
  itemPageIndex: 1
  itemX: 1960
  itemY: 890
  itemWidth: 400
  itemHeight: 70
  itemPattern: dd MMMM yyyy
 2151:
  itemPageIndex: 0
  itemX: 2000
  itemY: 796
  itemWidth: 500
  itemHeight: 70
  itemPattern: dd/MM/yyyy

我得到的例外是

thingProperties.getLayouts().get(3042).getItemX();

Answer 1

经过大量调试后，解决方案最终变得非常简单。如果我将我的属性类更改为以下它可以工作。

@Component
@ConfigurationProperties(prefix = "thing")
public class ThingProperties {

 private Map<String, ThingLayout> layouts = new HashMap<>();

 public Map<String, ThingLayout> getLayouts() {
     return layouts;
 }

 public void setLayouts(final Map<String, ThingLayout> layouts) {
     this.layouts = new HashMap(layouts);
 }
}

请注意，我现在正在初始化getter之外的布局对象。

Spring试图在

中为每个地图键创建一个默认值

org.springframework.beans.AbstractNestablePropertyAccessor#setDefaultValue(org.springframework.beans.AbstractNestablePropertyAccessor.PropertyTokenHolder)

默认值创建工作正常，但该值未在

中正确设置到地图中

org.springframework.beans.AbstractNestablePropertyAccessor#setPropertyValue(org.springframework.beans.AbstractNestablePropertyAccessor.PropertyTokenHolder, org.springframework.beans.PropertyValue)

创建弹簧引导时的空指针ConfigurationProperties Map <string，object =“”>

1 个答案: