Spring Mongodb-无法实例化bean类[java.util.List]：指定的类是一个接口
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Spring Mongodb- Could not instantiate bean class [java.util.List]: Specified class is an interface
提问by VBJ
my project is using Spring data mongodb. I was not having below error until i made an edit to one of the document that has a field with Array of Documents in it. It was working fine before but now I keep getting the below error.
我的项目正在使用 Spring 数据 mongodb。直到我对其中包含文档数组字段的文档之一进行编辑后，我才遇到以下错误。以前工作正常，但现在我不断收到以下错误。
The field i updated was impapps in the Projects POJO class. I am not sure how to clear this error tried different things but did not work out.
我更新的字段是 Projects POJO 类中的 impapps。我不知道如何清除此错误尝试了不同的方法但没有解决。
SEVERE: Servlet.service() for servlet [appServlet] in context with path [/mongodproject] threw exception [Request processing failed; nested exception is org.springframework.data.mapping.model.MappingInstantiationException: Could not instantiate bean class [java.util.List]: Specified class is an interface] with root cause
org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [java.util.List]: Specified class is an interface
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:101)
at org.springframework.data.convert.ReflectionEntityInstantiator.createInstance(ReflectionEntityInstantiator.java:60)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:232)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:212)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1008)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.access0(MappingMongoConverter.java:75)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:957)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getValueInternal(MappingMongoConverter.java:713)
Here are my POJO and Spring Repository class.
这是我的 POJO 和 Spring Repository 类。
Project POJO Class
项目 POJO 类
@Document(collection="releases")
public class Project {
@Id
private String id;
......
@Field("impapps")
private List<ImpactedApplications> impapps=new ArrayList<ImpactedApplications>();
.....getters/setters
}
ImpactedApplication POJO Class:
ImpactedApplication POJO 类：
public class ImpactedApplications {
@Field("appid")
private String appId;
.....
@Field("repository")
private List<ScriptsRepo> rep=new ArrayList<ScriptsRepo>();
@Field("artifacts")
private List<Artifacts> artifacts=new ArrayList<Artifacts>();
//getter and setters
}
}
Artifacts POJO Class
工件 POJO 类
public class Artifacts {
@Field("artifacttype")
private String artifactType;
@Field("documentlink")
private String documentLink;
@Field("arttestphase")
private String artTestPhase;
@Field("artifactname")
private ArtifactsEnums artifactsNames;
@Field("startdate")
private String startDate;
@Field("enddate")
private String endDate;
@Field("peerrev")
private boolean peerReview;
@Field("busrev")
private boolean busReview;
@Field("na")
private boolean na;
Spring Repository classes
Spring 存储库类
public interface ProjectRepository extends Repository<Project, String> {
Project findById(String id);
List<Project> findByYearAndReleaseMonthNoOrderByProjectNameDesc(String year,String month, Sort sort);
Project findByYearAndReleaseMonthNoAndId(String year, String month,String id);
Whenever i call the above methods i keep getting the exception.
每当我调用上述方法时，我都会收到异常。
Below is how my document is looking currently.
以下是我的文档目前的外观。
采纳答案by Oliver Drotbohm
The impappsfield in your document is not an array but a nested document. So if you change your List<ImpactedApplications>to a simple ImpactedApplicationsthis should read fine.
impapps文档中的字段不是数组而是嵌套文档。所以如果你把你的改成List<ImpactedApplications>简单的，ImpactedApplications这应该很好读。
回答by bastien
I have got the same exception :
我有同样的例外：
Try to declare your field like this :
尝试像这样声明您的字段：
@Field("impapps")
ArrayList<ImpactedApplications> impapps = new ArrayList<ImpactedApplications>();
I don't like to do that but it works for me.
我不喜欢那样做，但它对我有用。
edit:
编辑：
My issue was due to unwind operation during aggregation. It transform array (declared as List<> in my class) into object and then reflection doesn't work because spring was expecting a list.
我的问题是由于聚合期间的展开操作。它将数组（在我的类中声明为 List<> ）转换为对象，然后反射不起作用，因为 spring 期待一个列表。
