mongoTemplate.findAll（）抛出异常

Question

当我尝试使用mongoTemplate.findAll（）方法时遇到问题。这是一个异常的堆栈跟踪：

SEVERE: Servlet.service() for servlet [mvc-dispatcher] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.data.mapping.model.MappingInstantiationException: Failed to instantiate java.io.File using constructor NO_CONSTRUCTOR with arguments ] with root cause
java.lang.NoSuchMethodException: java.io.File.<init>()
    at java.lang.Class.getConstructor0(Class.java:2892)
    at java.lang.Class.getDeclaredConstructor(Class.java:2058)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:105)
    at org.springframework.data.convert.ReflectionEntityInstantiator.createInstance(ReflectionEntityInstantiator.java:61)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:243)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:223)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1099)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.access$100(MappingMongoConverter.java:76)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1048)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getValueInternal(MappingMongoConverter.java:798)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:256)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:249)
    at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:294)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:249)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:223)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:187)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:183)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:76)
    at org.springframework.data.mongodb.core.MongoTemplate$ReadDbObjectCallback.doWith(MongoTemplate.java:2105)
    at org.springframework.data.mongodb.core.MongoTemplate.executeFindMultiInternal(MongoTemplate.java:1789)
    at org.springframework.data.mongodb.core.MongoTemplate.findAll(MongoTemplate.java:1206)
    at com.ub.geopoints_test.tracks.services.TracksGeopointsService.findAllTracks(TracksGeopointsService.java:112)
    at com.ub.geopoints_test.dots.services.MySaxParser.setUpMySaxParser(MySaxParser.java:42)
    at com.ub.geopoints_test.tracks.controllers.TracksGeopointsController.tracks(TracksGeopointsController.java:74)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2476)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2465)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

以下是我使用findAll（）方法的代码：

@Service
public class MySaxParser extends DefaultHandler{
@Autowired
private MongoTemplate mongoTemplate;
@Autowired
private TracksGeopointsService tracksGeopointsService;

private List<DotGeopointsDoc> dotGeopointsDocList;
private String xmlFileName;
private String tmpValue;
private DotGeopointsDoc dotGeopointsDoc;
private TracksGeopointsDoc tracksGeopointsDoc = new TracksGeopointsDoc();

public void setUpMySaxParser(String bookXmlFileName, File file) {
    this.xmlFileName = bookXmlFileName;
    dotGeopointsDocList = new ArrayList<DotGeopointsDoc>();
    dotGeopointsDoc = new DotGeopointsDoc();
    List<TracksGeopointsDoc> tracks = tracksGeopointsService.findAllTracks(); // Here I get an exception above.
    if (tracks.size() != 0) {
        tracksGeopointsDoc = mongoTemplate.findOne(new Query(Criteria.where("file").is(file)), TracksGeopointsDoc.class);
    }
    parseDocument();
}
// ....
// some other code

这是我的TrackGeopointsDoc类：

@Document
public class TracksGeopointsDoc {

@Id
private ObjectId id;

private List<DotGeopointsDoc> dots = new ArrayList<DotGeopointsDoc>();
private File file;

public ObjectId getId() {
    return id;
}

public void setId(ObjectId id) {
    this.id = id;
}

public List<DotGeopointsDoc> getDots() {
    return dots;
}

public void setDots(List<DotGeopointsDoc> dots) {
    this.dots = dots;
}

public File getFile() {
    return file;
}

public void setFile(File file) {
    this.file = file;
}
}

拜托，有人可以帮我吗？

Answer 1

这种例外意味着您的代码无法找到java.io.File的无参数构造函数（因为它没有一个）。

我的怀疑在于private File file的{​​{1}}属性。我不认为你在MongoDB中存储文件的方式，默认情况下每个文档的大小限制在16mb左右。

您必须将文件存储为序列化字符串（请记住文档限制），或使用GridFS as recommended in the doc.