java.lang.NoSuchMethodException: [Lcom.dn.vo.User ;. <init>()

Question

Я использую Spring MVC для создания веб-приложения. Я создал новое VO с именем User и создал метод POST для обработки VO. VO оказывает конструктор по умолчанию, но я получаю

java.lang.NoSuchMethodException: [Lcom.dn.vo.User;.<init>(). 

код участвует следующим образом:

VO Пользователь

package com.dn.vo; 

import java.io.Serializable; 

import javax.persistence.Column; 
import javax.persistence.Entity; 
import javax.persistence.GeneratedValue; 
import javax.persistence.Id; 
import javax.persistence.Table; 

import org.springframework.beans.factory.annotation.Autowired; 

import com.dn.enums.Salutation; 


@Entity 
@Table(name = "PHONE_USER") 
public class User implements Serializable { 

    long userId; 
    String firstName; 
    String surName; 
    Salutation salutation; 

    public User() { 
     super(); 
    } 

    public User(long userId, String firstName, String surName, Salutation salutation) { 
     super(); 
     this.userId = userId; 
     this.firstName = firstName; 
     this.surName = surName; 
     this.salutation = salutation; 
    } 

    @Id 
    @GeneratedValue 
    @Column(name = "USER_ID", unique = true, nullable = false, precision = 5, scale = 0) 
    public long getUserId() { 
     return userId; 
    } 

    public void setUserId(long userId) { 
     this.userId = userId; 
    } 

    @Column(name = "FIRST_NAME", nullable = false, length = 20) 
    public String getFirstName() { 
     return firstName; 
    } 

    public void setFirstName(String firstName) { 
     this.firstName = firstName; 
    } 


    @Column(name = "SURNAME", nullable = false, length = 20) 
    public String getSurName() { 
     return surName; 
    } 

    public void setSurName(String surName) { 
     this.surName = surName; 
    } 

    @Column(name = "SALUTATION", nullable = false, length = 20) 
    public Salutation getSalutation() { 
     return salutation; 
    } 

    public void setSalutation(Salutation salutation) { 
     this.salutation = salutation; 
    } 

    @Override 
    public String toString() { 
     return firstName+" "+surName; 
    } 

} 

MVC контроллер

package com.dn.controller; 

import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.stereotype.Controller; 
import org.springframework.web.bind.annotation.RequestMapping; 
import org.springframework.web.bind.annotation.RequestMethod; 
import org.springframework.web.bind.annotation.ResponseBody; 

import com.dn.db.DBConnectionProvider; 
import com.dn.vo.User; 

@Controller 
public class UserRegistrationController { 

    @Autowired 
    private DBConnectionProvider dbConnectionProvider; 


    @ResponseBody @RequestMapping(value= "/createUser", method = RequestMethod.POST, headers="Accept=application/json") 
    public void createUser(User user) { 

     System.out.println(user.toString()); 

    } 



@ResponseBody @RequestMapping(value= "/createUsers", method = RequestMethod.POST, headers="Accept=application/json") 
    public void createUser(User[] user) { 

     System.out.println(user.toString()); 

    } 


} 

HTTP Client Test

package com.dn.controller; 

import java.util.ArrayList; 
import java.util.List; 

import org.apache.http.HttpResponse; 
import org.apache.http.client.HttpClient; 
import org.apache.http.client.entity.UrlEncodedFormEntity; 
import org.apache.http.client.methods.HttpPost; 
import org.apache.http.impl.client.DefaultHttpClient; 
import org.apache.http.message.BasicHeader; 
import org.apache.http.message.BasicNameValuePair; 
import org.codehaus.jackson.map.ObjectMapper; 

import com.dn.enums.Salutation; 
import com.dn.vo.User; 

public class UserRegistrationControllerTest { 

    public static void main(String[] args) { 

     UserRegistrationControllerTest test = new UserRegistrationControllerTest(); 
     test.testUserArrayInput(); 
    } 

    private void testSingleUserInput(){ 

     HttpClient httpClient = null; 
     try { 
      httpClient = new DefaultHttpClient(); 
      String url = "http://localhost:8080/DNServer/createUser"; 
      HttpPost httpPost = new HttpPost(url); 
      httpPost.setHeader(new BasicHeader("Accept", "application/json")); 

      User region = new User(); 
      region.setFirstName("ABC"); 
      region.setSurName("XYZ"); 
      region.setSalutation(Salutation.Mr); 

      ObjectMapper mapper = new ObjectMapper(); 
      System.out.println(mapper.writeValueAsString(region)); 

      List nameValuePairs = new ArrayList(); 
      nameValuePairs.add(new BasicNameValuePair("user", mapper.writeValueAsString(region))); 
      httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); 

      HttpResponse response = httpClient.execute(httpPost); 

      System.out.println("test Single User Input done"+response); 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

    } 


    private void testUserArrayInput(){ 
     HttpClient httpClient = null; 
     try { 
      httpClient = new DefaultHttpClient(); 
      String url = "http://localhost:8080/DNServer/createUsers"; 
      HttpPost httpPost = new HttpPost(url); 
      httpPost.setHeader(new BasicHeader("Accept", "application/json")); 

      User[] regions = new User[1]; 
      User region = new User(); 
      region.setFirstName("XYZ"); 
      region.setSurName("ABC"); 
      region.setSalutation(Salutation.Mr); 
      regions[0] = region; 



      ObjectMapper mapper = new ObjectMapper(); 
      System.out.println(mapper.writeValueAsString(regions)); 

      List nameValuePairs = new ArrayList(); 
      nameValuePairs.add(new BasicNameValuePair("users", mapper.writeValueAsString(regions))); 
      httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); 

      HttpResponse response = httpClient.execute(httpPost); 
      System.out.println("done"); 

     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 


} 

Полный Трассировка стека

SEVERE: Servlet.service() for servlet [DNServlet] in context with path [/DNServer] threw exception [Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [[Lcom.dn.vo.User;]: No default constructor found; nested exception is java.lang.NoSuchMethodException: [Lcom.dn.vo.User;.<init>()] with root cause 
java.lang.NoSuchMethodException: [Lcom.dn.vo.User;.<init>() 
    at java.lang.Class.getConstructor0(Class.java:2721) 
    at java.lang.Class.getDeclaredConstructor(Class.java:2002) 
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:105) 
    at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.createAttribute(ModelAttributeMethodProcessor.java:138) 
    at org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttribute(ServletModelAttributeMethodProcessor.java:81) 
    at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:104) 
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:79) 
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:157) 
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:124) 
    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:749) 
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689) 
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83) 
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938) 
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870) 
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961) 
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:644) 
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:725) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:301) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:74) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1017) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:652) 
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1575) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1533) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) 
    at java.lang.Thread.run(Thread.java:722)`enter code here` 

Answer 1

Я думаю, что ключ находится в имени метода:

[Lcom.dn.vo.User;.<init>() 

Когда мы деконструкции, что весна, как представляется, пытаться вызвать конструктор no-args (метод <init>()) для типа [Lcom.dn.vo.User;. Но этот тип означает «массив com.dn.vo.User». И классы массива не имеют конструкторов.

Я вижу код в своем модульном тесте, который создает User[] и, как представляется, передает его в виде сегмента в запросе POST для «/ createUsers». Но класс MVC не имеет метода, который привязывается к «/ createUsers».

Это правильно ???