任何人都可以告诉我为什么我会在null pointer exception的结果课中获得这个messageSource吗？
我跟着这个。 http://www.mkyong.com/spring/spring-how-to-access-messagesource-in-bean-messagesourceaware/
并且可以在我的控制器中使用消息源，如下所示：
工作代码：---
package web.controller;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import web.entity.Users;
import web.service.UserService;
import web.service.common.Result;
//import javax.servlet.http.HttpServletRequest;
//import javax.servlet.http.HttpSession;
/**
*
* @author syncsys
*/
@Controller
public class UserController {
@Autowired
private UserService userService;
@Autowired
private MessageSource messages;
@RequestMapping(value = "/login", method = RequestMethod.GET)
public String getLoginPage(@RequestParam(value="error", required=false) boolean error,
ModelMap model) {
System.out.println("Received request to show login page");
String message = null;
if (error == true) {
message = messages.getMessage("message.invalidCreds", new Object [] {"UserName"}, "Invalid credentials", null);
// Assign an error message
model.put("invalidCreds", message);
} else {
model.put("invalidCreds", "");
}
return "/login/login";
}
主要错误：
web.service.common.Result.<init>(Result.java:29)
web.service.UserServiceImpl.save(UserServiceImpl.java:30)
web.controller.UserController.createAdmin(UserController.java:121)
调试：
debug --- a
debug --- b
Hibernate: select users0_.id as id1_15_, users0_.description as descript2_15_, users0_.email as email3_15_, users0_.isEnabled as isEnable4_15_, users0_.name as name5_15_, users0_.password as password6_15_, users0_.type as type7_15_ from Users users0_ where users0_.email=?
debug --- d
result class test --------- 1
道：
public Users save(Users user) {
Users userToBeReturned = entityManager.merge(user);
return userToBeReturned;
}
public boolean doesLoginIdExists(String email){
System.out.println("debug --- a");
String queryString = "SELECT user FROM Users AS user " +
"WHERE user.email = :email";
Query query = entityManager.createQuery(queryString);
query.setParameter("email", email);
System.out.println("debug --- b");
List<?> list = query.getResultList();
if(list == null || list.size() == 0){
System.out.println("debug --- c");
return false;
}else{
System.out.println("debug --- d");
return true;
}
}
服务：
public Result save(Users user){
if( userDAO.doesLoginIdExists(user.getEmail()) ){
############## line 30 #############################################
return new Result(false,null,Arrays.asList("error.emailAlreadyExists"/*,"string"*/) );
}else{
Users userToBeReturned = userDAO.save(user);
return new Result(true,userToBeReturned,Arrays.asList("success.userCreated"/*,"string"*/));
}
控制器：
@RequestMapping("/users/createadmin")
public String createAdmin(ModelMap model){
Users user = new Users();
user.setEmail("admin@admin.com");
user.setName("Admin");
user.setPassword("admin");
############## line 121 ##################################################
Result result = userService.save(user);
if(result.getIsSuccessful()){
model.put("successMessages", result.getMessageList());
}else{
model.put("errorMessages", result.getMessageList());
}
return "/users/createadmin";
}
结果类
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package web.service.common;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.context.MessageSourceAware;
import org.springframework.context.MessageSourceResolvable;
import org.springframework.context.NoSuchMessageException;
/**
*
* @author syncsys
*/
public class Result implements MessageSourceAware{
private boolean isSuccessful;
private Object object;
private List messageList = new ArrayList();
@Autowired
private MessageSource messageSource;
public Result(boolean isSuccessful, Object object, List errorList){
this.isSuccessful = isSuccessful;
this.object = object;
if(errorList != null){
for (Object error : errorList){
System.out.println("result class test --------- 1");
#########################line 29 ###################
String errorMessage = messageSource.getMessage((String)error, new Object [] {"error-"}, "error-", null);
System.out.println("result class test --------- 2");
this.messageList.add(errorMessage);
System.out.println("result class test --------- 3");
}
}
}
/**
* @return the isSuccessful
*/
public boolean getIsSuccessful() {
return isSuccessful;
}
/**
* @param isSuccessful the isSuccessful to set
*/
public void setIsSuccessful(boolean isSuccessful) {
this.isSuccessful = isSuccessful;
}
/**
* @return the object
*/
public Object getObject() {
return object;
}
/**
* @param object the object to set
*/
public void setObject(Object object) {
this.object = object;
}
/**
* @return the messageList
*/
public List getMessageList() {
return messageList;
}
/**
* @param messageList the messageList to set
*/
public void setMessageList(List messageList) {
this.messageList = messageList;
}
@Override
public void setMessageSource(MessageSource messageSource) {
this.messageSource = messageSource;
}
}
详细错误：
HTTP Status 500 - Request processing failed; nested exception is java.lang.NullPointerException
type Exception report
message Request processing failed; nested exception is java.lang.NullPointerException
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:948)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
root cause
java.lang.NullPointerException
web.service.common.Result.<init>(Result.java:29)
web.service.UserServiceImpl.save(UserServiceImpl.java:30)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:601)
org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
$Proxy50.save(Unknown Source)
web.controller.UserController.createAdmin(UserController.java:121)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:601)
org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.32 logs.
Apache Tomcat/7.0.32
答案 0 :(得分：1)
在服务类的save方法中，您要实例化Result类。
new Result(false,null,Arrays.asList("error.emailAlreadyExists"/*,"string"*/) );
在Result课程中，您Autowiring字段MessageSource
@Autowired
private MessageSource messageSource;
spring无法自动装配您实例化的任何字段。
对于Spring Autowire任何字段，您需要允许spring实例化（维护）Result对象。