org.springframework.web.util.NestedServletException：请求处理失败; 嵌套exception是REST with Spring中的java.lang.NullPointerException
我正在尝试使用Spring创建REST服务。当我尝试访问该服务时，它返回正确的数据，但显示 –
Exception handling request to /RESTServ/user/2: org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) [jboss-servlet-api_3.1_spec-1.0.0.Final.jar:1.0.0.Final] at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [jboss-servlet-api_3.1_spec-1.0.0.Final.jar:1.0.0.Final] at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78) at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:113) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:61) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61) at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:240) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:227) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:73) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:146) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at io.undertow.server.Connectors.executeRootHandler(Connectors.java:177) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:727) [undertow-core-1.0.15.Final.jar:1.0.15.Final] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [rt.jar:1.8.0_45] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [rt.jar:1.8.0_45] at java.lang.Thread.run(Thread.java:745) [rt.jar:1.8.0_45] Caused by: java.lang.NullPointerException at java.util.ArrayList.(ArrayList.java:177) [rt.jar:1.8.0_45] at io.undertow.servlet.spec.HttpServletResponseImpl.getHeaders(HttpServletResponseImpl.java:248) [undertow-servlet-1.0.15.Final.jar:1.0.15.Final] at org.springframework.http.server.ServletServerHttpResponse$ServletResponseHttpHeaders.get(ServletServerHttpResponse.java:160) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.http.server.ServletServerHttpResponse$ServletResponseHttpHeaders.containsKey(ServletServerHttpResponse.java:142) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.addContentDispositionHeader(AbstractMessageConverterMethodProcessor.java:349) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:221) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:153) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:165) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:80) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:126) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) [spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE] ... 30 more 任何人都可以帮我解决这个问题吗？ 我已经检查了它返回的数据，并且通过应用断点它不是null，但它仍然显示上面的exception。
编辑：
代码是： User.java包com.rest.service;
public class User { private int userid; private String firstName; private String lastName; private String email; public int getUserid() { return userid; } public void setUserid(int userid) { this.userid = userid; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } @Override public String toString() { return "User [userid=" + userid + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]"; } }
SpringServiceController.java
package com.rest.controller; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RestController; import com.rest.dao.UserService; import com.rest.service.User; @RestController @RequestMapping("/user/") public class SpringServiceController { UserService userService = new UserService(); @RequestMapping(value = "/{id}", method = RequestMethod.GET, headers = "Accept=application/json") public User getUser(@PathVariable int id) { User user = userService.getUserById(id); return user; } }
我使用UserService.java从数据库获取数据DBUtility是连接到JDBC的类
package com.rest.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.List; import com.rest.service.User; import com.rest.utility.DBUtility; public class UserService { private Connection connection; public UserService() { connection = DBUtility.getConnection(); } public List getAllUsers() { List users = new ArrayList(); try { Statement statement = connection.createStatement(); ResultSet rs = statement .executeQuery("select * from tblUser"); while (rs.next()) { User user = new User(); user.setUserid(rs.getInt("userid")); user.setFirstName(rs.getString("firstname")); user.setLastName(rs.getString("lastname")); user.setEmail(rs.getString("email")); users.add(user); } } catch (SQLException e) { e.printStackTrace(); } return users; } public User getUserById(int userId) { User user = new User(); try { PreparedStatement preparedStatement = connection.prepareStatement("select * from tblUser where userid=?"); preparedStatement.setInt(1, userId); ResultSet rs = preparedStatement.executeQuery(); if (rs.next()) { user.setUserid(rs.getInt("userid")); user.setFirstName(rs.getString("firstname")); user.setLastName(rs.getString("lastname")); user.setEmail(rs.getString("email")); } } catch (SQLException e) { e.printStackTrace(); }catch (Exception e) { System.out.println("Exception is: "+e); e.printStackTrace(); } return user; } }
我的web.xml是
RESTServ index.jsp rest org.springframework.web.servlet.DispatcherServlet contextConfigLocation /WEB-INF/rest-servlet.xml 1 rest /* org.springframework.web.context.ContextLoaderListener
这是我的rest-servlet.xml
PS：当我从spring xml文件中删除注释驱动标记时，还有一件事就是它适用于简单的数据类型。 但它不适用于需要json转换的地方。我正在使用WildFly – 8.1
这是WildFly的问题 – 8.1你必须使用WildFly – 8.2或使用Jboss 7。
我们在试用期间遇到了这个问题，将野生飞行8.1.0-决赛的spring-boot-1.2.2-Final迁移到了野生飞行8.1.0-Final的spring-boot-1.3.2-Final。 在wildfly 8.2.1-Final上不会出现此错误，因此如果你有选择tp udate你的wildfly版本，你应该这样做。
但是如果你仍然需要使用wildfly-8.1.0-Final，那么你可以修补它。
1）获取https://github.com/undertow-io/undertow/archive/1.0.15.Final.zip
2）编辑位于模块servlet中的io.undertow.servlet.spec.HttpServletResponseImpl
@Override public String getHeaders(final String name) { return new ArrayList(exchange.getResponseHeaders().get(name)); }
至
@Override public Collection getHeaders(final String name) { final HeaderValues headerValues = exchange.getResponseHeaders().get(name); if (headerValues != null) { return new ArrayList (headerValues); } return new ArrayList (); }
使用maven包下载servlet然后覆盖
{wildfly根目录} /modules/system/layers/base/io/undertow/servlet/main/undertow-servlet-1.0.15.Final.jar
与文件
{暗流根目录} /servlet/target/undertow-servlet-1.0.15.Final.jar
这将解决此错误。
如果您正在使用maven ，请在pom.xml添加下面指定的JSON Databinding依赖项，并使用@JsonRootName(value = "user")注释User类，
org.codehaus.jackson jackson-jaxrs 1.9.13 org.codehaus.jackson jackson-xc 1.9.13
这可能对那些无法在项目中升级Wildfly 8.1.0以解决此问题的人有所帮助。 Ingvar上面修补代码的答案帮了我很多，这里有一个脚本可以在一个命令中执行补丁（保留以前副本的备份）：