我正在尝试使用Spring Framework 5构建简单的注册并登录5.我试图通过实现Java配置类来避免XML配置。我不想使用Hibernate，因为我想在使用简单但前进的Hibernate之前先学习与Spring JDBC一起使用。我尝试从属性文件加载数据库凭据。
我提交注册表格后我会得到此例外。
我试图使用println方法和记录器显示错误，但由于某种原因，我不需要显示出错误。所以这是两件事
-
无法准确找到什么是创建NullPoInterException的原因，因为它说它是嵌套的例外。我认为是数据库连接引起了这个问题，我很困惑为什么如果是数据库连接，我找不到SQLDRIVER类。
-
为什么我无法显示导致NULL异常的变量的输出，为什么我的Logger实现不显示任何错误的详细信息。
我尝试了各种方法来解决它，但由于无法使其正常工作而浪费了很长时间。因此，我在这里寻求专家的帮助。
我认为尝试加载数据库凭据以使数据库连接起作用的方式并不顺利，因为数据库连接仍然很无效。如何使用Java Config类（而不是XML方法）从属性文件加载数据库并在DAO中使用它？
database-properties.properties
jdbc.driverClassName=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/tutorstudentdb1
jdbc.user=webadmin
jdbc.pass=Password1
dispatcherconfig类
package com.rabin.tutorstudent.config;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
public class DispatcherConfig extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class<?>[] getRootConfigClasses() {
return new Class[] {PersistanceConfig.class};
}
@Override
protected Class<?>[] getServletConfigClasses() {
return new Class[] {SpringConfig.class};
}
@Override
protected String[] getServletMappings() {
return new String[] {"/"};
}
}
persistanceconfig class
package com.rabin.tutorstudent.config;
import javax.sql.DataSource;
import org.apache.tomcat.dbcp.dbcp2.BasicDataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@Configuration
@EnableTransactionManagement
@PropertySource({"classpath:database-properties.properties"})
@ComponentScan({"com.rabin.tutorstudent"})
public class PersistanceConfig {
//env
@Autowired
private Environment env;
@Bean
public DataSource dataSource() {
BasicDataSource dataSource = new BasicDataSource();
dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
dataSource.setUrl(env.getProperty("jdbc.url"));
dataSource.setUsername(env.getProperty("jdbc.user"));
dataSource.setPassword(env.getProperty("jdbc.pass"));
return dataSource;
}
}
springconfig class
package com.rabin.tutorstudent.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import org.springframework.web.servlet.view.JstlView;
@Configuration
@EnableWebMvc
//@ComponentScan({"com.rabin.tutorstudent"})
@PropertySource({"classpath:database-properties.properties"})
@ComponentScan(basePackages= "com.rabin.tutorstudent")
public class SpringConfig {
@Bean
public ViewResolver viewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix("/WEB-INF/views/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
}
userdaoimpl
package com.rabin.tutorstudent.daoimpl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.List;
import javax.sql.DataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import com.rabin.tutorstudent.dao.UserDAO;
import com.rabin.tutorstudent.model.User;
public class UserDAOImpl implements UserDAO {
public final Logger logger = LoggerFactory.getLogger(UserDAOImpl.class);
@Autowired
private DataSource dataSource;
/*
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
System.out.print(dataSource);
}
*/
public void save(User user) {
String query = "insert into user (username, password, firstname, lastname, email, role) values (?,?,?,?,?,?)";
logger.debug(query);
Connection con = null;
logger.debug("Connection Initialization "+con);
PreparedStatement ps = null;
try {
logger.debug("Datasource value=" +dataSource);
con = dataSource.getConnection();
logger.info("Connection to db"+con);
System.out.println("Connection :"+con);
ps = con.prepareStatement(query);
//ps.setLong(parameterIndex, x);
ps.setString(1, user.getUsername());
ps.setString(2, user.getPassword());
ps.setString(3, user.getFirstName());
ps.setString(4, user.getLastName());
ps.setString(5, user.getEmail());
ps.setString(6, user.getRole());
int out = ps.executeUpdate();
if(out !=0){
System.out.println("Employee saved with id="+user.getId());
} else {
System.out.println("Employee save failed with id="+user.getId());
}
} catch (SQLException e) {
System.out.println("Sql error" +e.getMessage());
}
}
public User getById(Long id) {
// TODO Auto-generated method stub
return null;
}
public void update(User user) {
// TODO Auto-generated method stub
}
public void deleteById(Long id) {
// TODO Auto-generated method stub
}
public List<User> getAll() {
// TODO Auto-generated method stub
return null;
}
}
userdao
package com.rabin.tutorstudent.dao;
import java.util.List;
import com.rabin.tutorstudent.model.User;
public interface UserDAO {
//Create - insert
public void save(User user);
//Read - select
public User getById(Long id);
//Update - change
public void update(User user);
//Delete - Remove
public void deleteById(Long id);
// Get All
public List<User> getAll();
}
IngipController
package com.rabin.tutorstudent.controller;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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.RequestParam;
import org.springframework.web.servlet.ModelAndView;
import com.rabin.tutorstudent.daoimpl.UserDAOImpl;
import com.rabin.tutorstudent.model.User;
@Controller
public class SignUpController {
public final Logger logger = LoggerFactory.getLogger(SignUpController.class);
@Autowired
// sessionFactory;
@RequestMapping(value = "/register", method = RequestMethod.GET)
public String signUp() {
return "register";
}
@RequestMapping(value = "/register", method = RequestMethod.POST)
public ModelAndView signUpPost(
@RequestParam("username") String username,
@RequestParam("password") String password,
@RequestParam("firstname") String firstname,
@RequestParam("lastname") String lastname,
@RequestParam("email") String email,
@RequestParam("role") String role) {
logger.debug("Inside signUpPost method.");
ModelAndView mv = new ModelAndView();
logger.info("Model view ="+mv);
User user = new User(username, password, email, firstname, lastname, role);
user.setUsername(username);
user.setPassword(password);
user.setFirstName(firstname);
user.setLastName(lastname);
user.setEmail(email);
user.setRole(role);
//dao call
UserDAOImpl uDAO = new UserDAOImpl();
//UserDAO uDAO = new UserDAO();
//User u = new User(username, password, email, firstname, lastname, role);
//uDAO.insertUser(u);
uDAO.save(user);
System.out.println("User Registered..");
return mv;
}
}
用户
package com.rabin.tutorstudent.model;
public class User {
private Long id;
private String username;
private String password;
private String email;
private String firstName;
private String lastName;
private String role;
public User() {
super();
}
public User(Long id, String username, String password, String email, String firstName, String lastName,
String role) {
super();
this.id = id;
this.username = username;
this.password = password;
this.email = email;
this.firstName = firstName;
this.lastName = lastName;
this.role = role;
}
public User(String username, String password, String email, String firstName, String lastName, String role) {
super();
this.username = username;
this.password = password;
this.email = email;
this.firstName = firstName;
this.lastName = lastName;
this.role = role;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
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 getRole() {
return role;
}
public void setRole(String role) {
this.role = role;
}
}
这是我的控制台输出，使我嵌套了NullPoInterException。
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Server version: Apache Tomcat/8.5.38
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Server built: Feb 5 2019 11:42:42 UTC
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Server number: 8.5.38.0
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: OS Name: Windows 10
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: OS Version: 10.0
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Architecture: amd64
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Java Home: C:Program FilesJavajre1.8.0_152
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: JVM Version: 1.8.0_152-b16
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: JVM Vendor: Oracle Corporation
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: CATALINA_BASE: C:UsersG3eclipse-workspace.metadata.pluginsorg.eclipse.wst.server.coretmp1
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: CATALINA_HOME: C:UsersG3Downloadsapache-tomcat-8.5.38
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Command line argument: -Dcatalina.base=C:UsersG3eclipse-workspace.metadata.pluginsorg.eclipse.wst.server.coretmp1
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Command line argument: -Dcatalina.home=C:UsersG3Downloadsapache-tomcat-8.5.38
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Command line argument: -Dwtp.deploy=C:UsersG3eclipse-workspace.metadata.pluginsorg.eclipse.wst.server.coretmp1wtpwebapps
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Command line argument: -Djava.endorsed.dirs=C:UsersG3Downloadsapache-tomcat-8.5.38endorsed
Feb 28, 2019 5:47:03 PM org.apache.catalina.startup.VersionLoggerListener log
INFO: Command line argument: -Dfile.encoding=Cp1252
Feb 28, 2019 5:47:03 PM org.apache.catalina.core.AprLifecycleListener lifecycleEvent
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:Program FilesJavajre1.8.0_152bin;C:WINDOWSSunJavabin;C:WINDOWSsystem32;C:WINDOWS;C:/Program Files/Java/jre1.8.0_152/bin/server;C:/Program Files/Java/jre1.8.0_152/bin;C:/Program Files/Java/jre1.8.0_152/lib/amd64;C:Program Files (x86)InteliCLS Client;C:ProgramDataOracleJavajavapath;C:Program FilesInteliCLS Client;C:Windowssystem32;C:Windows;C:WindowsSystem32Wbem;C:WindowsSystem32WindowsPowerShellv1.0;C:WINDOWSsystem32;C:WINDOWS;C:WINDOWSSystem32Wbem;C:WINDOWSSystem32WindowsPowerShellv1.0;C:Program Files (x86)IntelIntel(R) Management Engine ComponentsDAL;C:Program FilesIntelIntel(R) Management Engine ComponentsDAL;C:Program Files (x86)IntelIntel(R) Management Engine ComponentsIPT;C:Program FilesIntelIntel(R) Management Engine ComponentsIPT;C:WINDOWSSystem32OpenSSH;C:Program FilesGitcmd;C:Program FilesIntelWiFibin;C:Program FilesCommon FilesIntelWirelessCommon;C:Program Files (x86)Bracketscommand;C:Program FilesNVIDIA CorporationNVIDIA NvDLISR;C:Program Files (x86)NVIDIA CorporationPhysXCommon;D:xamppphp;C:ProgramDataComposerSetupbin;C:UsersG3AppDataLocalProgramsPythonPython37-32Scripts;C:UsersG3AppDataLocalProgramsPythonPython37-32;C:UsersG3AppDataLocalMicrosoftWindowsApps;C:UsersG3AppDataRoamingComposervendorbin;C:UsersG3Desktop;;.]
Feb 28, 2019 5:47:03 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-nio-8080"]
Feb 28, 2019 5:47:04 PM org.apache.tomcat.util.net.NioSelectorPool getSharedSelector
INFO: Using a shared selector for servlet write/read
Feb 28, 2019 5:47:04 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-nio-8009"]
Feb 28, 2019 5:47:04 PM org.apache.tomcat.util.net.NioSelectorPool getSharedSelector
INFO: Using a shared selector for servlet write/read
Feb 28, 2019 5:47:04 PM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 702 ms
Feb 28, 2019 5:47:04 PM org.apache.catalina.core.StandardService startInternal
INFO: Starting service [Catalina]
Feb 28, 2019 5:47:04 PM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/8.5.38
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Feb 28, 2019 5:47:06 PM org.apache.catalina.core.ApplicationContext log
INFO: 1 Spring WebApplicationInitializers detected on classpath
Feb 28, 2019 5:47:06 PM org.apache.jasper.servlet.TldScanner scanJars
INFO: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
Feb 28, 2019 5:47:06 PM org.apache.catalina.core.ApplicationContext log
INFO: Initializing Spring root WebApplicationContext
Feb 28, 2019 5:47:08 PM org.apache.catalina.core.ApplicationContext log
INFO: Initializing Spring FrameworkServlet 'dispatcher'
Feb 28, 2019 5:47:09 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-nio-8080"]
Feb 28, 2019 5:47:09 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-nio-8009"]
Feb 28, 2019 5:47:09 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 5279 ms
Feb 28, 2019 5:47:40 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [dispatcher] in context with path [/tutorstudent] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException
at com.rabin.tutorstudent.daoimpl.UserDAOImpl.save(UserDAOImpl.java:41)
at com.rabin.tutorstudent.controller.SignUpController.signUpPost(SignUpController.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:871)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:777)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:881)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
浏览器上的输出
HTTP Status 500 – Internal Server Error
Type Exception Report
Message Request processing failed; nested exception is java.lang.NullPointerException
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:986)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:881)
javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
Root Cause
java.lang.NullPointerException
com.rabin.tutorstudent.daoimpl.UserDAOImpl.save(UserDAOImpl.java:41)
com.rabin.tutorstudent.controller.SignUpController.signUpPost(SignUpController.java:53)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:871)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:777)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:881)
javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
问题不是数据源初始化，而是从属性文件中拾取值，因为在初始化时没有错误，但是，这是@auotwired没有在Daoimpl工作。可能是因为您不使用@component注释。Spring不知道它必须在Daoimpl中自动data source。
另外，为什么不在SignUpController中的Autowire UserDAO您手中拿着DI，并期望Spring可以为您自动使用一些东西。如果您打算自己实例化对象，则还应设置数据源。我建议您参考一些样本以使其变得简单。