jdbcTemplate is null and throws null pointer exception
In your controller, you are creating a new UserDaoImpl :
@RequestMapping(method = RequestMethod.GET, value="/{userId}", produces = {MediaType.APPLICATION_JSON_VALUE})
ResponseEntity<User> getUser(@PathVariable int userId){
UserDaoImpl user = new UserDaoImpl(); // <-- HERE
User u = new User();
u=user.getUser(userId);
return new ResponseEntity<User>(u, HttpStatus.OK);
}
This UserDaoImpl is not managed by spring, and not configured/autowired. You should inject in your controller the instance of UserDao configured in the xml :
@Autowired
private UserDao userDao;
@RequestMapping(method = RequestMethod.GET, value="/{userId}", produces = {MediaType.APPLICATION_JSON_VALUE})
ResponseEntity<User> getUser(@PathVariable int userId){
User u = userDao.getUser(userId);
return new ResponseEntity<User>(u, HttpStatus.OK);
}
kanra-san
Updated on February 10, 2020Comments
-
kanra-san over 4 years
I am new to Spring. I am trying to develop REST API using Spring web MVC. I am trying to fetch some data using JdbcTemplate from my database (MySQL). But when i run the code in the server I am getting
500- Internal Server Error
and the stack trace showsjava.lang.NullPointerException
. When i tried to debug the code i found out that jdbcTemplate variable has null value. I have tried every solution provided in web but still getting the same error.Here is my applicationContext.xml file
<context:component-scan base-package="com.cinema.repository" /> <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate"> <property name="dataSource" ref="dataSource" /> </bean> <bean id="userDao" class="com.cinema.repository.UserDaoImpl"> <property name="jdbcTemplate" ref="jdbcTemplate" /> </bean> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${jdbc.driverClassName}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> </bean> <context:property-placeholder location="/WEB-INF/jdbc.properties" />
My UserDaoImpl.java looks is:
public class UserDaoImpl implements UserDao { private JdbcTemplate jdbcTemplate; public JdbcTemplate getJdbcTemplate() { return jdbcTemplate; } @Autowired public void setJdbcTemplate(JdbcTemplate jdbcTemplate) { this.jdbcTemplate = jdbcTemplate; } public User getUser(int userId) { String sql ="SELECT * FROM user_tbl WHERE user_id = ?"; return this.jdbcTemplate.queryForObject(sql,new Object[]{new Integer(userId)}, new UserMapper() ); } private static final class UserMapper implements RowMapper<User>{ public User mapRow(ResultSet rs, int rowCount) throws SQLException { User u = new User(); u.setUserId(rs.getInt("user_id")); u.setUserName(rs.getString("username")); u.setPassword(rs.getString("password")); u.setEmailId(rs.getString("email")); u.setRole(rs.getString("role")); return u; } } }
And my controller class is UserController.java:
@RestController @RequestMapping(value="/user") public class UserController { @RequestMapping(method = RequestMethod.GET, value="/{userId}", produces = {MediaType.APPLICATION_JSON_VALUE}) ResponseEntity<User> getUser(@PathVariable int userId){ UserDaoImpl user = new UserDaoImpl(); User u = new User(); u=user.getUser(userId); return new ResponseEntity<User>(u, HttpStatus.OK); } }
and i am getting the following stack trace while running the application:
10-Feb-2016 02:50:28.165 SEVERE [tomcat-http--5] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [spring] in context with path [/booking] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause java.lang.NullPointerException at com.cinema.repository.UserDaoImpl.getUser(UserDaoImpl.java:31) at com.cinema.web.UserController.getUser(UserController.java:21) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:969) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:860) at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845) at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) 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:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:277) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)
Please tell me what i am doing wrong here. I have been stuck on this problem for a week now and still cannot make my code work. Thanks in advance.
-
duffymo over 8 yearsRight - calling new means Spring is not involved; you are responsible from then on. It's all or nothing: either Spring handles the creation and DI or you do.
-
Philip Rego about 3 yearsMy UserDao is autowired, implements JdbcDaoSupport and calls setDataSource() with a good datasource, but getJdbcTemplate() is null. Someone please give full answer.
-
Jérémie B about 3 years@PhilipRego you should probably ask your own question instead of downvoting an accepted answer for another issue.
-
Philip Rego about 3 yearsI didn't want to ask a duplicate question and your answer didn't work for me. queryForObject was giving NPE because an int (primitive type) was assigned to queryForObject.