java.lang.NullPointerException in spring datasource

Question

I done the database table in MySql . I want connection between spring application and database . For example , i am inserting value in edit-text it could be saved in Database(MySql) But i got the error . I am new for spring , please need help .

Following is my error log.

16:05:44,784 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/SpringSample].[mvc-dispatcher]] (http-localhost/127.0.0.1:8080-1) Servlet.service() for servlet mvc-dispatcher threw exception: java.lang.NullPointerException
at com.rxoffice.test.controller.JDBCStudentDAO.findByStudentId(JDBCStudentDAO.java:65) [classes:]
at com.rxoffice.test.controller.Home.hi(Home.java:33) [classes:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.6.0_32]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [rt.jar:1.6.0_32]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [rt.jar:1.6.0_32]
at java.lang.reflect.Method.invoke(Method.java:597) [rt.jar:1.6.0_32]
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176) [spring-web-3.0.5.RELEASE.jar:3.0.5.RELEASE]
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426) [spring-webmvc-3.0.5.RELEASE.jar:3.0.5.RELEASE]
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414) [spring-webmvc-3.0.5.RELEASE.jar:3.0.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790) [spring-webmvc-3.0.5.RELEASE.jar:3.0.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719) [spring-webmvc-3.0.5.RELEASE.jar:3.0.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644) [spring-webmvc-3.0.5.RELEASE.jar:3.0.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549) [spring-webmvc-3.0.5.RELEASE.jar:3.0.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:734) [jboss-servlet-api_3.0_spec-1.0.1.Final.jar:1.0.1.Final]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.1.Final.jar:1.0.1.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.17.Final.jar:]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.17.Final.jar:]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.17.Final.jar:]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.17.Final.jar:]
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:165) [jboss-as-web-7.1.3.Final.jar:7.1.3.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.17.Final.jar:]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.17.Final.jar:]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.17.Final.jar:]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:372) [jbossweb-7.0.17.Final.jar:]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.17.Final.jar:]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:679) [jbossweb-7.0.17.Final.jar:]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:931) [jbossweb-7.0.17.Final.jar:]
at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_32]

following are my files .

JDBCStudentDAO.java -

 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;

 import javax.sql.DataSource;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.jdbc.core.JdbcTemplate;

  public class JDBCStudentDAO implements StudentDAO {

/*@Autowired
DataSource dataSource;*/
private DataSource dataSource;
JdbcTemplate jdbcTemplate;

public void setDataSource(DataSource dataSource) {
    this.dataSource = dataSource;
}


@Override
public void insert(Student student) {
    // TODO Auto-generated method stub

    String sql = "INSERT INTO student_info " + "(id , name) VALUES (?, ?)";
    Connection conn = null;


    try {
            conn = dataSource.getConnection();
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, student.getId());
            ps.setString(2, student.getName());
            ps.executeUpdate();
            ps.close();

    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }finally{

            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {}
            }
    }


}

@Override
public Student findByStudentId(int stdId) {
    // TODO Auto-generated method stub

    String sql = "SELECT * FROM student_info WHERE id = ?";

    Connection conn = null;

    try {
        conn = dataSource.getConnection();
        PreparedStatement ps = conn.prepareStatement(sql);
        ps.setInt(1, stdId);
        Student student = null;
        ResultSet rs = ps.executeQuery();
        if (rs.next()) {
            student = new Student(
                rs.getInt("id"),
                rs.getString("name")
            );
        }
        rs.close();
        ps.close();
        return student;
    } catch (SQLException e) {
        throw new RuntimeException(e);
    } finally {
        if (conn != null) {
            try {
            conn.close();
            } catch (SQLException e) {}
        }
    }
}

Answer 1

As you mention in the comments, the error occurs at dataSource.getConnection() - meaning that dataSource is null. You have commented out autowiring that bean, so you're probably forgetting to explicitly setting it:

/*@Autowired DataSource dataSource;*/
private DataSource dataSource;

public void setDataSource(DataSource dataSource) {
    this.dataSource = dataSource;
}

The relevant parts of your applicationContext.xml file might shed more light on the problem - you might need

<context:annotation-config/>
<context:component-scan base-package="com.whatever.jdbc... , more.packages.to.scan,..."/>

or an explicit <property name="dataSource" ref="..." /> on the JDBCStudentDao bean XML config.

Cheers,

Answer 2

As stated in the comments, DataSource is null. The reason for that is that it hasn't been injected. To fix this, do the following:

1) Make sure JDBCStudentDAO is loaded by spring (applicationContext.xml should be loaded by whatever means, wither by explicitly loading the context or declaration in web.xml)

2) Make Sure DataSource is initialized in your applicationContext.xml or remove the comment before @Autowired

When you start your application, you should see messages that indicate that your datasource is bound (to the database configured in your applicationContext.xml) and that your DAO and entities have been loaded.