Connection error to postgresql via servlets

StackOverflow https://stackoverflow.com/questions/23502653

  •  16-07-2023
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Question

I am new to postgresql and JDBC.I am not able to figure out my mistake.I have filled in the port number,password and username correctly.

My Code: 

package ieiPackage;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.sql.*;

/**
 * Servlet implementation class login1
 */

@WebServlet("/login1")
public class login1 extends HttpServlet {
    private static final long serialVersionUID = 1L;

/**
 * @see HttpServlet#HttpServlet()
 */
public login1() {
    super();
    // TODO Auto-generated constructor stub
}

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    System.out.println("-------- PostgreSQL "
            + "JDBC Connection Testing ------------");

    try {

        Class.forName("org.postgresql.Driver");

    } catch (ClassNotFoundException e) {

        System.out.println("Where is your PostgreSQL JDBC Driver? "
                + "Include in your library path!");
        e.printStackTrace();
        return;

    }

    System.out.println("PostgreSQL JDBC Driver Registered!");

    Connection connection = null;

    try {

        connection = DriverManager.getConnection(
                "jdbc:postgresql://localhost:5432/members","xxxx","xxxx");

    } catch (SQLException e) {

        System.out.println("Connection Failed! Check output console");
        e.printStackTrace();
        return;

    }

    if (connection != null) {
        System.out.println("You made it, take control your database now!");
    } else {
        System.out.println("Failed to make connection!");
    }
}


/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
}

}

The Error in the console:

-------- PostgreSQL JDBC Connection Testing ------------ Where is your PostgreSQL JDBC Driver? Include in your library path! java.lang.ClassNotFoundException: org.postgresql.Driver at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at ieiPackage.login1.doGet(login1.java:36) at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:313) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)

Was it helpful?

Solution

The problem is that postgresql driver cannot be found in classpath at runtime.

In orde to solve it: a) if you use Maven add the following to pom.xml

<dependency>
    <groupId>postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>9.1-901.jdbc4</version>
</dependency>

b) Otherwise just download the driver from link and place it into WEB-INF/lib folder

OTHER TIPS

My guess would be that your application cannot find the postgresql jdbc driver. Is it in your class path when executing?

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