The infamous java.sql.SQLException: No suitable driver found

Question

I'm trying to add a database-enabled JSP to an existing Tomcat 5.5 application (GeoServer 2.0.0, if that helps).

The app itself talks to Postgres just fine, so I know that the database is up, user can access it, all that good stuff. What I'm trying to do is a database query in a JSP that I've added. I've used the config example in the Tomcat datasource example pretty much out of the box. The requisite taglibs are in the right place -- no errors occur if I just have the taglib refs, so it's finding those JARs. The postgres jdbc driver, postgresql-8.4.701.jdbc3.jar is in $CATALINA_HOME/common/lib.

Here's the top of the JSP:

<%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<sql:query var="rs" dataSource="jdbc/mmas">
  select current_validstart as ValidTime from runoff_forecast_valid_time
</sql:query>

The relevant section from $CATALINA_HOME/conf/server.xml, inside the <Host> which is in turn within <Engine>:

<Context path="/gs2" allowLinking="true">
  <Resource name="jdbc/mmas" type="javax.sql.Datasource"
      auth="Container" driverClassName="org.postgresql.Driver"
      maxActive="100" maxIdle="30" maxWait="10000"
      username="mmas" password="very_secure_yess_precious!"
      url="jdbc:postgresql//localhost:5432/mmas" />
</Context>

These lines are the last in the tag in webapps/gs2/WEB-INF/web.xml:

<resource-ref>
  <description>
     The database resource for the MMAS PostGIS database
  </description>
  <res-ref-name>
     jdbc/mmas
  </res-ref-name>
  <res-type>
     javax.sql.DataSource
  </res-type>
  <res-auth>
     Container
  </res-auth>
</resource-ref>

Finally, the exception:

   exception
    org.apache.jasper.JasperException: Unable to get connection, DataSource invalid: "java.sql.SQLException: No suitable driver"
    [...wads of ensuing goo elided]

Answer 1

The infamous java.sql.SQLException: No suitable driver found

This exception can have basically two causes:

1. JDBC driver is not loaded

You need to ensure that the JDBC driver is placed in server's own /lib folder.

Or, when you're actually not using a server-managed connection pool data source, but are manually fiddling around with DriverManager#getConnection() in WAR, then you need to place the JDBC driver in WAR's /WEB-INF/lib and perform ..

Class.forName("com.example.jdbc.Driver");

.. in your code before the first DriverManager#getConnection() call whereby you make sure that you do not swallow/ignore any ClassNotFoundException which can be thrown by it and continue the code flow as if nothing exceptional happened. See also Where do I have to place the JDBC driver for Tomcat's connection pool?

2. Or, JDBC URL is in wrong syntax

You need to ensure that the JDBC URL is conform the JDBC driver documentation and keep in mind that it's usually case sensitive. When the JDBC URL does not return true for Driver#acceptsURL() for any of the loaded drivers, then you will also get exactly this exception.

In case of PostgreSQL it is documented here.

With JDBC, a database is represented by a URL (Uniform Resource Locator). With PostgreSQL™, this takes one of the following forms:

• jdbc:postgresql:database
• jdbc:postgresql://host/database
• jdbc:postgresql://host:port/database

In case of MySQL it is documented here.

The general format for a JDBC URL for connecting to a MySQL server is as follows, with items in square brackets ([ ]) being optional:

jdbc:mysql://[host1][:port1][,[host2][:port2]]...[/[database]] » [?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

In case of Oracle it is documented here.

There are 2 URL syntax, old syntax which will only work with SID and the new one with Oracle service name.

Old syntax jdbc:oracle:thin:@[HOST][:PORT]:SID

New syntax jdbc:oracle:thin:@//[HOST][:PORT]/SERVICE

---

See also:

• Where do I have to place the JDBC driver for Tomcat's connection pool?
• How to install JDBC driver in Eclipse web project without facing java.lang.ClassNotFoundexception
• How should I connect to JDBC database / datasource in a servlet based application?
• What is the difference between "Class.forName()" and "Class.forName().newInstance()"?
• Connect Java to a MySQL database

Answer 2

I've forgot to add the PostgreSQL JDBC Driver into my project (Mvnrepository).

Gradle:

// http://mvnrepository.com/artifact/postgresql/postgresql
compile group: 'postgresql', name: 'postgresql', version: '9.0-801.jdbc4'

Maven:

<dependency>
    <groupId>postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>9.0-801.jdbc4</version>
</dependency>

You can also download the JAR and import to your project manually.

Answer 3

url="jdbc:postgresql//localhost:5432/mmas"

That URL looks wrong, do you need the following?

url="jdbc:postgresql://localhost:5432/mmas"

Answer 4

I faced the similar issue. My Project in context is Dynamic Web Project(Java 8 + Tomcat 8) and error is for PostgreSQL Driver exception: No suitable driver found

It got resolved by adding Class.forName("org.postgresql.Driver") before calling getConnection() method

Here is my Sample Code:

try {
            Connection conn = null;
            Class.forName("org.postgresql.Driver");
            conn = DriverManager.getConnection("jdbc:postgresql://" + host + ":" + port + "/?preferQueryMode="
                    + sql_auth,sql_user , sql_password);
        } catch (Exception e) {
            System.out.println("Failed to create JDBC db connection " + e.toString() + e.getMessage());
        }