问题

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]

回答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

回答2:

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

That URL looks wrong, do you need the following?

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

回答3:

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());
        }

回答4:

I've forgot to add the PostgreSQL JDBC Driver into 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.

回答5:

I found the followig tip helpful, to eliminate this issue in Tomcat -

be sure to load the driver first doing a Class.forName(" org.postgresql.Driver"); in your code.

This is from the post - https://www.postgresql.org/message-id/e13c14ec050510103846db6b0e@mail.gmail.com

The jdbc code worked fine as a standalone program but, in TOMCAT it gave the error -'No suitable driver found'

回答6:

It might be worth noting that this can also occur when Windows blocks downloads that it considers to be unsafe. This can be addressed by right-clicking the jar file (such as ojdbc7.jar), and checking the 'Unblock' box at the bottom.

Windows JAR File Properties Dialog:

回答7:

I was using jruby, in my case I created under config/initializers

postgres_driver.rb

$CLASSPATH << '~/.rbenv/versions/jruby-1.7.17/lib/ruby/gems/shared/gems/jdbc-postgres-9.4.1200/lib/postgresql-9.4-1200.jdbc4.jar'

or wherever your driver is, and that's it !

回答8:

As well as adding the MySQL JDBC connector ensure the context.xml (if not unpacked in the Tomcat webapps folder) with your DB connection definitions are included within Tomcats conf directory.

回答9:

I had this exact issue when developing a Spring Boot application in STS, but ultimately deploying the packaged war to WebSphere(v.9). Based on previous answers my situation was unique. ojdbc8.jar was in my WEB-INF/lib folder with Parent Last class loading set, but always it says it failed to find the suitable driver.

My ultimate issue was that I was using the incorrect DataSource class because I was just following along with online tutorials/examples. Found the hint thanks to David Dai comment on his own question here: Spring JDBC Could not load JDBC driver class [oracle.jdbc.driver.OracleDriver]

Also later found spring guru example with Oracle specific driver: https://springframework.guru/configuring-spring-boot-for-oracle/

Example that throws error using org.springframework.jdbc.datasource.DriverManagerDataSource based on generic examples.

@Config
@EnableTransactionManagement
public class appDataConfig {
 \* Other Bean Defs *\
    @Bean
    public DataSource dataSource() {
        // configure and return the necessary JDBC DataSource
        DriverManagerDataSource dataSource = new DriverManagerDataSource("jdbc:oracle:thin:@//HOST:PORT/SID", "user", "password");
        dataSource.setSchema("MY_SCHEMA");
        return dataSource;
    }
}

And the corrected exapmle using a oracle.jdbc.pool.OracleDataSource:

@Config
@EnableTransactionManagement
public class appDataConfig {
/* Other Bean Defs */
@Bean
    public DataSource dataSource() {
        // configure and return the necessary JDBC DataSource
        OracleDataSource datasource = null;
        try {
            datasource = new OracleDataSource();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        datasource.setURL("jdbc:oracle:thin:@//HOST:PORT/SID");
        datasource.setUser("user");
        datasource.setPassword("password");

        return datasource;
    }
}

回答10:

I encountered this issue by putting a XML file into the src/main/resources wrongly, I deleted it and then all back to normal.

回答11:

A very silly mistake which could be possible resulting is adding of space at the start of the JDBC URL connection.

What I mean is:-

suppose u have bymistake given the jdbc url like

String jdbcUrl=" jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false&serverTimeZone=UTC";

(Notice there is a space in the staring of the url, this will make the error)

the correct way should be:

String jdbcUrl="jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false&serverTimeZone=UTC";

(Notice no space in the staring, you may give space at the end of the url but it is safe not to)

回答12:

I was having the same issue with mysql datasource using spring data that would work outside but gave me this error when deployed on tomcat.

The error went away when I added the driver jar mysql-connector-java-8.0.16.jar to the jres lib/ext folder

However I did not want to do this in production for fear of interfering with other applications. Explicity defining the driver class solved this issue for me

    spring.datasource.driver-class-name: com.mysql.cj.jdbc.Driver

回答13:

Run java with CLASSPATH environmental variable pointing to driver's JAR file, e.g.

CLASSPATH='.:drivers/mssql-jdbc-6.2.1.jre8.jar' java ConnectURL

Where drivers/mssql-jdbc-6.2.1.jre8.jar is the path to driver file (e.g. JDBC for for SQL Server).

The ConnectURL is the sample app from that driver (samples/connections/ConnectURL.java), compiled via javac ConnectURL.java.

来源：https://stackoverflow.com/questions/1911253/the-infamous-java-sql-sqlexception-no-suitable-driver-found

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postgresql

Tomcat

jdbc

GeoServer

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

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