I'm building a web application, which uses the Spring Framework 4.1.3 and using Jersey for the RESTful web service.
I want to connect to a Redis server and I'm using Spring Data Redis
with the Jedis
driver.
This is how my Beans.xml
file looks like:
<!-- Jedis ConnectionFactory -->
<bean id="jedisConnFactory"
class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
p:host-name="server" p:port="6379" p:use-pool="true"
/>
<!-- redis template definition -->
<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"
p:connection-factory-ref="jedisConnFactory"
/>
This is the Servlet with the access to the Redis server:
import javax.annotation.Resource;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.ListOperations;
import org.springframework.data.redis.core.RedisTemplate;
@Path("/")
public class RoutesServlet {
@Autowired
private RedisTemplate<String, String> template;
// inject the template as ListOperations
@Resource(name="redisTemplate")
private ListOperations<String, String> listOps;
@GET
@Produces("text/plain")
public String index() {
listOps.leftPush("user", "name");
...
At this point I'm getting a NullPointerException. I'm guessing the @Resource
annotation is not working properly for some reason. Any ideas?
This is my full Beans.xml
file:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
xmlns:p="http://www.springframework.org/schema/p"
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd ">
<!-- Initialization for data source -->
<!--bean id="dataSource" class="db.mysql.DBConn"> </bean -->
<bean id="dataSource" class="org.apache.tomcat.jdbc.pool.DataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/insider" />
<property name="username" value="root" />
<property name="password" value="" />
<property name="jmxEnabled" value="true" />
<property name="testWhileIdle" value="false" />
<property name="testOnBorrow" value="true" />
<property name="validationQuery" value="SELECT 1" />
<property name="testOnReturn" value="false" />
<property name="validationInterval" value="30000" />
<property name="timeBetweenEvictionRunsMillis" value="30000" />
<property name="maxActive" value="100" />
<property name="initialSize" value="10" />
<property name="maxWait" value="10000" />
<property name="removeAbandonedTimeout" value="60" />
<property name="minEvictableIdleTimeMillis" value="30000" />
<property name="minIdle" value="10" />
<property name="logAbandoned" value="true" />
<property name="removeAbandoned" value="true" />
<property name="jdbcInterceptors"
value="org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer" />
</bean>
<!-- Definition for categoryJDBCTemplate bean -->
<bean id="categoryJDBCTemplate" class="db.mysql.CategoryJDBCTemplate">
<property name="dataSource" ref="dataSource" />
</bean>
<!-- Definition for itemJDBCTemplate bean -->
<bean id="itemJDBCTemplate" class="db.mysql.ItemJDBCTemplate">
<property name="dataSource" ref="dataSource" />
</bean>
<!-- Definition for userJDBCTemplate bean -->
<bean id="userJDBCTemplate" class="db.mysql.UserJDBCTemplate">
<property name="dataSource" ref="dataSource" />
</bean>
<!-- Definition for reviewJDBCTemplate bean -->
<bean id="reviewJDBCTemplate" class="db.mysql.ReviewJDBCTemplate">
<property name="dataSource" ref="dataSource" />
</bean>
<!-- Jedis ConnectionFactory -->
<bean id="jedisConnFactory"
class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
p:host-name="server" p:port="6379" p:use-pool="true"
/>
<!-- redis template definition -->
<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"
p:connection-factory-ref="jedisConnFactory"
/>
</beans>
I believe it is simply so that the bean with the name redisTemplate
is of type RedisTemplate
. One way to retrieve the ListOperations
is to do the following:
public class RedisExample {
// Just use the RedisTemplate - don't inject the ListOperations
private final RedisTemplate<String, String> redisTemplate;
// Use constructor injection (preferred over field injection)
@Autowired
public RedisExample(final RedisTemplate<String, String> redisTemplate) {
this.redisTemplate = redisTemplate;
}
public void addLink(String userId, URL url) {
// Here is the trick:
// You can either retrieve the ListOperations this way
ListOperations<String, String> listOps = redisTemplate.opsForList();
listOps.leftPush(userId, url.toExternalForm());
// or, you can retrieve it this way
redisTemplate.boundListOps(userId).leftPush(url.toExternalForm());
}
}
The example shows that you should inject a ListOperations
bean with the name redisTemplate
. Since there is no such bean the injection fails. Simply remove the @Resource
annotation (and the field) and use the code as described above.
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