How to query Oracle SQL with Spring Boot WAR? - spring

Question

Following the Spring Boot reference guides, I've set up a Hello World example. My workplace uses Ant, so I implemented build.xml based on https://www.mkyong.com/ant/ant-spring-mvc-and-war-file-example/ The resultant WAR file works correctly when deployed onto the WebLogic 12c server. Note: As per this guide, .properties files are copied to ${web.classes.dir}.
Now, I want to query the server's Oracle SQL database via JNDI. Following various parts of the Spring Boot references & guides, this is my modified code at present:
#SpringBootApplication
public class Application extends SpringBootServletInitializer implements WebApplicationInitializer {
#Autowired
private static JdbcTemplate jdbcTemplate;
#Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(Application.class);
}
public static void main(String[] args) throws Exception {
SpringApplication.run(Application.class, args);
}
public static void update(String query) {
jdbcTemplate.update(query);
}
}
#RestController
#RequestMapping("/query")
public class CrudController {
#RequestMapping(value="/update", method=RequestMethod.GET)
public String update(#PathVariable String tableName, /* other params */) {
// Generates query from params
Application.update(query);
return query;
}
}
I've also added an application.properties file which contains a single line in accordance with the Spring reference guide:
spring.datasource.jndi-name=jndiName
At this point, the WAR can still deploy onto the server but when I go to http://ipaddr:port/appName/query/update?params I get a NullPointerException. I've separately verified that update() correctly generates a SQL query with valid syntax, so I suspect I've gotten the database configuration wrong.
What's the correct way to connect to the JNDI database and execute a query?
Edit:
After updating my code according to Strelok's answer, I tried to run the updated WAR file on the WebLogic server, which subsequently throws the following exception:
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'crudController': Injection of autowired dependencies failed; ...
...
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.jdbc.core.JdbcTemplate main.java.controllers.CrudController.jdbcTemplate; ...
...
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionExcept‌​ion: No qualifying bean of type [org.springframework.jdbc.core.JdbcTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {#org.springframework.beans.factory.annotation.Autowired(req‌​uired=true)}
I tried modifying the #Autowired annotation to #Autowired(required=true) but that didn't change anything. How can I resolve this?

Answer 1

Your JdbcTemplate is static and is located in your application class, whereas it should belong in your controller. That's where you should use it.
Spring cannot inject static fields directly, so make sure anything injected by Spring is never static. Your code should look something like this:
Application.java
#SpringBootApplication
public class Application extends SpringBootServletInitializer implements WebApplicationInitializer {
#Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(Application.class);
}
public static void main(String[] args) throws Exception {
SpringApplication.run(Application.class, args);
}
}
CrudController.java
#RestController
#RequestMapping("/query")
public class CrudController {
#Autowired
private JdbcTemplate jdbcTemplate;
#RequestMapping(value="/update", method=RequestMethod.GET)
public String update(#PathVariable String tableName, /* other params */) {
jdbcTemplate.update(query);
return query;
}
}