autowired component is null - java

I'm developing a web application with spring. I've had no problem autowiring and using database #Service classes. Now I'm trying to read a global property file and provide the values to all classes that need them. The solution I've come up with so far seem to be overly complicated (too many classes - AppConfig, ServerConfig iface, ElasticServerConfig) for such a trivial task but I could live with it if it worked.
my applicationContext.xml contains
<context:component-scan base-package="my.package" />
AppConfig.java:
package my.package.configuration;
#Configuration
#PropertySource("classpath:application.properties")
public class AppConfig {
}
ServerConfig.java:
public interface ServerConfig {
String getUrl();
String getUser();
String getPassword();
}
ElasticSearchConfig.java:
package my.package.configuration;
#Component(value = "elasticServerConfig")
public class ElasticServerConfig implements ServerConfig {
private static final Logger LOGGER = LogManager.getLogger(ElasticServerConfig.class);
private String url;
private String user;
private String password;
#Autowired
public ElasticServerConfig(final Environment env) {
this.url = env.getProperty("elastic_server.url");
this.user = env.getProperty("elastic_server.user");
this.password = env.getProperty("elastic_server.password");
LOGGER.debug("url=" + url + "; user=" + user + "; password=" + password); // this works!
}
#Override
public final String getUrl() {
return url;
}
#Override
public final String getUser() {
return user;
}
#Override
public final String getPassword() {
return password;
}
}
When the web application boots, the ElasticServerConfig constructor prints out the correct url/user/pwd as read from application.properties. However an instance of ElasticServerConfig is not injected into a Search object:
package my.package.util;
public class Search {
#Autowired
#Qualifier("elasticServerConfig")
private ServerConfig elasticServerConfig;
public final List<Foobar> findByPatternAndLocation() {
if (elasticServerConfig == null) {
LOGGER.error("elasticServerConfig is null!");
}
// and i get a NullPointerException further on
// snip
}
}

You have to register the Search class as a Spring Bean and take it from the Spring context when you want to use it. It's important to get the bean from the spring context. If you create an object of that class with new, Spring has no way to know about that class and mange it's dependencies.
You can get get a bean from the Spring context by #Autowire it somewhere or by accessing an instance of the context and use the getBean method:
#Configuration
#PropertySource("classpath:application.properties")
public class AppConfig {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(AppConfig.class, args);
ctx.getBean...
}
}
Either use #Component annotation on the class and make sure that the class is in package thats under my.package
or register it in the configuration class
#Configuration
#PropertySource("classpath:application.properties")
public class AppConfig {
#Bean
public Search search(){
return new Search();
}
}

Related

unable to read properties using enableconfigurationproperties

#SpringBootApplication
#EnableConfigurationProperties({GlobalProperties.class})
public class Application {
public static void main(String[] args) {
ApplicationContext context = SpringApplication.run(Application.class, args);
GlobalProperties globalProperties = context.getBean(GlobalProperties.class);
System.out.println(globalProperties);
}
}
#PropertySource("classpath:global.properties")
#ConfigurationProperties("app")
public class GlobalProperties {
private String error;
private List<Menu> menus = new ArrayList<>();
private Compiler compiler = new Compiler();
//getters and setters and tostring
public static class Menu {
private String name;
private String path;
private String title;
//getters and setters and tostring
}
public static class Compiler {
private String timeout;
private String outputFolder;
//getters and setters and tostring
}
#Override
public String toString() {
return "GlobalProperties [error=" + error + ", menus=" + menus + ", compiler=" + compiler + "]";
}
}
global.properties is in src/main/resources
#Logging
logging.level.org.springframework.web=ERROR
logging.level.com.mkyong=DEBUG
#Global
email=test#mkyong.com
thread-pool=10
#App
app.menus[0].title=Home
app.menus[0].name=Home
app.menus[0].path=/
app.menus[1].title=Login
app.menus[1].name=Login
app.menus[1].path=/login
app.compiler.timeout=5
app.compiler.output-folder=/temp/
app.error=/error/
This is the result when i run the above Application program
GlobalProperties [error=null, menus=[], compiler=Compiler{timeout='null', outputFolder='null'}]
But if i comment out #EnableConfigurationProperties({GlobalProperties.class}) annotation on Application class and add #Component annotation on GlobalProperties i am getting expected result
GlobalProperties [error=/error/, menus=[Menu{name='Home', path='/', title='Home'}, Menu{name='Login', path='/login', title='Login'}], compiler=Compiler{timeout='5', outputFolder='/temp/'}]
Why can't i use enableconfigurationproperty annotation here?
This should work
#PropertySource("classpath:global.properties")
#Configuration
#ConfigurationProperties("app")
public class GlobalProperties {
......
}
You have to use #ConfigurationProperties in conjuction with #Configuration or #Component.
Why ?
Its simple. Unless you have one of these annotations(#Configuration, #Component, #Service ... etc), it is a regular java class and not a spring bean, hencespring will not scan this class during startup. Which means, it cannot inject the properties.
#PropertySource annotation doesn't work without any of #Component or #Configuration annotations. You must properly register your properties file. You can do somethink like this:
#SpringBootApplication
#PropertySource("classpath:global.properties")
#EnableConfigurationProperties({GlobalProperties.class})
public class Application {
public static void main(String[] args) {
ApplicationContext context = SpringApplication.run(Application.class, args);
GlobalProperties globalProperties = context.getBean(GlobalProperties.class);
System.out.println(globalProperties);
}
}
Or you can move related properties to application.properties file, that configured in spring boot by default.
GlobalProperties is a POJO the way you defined it, not a Spring Bean.
Annotating the class with #Component or #Configuration will make the class a Spring Bean and you will be able to retrieve it from the Spring Context.
To see how to use #EnableConfigurationProperties I recommend you to check this article: https://spring.io/blog/2013/10/30/empowering-your-apps-with-spring-boot-s-property-support.

Spring-Boot multi module project load property-file

I have a Spring-Boot-Application as a multimodule-Project in maven. The structure is as follows:
Parent-Project
|--MainApplication
|--Module1
|--ModuleN
In the MainApplication project there is the main() method class annotated with #SpringBootApplication and so on. This project has, as always, an application.properties file which is loaded automatically. So I can access the values with the #Value annotation
#Value("${myapp.api-key}")
private String apiKey;
Within my Module1 I want to use a properties file as well (called module1.properties), where the modules configuration is stored. This File will only be accessed and used in the module. But I cannot get it loaded. I tried it with #Configuration and #PropertySource but no luck.
#Configuration
#PropertySource(value = "classpath:module1.properties")
public class ConfigClass {
How can I load a properties file with Spring-Boot and access the values easily? Could not find a valid solution.
My Configuration
#Configuration
#PropertySource(value = "classpath:tmdb.properties")
public class TMDbConfig {
#Value("${moviedb.tmdb.api-key}")
private String apiKey;
public String getApiKey() {
return apiKey;
}
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
}
Calling the Config
#Component
public class TMDbWarper {
#Autowired
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
public TMDbWarper(){
tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
}
I'm getting an NullPointerException in the constructor when I autowire the warper.
For field injection:
Fields are injected right after construction of a bean, before any config methods are invoked. Such a config field does not have to be public. Refer Autowired annotation for complete usage. Use constructor injection in this case like below:
#Component
public class TMDbWarper {
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
#Autowired
public TMDbWarper(final TMDbConfig tmdbConfig){
this.tmdbConfig = tmdbConfig;
tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
}
(or)
Use #PostConstruct to initialise like below:
#Component
public class TMDbWarper {
#Autowired
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
#PostConstruct
public void init() {
// any initialisation method
tmdbConfig.getConfig();
}
Autowiring is performed just after the creation of the object(after calling the constructor via reflection). So NullPointerException is expected in your constructor as tmdbConfig field would be null during invocation of constructor
You may fix this by using the #PostConstruct callback method as shown below:
#Component
public class TMDbWarper {
#Autowired
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
public TMDbWarper() {
}
#PostConstruct
public void init() {
tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
}
public TmdbApi getTmdbApi() {
return this.tmdbApi;
}
}
Rest of your configuration seems correct to me.
Hope this helps.
Here is a Spring Boot multi-module example where you can get properties in different module.
Let's say I have main application module, dataparse-module, datasave-module.
StartApp.java in application module:
#SpringBootApplication
public class StartApp {
public static void main(String[] args) {
SpringApplication.run(StartApp.class, args);
}
}
Configuration in dataparse-module. ParseConfig.java:
#Configuration
public class ParseConfig {
#Bean
public XmlParseService xmlParseService() {
return new XmlParseService();
}
}
XmlParseService.java:
#Service
public class XmlParseService {...}
Configuration in datasave-module. SaveConfig.java:
#Configuration
#EnableConfigurationProperties(ServiceProperties.class)
#Import(ParseConfig.class)//get beans from dataparse-module - in this case XmlParseService
public class SaveConfig {
#Bean
public SaveXmlService saveXmlService() {
return new SaveXmlService();
}
}
ServiceProperties.java:
#ConfigurationProperties("datasave")
public class ServiceProperties {
private String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
application.properties in datasave-module in resource/config folder:
datasave.message=Multi-module Maven project!
threads.xml.number=5
file.location.on.disk=D:\temp\registry
Then in datasave-module you can use all your properties either through #Value.
SaveXmlService.java:
#Service
public class SaveXmlService {
#Autowired
XmlParseService xmlParseService;
#Value("${file.location.on.disk: none}")
private String fileLocation;
#Value("${threads.xml.number: 3}")
private int numberOfXmlThreads;
...
}
Or through ServiceProperties:
Service.java:
#Component
public class Service {
#Autowired
ServiceProperties serviceProperties;
public String message() {
return serviceProperties.getMessage();
}
}
I had this situation before, I noticed that the properties file was not copied to the jar.
I made the following to get it working:
In the resources folder, I have created a unique package, then stored my application.properties file inside it. e.g: com/company/project
In the configuration file e.g: TMDBConfig.java I have referenced the full path of my .properties file:
#Configuration
#PropertySource("classpath:/com/company/project/application.properties")
public class AwsConfig
Build and run, it will work like magic.
You could autowire and use the Enviornment bean to read the property
#Configuration
#PropertySource(value = "classpath:tmdb.properties")
public class TMDbConfig {
#Autowired
private Environment env;
public String getApiKey() {
return env.getRequiredProperty("moviedb.tmdb.api-key");
}
}
This should guarantee that property is read from the context when you invoke the getApiKey() method regardless of when the #Value expression is resolved by PropertySourcesPlaceholderConfigurer.

Spring Autowiring a property within an autowired bean

I'm a newbie to Spring. I'm facing a problem with Spring-Boot. I'm trying to autowire a field from an external config file into an autowired bean. I have the following classes
App.java
public class App {
#Autowired
private Service service;
public static void main(String[] args) {
final SpringApplication app = new SpringApplication(App.class);
//app.setShowBanner(false);
app.run();
}
#PostConstruct
public void foo() {
System.out.println("Instantiated service name = " + service.serviceName);
}
}
AppConfig.java
#Configuration
#ConfigurationProperties
public class AppConfig {
#Bean
public Service service() {
return new Service1();
}
}
Service Interface
public interface Service {
public String serviceName ="";
public void getHistory(int days , Location location );
public void getForecast(int days , Location location );
}
Service1
#Configurable
#ConfigurationProperties
public class Service1 implements Service {
#Autowired
#Value("${serviceName}")
public String serviceName;
//Available in external configuration file.
//This autowiring is not reflected in the main method of the application.
public void getHistory(int days , Location location)
{
//history code
}
public void getForecast(int days , Location location )
{
//forecast code
}
}
I'm unable to display the service name variable in the postconstruct method of the App class. Am I doing this right?
You can load properties in different ways:
Imagine the following application.properties which is automatically loaded by spring-boot.
spring.app.serviceName=Boot demo
spring.app.version=1.0.0
Inject values using #Value
#Service
public class ServiceImpl implements Service {
#Value("${spring.app.serviceName}")
public String serviceName;
}
Inject values using #ConfigurationProperties
#ConfigurationProperties(prefix="spring.app")
public class ApplicationProperties {
private String serviceName;
private String version;
//setters and getters
}
You can access to this properties from another class using #Autowired
#Service
public class ServiceImpl implements Service {
#Autowired
public ApplicationProperties applicationProperties;
}
As you can notice the prefix will be spring.app then spring-boot will match the properties prefix with that and look for serviceName and version and values will be injected.
Considering you have you class App annotated with #SpringBootApplication and App class in the top package You can put your serviceName inside application.properties and inject it using #Value("${serviceName}"). Do not use #Component on a class if you are already using #Bean on configuration it will clash, and so #Autowired with #Value
See docs for more info
You will end with something like
#Service // #Component specialization
public class Service1 implements Service {
#Value("${serviceName}")
public String serviceName;
//Available in external configuration file.
//This autowiring is not reflected in the main method of the application.
public void getHistory(int days , Location location)
{
//history code
}
public void getForecast(int days , Location location )
{
//forecast code
}
}
No need for #Bean declaration when you have #Component/#Service/#Repository
#Configuration
public class AppConfig { //other stuff here not duplicated beans }
And your main class
package com.app;
#SpringBootApplication // contains #EnableAutoConfiguration #ComponentScan #Configuration
public class App {
#Autowired
private Service service;
public static void main(String[] args) {
final SpringApplication app = new SpringApplication(App.class);
//app.setShowBanner(false);
app.run();
}
#PostConstruct
public void foo() {
System.out.println("Instantiated service name = " + service.serviceName);
}
}

spring-boot properties not #Autowired

I am trying to get a Spring-boot application going and I am not sure what I am doing wrong here. I have a application.properties file at src/main/resources & src/test/resources. I have an #Bean for my ConfigurationSettings so that I can use them throughout my application:
#Component
public class ConfigurationSettings {
private String product;
private String version;
private String copyright;
private String appName;
private String appDescription;
...
// getters and setters
}
Here is how I kick the application off:
#Configuration
#EnableJpaRepositories
#EnableAutoConfiguration
#EnableConfigurationProperties
#PropertySources(value = {#PropertySource("classpath:application.properties")})
#ComponentScan(basePackages = "com.product")
#EnableScheduling
public class OFAC {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run( OFAC.class, args );
}
And here is my configuration class:
#Configuration
#ComponentScan(basePackages = {"com.product"})
#PropertySources(value = {#PropertySource("classpath:application.properties")})
public class OFAConfiguration {
#Autowired
private Environment env;
#Bean
public ConfigurationSettings configurationSettings() {
ConfigurationSettings configurationSettings = new ConfigurationSettings();
configurationSettings.setAppDescription( env.getRequiredProperty("app.description" ) );
configurationSettings.setAppName( env.getRequiredProperty( "app.name" ) );
configurationSettings.setServerPort( env.getRequiredProperty( "server.port" ) );
return configurationSettings;
}
I am trying to use it in a controller:
#RestController
public class AboutController {
#Autowired
private ConfigurationSettings configurationSettings;
#RequestMapping(value = "/about", method = RequestMethod.GET)
public About index() {
String product = configurationSettings.getProduct();
String version = configurationSettings.getVersion();
String copyright = configurationSettings.getCopyright();
return new About( product, version, copyright );
}
}
However, when step thru this, all the values of ConfigurationSettings are null. I do have a test that successfully loads the values:
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes = {OFAConfiguration.class})
public class OFAConfigurationTest {
#Autowired
private Environment environment;
#Autowired
private ConfigurationSettings configurationSettings;
#Test
public void testConfigurationLoads() {
assertNotNull(environment);
Assert.assertNotNull(configurationSettings);
}
#Test
public void testConfigurationSettingValues() {
assertEquals("Product Name", configurationSettings.getProduct());
assertEquals("0.0.1", configurationSettings.getVersion());
assertEquals("2014 Product", configurationSettings.getCopyright());
}
Can anyone see why the ConfigurationSettings are not being populated in my Controller?
Your configuration leads to 2 instances of the ConfigurationSettings class and probably one instance overrides the other.
The 'ConfigurationSettings' has the #Component annotation as you are scanning for components (#ComponentScan) this will lead to an instance. You also have a #Bean annotated method which also leads to an instance. The latter is overridden with the first.
In short remove the #Component annotation as that isn't needed because you already have a factory method for this class.
public class ConfigurationSettings { ... }
You should also remove the #PropertySource annotations as Spring-Boot will already load the application.properties for you.
Finally you should not use the #ContextConfiguration annotation on your test class but the #SpringApplicationConfiguration and pass in your application class (not your configuration class!).
#RunWith(SpringJUnit4ClassRunner.class)
#SpringApplicationConfiguration(classes=OFAC.class)
public class OFAConfigurationTest {
#Autowired
private Environment environment;
#Autowired
private ConfigurationSettings configurationSettings;
#Test
public void testConfigurationLoads() {
assertNotNull(environment);
assertNotNull(configurationSettings);
}
#Test
public void testConfigurationSettingValues() {
assertEquals("Product Name", configurationSettings.getProduct());
assertEquals("0.0.1", configurationSettings.getVersion());
assertEquals("2014 Product", configurationSettings.getCopyright());
}
This will fix your runtime configuration problems and will let your test use the power of Spring Boot to configure your application.

Proper Inheritance for Spring Configurations

I am creating a project utilizing the new Spring configurations. I have a base class which holds a few properties:
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes = {Basic.class, Protected.class})
public class BaseTest {
#Autowired(required = false) protected String userName;
#Autowired(required = false) protected String password;
#Autowired protected String baseURL;
#Test
public void outputData() {
System.out.println("UserName: " + userName + " Password: "
+ password + "Base URL: " + baseURL);
}
}
#ActiveProfiles("default,protected")
public abstract class ProtectedTest extends BaseTest
{
#Autowired protected String userName;
#Autowired protected String password;
}
#Configuration #Profile("default")
public class Basic {
#Bean public String baseURL() { return "http://www.baseURL.com"; }
}
#Configuration #Profile("protected")
public class Protected {
#Bean public String userName() { return "userName"; }
#Bean public String password() { return "password"; }
}
However, when I go to run my protected tests I receive a notification that the base URL is not wired in properly. Since it extends the BaseTest, and has both profiles active, why am I not receiving the baseURL bean?
It has to be #ActiveProfiles({"default","protected"}), in your case it will assume that the profile by name default, protected is active, not default and protected
One more thing is that annotation in base class BaseTest is not derived by the ProtectedTest, so you will again need to put #RunWith and #ContextConfiguration for your test to run

Categories

Resources