#autowire beans and #value properties after object mapper deserialized json - spring

I am using spring framework.
I am using objectMapper to desiriale store.json file:
service:
objectMapper.readValue(new File(jsonFilePath), Store.class)
store.json:
{
"type": "Store",
"name": "myStore",
}
Store.class:
#Value("${store.size:1000}")
private Integer sroreSize;
#autowire
private storePersistency storePersistency;
public Store(#JsonProperty("name") String name) {
super(name);
}
I am trying find out how to #autowire beans and #value properties in store.class, beans and properties that exist in applicationContext.
In current example sroreSize and storePersistency still null.
I know that I can inject fields to object mapper and then use #JacksonInject annotation but I have a lot of field to inject - not a good option for me.
Custom desirializer also not a good option for me.
Is there any way not to use custom desirializer or not to inject every bean/property that I need in store.class?
Something that injects all the beans and properties and I simply can use it in Store.class.

So you want some Store fields like storePersistency and sroreSize to be initialized once at application startup (which is when Spring will setup the application context) and then at runtime create multiple different Store objects differing in some fields as name that are initialized by Jackson.
I suggest annotating Store with #Component to get Spring to initialize #Value and #Autowired fields. The #Scope annotation will cause a new independent Store instance to be created each time. Simplified example:
#Component
#Scope(SCOPE_PROTOTYPE)
class Store {
private String name;
#Value("${store.size:1000}")
private Integer sroreSize;
}
Then the key is method readerForUpdating where you can pass an existing instance of Store and Jackson will update that instead of creating a new one as usually:
Store store = context.getBean(Store.class);
objectMapper.readerForUpdating(store).readValue("{\"name\":\"myStore\"}");
Where context is a Spring ApplicationContext reference that I autowired in a test class. You don't need to use the return value of readValue in this case, just inspect the existing store variable and name will be updated.

Related

how to use org.springframework.format.Formatter.print()

#Configuration
public class MyWebMvcConfigurationSupport extends WebMvcConfigurationSupport {
#Override
public FormattingConversionService mvcConversionService() {
FormattingConversionService f = super.mvcConversionService();
f.addFormatter(new DateFormatter("yyyy-MM-dd"));
return f;
}
}
#RestController
public class TestController {
#GetMapping
public Date test(Date date) {
return date;
}
}
When we access http://localhost:8080?date=2021-09-04, the argument type is converted through the DateFormatter's parse method, which relies on the SpringMVC framework to do the conversion. I wonder if the print method can also be invoked through the framework to return a string.
Do we need to manually invoke the print method, for example
#RestController
public class TestController {
#Resource
private FormattingConversionService conversionService;
#GetMapping
public String test(Date date) {
return conversionService.convert(date, String.class);
}
}
Inside the controller
You could use a class extending java.text.Format like SimpleDateFormatin your controller:
#RestController
public class TestController {
private static final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
#GetMapping
public String test(Date date) {
return dateFormat.format(date);
}
}
At application level
Use DateTimeFormatterRegistrar to register your formats, like described in this tutorial.
Then you can register this set of formatters at Spring's FormattingConversionService.
Using Jackson
However if you would like to work with JSON or XML you should consider using FasterXML's Jackson. See similar question:
Spring 3.2 Date time format
This is the interface representing the environment in which the current application is running. It models two key aspects of the application environment: profiles and properties. The methods related to property access are exposed via the PropertyResolver superinterface.
A profile is a named, logical group of bean definitions to be registered with the container only if the given profile is active. Beans may be assigned to a profile whether defined in XML or via annotations; see the spring-beans 3.1 schema or the #Profile annotation for syntax details. The role of the Environment object with relation to profiles is in determining which profiles (if any) are currently active, and which profiles (if any) should be active by default.
Properties play an important role in almost all applications, and may originate from a variety of sources: properties files, JVM system properties, system environment variables, JNDI, servlet context parameters, ad-hoc Properties objects, Maps, and so on. The role of the environment object with relation to properties is to provide the user with a convenient service interface for configuring property sources and resolving properties from them.
Beans managed within an ApplicationContext may register to be EnvironmentAware or #Inject the Environment in order to query profile state or resolve properties directly.
In most cases, however, application-level beans should not need to interact with the Environment directly but instead may have to have ${...} property values replaced by a property placeholder configurer such as PropertySourcesPlaceholderConfigurer, which itself is EnvironmentAware and as of Spring 3.1 is registered by default when using context:property-placeholder/.
Configuration of the environment object must be done through the ConfigurableEnvironment interface, returned from all AbstractApplicationContext subclass getEnvironment() methods. See ConfigurableEnvironment Javadoc for usage examples demonstrating manipulation of property sources prior to application context refresh().

Spring Boot + MongoDB+create collection

I have a problem. After having created a Spring Boot project with Eclipse and configuring the application.properties file, my collections are not created, whereas after execution, the Eclipse console signals that the connection to MongoDB has been carried out normally. I don't understand what's going on. With MySQL we had the tables created so I expected the creation of the collections, but nothing.
Summary, I don't see my collection (class annoted #Document) in MongoDB after deployment.
New collection won't be created until you insert at least one document. Refer the document Create Collection
You could do this in two ways through Spring. I tested the instructions below in Spring 2.1.7.
With just a #Document class, Spring will not create a collection in Mongo. It will however create a collection if you do the following:
You have a field you want to index in the collection, and you annotate it as such in the Java class. E.g.
#Indexed(unique = true)
private String indexedData;
Create a repository for the collection:
public interface MyClassRepository extends MongoRepository<MyClass, String> {
}
If you don't need/want an index, the second way of doing this would be to add some code that runs at startup, adds a dummy value in the collection and deletes it again.
#Configuration
public class LoadDatabase {
#Bean
CommandLineRunner initDb(MyClassRepository repository) {
// create an instance of your #Document annotated class
MyClass myDocument = new MyClass();
myDocument = repository.insert(myDocument);
repository.delete(myDocument);
}
}
Make sure your document class has a field of the correct type (String by default), annotated with #Id, to map Mongo's _id field.

Spring return dynamic instance based of String value

Java Spring question:
I have a interface MyInterface with one method
void exec (String str);
I have many implementation of MyInterface, say Oneimpl, anotherimpl yetanotherimpl...and so on and can keep adding new implementations.
how do I obtain an instance of a specific implementation using just the name of the implementing class passed as a STRING value , say "someRandomImpl"
The code should be dynamic and can provide a instance of new implementations without code change.
implements ApplicationContextAware
it will autowired ApplicationContext object
use the object like
context.getBean(beanName)
then you get the bean

Spring - Retrieve all scanned packages

I'm creating a Spring Starter project and need to get all classes which are marked with a custom annotation. The annotated class is not a spring bean.
My current solution is to use the ClassPathScanningCandidateComponentProvider to find the required classes.
ClassPathScanningCandidateComponentProvider scanner =
new ClassPathScanningCandidateComponentProvider(false);
scanner.addIncludeFilter(new AnnotationTypeFilter(CustomAnnotation.class));
candidates = scanner.findCandidateComponents("THE MISSING PACKAGE NAME");
The problem is that I'm currently provide an empty package String so that all packages/classes are scanned which slows the startup down.
I need to access the packages which are scanned by Spring to avoid the scanning of all packages and classes.
Is there a way to retrieve all packages programmatically which are scanned by Spring or is there an alternative solution to retrieve custom annotated classes which are not Spring beans.
Greets
One solution without the need to make a full classpath scan is to use the AutowiredAnnotationBeanPostProcessor:
private List<Class<?>> candidates = new ArrayList<>();
#Override
public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
if(beanClass.isAnnotationPresent(YourAnnotation.class)){
candiates.add(beanClass));
System.out.println(beanClass);
return new Object();
}
}
#Bean
public CandiateHolder candidates() {
return new CandidateHolder(candidates);
}
You can check if the bean class which should be instantiated has the required annotation. If its the case you add the class to a property to expose it later as a bean. Instead of returning null you have to return an instance of a new Object. The returned object can be used to wrap the class in a proxy. Cause I don't need an instance I will return a simple new object. Its maybe a dirty hack but it works.
I have to use this kind of hack cause an instantiation of the needed object will result in an runtime error cause it has to be instantiated in the framework I use.

How do I get a property value from an ApplicationContext object? (not using an annotation)

If I have:
#Autowired private ApplicationContext ctx;
I can get beans and resources by using one of the the getBean methods. However, I can't figure out how to get property values.
Obviously, I can create a new bean which has an #Value property like:
private #Value("${someProp}") String somePropValue;
What method do I call on the ApplicationContext object to get that value without autowiring a bean?
I usually use the #Value, but there is a situation where the SPeL expression needs to be dynamic, so I can't just use an annotation.
In the case where SPeL expression needs to be dynamic, get the property value manually:
somePropValue = ctx.getEnvironment().getProperty("someProp");
If you are stuck on Spring pre 3.1, you can use
somePropValue = ctx.getBeanFactory().resolveEmbeddedValue("${someProp}");
Assuming that the ${someProp} property comes from a PropertyPlaceHolderConfigurer, that makes things difficult. The PropertyPlaceholderConfigurer is a BeanFactoryPostProcessor and as such only available at container startup time. So the properties are not available to a bean at runtime.
A solution would be to create some sort of a value holder bean that you initialize with the property / properties you need.
#Component
public class PropertyHolder{
#Value("${props.foo}") private String foo;
#Value("${props.bar}") private String bar;
// + getter methods
}
Now inject this PropertyHolder wherever you need the properties and access the properties through the getter methods

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