I'm experimenting with the old Petclinic example and I noticed that the vets ArrayList in the SimpleJdbcClinic exists for the life of the session. It seems like it should exist only for the request since I don't see any annotations putting it into the session context. Could someone point out what I'm failing to understand?
Here is the vets class:
#XmlRootElement
public class Vets {
private List<Vet> vets;
#XmlElement
public List<Vet> getVetList() {
if (vets == null) {
vets = new ArrayList<Vet>();
}
return vets;
}
}
The service:
#Service
#ManagedResource("petclinic:type=Clinic")
public class SimpleJdbcClinic implements Clinic, SimpleJdbcClinicMBean {
private SimpleJdbcTemplate simpleJdbcTemplate;
private SimpleJdbcInsert insertOwner;
private SimpleJdbcInsert insertPet;
private SimpleJdbcInsert insertVisit;
private final List<Vet> vets = new ArrayList<Vet>();
:
:
#Transactional(readOnly = true)
public Collection<Vet> getVets() throws DataAccessException {
synchronized (this.vets) {
if (this.vets.isEmpty()) {
refreshVetsCache();
}
return this.vets;
}
}
}
The controller mapping:
#RequestMapping("/vets")
public ModelMap vetsHandler() {
Vets vets = new Vets();
vets.getVetList().addAll(this.clinic.getVets());
return new ModelMap(vets);
}
Once the vets list is created it survives multiple requests.
Thanks
I think it avoids redundant database calls by storing all vets in the private final List<Vet> vets. Also vets variable is a property of a singleton #Service SimpleJdbcClinic
Related
I am trying out to write data to my local Elasticsearch Docker Container (7.4.2), for simplicity I used the AbstractReactiveElasticsearchConfiguration given from Spring also Overriding the entityMapper function. The I constructed my repository extending the ReactiveElasticsearchRepository
Then in the end I used my autowired repository to saveAll() my collection of elements containing the data. However Elasticsearch doesn't write any data. Also i have a REST controller which is starting my whole process returning nothing basicly, DeferredResult>
The REST method coming from my ApiDelegateImpl
#Override
public DeferredResult<ResponseEntity<Void>> openUsageExporterStartPost() {
final DeferredResult<ResponseEntity<Void>> deferredResult = new DeferredResult<>();
ForkJoinPool.commonPool().execute(() -> {
try {
openUsageExporterAdapter.startExport();
deferredResult.setResult(ResponseEntity.accepted().build());
} catch (Exception e) {
deferredResult.setErrorResult(e);
}
}
);
return deferredResult;
}
My Elasticsearch Configuration
#Configuration
public class ElasticSearchConfig extends AbstractReactiveElasticsearchConfiguration {
#Value("${spring.data.elasticsearch.client.reactive.endpoints}")
private String elasticSearchEndpoint;
#Bean
#Override
public EntityMapper entityMapper() {
final ElasticsearchEntityMapper entityMapper = new ElasticsearchEntityMapper(elasticsearchMappingContext(), new DefaultConversionService());
entityMapper.setConversions(elasticsearchCustomConversions());
return entityMapper;
}
#Override
public ReactiveElasticsearchClient reactiveElasticsearchClient() {
ClientConfiguration clientConfiguration = ClientConfiguration.builder()
.connectedTo(elasticSearchEndpoint)
.build();
return ReactiveRestClients.create(clientConfiguration);
}
}
My Repository
public interface OpenUsageRepository extends ReactiveElasticsearchRepository<OpenUsage, Long> {
}
My DTO
#Data
#Document(indexName = "open_usages", type = "open_usages")
#TypeAlias("OpenUsage")
public class OpenUsage {
#Field(name = "id")
#Id
private Long id;
......
}
My Adapter Implementation
#Autowired
private final OpenUsageRepository openUsageRepository;
...transform entity into OpenUsage...
public void doSomething(final List<OpenUsage> openUsages){
openUsageRepository.saveAll(openUsages)
}
And finally my IT test
#SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
#Testcontainers
#TestPropertySource(locations = {"classpath:application-it.properties"})
#ContextConfiguration(initializers = OpenUsageExporterApplicationIT.Initializer.class)
class OpenUsageExporterApplicationIT {
#LocalServerPort
private int port;
private final static String STARTCALL = "http://localhost:%s/open-usage-exporter/start/";
#Container
private static ElasticsearchContainer container = new ElasticsearchContainer("docker.elastic.co/elasticsearch/elasticsearch:6.8.4").withExposedPorts(9200);
static class Initializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
#Override
public void initialize(final ConfigurableApplicationContext configurableApplicationContext) {
final List<String> pairs = new ArrayList<>();
pairs.add("spring.data.elasticsearch.client.reactive.endpoints=" + container.getContainerIpAddress() + ":" + container.getFirstMappedPort());
pairs.add("spring.elasticsearch.rest.uris=http://" + container.getContainerIpAddress() + ":" + container.getFirstMappedPort());
TestPropertyValues.of(pairs).applyTo(configurableApplicationContext);
}
}
#Test
void testExportToES() throws IOException, InterruptedException {
final List<OpenUsageEntity> openUsageEntities = dbPreparator.insertTestData();
assertTrue(openUsageEntities.size() > 0);
final String result = executeRestCall(STARTCALL);
// Awaitility here tells me nothing is in ElasticSearch :(
}
private String executeRestCall(final String urlTemplate) throws IOException {
final String url = String.format(urlTemplate, port);
final HttpUriRequest request = new HttpPost(url);
final HttpResponse response = HttpClientBuilder.create().build().execute(request);
// Get the result.
return EntityUtils.toString(response.getEntity());
}
}
public void doSomething(final List<OpenUsage> openUsages){
openUsageRepository.saveAll(openUsages)
}
This lacks a semicolon at the end, so it should not compile.
But I assume this is just a typo, and there is a semicolon in reality.
Anyway, saveAll() returns a Flux. This Flux is just a recipe for saving your data, and it is not 'executed' until subscribe() is called by someone (or something like blockLast()). You just throw that Flux away, so the saving never gets executed.
How to fix this? One option is to add .blockLast() call:
openUsageRepository.saveAll(openUsages).blockLast();
But this will save the data in a blocking way effectively defeating the reactivity.
Another option is, if the code you are calling saveAll() from supports reactivity is just to return the Flux returned by saveAll(), but, as your doSomething() has void return type, this is doubtful.
It is not seen how your startExport() connects to doSomething() anyway. But it looks like your 'calling code' does not use any notion of reactivity, so a real solution would be to either rewrite the calling code to use reactivity (obtain a Publisher and subscribe() on it, then wait till the data arrives), or revert to using blocking API (ElasticsearchRepository instead of ReactiveElasticsearchRepository).
I'm using Spring Boot for a project, I'm stuck with lazy loading.
What I want to do is load data in my controller, then send to presentable object, that will extract needed information and the JSON serializer do the bad work to create my custom HTTP response.
the problem occurs when the UserPresentation class calls the folder getter, the error is the well known: could not initialize proxy - no Session.
Of course the default fetch is LAZY for the folder and I want this, but I don't know how to prepare the object to be usable in the Presentation.
I copy-pasted only Folder set to be clear and short, but I've more collection inside User class, all of them give me the same problem.
I know that I could call getter in controller just to initialize Collections, but I find this like an hardcoding, in fact if I want add something to presentable I need to do in controller too.
I've tried too with #Transactional but not works.
Here are my class:
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "USER_ID")
private Integer id;
#Column(unique = true)
private String email;
private String password;
#Enumerated(EnumType.STRING)
private Authority userAuthority;
#OneToMany(mappedBy = "owner", cascade = CascadeType.ALL)
private Set<Folder> ownFolders = new HashSet<>();
... getter setter
}
#RestController
public class UserController {
#GetMapping(value = "/api/user", produces = APPLICATION_JSON_VALUE)
public CustomResponseEntity userInfo() {
User currentUser = loginService.getCurrentUser();
UserPresentation userPresentation = new UserPresentation(currentUser);
return ResponseManager.respondData(userPresentation);
}
}
public class UserPresentation implements Presentable {
private User user;
public UserPresentation(User user) {
this.user = user;
}
public Integer getId() {
return user.getId();
}
public String getEmail() {
return user.getUsername();
}
public String getAuthority() {
return user.getUserAuthority().name();
}
public boolean isEnabled() {
return user.isEnabled();
}
public Integer getOwnFolders() {
Set<Folder> folderList = user.getOwnFolders();
if (folderList == null)
return 0;
return folderList.size();
}
}
Last two just to be clear
public class ResponseManager {
// DATA
public static ResponseEntity respondData(Presentable presentable, String token) {
CustomResponse response = new DataResponse<>(presentable);
return new ResponseEntity<>(response, HttpStatus.OK);
}
}
public class DataResponse<T extends Presentable> extends CustomResponse {
private T data;
public T getData() {
return data;
}
private void setData(T data) {
this.data = data;
}
public DataResponse(T data) {
this.setData(data);
}
#Override
public String getType() {
return DATA;
}
}
I suppose you load the current user form the database with:
User currentUser = loginService.getCurrentUser();
and the getCurrentUser() method is transactional. You can either:
Use JPQL like this:
"select u from User u join fetch u.ownFolders where ... " to load the user's info (this way ownFolders relation is eagerly fetched)
or
Simply call user.getOwnFolders() inside getCurrentUser() to trigger
the fetch.
I found a way, even is a little bit dirty it allows me to do what I want without big change at the code.
Practically the problem occurs during the JSON serialization, that run outside of my control (somewhere inside Spring classes just before send HTTP response), so I manually serialized every Presentable object inside a #Transactional block just after its creation.
These are the changed classes:
public class UserPresentation implements Presentable {
private User user;
public UserPresentation(User user) {
this.user = user;
this.initialize() //ADDED (called here and in every other class that implements Presentable)
}
...getter and setter (which I want as JSON fields)
}
#RestController
public class UserController {
#Transactional //ADDED
#GetMapping(value = "/api/user", produces = APPLICATION_JSON_VALUE)
public CustomResponseEntity userInfo() {
User currentUser = loginService.getCurrentUser();
UserPresentation userPresentation = new UserPresentation(currentUser);
return ResponseManager.respondData(userPresentation);
}
}
Before this fix, the interface was used only to use Polymorfism inside ResponseManager, so was empty
public interface Presentable {
default void initialize() {
try {
new ObjectMapper().writeValueAsString(this);
} catch (JsonProcessingException e) {
throw new RuntimeJsonMappingException(e.getMessage());
}
}
}
I would suggest you use https://github.com/FasterXML/jackson-datatype-hibernate
The module supports datatypes of Hibernate versions 3.x , 4.x and 5.x; as well as some of the associated behavior such as lazy-loading and detection of transiency (#Transient annotation).
It knows how to handle Lazy loading after the session is closed , it will skip the json conversion for objects marked as Lazy fetch when outside session
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-hibernate5</artifactId>
<version>2.9.8</version>
</dependency>
ObjectMapper mapper = new ObjectMapper();
// for Hibernate 4.x:
mapper.registerModule(new Hibernate4Module());
// or, for Hibernate 5.x
mapper.registerModule(new Hibernate5Module());
// or, for Hibernate 3.6
mapper.registerModule(new Hibernate3Module());
#Configuration
public class WebMvcConfig implements WebMvcConfigurer {
/*
* Here we register the Hibernate4Module into an ObjectMapper, then set this * custom-configured ObjectMapper to the MessageConverter and return it to be * added to the HttpMessageConverters of our application
*/
public MappingJackson2HttpMessageConverter jacksonMessageConverter() {
MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();
ObjectMapper hibernateAwareObjectMapper = new ObjectMapper();
hibernateAwareObjectMapper.enable(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS);
hibernateAwareObjectMapper.enable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
// Registering Hibernate5Module to support lazy objects
hibernateAwareObjectMapper.registerModule(new Hibernate5Module());
messageConverter.setObjectMapper(hibernateAwareObjectMapper);
return messageConverter;
}
}
XML config
<mvc:annotation-driven>
<mvc:message-converters>
<!-- Use the HibernateAware mapper instead of the default -->
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="objectMapper">
<bean class="path.to.your.HibernateAwareObjectMapper" />
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
I am running a Spring Boot application with a PostConstruct method to populate a POJO before application initialization. This is to ensure that the database isn't hit by multiple requests to get the POJO content after it starts running.
I'm able to pull the data from Oracle database through Hibernate query and store it in my POJO. The problem arises when I try to access the stored data. The dataset contains a list of objects that contain strings and numbers. Just trying to print the description of the object at the top of the list raises a class cast exception. How should I mitigate this issue?
#Autowired
private TaskDescrBean taskBean;
#PostConstruct
public void loadDescriptions() {
TaskDataLoader taskData = new TaskDataLoader(taskBean.acquireDataSourceParams());
List<TaskDescription> taskList = tdf.getTaskDescription();
taskBean.setTaskDescriptionList(taskList);
System.out.println("Task description size: " + taskBean.getTaskDescriptionList().get(0).getTaskDescription());
}
My POJO class:
#Component
public class TaskDescrBean implements ApplicationContextAware {
#Resource
private Environment environment;
protected List<TaskDescription> taskDescriptionList;
public Properties acquireDataSourceParams() {
Properties dataSource = new Properties();
dataSource.setProperty("hibernate.connection.driver_class", environment.getProperty("spring.datasource.driver-class-name"));
dataSource.setProperty("hibernate.connection.url", environment.getProperty("spring.datasource.url"));
dataSource.setProperty("hibernate.connection.username", environment.getProperty("spring.datasource.username"));
dataSource.setProperty("hibernate.connection.password", environment.getProperty("spring.datasource.password"));
return dataSource;
}
public List<TaskDescription> getTaskDescriptionList() {
return taskDescriptionList;
}
public void setTaskDescriptionList(List<TaskDescription> taskDescriptionList) {
this.taskDescriptionList = taskDescriptionList;
}
public ApplicationContext getApplicationContext() {
return applicationContext;
}
public void setApplicationContext(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}
}
My DAO class:
public class TaskDataLoader {
private Session session;
private SessionFactory sessionFactory;
public TaskDataLoader(Properties connectionProperties) {
Configuration config = new Configuration().setProperties(connectionProperties);
config.addAnnotatedClass(TaskDescription.class);
sessionFactory = config.buildSessionFactory();
}
#SuppressWarnings("unchecked")
public List<TaskDescription> getTaskDescription() {
List<TaskDescription> taskList = null;
session = sessionFactory.openSession();
try {
String description = "from TaskDescription des";
Query taskDescriptionQuery = session.createQuery(description);
taskList = taskDescriptionQuery.list();
System.out.println("Task description fetched. " + taskList.getClass());
} catch (Exception e) {
e.printStackTrace();
} finally {
session.close();
}
return taskList;
}
TaskDescription Entity:
#Entity
#Table(name="TASK_DESCRIPTION")
#JsonIgnoreProperties
public class TaskDescription implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name="TASK_DESCRIPTION_ID")
private Long taskDescriptionId;
#Column(name="TASK_DESCRIPTION")
private String taskDescription;
public Long getTaskDescriptionId() {
return taskDescriptionId;
}
public void setTaskDescriptionId(Long taskDescriptionId) {
this.taskDescriptionId = taskDescriptionId;
}
public String getTaskDescription() {
return taskDescription;
}
public void setTaskDescription(String taskDescription) {
this.taskDescription = taskDescription;
}
}
StackTrace
Instead of sending the List in the return statement, I transformed it into a JSON object and sent its String representation which I mapped back to the Object after transforming it using mapper.readValue()
I'm building a "class cache", with classes I want to call later.
The main goal is that I don't want scan the context every time that a class instance is needed.
# Model / Repository classes
#Getter
#RequiredArgsConstructor
public class Block implements Serializable {
private final String className;
private final Set<String> classCandidates = new HashSet<>();
public boolean addCandidate(final String classCandidate) {
return this.classCandidates.add(classCandidate);
}
}
#Slf4j
#Component
#CacheConfig(cacheNames = ConstantsCache.CACHE_BLOCK)
public class BlockRepository {
#Cacheable(key = "#className")
public Block findByInputClass(final String className) {
log.info("---> Loading classes for class '{}'", className);
val block = new Block(className);
findCandidates(block);
return block;
}
}
First to evaluate the cache, I've put the cache method #Autowired in a #RestController, wich works fine. The cache is populated when I call the rest method.
#RestController
public class Controller {
#Autowired
BlockRepository blockRepository;
#RequestMapping("/findByInputClass")
public Block findByInputClass(#RequestParam("className") final String className) {
return blockRepository.findByInputClass(className);
}
}
After doing that, I've moved the #Autowired object to a #Service, creating a method to self-populate the cache. But this does not work. The cache is not populated when the #PostConstructor method is called.
#Slf4j
#Component
public class BlockCacheService {
#Autowired
BlockRepository blockRepository;
#PostConstruct
private void postConstruct() {
log.info("*** {} PostConstruct called.", this.getClass().getTypeName());
val block = blockRepository.findByInputClass(ConstantsGenerics.BLOCK_PARENT_CLASS);
final Set<String> inputClasses = getInputFromCandidates(block.getClassCandidates());
appendClassesToCache(inputClasses);
}
private void appendClassesToCache(final Set<String> inputClasses) {
for (val inputClass : inputClasses) {
blockRepository.findByInputClass(inputClass);
}
}
}
How can I properly populate the cache using a service or component, that must start with the application.
Thanks in advance.
EDIT:
I've found a possible solution here: https://stackoverflow.com/a/28311225/1703546
Than I've changed the #Service code to put the cache manually instead of use the #Cacheable magic abstraction.
The class now is like this.
#Slf4j
#Component
public class BlockCacheService {
#Autowired
CacheManager cacheManager;
#Autowired
BlockRepository blockRepository;
#PostConstruct
private void postConstruct() {
log.info("*** {} PostConstruct called.", this.getClass().getTypeName());
val block = blockRepository.findByInputClass(ConstantsGenerics.BLOCK_PARENT_CLASS);
final Set<String> inputClasses = getInputFromCandidates(block.getClassCandidates());
appendClassesToCache(inputClasses);
}
private void appendClassesToCache(final Set<String> inputClasses) {
for (val inputClass : inputClasses) {
val block = blockRepository.findByInputClass(inputClass);
cacheManager.getCache(ConstantsCache.CACHE_BLOCK).put(block.getClassName(), block);
}
}
}
Now the cache is populated correctly, but the question is, this is the best solution?
Thanks.
You can't use an aspect in #PostConstruct as it may not have been created yet (and that is documented by the way).
One possible way to make that work is to implement SmartInitializingBean instead as it gives a callback when all singletons have been fully initialized (including their aspect. Changing that on your original service should work.
Having said that, this code of yours has an impact on the startup time. Why don't you let your cache to be filled lazily instead?
I need to create an unmodifiable map generated from data obtained by querying a database. How, or can I, or is there a better way to do this using spring annotations?
I ran into a problem when creating a singleton for my Regions class and then trying to #Autowire in a RegionService to grab the object from the DAO. The problem is that spring can't instantiate the RegionService because it needs to instantiate the static singleton class Regions which needs to get data from the database as shown below in the constructor.
Please see me classes below (I've removed multiple unneeded methods that don't pertain to this question):
public final class Region {
private static final String DEFAULT_SEPERATOR = "-";
private final Integer key;
private final String description;
public Region(Integer pKey, String pDescription) {
this.key = pKey;
this.description = pDescription;
}
public Integer getKey() {
return this.key;
}
public String getValue() {
return this.description;
}
}
Here is my singleton:
public final class Regions {
private static Regions regionsInstance = null;
#Autowired
private RegionService regionService;
static Map<Integer, Region> regions;
private Regions() {
final Map<Integer, Region> tempRegions = new HashMap<Integer, Region>();
for (final Region region : this.regionService.retrieveAll()) {
tempRegions.put(region.getKey(), region);
}
regions = Collections.unmodifiableMap(tempRegions);
}
public static synchronized Regions getRegionsInstance() {
if (regionsInstance == null) {
regionsInstance = new Regions();
}
return regionsInstance;
}
public Region getRegion(final Integer pKey) {
return regions.get(pKey);
}
public List<Region> getRegions() {
return (List<Region>) regions.values();
}
}
My DAO and Service are just interfaces, no need to post those, here are my Impls:
#Service
public class RegionServiceImpl implements RegionService {
#Autowired
private RegionDAO regionDao;
#Override
public List<Region> retrieveAll() {
return this.regionDao.retrieveAll();
}
}
My DAOImpl (tested and works, just posting to give you the full picture):
#Repository
public class RegionDAOImpl implements RegionDAO {
private static final String SQL_RETRIEVE_REGIONS = "some random SQL";
#Autowired
private JdbcTemplate jdbcTemplate;
#Override
public List<Region> retrieveAll() {
try {
return this.jdbcTemplate.query(SQL_RETRIEVE_REGIONS, new ResultSetExtractor<List<Region>>() {
#Override
public List<Region> extractData(ResultSet rs) throws SQLException, DataAccessException {
return RegionDAOImpl.this.mapRegionData(rs);
}
});
} catch (final DataAccessException dae) {
throw new DaoException("Could not retrieve regionList from database. " + dae);
}
}
protected final List<Region> mapRegionData(ResultSet rs) throws SQLException {
final List<Region> regionList = new ArrayList<Region>();
while (rs.next()) {
regionList.add(new Region(rs.getInt("REGION_CD"), rs.getString("REGION_TXT")));
}
return Collections.unmodifiableList(regionList);
}
}
Then I run my test(I took out unneeded crap):
#..annotated with things you don't need to know
public class RetrieveRegionsTest {
#Autowired
private Regions r;
#Test
public void getAndLogRegion() {
final List<Region> regionDescriptions = new ArrayList<Region>(this.r.getRegions());
for (final Region region : regionDescriptions) {
LOGGER.info(region.getValue());
}
}
Yes my configuration and classpaths are set up properly. I can get this to work other ways, just not by accessing the Regions singleton which is what I want. Now I know I could take off the #Autowired on the RegionService in my Regions singleton and just create a new instance of RegionService, but that would defeat the purpose of springs #Autowired feature.
Any thoughts, ideas, comments?