I'm using struts2 and hibernate and I want to know how to store and retrieve images from database using hibernate annotations in the POJO class
Best way to store images in the database in in format of Byte arraylike you have to upload images using struts2 file upload utility and den pass it on to hibernate as byte[] image;
in your mapping you have to do something like
#Column( name = "IMAGE" )
#Lob(type = LobType.BLOB)
private byte[] image;
How to use annotation for this is very well described in the following thread
proper hibernate annotation for byte[]
The answer is as following
private byte[] imageBefore;
#Type(type="org.hibernate.type.BinaryType")
#Column (name = "IMAGE_BEFORE")
public byte[] getImageBefore() {
return imageBefore;
}
refer to this link if you're not using annotations and for a complete reference
Or simply:
#Lob
private byte[] picture;
Related
I am using Spring Data Elasticsearch in my project. I have a class like this,
#Document("example")
class Example {
#Id
private String id;
private String name;
private String game;
private String restField;
}
What I need is when ever I am saving the Example object to elasticsearch I am removing a value. But when I am getting the data from elasticsearch I need that removed value to be appended.
save(Example example) {
example.setRestField(example.getRestField().replace("***", ""));
exampleRepository.save(example);
}
get(String id) {
Example example = exampleRepository.findById(id);
example.getRestField().concat("***");
return example;
}
Right now I am doing like the above way. But can we use a custom converter for this? I checked the converter examples for Spring Data Elasticsearch but those are for different different objects. How I can create a custom converter only for this particular String field restField? I don't want to apply this converter for other String fields.
Currently there is no better solution. The converters registered for Spring Data Elasticsearch convert from a class to a String and back. Registering a converter for your case would convert any String property of every entity.
I had thought about custom converters for properties before, I have created a ticket for this.
Edit 05.11.2021:
Implemented with https://github.com/spring-projects/spring-data-elasticsearch/pull/1953 and will be available from 4.3.RC1 on.
I have a spring app, that pushes data in an s3 bucket.
public class Ebook implements Serializable {
#Column(name= "cover_path", unique = true, nullable = true)
private String coverPath;
private String coverDownloadUrl;
#Value("${aws.cloudfront.region}")
private String awsCloudFrontDns;
#PostLoad
public void init(){
// I want to access the property here
System.out.println("PostConstruct");
String coverDownloadUrl = "https://"+awsCloudFrontDns+"/"+coverPath;
}
When a data is pushed, let's say my cover here, I get the key 1/test-folder/mycover.jpg which is the important part of the future http URL of the data.
When I read the data from database, I enter inside #PostLoad method and I want construct the complete URL using the cloudfront value. This value changes frequently so we don't want to save hardly in the database.
How could I do to construct my full path just after reading the data in database?
The only way to do this is to use a service that update the data after using repository to read it? For readbyId it can be a good solution, but for reading list or using other jpa methods, this solutions won't work because I have each time to create a dedicated service for the update.
It doesn't look good for Entity to depend on property.
How about EntityListener.
#Component
public class EbookEntityListener {
#Value("${aws.cloudfront.region}")
private String awsCloudFrontDns;
#PostLoad
void postload(Ebook entity) { entity.updateDns(awsCloudFrontDns); }
}
I recommend trying this way :)
In a regular entity for SDR, it takes care of all properties of an entity for you saving it to the database. But how do you handle files?
#Entity
public class User {
String name;
Set<File> myfiles; //how can I make this work?
}
#RepositoryRestResource
public interface UserRepository extends JpaRepository<User, Long> {}
How can I make it so that a User owns a list of files, can upload and download them?
This is not really possible with Spring Data/REST as it focusses on structured data; i.e. tables and associations, for the most part.
#Lob is problematic as it forces you to store your content in the database which isn't necessarily where you want to store it. The file-system or S3 might be better for example.
byte[] is also problematic if you have very large files as you will likely cause OutOfMemoryExceptions.
Instead, there is a community project called Spring Content that addresses exactly the problem you are trying to solve.
Spring Content provides the same programming paradigms as Spring Data/REST for unstructured data; i.e. images, documents, movies, etc. So, using this project you can associate one, or in your case, many "content" objects with your Spring Data entities and manage them over HTTP just like you do with your Spring Data Entities too.
Its pretty simple to add to your project, as follows:
pom.xml (boot starters also available)
<!-- Java API -->
<dependency>
<groupId>com.github.paulcwarren</groupId>
<artifactId>spring-content-fs</artifactId>
<version>1.0.0.M4</version>
</dependency>
<!-- REST API -->
<dependency>
<groupId>com.github.paulcwarren</groupId>
<artifactId>spring-content-rest</artifactId>
<version>1.0.0.M4</version>
</dependency>
Configuration
#Configuration
#EnableFilesystemStores
#Import("org.springframework.content.rest.config.RestConfiguration.class")
public class ContentConfig {
#Bean
FileSystemResourceLoader fileSystemResourceLoader() throws IOException {
return new FileSystemResourceLoader(new File("/path/to/uploaded/files").getAbsolutePath());
}
}
To associate content, modify your User entity as follows:
#Entity
public class User {
String name;
List<Image> images;
}
Add an Image entity:
#Entity
public class Image {
#ContentId
private String contentId;
#ContentLength
private long contentLength = 0L;
#MimeType
private String mimeType = "text/plain";
}
And to this add a "store" (the equivalent of a Repository but for content):
ImageStore.java
#StoreRestResource
public interface ImageStore extends FilesystemContentStore<Image, String> {}
This is all you need to create REST endpoints # /users/{userId}/images. When your application starts, Spring Content will look at your dependencies seeing Spring Content Filesystem, look at your ImageStore interface and inject a filesystem-based implementation of that interface. It will also see the Spring Content REST dependency and inject an #Controller implementation that forwards HTTP requests to your ImageStore. Just like Spring Data does for your UserRepository. This saves you having to implement any of this yourself which I think is what you are after.
So...
To manage content with the injected REST API:
curl -X POST /users/{userId}/images -F file=#/path/to/image.jpg
will store the image on the filesystem at `` and associate it with the user entity whose id is userId.
curl /users/{userId}/images/{contentId} -H "Accept: image/jpeg"
will fetch it again and so on...supports all CRUD methods and video streaming as well BTW!
There are a couple of getting started guides here. The reference guide for Spring Content Filesystem is here. And there is a tutorial video here. The coding bit starts about 1/2 way through.
A couple of additional points:
- if you use the Spring Boot Starters then you don't need the #Configuration for the most part.
- Just like Spring Data is an abstraction, so is Spring Content so you aren't limited to storing your images on the filesystem. You could store them as BLOBs in the database, or in cloud storage like S3.
HTH
I suggest you can use #Lob instead to save file data (fileData variable below)
#Entity
public class File {
#Id
#GeneratedValue(generator = "uuid")
#GenericGenerator(name = "uuid", strategy = "uuid2")
private String id;
private String fileName;
private String fileType;
#Lob
private byte[] fileData;
}
I'm creating a Spring Boot application and I am using AngularJS on the frontend.
Upon submitting a form with the appropiate parameters, Spring is supposed to use bookRepository.save() method in order to save the provided data in the MongoDB. The problem is, this action gets carried on, but the structure of my model is not respected.
#Document(collection = "books")
public class Book {
private String id;
private String title;
private String author;
private String description;
private String cover;
// Getters and setters below.
}
The final outcome after following the above process: instead of having a record following the above structure inserted in MongoDB, I only end up with a field containing _id and _class.
Any ideas as to why is this happening?
Here is a part of Files.java
#Entity(name="files")
public class Files {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String title;
#ElementCollection
private List<String> filenames= new ArrayList<String>();
//<< getter and setter >>
}
it is correctly created the table 'Files' and 'Files_filenames' on mySql
and I can put data there on Controller with it
Files files = new Files();
files.setTitle(ufile.getTitle());
files.setFilenames(Arrays.asList(ufile.getFilename().split(",")));
so far, everything looks ok
However, when I try to get the data from the database, the filename always returns something like 'persistentbag' not ArrayList.
I would like to know how to get ArrayList from the database
I'm using Spring data JPA using Hibernate as a Jpa vendor.
Thanks in advance
PersistentBag is a List (i.e., it implements List), therefore you can use it as a regular List. There is no need to care about actual implementation of that List in this case.