Java Spring Boot JPA(Hibernate) 如何保存图像

How Spring Boot JPA(Hibernate) saves Images

提问by Manoj Sharma

I just want to simply ask when Spring Boot Web Application's JPA saves Data or BLOB(using @LOB) or byte array data in the Database what is the real form of Saving The Images in Database. is it going to save the Whole byte data in Database or it is going to save only the reference or Address for that byte Array Object and in reality saving it into the System's file Space.

我只想简单地问一下Spring Boot Web Application的JPA何时在数据库中保存Data或BLOB（使用@LOB）或字节数组数据时，在数据库中保存图像的真实形式是什么。它是将整个字节数据保存在数据库中，还是只保存该字节数组对象的引用或地址，实际上将其保存到系统的文件空间中。

I want to ask Specifically for Spring Boot JPA Repository. Please explain it. and if any demo example to Test it out please provide it

我想专门询问 Spring Boot JPA 存储库。请解释一下。如果有任何演示示例来测试它，请提供它

回答by Ahmed Itani

It will save all the bytes in the database it will not export it to a file system and save the directory. You have to specifically do that part in the code.

它将保存数据库中的所有字节，不会将其导出到文件系统并保存目录。您必须在代码中专门执行该部分。

回答by Ph03n1x

Go to this repositoryand go to the display-image-from-dbbranch. The basic approach is the following:

转到此存储库并转到display-image-from-db分支。基本方法如下：

• In the entity you have:

  @Lob
  private Byte[] image;
  

• ImageController.java- you get the image via a MultipartFile

  @PostMapping("recipe/{id}/image")
  public String handleImagePost(@PathVariable String id, @RequestParam("imagefile") MultipartFile file){
  
      imageService.saveImageFile(Long.valueOf(id), file);
  
      return "redirect:/recipe/" + id + "/show";
  }
  

• Call the imageServiceto save the image passing the fileas an argument.

• The service basically copies the image content to a byte array, and finally you assign this byte array to your entity.

  @Override
  @Transactional
  public void saveImageFile(Long recipeId, MultipartFile file) {
  
  try {
      Recipe recipe = recipeRepository.findById(recipeId).get();
  
      Byte[] byteObjects = new Byte[file.getBytes().length];
  
      int i = 0;
  
      for (byte b : file.getBytes()){
          byteObjects[i++] = b;
      }
  
      recipe.setImage(byteObjects);
  
      recipeRepository.save(recipe);
  } catch (IOException e) {
      //todo handle better
      log.error("Error occurred", e);
  
      e.printStackTrace();
  }
  }
  

• 在实体中，您拥有：

  @Lob
  private Byte[] image;
  

• ImageController.java- 你通过a获得图像 MultipartFile

  @PostMapping("recipe/{id}/image")
  public String handleImagePost(@PathVariable String id, @RequestParam("imagefile") MultipartFile file){
  
      imageService.saveImageFile(Long.valueOf(id), file);
  
      return "redirect:/recipe/" + id + "/show";
  }
  

• 调用imageService以保存将 传递file为参数的图像。

• 该服务基本上将图像内容复制到一个字节数组中，最后您将这个字节数组分配给您的实体。

  @Override
  @Transactional
  public void saveImageFile(Long recipeId, MultipartFile file) {
  
  try {
      Recipe recipe = recipeRepository.findById(recipeId).get();
  
      Byte[] byteObjects = new Byte[file.getBytes().length];
  
      int i = 0;
  
      for (byte b : file.getBytes()){
          byteObjects[i++] = b;
      }
  
      recipe.setImage(byteObjects);
  
      recipeRepository.save(recipe);
  } catch (IOException e) {
      //todo handle better
      log.error("Error occurred", e);
  
      e.printStackTrace();
  }
  }
  

For the full source code go to the repo, that will definitely help. However I strongly suggest storing the files on the disk and not in the DB. The DB should only store the path to the files. For such solution here is an example: link

对于完整的源代码，请访问 repo，这肯定会有所帮助。但是我强烈建议将文件存储在磁盘上而不是数据库中。DB 应该只存储文件的路径。对于这样的解决方案，这里有一个例子：链接

回答by Paul Warren

To answer the question directly the content is stored in the database. This may, or may not work for you. As @dgarceran mentions there are a bunch of pros and cons. Either way I would recommend that you take a look at Spring Content.

为了直接回答问题，内容存储在数据库中。这可能适用，也可能不适用于您。正如@dgarceran 提到的，有很多优点和缺点。无论哪种方式，我都建议您查看Spring Content。

This project provides an abstraction for content/BLOBs. It is to unstructured data, what Spring Data is to structured data. It has modules that support JPA (BLOBs), Filesystem, Mongo's GridFS and S3. Regardless of the module you choose it will save you from having to write any of that boilerplate code like that provided by @Ph03n1x.

该项目为内容/BLOB 提供了抽象。它是非结构化数据，Spring Data 是结构化数据。它具有支持 JPA (BLOB)、文件系统、Mongo 的 GridFS 和 S3 的模块。无论您选择哪个模块，它都会使您不必编写任何由@Ph03n1x 提供的样板代码。

With Spring Content all you need to do is create an a ContentStoreinterface and Spring Content will provide the implementation and controller for you. The implementation is efficient as it will stream content between client and database (rather than load the entire file into memory as Ph03n1x's example does). The abstraction also makes it easy to change the storage model later, should you need to.

使用 Spring Content，您需要做的就是创建一个ContentStore接口，Spring Content 将为您提供实现和控制器。该实现是高效的，因为它将在客户端和数据库之间传输内容（而不是像 Ph03n1x 的示例那样将整个文件加载到内存中）。如果您需要，抽象还使以后更改存储模型变得容易。

There is a getting started guides hereand a video tutorial here.

有一个快速入门指南在这里和视频教程在这里。

HTH

HTH