Java 正在响应中发送包含blob的实体对象

我正在尝试创建一个springboot用户管理应用程序

我有一个实体对象，它包含两个blob元素

 @Entity
    @Table(name="user_meta_profile")
    public class UserMetaProfile implements Serializable {
        private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "user_id")
    private int user_id;

    @Column(name = "resume_file")
    @Lob
    private Blob resume_file;

    @Column(name = "photo")
    @Lob
    private Blob photo;

    @Column(name = "username")
    private String username;

    public int getUser_id() {
        return user_id;
    }

    public void setUser_id(int user_id) {
        this.user_id = user_id;
    }

    public Blob getResume_file() {
        return resume_file;
    }

    public void setResume_file(Blob resume_file) {
        this.resume_file = resume_file;
    }

    public Blob getPhoto() {
        return photo;
    }

    public void setPhoto(Blob photo) {
        this.photo = photo;
    }

   public void setUsername(String username) {
        this.username = username;
    }
}

如您所见，有两个blob项“resume\u file”和“photo”

我想向API调用发回一个JSON响应

我的控制器代码如下所示

 @Controller
    @RequestMapping("/v1")
    public class UsersController {

    @Autowired 
        private IUserMetaProfileService userMetaProfileService;


    @GetMapping("MetaProfile/{id}")
        public ResponseEntity<UserMetaProfile> getUserMetaProfileById(@PathVariable("id") Integer id) {
            UserMetaProfile userMetaProfile = userMetaProfileService.getUsersById(id);
            return new ResponseEntity<UserMetaProfile>(userMetaProfile, HttpStatus.OK);
        }

    }

---

由于JSON不能包含二进制数据，您需要将这些字段序列化为其他内容。您有两个选择：

如果您打算将二进制文件显示为图像（因为您的是照片），则可以将其序列化为数据uri

改为发送照片链接，并创建一个控制器方法，该方法将输出具有适当内容类型的二进制数据（超出此处的范围）

因此，对于选项1，您可以执行以下操作：

@Entity
@Table(name="user_meta_profile")
public class UserMetaProfile implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "user_id")
    private int user_id;

    @Column(name = "resume_file")
    @Lob
    private Blob resume_file;

    @Column(name = "photo")
    @Lob
    private Blob photo;

    @Column(name = "username")
    private String username;

    public int getUser_id() {
        return user_id;
    }

    public void setUser_id(int user_id) {
        this.user_id = user_id;
    }

    @JsonIgnore // disable serializing this field by default
    public Blob getResume_file() {
        return resume_file;
    }

    // serialize as data uri insted
    @JsonProperty("resumeData")
    public String getResume() {
      // just assuming it is a word document. you would need to cater for different media types
      return "data:application/vnd.openxmlformats-officedocument.wordprocessingml.document;base64," + new String(Base64.getEncoder().encode(resume_file.getBytes()));
    }

    public void setResume_file(Blob resume_file) {
        this.resume_file = resume_file;
    }

    @JsonIgnore // disable this one too
    public Blob getPhoto() {
        return photo;
    }

    // serialize as data uri instead
    @JsonProperty("photoData")
    public String getPhotoBase64() {
      // just assuming it is a jpeg. you would need to cater for different media types
      return "data:image/jpeg;base64," + new String(Base64.getEncoder().encode(photo.getBytes()));
    }

    public void setPhoto(Blob photo) {
        this.photo = photo;
    }

   public void setUsername(String username) {
        this.username = username;
    }
}

对于照片位，

photoData

JSON属性的值可以直接设置为

img

标记的

src

属性，照片将以HTML格式呈现。使用简历文件，您可以将其作为href附加到

---

仅供参考，如果文件很大，JSON会很大，并且可能会降低浏览器的速度。

您尝试将二进制文件添加到JSON字符串中。这是不可能的。如果您真的想将二进制文件添加到JSON字符串中，则必须对二进制文件进行base64编码。

@Entity
@Table(name="user_meta_profile")
public class UserMetaProfile implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "user_id")
    private int user_id;

    @Column(name = "resume_file")
    @Lob
    private Blob resume_file;

    @Column(name = "photo")
    @Lob
    private Blob photo;

    @Column(name = "username")
    private String username;

    public int getUser_id() {
        return user_id;
    }

    public void setUser_id(int user_id) {
        this.user_id = user_id;
    }

    @JsonIgnore // disable serializing this field by default
    public Blob getResume_file() {
        return resume_file;
    }

    // serialize as data uri insted
    @JsonProperty("resumeData")
    public String getResume() {
      // just assuming it is a word document. you would need to cater for different media types
      return "data:application/vnd.openxmlformats-officedocument.wordprocessingml.document;base64," + new String(Base64.getEncoder().encode(resume_file.getBytes()));
    }

    public void setResume_file(Blob resume_file) {
        this.resume_file = resume_file;
    }

    @JsonIgnore // disable this one too
    public Blob getPhoto() {
        return photo;
    }

    // serialize as data uri instead
    @JsonProperty("photoData")
    public String getPhotoBase64() {
      // just assuming it is a jpeg. you would need to cater for different media types
      return "data:image/jpeg;base64," + new String(Base64.getEncoder().encode(photo.getBytes()));
    }

    public void setPhoto(Blob photo) {
        this.photo = photo;
    }

   public void setUsername(String username) {
        this.username = username;
    }
}

<a href={photoData value here} download>Download Resume File</a>