Blob In Database Using JPA

Story

My aim is creating a web service for responding as File whose type is oracle.sql.BLOB.

Oh! I could barely find the problem which always shows could not deserialize. At first, I read the section and knew that it was caused by composite key because I did not create both hashCode and equals functions. But it still not worked. Why? See Solution.

I finally inspired by this post.

check whether they are serializable itself and all their fields either serializable too

So that I started searching the method of JPA for Blob and I found this. It described how to insert and retrieve Blob type. Anyway, let’s see the sample.

Sample

	package com.sample.entity;
	import java.math.BigDecimal;
	import javax.persistence.Column;
	import javax.persistence.Entity;
	import javax.persistence.Id;
	import javax.persistence.IdClass;
	import javax.persistence.Lob;
	import javax.persistence.Table;
	@Entity
	@Table(name = "Sample")
	@IdClass(SampleCPK.class)
	public class Sample {
	@Id
	@Column(nullable=false)
	private String id;
	@Id
	@Column(nullable=false)
	private BigDecimal sNo;
	@Column
	private String attachName;
	@Column
	private String attachType;
	@Lob
	@Column
	private byte[] attachFile;
	/*
	* This constructor is only for JPA.
	* */
	Sample() {
	}
	/*
	Getters & Setters...
	*/
	}

view raw Sample.java hosted with ❤ by GitHub

	package com.sample.entity;
	import java.io.Serializable;
	import java.math.BigDecimal;
	public class SampleCPK implements Serializable {
	private String id;
	private BigDecimal sNo;
	public SampleCPK(){}
	public String getId() {
	return id;
	}
	public BigDecimal getSNo() {
	return sNo;
	}
	@Override
	public int hashCode() {
	final int prime = 31;
	int result = 1;
	result = prime * result + ((id == null) ? 0 : id.hashCode());
	result = prime * result + sNo.intValue();
	return result;
	}
	@Override
	public boolean equals(Object obj) {
	if (this == obj)
	return true;
	if (obj == null)
	return false;
	if (getClass() != obj.getClass())
	return false;
	SampleCPK other = (SampleCPK) obj;
	if (id == null) {
	if (other.id != null)
	return false;
	if (sNo != other.sNo)
	return false;
	return true;
	}
	}

view raw SampleCPK.java hosted with ❤ by GitHub