Hibernate Annotations - Composite Key

There are several ways to create an ORM mapped to a composite key using hibernate annotations.

A code sample that shows how to create a composite key with hibernate annotations can be find below:

The Composite Key class:

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import javax.persistence.Embeddable;

@Embeddable

public class MyCompositeKey implements Serializable {

private static final long serialVersionUID = 8057719523073696665L;

private String name;

private String value;

public MyCompositeKey() {

}

public MyCompositeKey(String name, String value) {

this.name = name;

this.value = value;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getValue() {

return value;

}

public void setValue(String value) {

this.value = value;

}

@Override

public int hashCode() {

final int prime = 31;

int result = 1;

result = prime * result + ((name== null) ? 0 : name.hashCode());

result = prime * result + ((value== null) ? 0 : value.hashCode());

return result;

}

@Override

public boolean equals(Object obj) {

if (this == obj)

return true;

if (obj == null)

return false;

if (getClass() != obj.getClass())

return false;

MyCompositeKey other = (MyCompositeKey)obj;

if (name == null) {

if (other.name != null)

return false;

} else if (!name.equals(other.name))

return false;

if (value == null) {

if (other.value != null)

return false;

} else if (!value.equals(other.value))

return false;

return true;

}

}

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The ORM class with the composite key mappings:

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import javax.persistence.AttributeOverride;

import javax.persistence.AttributeOverrides;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.Id;

import javax.persistence.Table;

@Entity

@Table(name = "my_table_name")

public class MyClassOrm {

private MyCompositeKey id;

private String data;

public MyClassOrm() {

}

@Id

@AttributeOverrides( {

@AttributeOverride(name = "name", column = @Column(name = "name")),

@AttributeOverride(name = "value", column = @Column(name = "value")) })

public MyCompositeKey getId() {

return id;

}

public void setId(MyCompositeKey id) {

this.id = id;

}

@Column(name = "data")

public String getData() {

return data;

}

public void setData(String data) {

this.data = data;

}

}