Hibernate-如何持久化HashMap

Question

Searching Stackoverflow, I saw that many people have my same problem, but I can't find out the solution looking at the other posts. So:

I am trying to persist a Hibernate class, but without using an Entity Object. Instead I am using a Map.

This is my map:

Map<String, Object> record;
record = new HashMap<String, Object>();

...

record.put("key1", "value");
record.put("key2", "value");
record.put("field1", "value");
record.put("field2", "value");
record.put("field3", "value");
record.put("field4", "value");
record.put("field5", "value");
record.put("field6", value);
record.put("field7", value);

and this is the hbm.xml

<class entity-name="entity_name" dynamic-update="true">
<composite-id name="Key1Key2" class="classname">
    <key-property name="Key1" column="Key1" type="string"/>
    <key-property name="Key2" column="Key2" type="string"/>
</composite-id>
    <property name="field1" column="field1" type="string"/>
    <property name="field2" column="field2" type="string"/>
    <property name="field3" column="field3" type="string"/>
    <property name="field4" column="field4" type="string"/>
    <property name="field5" column="field5" type="string"/>
    <property name="field6" column="field6" type="double"/>
    <property name="field7" column="field7" type="double"/>
</class>

When I try to persist the record:

super.session.persist("entity_name", record)

This error is returned:

org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save()

Can anyone help me? Thank in advance!

Answer 1

I solved the question changing the composite-id properties like this:

<composite-id class="CompositeId" mapped="true">

( mapped="true" is the key of the solution)

and then assigning the key-properties values in the hashmap.

Answer 2

Short answer: your class needs to be a POJO.

Long answer: you need to create a separate class for composite IDs, something like

public final class CompositeId implements Serializable {
  private String first;
  private String second;

  // getters, setters, hashCode, equals
}

Your persistent object would be

public class YourClass {
  private CompositeId id;
  private Map map;

  public YourClass() {
    this.map = new HashMap();
  }

  public void setId(CompositeId id) {
    this.id = id;
  }

  public CompositeId getId() {
    return id;
  }

  public void setField1(String field1) {
    this.map.put("field1", field1);
  }  

  public String getField1() {
    return map.get("field1");
  }  
  // and so forth
}

And, finally, your .hbm.xml:

<class entity-name="entity_name" dynamic-update="true">
<composite-id name="id" class="CompositeId">
    <key-property name="first" column="Key1" type="string"/>
    <key-property name="second" column="Key2" type="string"/>
</composite-id>
    <property name="field1" column="field1" type="string"/>
    <property name="field2" column="field2" type="string"/>
    <property name="field3" column="field3" type="string"/>
    <property name="field4" column="field4" type="string"/>
    <property name="field5" column="field5" type="string"/>
    <property name="field6" column="field6" type="double"/>
    <property name="field7" column="field7" type="double"/>
</class>