java - How does hibernate decide update/save associated objects -

anyone me explain hibernate. how save/update child objects when save/update parent object. especially, child object @embeddedid mapping

@embeddable public class bomlevelkey implements serializable{ /**  *   */ private static final long serialversionuid = 1l; item item; long organizationid; item componentitem;  @column(name = "organization_id") public long getorganizationid() {     return organizationid; } public void setorganizationid(long organizationid) {     this.organizationid = organizationid; }  @manytoone @joincolumn(name = "inventory_item_id") public item getitem() {     return item; } public void setitem(item item) {     this.item = item; }  @manytoone @joincolumn(name = "component_item_id") public item getcomponentitem() {     return componentitem; } public void setcomponentitem(item componentitem) {     this.componentitem = componentitem; }  @override public boolean equals(object obj) {     if (obj == null || !(obj instanceof bomlevelkey)) {         return false;     }     bomlevelkey key = (bomlevelkey) obj;     if (key.getitem().getinventoryitemid() == this.getitem()             .getinventoryitemid()             && key.getcomponentitem().getinventoryitemid() ==                     .getcomponentitem().getinventoryitemid()             && key.getorganizationid() == this.getorganizationid()) {         return true;     }     return false; } }  @entity @table(name = "es_bom_levels", schema = "xx_vms") public class itemconversionattributes implements serializable{     /**      *       */     private static final long serialversionuid = 1l;     private double componentroutingyield;     private double forwardroutingyield;     private double conversionfactor;     private double cumulativeleadtime;     private integer organizationid;     private item componentitem;     private bomlevelkey id;  @embeddedid public bomlevelkey getid() {     return id; }  public void setid(bomlevelkey id) {     this.id = id; }  /** * @hibernate.property  * column="component_routing_yield" * **/ @column(name="component_routing_yield") public double getcomponentroutingyield(){ return componentroutingyield; }  public void setcomponentroutingyield(double componentroutingyield){ this.componentroutingyield= componentroutingyield; }  /** * @hibernate.property  * column="forward_routing_yield" * **/ @column(name="forward_routing_yield") public double getforwardroutingyield(){ return forwardroutingyield; }  public void setforwardroutingyield(double forwardroutingyield){ this.forwardroutingyield = forwardroutingyield; }  /** * @hibernate.property  * column="conversion_factor" * **/ @column(name="conversion_factor") public double getconversionfactor(){ return conversionfactor; }  public void setconversionfactor(double conversionfactor){ this.conversionfactor = conversionfactor; }  /** * @hibernate.property  * column="cumulative_lead_time" * **/ @column(name="cumulative_lead_time") public double getcumulativeleadtime(){ return cumulativeleadtime; }  public void setcumulativeleadtime(double cumulativeleadtime){ this.cumulativeleadtime = cumulativeleadtime; }  /**  * @hibernate.property  * column="organization_id"  *  **/ @column(name="organization_id", insertable = false, updatable = false) public integer getorganizationid(){ return organizationid; }  public void setorganizationid(integer organizationid){ this.organizationid = organizationid; }  /** * @hibernate.many-to-one * column="component_item_id" * insert="false" * update="false" * **/ @manytoone(targetentity=item.class) @joincolumn(name="component_item_id", insertable=false, updatable=false) @notfound(action=notfoundaction.ignore) public item getcomponentitem(){ return componentitem; }  public void setcomponentitem(item componentitem){ this.componentitem = componentitem; } 

}

in class item, i've mapping:

@onetomany(mappedby = "id.item") @mapkey(name = "id.componentitem") public map<item, itemconversionattributes> getconversionattributes(){ return conversionattributes; }  public void setconversionattributes(map<item, itemconversionattributes> conversionattributes) {     this.conversionattributes = conversionattributes; } 

save/update nothing.

its based on dao objects primary key's value.

if set default value , hibernate add otherwise update