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narkisr on 03/12/08


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java mapping enum Hibernate


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Java 5 Enum HIbernate mapping


 / Published in: Java
 

This is an example of how to map a Java 5 enum when using Hibernate ORM.

  1. import org.hibernate.HibernateException;
  2. import org.hibernate.usertype.ParameterizedType;
  3. import org.hibernate.usertype.UserType;
  4. import java.io.Serializable;
  5. import java.sql.PreparedStatement;
  6. import java.sql.ResultSet;
  7. import java.sql.SQLException;
  8. import java.sql.Types;
  9. import java.util.Properties;
  10.  
  11. /**
  12. * This class implements the Type that will be used in the hbm file, notice that
  13. * the JavaEnumToString & StringToJavaEnum implementation isn't provided
  14. * (all they do is to convert Enum<->String in a consistent way, same goes for
  15. * StringUtils (replaceable with apache commons StringUtils).
  16. */
  17. public class JavaEnumUserType implements UserType, ParameterizedType {
  18.  
  19. private static final int[] SQL_TYPE = new int[]{Types.VARCHAR};
  20.  
  21. private Class<? extends Enum> enumClass;
  22.  
  23.  
  24. private static JavaEnumToString javaEnumToString = new JavaEnumToString();
  25.  
  26. private static StringToJavaEnum stringToJavaEnum = new StringToJavaEnum();
  27.  
  28. public void setParameterValues(Properties parameters) {
  29. String enumClassName = parameters.getProperty("enumClass");
  30. try {
  31. enumClass = Class.forName(enumClassName).asSubclass(Enum.class);
  32. } catch (ClassNotFoundException e) {
  33. throw new HibernateException("Class " + enumClassName + " not found ", e);
  34. }
  35. }
  36.  
  37. public Object assemble(Serializable cached, Object owner)
  38. throws HibernateException {
  39. return cached;
  40. }
  41.  
  42. public Object deepCopy(Object value) throws HibernateException {
  43. return value;
  44. }
  45.  
  46. public Serializable disassemble(Object value) throws HibernateException {
  47. return (Enum) value;
  48. }
  49.  
  50. public boolean equals(Object x, Object y) throws HibernateException {
  51. return x == y;
  52. }
  53.  
  54. public int hashCode(Object x) throws HibernateException {
  55. return x.hashCode();
  56. }
  57.  
  58. public boolean isMutable() {
  59. return false;
  60. }
  61.  
  62. public Object nullSafeGet(ResultSet rs, String[] names, Object owner) throws HibernateException, SQLException {
  63. String value = rs.getString(names[0]);
  64. if (rs.wasNull() || StringUtils.isNullOrEmpty(value)) {
  65. return null;
  66. }
  67. return stringToJavaEnum.doConvert(value.trim(), enumClass);
  68. }
  69.  
  70. public void nullSafeSet(PreparedStatement st, Object value, int index) throws HibernateException, SQLException {
  71. if (value == null) {
  72. st.setNull(index, Types.VARCHAR);
  73. } else {
  74. String stringValue = javaEnumToString.doConvert((Enum) value);
  75. st.setString(index, stringValue);
  76. }
  77. }
  78.  
  79. public Object replace(Object original, Object target, Object owner)
  80. throws HibernateException {
  81. return original;
  82. }
  83.  
  84. public Class returnedClass() {
  85. return enumClass;
  86. }
  87.  
  88. public int[] sqlTypes() {
  89. return SQL_TYPE;
  90. }
  91.  
  92. }
  93.  
  94. // For example the following bean:
  95.  
  96. public class DummyBean{
  97.  
  98. private DummyEnum dummyProp;
  99.  
  100. public DummyEnum getDummyProp() {
  101. return dummyProp;
  102. }
  103.  
  104. public void setPageDescriptor(DummyEnum _dummyProp) {
  105. this.dummyProp = _dummyProp;
  106. }
  107.  
  108. }
  109.  
  110. // will be mapped in this fashion:
  111.  
  112. <hibernate-mapping>
  113. <class name="com.dummy.DummyBean" table="DUMMY_TABLE">
  114.  
  115. <property name="dummyProp" column="DUMMY_PROP">
  116. <type name="com.dummy.JavaEnumUserType">
  117. <param name="enumClass">com.dummy.DummyEnum</param>
  118. </type>
  119. </property>
  120. </hibernate-mapping>

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