|
1 package org.hibernate.id;
2
3 import java.io.Serializable  ;
4 import java.sql.Connection ;
5 import java.sql.PreparedStatement ;
6 import java.sql.ResultSet ;
7 import java.sql.SQLException ;
8 import java.util.Properties ;
9
10 import org.apache.commons.logging.Log;
11 import org.apache.commons.logging.LogFactory;
12 import org.hibernate.HibernateException;
13 import org.hibernate.MappingException;
14 import org.hibernate.exception.JDBCExceptionHelper;
15 import org.hibernate.dialect.Dialect;
16 import org.hibernate.engine.SessionImplementor;
17 import org.hibernate.mapping.Table;
18 import org.hibernate.type.Type;
19 import org.hibernate.util.StringHelper;
20
21
33 public class IncrementGenerator implements IdentifierGenerator, Configurable {
34
35 private static final Log log = LogFactory.getLog(IncrementGenerator.class);
36
37 private long next;
38 private String sql;
39 private Class returnClass;
40
41 public synchronized Serializable generate(SessionImplementor session, Object object)
42 throws HibernateException {
43
44 if (sql!=null) {
45 getNext( session );
46 }
47 return IdentifierGeneratorFactory.createNumber(next++, returnClass);
48 }
49
50 public void configure(Type type, Properties params, Dialect dialect)
51 throws MappingException {
52
53 String tableList = params.getProperty("tables");
54 if (tableList==null) tableList = params.getProperty(PersistentIdentifierGenerator.TABLES);
55 String [] tables = StringHelper.split(", ", tableList);
56 String column = params.getProperty("column");
57 if (column==null) column = params.getProperty(PersistentIdentifierGenerator.PK);
58 String schema = params.getProperty(PersistentIdentifierGenerator.SCHEMA);
59 String catalog = params.getProperty(PersistentIdentifierGenerator.CATALOG);
60 returnClass = type.getReturnedClass();
61
62
63 StringBuffer buf = new StringBuffer ();
64 for ( int i=0; i<tables.length; i++ ) {
65 if (tables.length>1) {
66 buf.append("select ").append(column).append(" from ");
67 }
68 buf.append( Table.qualify( catalog, schema, tables[i], dialect.getSchemaSeparator() ) );
69 if ( i<tables.length-1) buf.append(" union ");
70 }
71 if (tables.length>1) {
72 buf.insert(0, "( ").append(" ) ids_");
73 column = "ids_." + column;
74 }
75
76 sql = "select max(" + column + ") from " + buf.toString();
77 }
78
79 private void getNext( SessionImplementor session ) {
80
81 Connection conn = session.connection();
82 log.debug("fetching initial value: " + sql);
83
84 try {
85 PersistentIdentifierGenerator.SQL.debug(sql);
86 PreparedStatement st = conn.prepareStatement(sql);
87 ResultSet rs = null;
88 try {
89 rs = st.executeQuery();
90 if ( rs.next() ) {
91 next = rs.getLong(1) + 1;
92 if ( rs.wasNull() ) next = 1;
93 }
94 else {
95 next = 1;
96 }
97 sql=null;
98 log.debug("first free id: " + next);
99 }
100 finally {
101 if (rs!=null) rs.close();
102 st.close();
103 }
104
105 }
106 catch (SQLException sqle) {
107 throw JDBCExceptionHelper.convert(
108 session.getFactory().getSQLExceptionConverter(),
109 sqle,
110 "could not fetch initial value",
111 sql
112 );
113 }
114 }
115
116 }
117 |
Popular Tags |
Java API By Example, From Geeks To Geeks.