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1 /* |
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2 * Copyright 1998-2006 Sun Microsystems, Inc. All Rights Reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Sun designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Sun in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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22 * CA 95054 USA or visit www.sun.com if you need additional information or |
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23 * have any questions. |
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24 */ |
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25 |
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26 package java.sql; |
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27 |
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28 /** |
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29 * The interface used for the custom mapping of an SQL user-defined type (UDT) to |
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30 * a class in the Java programming language. The class object for a class |
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31 * implementing the <code>SQLData</code> interface will be entered in the |
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32 * appropriate <code>Connection</code> object's type map along with the SQL |
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33 * name of the UDT for which it is a custom mapping. |
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34 * <P> |
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35 * Typically, a <code>SQLData</code> implementation |
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36 * will define a field for each attribute of an SQL structured type or a |
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37 * single field for an SQL <code>DISTINCT</code> type. When the UDT is |
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38 * retrieved from a data source with the <code>ResultSet.getObject</code> |
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39 * method, it will be mapped as an instance of this class. A programmer |
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40 * can operate on this class instance just as on any other object in the |
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41 * Java programming language and then store any changes made to it by |
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42 * calling the <code>PreparedStatement.setObject</code> method, |
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43 * which will map it back to the SQL type. |
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44 * <p> |
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45 * It is expected that the implementation of the class for a custom |
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46 * mapping will be done by a tool. In a typical implementation, the |
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47 * programmer would simply supply the name of the SQL UDT, the name of |
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48 * the class to which it is being mapped, and the names of the fields to |
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49 * which each of the attributes of the UDT is to be mapped. The tool will use |
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50 * this information to implement the <code>SQLData.readSQL</code> and |
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51 * <code>SQLData.writeSQL</code> methods. The <code>readSQL</code> method |
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52 * calls the appropriate <code>SQLInput</code> methods to read |
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53 * each attribute from an <code>SQLInput</code> object, and the |
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54 * <code>writeSQL</code> method calls <code>SQLOutput</code> methods |
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55 * to write each attribute back to the data source via an |
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56 * <code>SQLOutput</code> object. |
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57 * <P> |
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58 * An application programmer will not normally call <code>SQLData</code> methods |
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59 * directly, and the <code>SQLInput</code> and <code>SQLOutput</code> methods |
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60 * are called internally by <code>SQLData</code> methods, not by application code. |
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61 * |
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62 * @since 1.2 |
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63 */ |
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64 public interface SQLData { |
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65 |
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66 /** |
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67 * Returns the fully-qualified |
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68 * name of the SQL user-defined type that this object represents. |
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69 * This method is called by the JDBC driver to get the name of the |
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70 * UDT instance that is being mapped to this instance of |
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71 * <code>SQLData</code>. |
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72 * |
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73 * @return the type name that was passed to the method <code>readSQL</code> |
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74 * when this object was constructed and populated |
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75 * @exception SQLException if there is a database access error |
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76 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support |
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77 * this method |
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78 * @since 1.2 |
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79 */ |
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80 String getSQLTypeName() throws SQLException; |
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81 |
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82 /** |
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83 * Populates this object with data read from the database. |
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84 * The implementation of the method must follow this protocol: |
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85 * <UL> |
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86 * <LI>It must read each of the attributes or elements of the SQL |
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87 * type from the given input stream. This is done |
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88 * by calling a method of the input stream to read each |
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89 * item, in the order that they appear in the SQL definition |
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90 * of the type. |
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91 * <LI>The method <code>readSQL</code> then |
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92 * assigns the data to appropriate fields or |
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93 * elements (of this or other objects). |
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94 * Specifically, it must call the appropriate <i>reader</i> method |
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95 * (<code>SQLInput.readString</code>, <code>SQLInput.readBigDecimal</code>, |
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96 * and so on) method(s) to do the following: |
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97 * for a distinct type, read its single data element; |
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98 * for a structured type, read a value for each attribute of the SQL type. |
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99 * </UL> |
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100 * The JDBC driver initializes the input stream with a type map |
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101 * before calling this method, which is used by the appropriate |
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102 * <code>SQLInput</code> reader method on the stream. |
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103 * |
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104 * @param stream the <code>SQLInput</code> object from which to read the data for |
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105 * the value that is being custom mapped |
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106 * @param typeName the SQL type name of the value on the data stream |
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107 * @exception SQLException if there is a database access error |
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108 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support |
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109 * this method |
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110 * @see SQLInput |
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111 * @since 1.2 |
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112 */ |
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113 void readSQL (SQLInput stream, String typeName) throws SQLException; |
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114 |
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115 /** |
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116 * Writes this object to the given SQL data stream, converting it back to |
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117 * its SQL value in the data source. |
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118 * The implementation of the method must follow this protocol:<BR> |
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119 * It must write each of the attributes of the SQL type |
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120 * to the given output stream. This is done by calling a |
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121 * method of the output stream to write each item, in the order that |
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122 * they appear in the SQL definition of the type. |
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123 * Specifically, it must call the appropriate <code>SQLOutput</code> writer |
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124 * method(s) (<code>writeInt</code>, <code>writeString</code>, and so on) |
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125 * to do the following: for a Distinct Type, write its single data element; |
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126 * for a Structured Type, write a value for each attribute of the SQL type. |
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127 * |
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128 * @param stream the <code>SQLOutput</code> object to which to write the data for |
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129 * the value that was custom mapped |
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130 * @exception SQLException if there is a database access error |
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131 * @exception SQLFeatureNotSupportedException if the JDBC driver does not support |
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132 * this method |
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133 * @see SQLOutput |
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134 * @since 1.2 |
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135 */ |
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136 void writeSQL (SQLOutput stream) throws SQLException; |
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137 } |