Added missing file.
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Bruce Momjian
parent
0f356be054
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342
src/interfaces/jdbc/postgresql/util/Serialize.java
Normal file
342
src/interfaces/jdbc/postgresql/util/Serialize.java
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package postgresql.util;
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import java.io.*;
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import java.lang.*;
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import java.lang.reflect.*;
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import java.net.*;
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import java.util.*;
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import java.sql.*;
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/**
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* This class uses PostgreSQL's object oriented features to store Java Objects.
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*
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* It does this by mapping a Java Class name to a table in the database. Each
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* entry in this new table then represents a Serialized instance of this
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* class. As each entry has an OID (Object IDentifier), this OID can be
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* included in another table.
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*
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* This is too complex to show here, and will be documented in the main
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* documents in more detail.
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*
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*/
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public class Serialize
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{
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// This is the connection that the instance refers to
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protected postgresql.Connection conn;
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// This is the table name
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protected String tableName;
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// This is the class name
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protected String className;
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// This is the Class for this serialzed object
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protected Class ourClass;
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/**
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* This creates an instance that can be used to serialize or deserialize
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* a Java object from a PostgreSQL table.
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*/
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public Serialize(postgresql.Connection c,String type) throws SQLException
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{
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try {
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conn = c;
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tableName = type.toLowerCase();
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className = toClassName(type);
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ourClass = Class.forName(className);
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} catch(ClassNotFoundException cnfe) {
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throw new SQLException("No class found for '"+type+"`");
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}
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// Second check, the type must be a table
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boolean status = false;
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ResultSet rs = conn.ExecSQL("select typname from pg_type,pg_class where typname=relname and typname='"+type+"'");
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if(rs!=null) {
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if(rs.next())
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status=true;
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rs.close();
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}
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// This should never occur, as postgresql has it's own internal checks
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if(!status)
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throw new SQLException("The table for "+type+" is not in the database. Contact the DBA, as the database is in an inconsistent state.");
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// Finally cache the fields within the table
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}
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/**
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* This fetches an object from a table, given it's OID
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* @param oid The oid of the object
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* @return Object relating to oid
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* @exception SQLException on error
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*/
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public Object fetch(int oid) throws SQLException
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{
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try {
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Object obj = ourClass.newInstance();
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// NB: we use java.lang.reflect here to prevent confusion with
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// the postgresql.Field
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java.lang.reflect.Field f[] = ourClass.getDeclaredFields();
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boolean hasOID=false;
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int oidFIELD=-1;
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StringBuffer sb = new StringBuffer("select");
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char sep=' ';
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for(int i=0;i<f.length;i++) {
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String n = f[i].getName();
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if(n.equals("oid")) {
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hasOID=true;
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oidFIELD=i;
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}
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sb.append(sep);
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sb.append(n);
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sep=',';
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}
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sb.append(" from ");
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sb.append(tableName);
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sb.append(" where oid=");
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sb.append(oid);
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DriverManager.println("store: "+sb.toString());
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ResultSet rs = conn.ExecSQL(sb.toString());
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if(rs!=null) {
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if(rs.next()) {
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for(int i=0;i<f.length;i++) {
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f[i].set(obj,rs.getObject(i+1));
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}
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}
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rs.close();
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} else
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throw new SQLException("Unexpected result from query");
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return obj;
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} catch(IllegalAccessException iae) {
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throw new SQLException(iae.toString());
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} catch(InstantiationException ie) {
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throw new SQLException(ie.toString());
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}
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}
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/**
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* This stores an object into a table, returning it's OID.<p>
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*
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* If the object has an int called OID, and it is > 0, then
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* that value is used for the OID, and the table will be updated.
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* If the value of OID is 0, then a new row will be created, and the
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* value of OID will be set in the object. This enables an object's
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* value in the database to be updateable.
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*
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* If the object has no int called OID, then the object is stored. However
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* if the object is later retrieved, amended and stored again, it's new
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* state will be appended to the table, and will not overwrite the old
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* entries.
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*
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* @param o Object to store (must implement Serializable)
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* @return oid of stored object
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* @exception SQLException on error
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*/
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public int store(Object o) throws SQLException
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{
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try {
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// NB: we use java.lang.reflect here to prevent confusion with
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// the postgresql.Field
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java.lang.reflect.Field f[] = ourClass.getDeclaredFields();
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boolean hasOID=false;
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int oidFIELD=-1;
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boolean update=false;
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// Find out if we have an oid value
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for(int i=0;i<f.length;i++) {
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String n = f[i].getName();
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if(n.equals("oid")) {
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hasOID=true;
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oidFIELD=i;
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// We are an update if oid != 0
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update = f[i].getInt(o)>0;
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}
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}
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StringBuffer sb = new StringBuffer(update?"update "+tableName+" set":"insert into "+tableName+" values ");
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char sep=update?' ':'(';
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for(int i=0;i<f.length;i++) {
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String n = f[i].getName();
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sb.append(sep);
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sb.append(n);
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sep=',';
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if(update) {
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sb.append('=');
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if(f[i].getType().getName().equals("java.lang.String")) {
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sb.append('\'');
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sb.append(f[i].get(o).toString());
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sb.append('\'');
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} else
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sb.append(f[i].get(o).toString());
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}
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}
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if(!update) {
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sb.append(") values ");
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sep='(';
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for(int i=0;i<f.length;i++) {
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String n = f[i].getName();
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if(f[i].getType().getName().equals("java.lang.String")) {
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sb.append('\'');
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sb.append(f[i].get(o).toString());
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sb.append('\'');
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} else
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sb.append(f[i].get(o).toString());
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}
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sb.append(')');
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}
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DriverManager.println("store: "+sb.toString());
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ResultSet rs = conn.ExecSQL(sb.toString());
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if(rs!=null) {
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rs.close();
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}
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// fetch the OID for returning
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int oid=0;
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if(hasOID) {
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// set the oid in the object
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f[oidFIELD].setInt(o,oid);
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}
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return oid;
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} catch(IllegalAccessException iae) {
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throw new SQLException(iae.toString());
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}
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}
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/**
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* This method is not used by the driver, but it creates a table, given
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* a Serializable Java Object. It should be used before serializing any
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* objects.
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* @param c Connection to database
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* @param o Object to base table on
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* @exception SQLException on error
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*/
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public static void create(postgresql.Connection con,Object o) throws SQLException
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{
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create(con,o.getClass());
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}
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/**
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* This method is not used by the driver, but it creates a table, given
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* a Serializable Java Object. It should be used before serializing any
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* objects.
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* @param c Connection to database
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* @param o Class to base table on
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* @exception SQLException on error
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*/
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public static void create(postgresql.Connection con,Class c) throws SQLException
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{
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if(c.isInterface())
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throw new SQLException("Cannot serialize an Interface");
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// See if the table exists
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String tableName = toPostgreSQL(c.getName());
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ResultSet rs = con.ExecSQL("select relname from pg_class where relname = '"+tableName+"'");
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if(!rs.next()) {
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DriverManager.println("found "+rs.getString(1));
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// No entries returned, so the table doesn't exist
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StringBuffer sb = new StringBuffer("create table ");
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sb.append(tableName);
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char sep='(';
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java.lang.reflect.Field[] fields = c.getDeclaredFields();
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for(int i=0;i<fields.length;i++) {
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Class type = fields[i].getType();
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// oid is a special field
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if(!fields[i].getName().equals("oid")) {
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sb.append(sep);
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sb.append(fields[i].getName());
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sb.append(' ');
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sep=',';
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if(type.isArray()) {
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// array handling
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} else {
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// convert the java type to postgresql, recursing if a class
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// is found
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String n = fields[i].getType().getName();
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int j=0;
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for(;j<tp.length && !tp[j][0].equals(n);j++);
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if(j<tp.length)
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sb.append(tp[j][1]);
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else {
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create(con,fields[i].getType());
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sb.append(toPostgreSQL(n));
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}
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}
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}
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}
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sb.append(")");
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// Now create the table
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DriverManager.println("Serialize.create:"+sb);
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con.ExecSQL(sb.toString());
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rs.close();
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} else {
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DriverManager.println("Serialize.create: table "+tableName+" exists, skipping");
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}
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}
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// This is used to translate between Java primitives and PostgreSQL types.
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private static final String tp[][] = {
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{"boolean", "int1"},
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{"double", "float8"},
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{"float", "float4"},
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{"int", "int4"},
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{"long", "int4"},
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{"short", "int2"},
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{"java.lang.String", "text"},
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{"java.lang.Integer", "int4"},
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{"java.lang.Float", "float4"},
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{"java.lang.Double", "float8"},
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{"java.lang.Short", "int2"}
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};
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/**
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* This converts a Java Class name to a postgresql table, by replacing . with
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* _<p>
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*
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* Because of this, a Class name may not have _ in the name.<p>
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* Another limitation, is that the entire class name (including packages)
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* cannot be longer than 32 characters (a limit forced by PostgreSQL).
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*
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* @param name Class name
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* @return PostgreSQL table name
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* @exception SQLException on error
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*/
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public static String toPostgreSQL(String name) throws SQLException
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{
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name = name.toLowerCase();
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if(name.indexOf("_")>-1)
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throw new SQLException("Class names may not have _ in them: "+name);
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if(name.length()>32)
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throw new SQLException("Class & Package name length cannot be longer than 32 characters. "+name+" is "+name.length()+" characters.");
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return name.replace('.','_');
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}
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/**
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* This converts a postgresql table to a Java Class name, by replacing _ with
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* .<p>
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*
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* @param name PostgreSQL table name
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* @return Class name
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* @exception SQLException on error
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*/
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public static String toClassName(String name) throws SQLException
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{
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name = name.toLowerCase();
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return name.replace('_','.');
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}
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}
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@ -9,10 +9,11 @@
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* didn't really belong there.
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-print.c,v 1.3 1998/06/15 19:30:26 momjian Exp $
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* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-print.c,v 1.4 1998/06/16 06:57:27 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <postgres.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <signal.h>
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