Java tutorial
/* * fmgVen - A Convention over Configuration Java ORM Tool * Copyright 2010 Fatih Mehmet Gler * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * under the License. */ package com.fmguler.ven; import com.fmguler.ven.util.Convert; import com.fmguler.ven.util.VenList; import java.beans.PropertyDescriptor; import java.math.BigDecimal; import java.util.Date; import java.util.HashSet; import java.util.Iterator; import java.util.List; import java.util.Set; import org.springframework.beans.BeanWrapper; import org.springframework.beans.BeanWrapperImpl; /** * Generates queries in the form of 'Convention over Configuration' for the specified objects. * @author Fatih Mehmet Gler */ public class QueryGenerator { private Set domainPackages; private Set dbClasses; private boolean debug = false; public QueryGenerator() { domainPackages = new HashSet(); dbClasses = new HashSet(); //the predefined database classes; this.dbClasses.add(Integer.class); this.dbClasses.add(String.class); this.dbClasses.add(Date.class); this.dbClasses.add(Double.class); this.dbClasses.add(Boolean.class); this.dbClasses.add(BigDecimal.class); } /** * Generates select query for the specified object class and specified joins. * @param joins set of joins that the query will contain * @param objectClass the object class to select from * @return the select SQL query */ public String generateSelectQuery(Class objectClass, Set joins) { long t1 = System.currentTimeMillis(); String objectName = Convert.toSimpleName(objectClass.getName()); String tableName = Convert.toDB(objectName); StringBuffer selectClause = new StringBuffer("select "); StringBuffer fromClause = new StringBuffer("from " + tableName); generateRecursively(0, tableName, objectName, objectClass, joins, selectClause, fromClause); selectClause.append(" 1=1"); if (debug) System.out.println("Ven - query generation time = " + (System.currentTimeMillis() - t1)); return selectClause.toString() + " \n" + fromClause.toString(); } public String generateCountQuery() { return null; } /** * Generates insert query for the specified object * @param object the object to generate insert query for * @return the insert SQL query */ public String generateInsertQuery(Object object) { BeanWrapper wr = new BeanWrapperImpl(object); String objectName = Convert.toSimpleName(object.getClass().getName()); String tableName = Convert.toDB(objectName); PropertyDescriptor[] pdArr = wr.getPropertyDescriptors(); //generate insert query StringBuffer query = new StringBuffer("insert into " + tableName + "("); StringBuffer values = new StringBuffer(" values("); for (int i = 0; i < pdArr.length; i++) { Class fieldClass = pdArr[i].getPropertyType(); //field class String columnName = Convert.toDB(pdArr[i].getName()); //column name String fieldName = pdArr[i].getName(); //field name //if (fieldName.equals("id")) continue; //remove if it does not break the sequence if (dbClasses.contains(fieldClass)) { //direct database field (Integer,String,Date, etc) query.append(columnName.equals("order") ? "\"order\"" : columnName); query.append(","); values.append(":").append(fieldName); values.append(","); } if (fieldClass.getPackage() != null && domainPackages.contains(fieldClass.getPackage().getName())) { //object query.append(Convert.toDB(fieldName)).append("_id"); query.append(","); values.append(":").append(fieldName).append(".id"); values.append(","); } } query.deleteCharAt(query.length() - 1); query.append(")"); values.deleteCharAt(values.length() - 1); values.append(");"); query.append(values); return query.toString(); } /** * Generates update query for the specified object * @param object the object to generate update query for * @return the update SQL query */ public String generateUpdateQuery(Object object) throws VenException { BeanWrapper wr = new BeanWrapperImpl(object); String objectName = Convert.toSimpleName(object.getClass().getName()); String tableName = Convert.toDB(objectName); PropertyDescriptor[] pdArr = wr.getPropertyDescriptors(); StringBuffer query = new StringBuffer("update " + tableName + " set "); for (int i = 0; i < pdArr.length; i++) { Class fieldClass = pdArr[i].getPropertyType(); //field class String columnName = Convert.toDB(pdArr[i].getName()); //column name String fieldName = pdArr[i].getName(); //field name if (dbClasses.contains(fieldClass)) { //direct database field (Integer,String,Date, etc) query.append(columnName.equals("order") ? "\"order\"" : columnName).append("=:").append(fieldName); query.append(","); } if (fieldClass.getPackage() != null && domainPackages.contains(fieldClass.getPackage().getName())) { //object query.append(columnName).append("_id=:").append(fieldName).append(".id"); query.append(","); } } query.deleteCharAt(query.length() - 1); query.append(" where id = :id ;"); return query.toString(); } /** * Generates delete query for the specified object class * @param objectClass the object class to generate query for * @return the delete SQL query */ public String generateDeleteQuery(Class objectClass) { StringBuffer query = new StringBuffer(); query.append("delete from ").append(Convert.toDB(Convert.toSimpleName(objectClass.getName()))) .append(" where id = :id;"); return query.toString(); } /** * Generates sequence query for the specified object * @param object the objectc to generate sequence query for * @return the SQL query to select next id */ public String generateSequenceQuery(Object object) throws VenException { String objectName = Convert.toSimpleName(object.getClass().getName()); String tableName = Convert.toDB(objectName); return "select nextval('" + tableName + "_id_seq');"; } //-------------------------------------------------------------------------- //PRIVATE METHODS //recursively generate select query private void generateRecursively(int level, String tableName, String objectPath, Class objectClass, Set joins, StringBuffer selectClause, StringBuffer fromClause) { BeanWrapper wr = new BeanWrapperImpl(objectClass); PropertyDescriptor[] pdArr = wr.getPropertyDescriptors(); for (int i = 0; i < pdArr.length; i++) { Class fieldClass = pdArr[i].getPropertyType(); //field class String fieldName = pdArr[i].getName(); //field name Object fieldValue = wr.getPropertyValue(fieldName); String columnName = Convert.toDB(pdArr[i].getName()); //column name //direct database class (Integer, String, Date, etc) if (dbClasses.contains(fieldClass)) { selectClause.append(tableName).append(".").append(columnName).append(" as ").append(tableName) .append("_").append(columnName); //column selectClause.append(", "); } //many to one association (object property) if (fieldClass.getPackage() != null && domainPackages.contains(fieldClass.getPackage().getName()) && joinsContain(joins, objectPath + "." + fieldName)) { String joinTableAlias = tableName + "_" + columnName; //alias for table to join since there can be multiple joins to the same table String joinTable = Convert.toDB(Convert.toSimpleName(fieldClass.getName())); //table to join fromClause.append(" left join ").append(joinTable).append(" ").append(joinTableAlias); fromClause.append(" on ").append(joinTableAlias).append(".id = ").append(tableName).append(".") .append(columnName).append("_id"); generateRecursively(++level, joinTableAlias, objectPath + "." + fieldName, fieldClass, joins, selectClause, fromClause); } //one to many association (list property) if (fieldValue instanceof List && joinsContain(joins, objectPath + "." + fieldName)) { Class elementClass = VenList.findElementClass((List) fieldValue); String joinTableAlias = tableName + "_" + columnName; //alias for table to join since there can be multiple joins to the same table String joinTable = Convert.toDB(Convert.toSimpleName(elementClass.getName())); //table to join String joinField = Convert.toDB(findJoinField((List) fieldValue)); //field to join fromClause.append(" left join ").append(joinTable).append(" ").append(joinTableAlias); fromClause.append(" on ").append(joinTableAlias).append(".").append(joinField).append("_id = ") .append(tableName).append(".id"); generateRecursively(++level, joinTableAlias, objectPath + "." + fieldName, elementClass, joins, selectClause, fromClause); } } } //check if the joins contain the specified join private boolean joinsContain(Set joins, String join) { Iterator it = joins.iterator(); while (it.hasNext()) { String str = (String) it.next(); if (str.startsWith(join)) { if (str.length() == join.length()) return true; else if (str.charAt(join.length()) == '.') return true; } } return false; } //return the join field of the elements in the list private String findJoinField(List list) { if (list instanceof VenList) { return ((VenList) list).getJoinField(); } else { //find according to 1.5 generic or some convention (e.g. parent_obj_id) return null; } } //-------------------------------------------------------------------------- //SETTERS /** * Add the domain packages that will be considered persistent * @param domainPackage the domain package */ public void addDomainPackage(String domainPackage) { domainPackages.add(domainPackage); } /** * Set debug mode, true will log all debug messages to System.out * <p> * Note: Use debug mode to detect problems only. It is not a general purpose logging mode. * @param debug set true to enable debug mode */ public void setDebug(boolean debug) { this.debug = debug; } }