daomethod.java

该源码包括了基于J2EE的数据持久层设计,设计中使用了DAO,Service,等模式,并在Struts下进行了测试．

package org.conference.datapersistence;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class DaoMethod {
	public static String QueryBuilding(HashMap hashtable) {
		StringBuffer QueryString = new StringBuffer();
		int index_string;
		QueryString.append("select distinct * from " + hashtable.get("tablename"));
		hashtable.remove("tablename");
		Iterator iterator = hashtable.entrySet().iterator();
		String linkchar = " where ";
		while (iterator.hasNext()) {
			Map.Entry entry = (Map.Entry) iterator.next();
			String key = (String) entry.getKey();
			// System.out.println("\n key: "+key+"\n");
			Object value = (Object) entry.getValue();
			// System.out.println("\n value: "+value+"\n");
			if (value != null) {
				if (value instanceof String) {
					if (key.endsWith("_$")) {
						index_string = key.indexOf("_$");
						QueryString.append(linkchar).append(
								key.substring(0, index_string)).append(
								" like'%").append(value).append("%' ");
					} else {
						if (key.endsWith("_S")) {
							index_string = key.indexOf("_S");
							QueryString.append(linkchar).append(
									key.substring(0, index_string)).append(
									" <='").append(value).append("' ");
						} else if (key.endsWith("_L")) {
							index_string = key.indexOf("_L");
							QueryString.append(linkchar).append(
									key.substring(0, index_string)).append(
									" >='").append(value).append("'");
						} else {
							QueryString.append(linkchar).append(key).append(
									"='").append(value).append("'");
						}
					}
				} else {
					 if (key.endsWith("_S")) {
						index_string = key.indexOf("_S");
						QueryString.append(linkchar).append(
								key.substring(0, index_string)).append(
								" <=").append(value);
					} else if (key.endsWith("_L")) {
						index_string = key.indexOf("_L");
						QueryString.append(linkchar).append(
								key.substring(0, index_string)).append(
								" >=").append(value);
					}
					else{
					QueryString.append(linkchar).append(key).append("=")
							.append(value);
					}
				}
				linkchar = " and ";
			}
		}
		 System.out.println("\n Query= "+QueryString.toString()+"\n");
		return QueryString.toString();
	}
}