statementparser.java

使用jsp开发的一个基于HSQLDB的快餐订购管理系统

package com.uiwz.db;

public class StatementParser
{
	public static int STR = 1;
	public static int NUM = 2;
	public static int DAT = 3;
	
	public static int SML = 1;
	public static int BIG = 2;
	public static int SML_EQL = 3;
	public static int BIG_EQL = 4;
	public static int LEFT_LK = 5;
	public static int RIGHT_LK = 6;
	public static int ALL_LK = 7;
	public static int EQL = 8;
	
	public static int DEFAULT_LEN = 100;
	private String[] cond = new String[DEFAULT_LEN];
	private int index = 0;
	private boolean flag = true;		//生成的条件语句前面是否要加上"and"
	
	public StatementParser(boolean flag)
	{
		this.flag = flag;
	}
	
	public void addField(String fieldName, String value, int dataType, int eqlType)
	{
		if(fieldName == null || fieldName.equals(""))
			return;
		if(value == null || value.equals("") || value.equals("null"))
			return;
		
		String s = null;
		
		if(dataType == STR)
		{
			if(eqlType == LEFT_LK)
				s = fieldName + " LIKE '%" + value + "'";
			else if(eqlType == RIGHT_LK)
				s = fieldName + " LIKE '" + value + "%'";
			else if(eqlType == ALL_LK)
				s = fieldName + " LIKE '%" + value + "%'";
			else
				s = fieldName + "='" + value + "'";
		}
		else if(dataType == NUM)
		{
			if(eqlType == BIG)
				s = fieldName + ">" + value;
			else if(eqlType == SML)
				s = fieldName + "<" + value;
			else
				s = fieldName + "=" + value;
		}
		else if(dataType == DAT)
		{
			if(eqlType == BIG)
				s = fieldName + "='" + value + "'";
			else if(eqlType == SML)
				s = fieldName + "<'" + value + "'";
			else if(eqlType == BIG_EQL)
				s = fieldName + ">='" + value + "'";
			else if(eqlType == SML_EQL)
				s = fieldName + "<='" + value + "'";
		}
		
		if(s == null || s.equals(""))
			return;
		
		if(index > DEFAULT_LEN - 1)
			return;
		
		cond[index] = s;
		index++;
	}
	
	public String parse()
	{
		String conditions = "";
		if(index < 1)
			return conditions;
		
		int len = index;
		
		for(int i=0; i<len; i++)
		{
			if(i == 0 && !flag)
				conditions = conditions + cond[i];
			else
				conditions = conditions  + " and " + cond[i];
		}
		
		return conditions;
	}
}