oqlparser.java

一个Java持久层类库

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package ActiveObject.core;

import java.util.Map;

/**
 *
 * @author tanjiazhang
 */
public class OQLParser {

    static final String alias = "abcdefghijklmnopqrstuvwxyz";

    public static final String MatchSymbol = "%";
    public static final String LikeKeyword = "like";
    public static final String PlaceSymbol = "?";
    
    /**
     * 将条件语句中的like语法转换为SQL支持的like语法
     * @param sql
     * @param args
     * @return
     */
    public static String parseLikeSyntax(StringBuffer sql, Object[] args)
    {
        return parseLikeSyntax(sql.toString(), args);
    }
    /**
     * 将条件语句中的like语法转换为SQL支持的like语法
     * @param sql
     * @param args
     * @return
     */
    public static String parseLikeSyntax(String sql, Object[] args)
    {//System.err.println(sql);
        int index = sql.indexOf(OQLParser.LikeKeyword);
        for(int i=0; index>0 && index<sql.length() ;)
        {
            int questIndex = sql.indexOf(OQLParser.PlaceSymbol, index+4);
            int nextIndex = sql.indexOf(OQLParser.LikeKeyword, index+4);
            if(nextIndex < 0)
                nextIndex = sql.length();//System.err.println((index+4)+" "+ questIndex +" "+nextIndex);
            if(questIndex < 0 || questIndex > nextIndex)
            {
                index = nextIndex;
                continue;
            }
            
            boolean preLike = false;
            boolean tailLike = false;
            if(sql.substring(index+4, questIndex).contains(OQLParser.MatchSymbol))
                preLike = true;
            if(sql.substring(questIndex, nextIndex).contains(OQLParser.MatchSymbol))
                tailLike = true;
            if(preLike)
                args[i] = "%"+args[i];
            if(tailLike)
                args[i] = args[i]+"%";
            
            index = nextIndex;
            i++;
        }
        sql = OQLParser.replaceLikeKeyword(sql);
        return sql.replaceAll(OQLParser.MatchSymbol, "");
    }
    
    /**
     * 将&符号转换为SQL支持的and关键字
     * @param sql
     * @return
     */
    private static final String replaceLikeKeyword(String sql)
    {
        return sql.replace("&", " and ");
    }

    public static String replaceWithAlias(String condition, Map<String, String> aliasMap)
    {
        for(String className : aliasMap.keySet())
        {
            condition = condition.replaceAll(className, aliasMap.get(className));
        }
        return condition;
    }
    
    public static final boolean isContentEmpty(String condition)
    {
        if(condition == null)
            return false;
        for(int i=0;i<condition.length();i++)
        {
            if(condition.charAt(i) != ' ')
                return false;
        }
        return true;
    }

    /**
     * 获取sql语句中参数占位符的个数
     * @param sql
     * @return
     */
    public static final int getPlaceSymbolCount(String sql)
    {
        if(sql == null)
            return 0;
        int count = 0;
        int index = sql.indexOf(OQLParser.PlaceSymbol);
        while(index > -1)
        {
            count++;
            index = sql.indexOf(OQLParser.PlaceSymbol, index+1);
        }
        return count;
    }

    public static void main(String... args)
    {
        System.out.println(getPlaceSymbolCount("a???"));
    }
}