import org.apache.ibatis.jdbc.AbstractSQL;import java.util.List;public class SqlBuilder extends AbstractSQL
    
      {    public SqlBuilder SELECT_AS(String column, String alias) {        return SELECT(column + " AS " + alias);    }    public SqlBuilder SELECT_DISTINCT_AS(String column, String alias) {        return SELECT(String.format("DISTINCT(%s) AS %s", column, alias));    }    public SqlBuilder SELECT_COUNT(String columns) {        return SELECT("COUNT(" + columns + ")");    }    public SqlBuilder SELECT_COUNT() {        return SELECT_COUNT("*");    }    public SqlBuilder FROM_AS(String table, String alias) {        return FROM(table + " AS " + alias);    }    public SqlBuilder WHERE_LIKE(String column, String keyword) {        return WHERE(column + " LIKE " + buildLikeCondition(keyword, true, true));    }    public SqlBuilder WHERE_LIKE_LEFT(String column, String keyword) {        return WHERE(column + " LIKE " + buildLikeCondition(keyword, true, false));    }    public SqlBuilder WHERE_LIKE_RIGHT(String column, String keyword) {        return WHERE(column + " LIKE " + buildLikeCondition(keyword, false, true));    }    public SqlBuilder WHERE_IN(String column, List
      list) {        return WHERE(column + " IN " + buildArrayCondition(list));    }    public SqlBuilder WHERE_NOT_IN(String column, List
      list) {        return WHERE(column + " NOT IN " + buildArrayCondition(list));    }    public SqlBuilder ORDER_BY_ASC(String columns) {        return ORDER_BY(columns + " ASC");    }    public SqlBuilder ORDER_BY_DESC(String columns) {        return ORDER_BY(columns + " DESC");    }    public String buildSql() {        return toString();    }    public String buildSqlAppendLimit(int pageSize, int pageNum) {        int offset = (pageNum - 1) * pageSize;        return toString() + String.format(" LIMIT %d, %d", offset, pageSize) ;    }    @Override    public SqlBuilder getSelf() {        return this;    }    /**     * 构造数组查询条件，用于"IN"或"NOT IN"条件查询     * @param list 参数列表，不能为空，仅支持数字或字符串的条件构造     * @return 构造结果，如(123,456,789)、('aa','bb','cc')     */    public static String buildArrayCondition(List
      list) {        if (list == null || list.isEmpty()) {            throw new IllegalArgumentException("args must not be empty");        }        StringBuilder arrayCondition = new StringBuilder("(");        for (Object arg : list) {            if (arg == null) {                continue;            }            if (arg instanceof Number) {                // 数字                arrayCondition.append(arg);            } else if (arg instanceof String) {                // 字符串                arrayCondition.append("'");                arrayCondition.append(arg);                arrayCondition.append("'");            } else {                // 其他不支持                throw new IllegalArgumentException("unsupported args");            }            arrayCondition.append(',');        }        // 替换最后一个“,”为“)”        arrayCondition.replace(arrayCondition.lastIndexOf(","), arrayCondition.length(), ")");        return arrayCondition.toString();    }    public static String buildLikeCondition(String keyword) {        return buildLikeCondition(keyword, true, true);    }    public static String buildLikeCondition(String keyword, boolean likePre, boolean likePost) {        if (keyword == null) {            throw new IllegalArgumentException("keyword must not be null");        }        if (!likePre && !likePost) {            throw new IllegalArgumentException("either likePre or likePost should be true");        }        StringBuilder sb = new StringBuilder("CONCAT(");        if (likePre) {            sb.append("'%', ");        }        sb.append(keyword);        if (likePost) {            sb.append(", '%'");        }        sb.append(")");        return sb.toString();    }}