用于辅助拼接HQL语句_工具

水深无声 2022-06-14 09:10 228阅读 0赞

package cn.itcast.oa.util;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import cn.itcast.oa.base.DaoSupport;
    import cn.itcast.oa.domain.PageBean;
    
    import com.opensymphony.xwork2.ActionContext;
    
    /**
     * 用于辅助拼接HQL语句_工具
     * 
     * @author 
     * @version V1.0
     */
    @SuppressWarnings({ "rawtypes" })
    public class QueryHelper {
    	private String fromClause;// From子句
    	private String whereClause = "";// Where子句
    	private String orderByClause = "";// OrderBy子句
    
    	private List<Object> parameters = new ArrayList<Object>();// 参数列表
    
    	/**
    	 * 生成From子句
    	 * 
    	 * @param clazz
    	 * @param alias
    	 *            别名
    	 */
    	public QueryHelper(Class clazz, String alias) {
    		fromClause = " from " + clazz.getSimpleName() + " " + alias;// from User u
    	}
    
    	/**
    	 * 拼接Where子句
    	 * 
    	 * @param condition
    	 * @param params
    	 */
    	public QueryHelper addCondition(String condition, Object... params) {
    		// 拼接
    		if (whereClause.length() == 0) {
    			whereClause = " where " + condition;// from User u where ?
    		} else {
    			whereClause += " and " + condition;// from User u where ?,and ?
    		}
    
    		// 参数
    		if (params != null) {
    			for (Object obj : params) {
    				parameters.add(obj);
    			}
    		}
    		return this;
    	}
    
    	/**
    	 * 如果第一个参数为true,则拼接Where子句
    	 * 
    	 * @param append
    	 * @param condition
    	 * @param params
    	 */
    	public QueryHelper addCondition(boolean append, String condition, Object... params) {
    		if (append) {
    			addCondition(condition, params);
    		}
    		return this;
    	}
    
    	/**
    	 * 拼接OrderBy子句
    	 * 
    	 * @param propertyName
    	 *            参于排序的属性名
    	 * @param asc
    	 *            true表示升序(1,2,3),false表示降序(3,2,1)
    	 */
    	public QueryHelper addOrderProperty(String propertyName, boolean asc) {
    		if (orderByClause.length() == 0) {
    			orderByClause = " Order by " + propertyName + (asc ? " asc " : " desc ");// from User u where ? order by ? asc/desc
    		} else {
    			orderByClause += " , " + propertyName + (asc ? " asc " : " desc ");// from User u where ? order by ? asc/desc,? asc/desc
    		}
    		return this;
    	}
    
    	/**
    	 * 如果第一个参数为true,则拼接OrderBy子句
    	 * 
    	 * @param append
    	 * @param propertyName
    	 * @param asc
    	 */
    	public QueryHelper addOrderProperty(boolean append, String propertyName, boolean asc) {
    		if (append) {
    			addOrderProperty(propertyName, asc);
    		}
    		return this;
    	}
    
    	/**
    	 * 获取生成用于查询数据列表的HQL语句
    	 * 
    	 * @return
    	 */
    	public String getListQueryHql() {
    		return fromClause + whereClause + orderByClause;
    	}
    
    	/**
    	 * 获取生成用于查询总记录数的HQL语句
    	 * 
    	 * @return
    	 */
    	public String getCountQueryHql() {
    		return " select count(*) " + fromClause + whereClause;
    	}
    
    	/**
    	 * 获取HQL中的参数值列表
    	 * 
    	 * @return
    	 */
    	public List<Object> getParameters() {
    		return parameters;
    	}
    
    	/**
    	 * 查询分页信息,并放到值栈栈顶
    	 * @param service
    	 * @param pageNum
    	 * @param pageSize
    	 */
    	public void preparePageBean(DaoSupport<?> service,int pageNum, int pageSize) {
    		PageBean pageBean = service.getPageBean(pageNum, pageSize, this);
    		ActionContext.getContext().getValueStack().push(pageBean);
    	}
    
    }