PaginationQuery.java

/* ==================================================================   
 * Created [2009-4-27 下午11:32:55] by Jon.King 
 * ==================================================================  
 * TSS 
 * ================================================================== 
 * mailTo:jinpujun@hotmail.com
 * Copyright (c) Jon.King, 2009-2012 
 * ================================================================== 
*/

package com.jinhe.tss.component.support.persistence.pagequery;

import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.persistence.EntityManager;
import javax.persistence.Query;

import org.apache.commons.collections.CollectionUtils;

import com.jinhe.tss.core.exception.BusinessException;
import com.jinhe.tss.core.persistence.QueryCondition;
import com.jinhe.tss.core.util.BeanUtil;
import com.jinhe.tss.core.util.EasyUtils;
import com.jinhe.tss.core.util.MacrocodeCompiler;

/**
 * 分页条件查询基类
 */
public abstract class PaginationQuery {

    static final String[] COMMON_IGNORE_PROPERTIES = new String[] { "page", "conditionMacrocodes", "class", "ignoreProperties", "order" };
	
    protected EntityManager em;
    
    protected String ql;  // SQL 或  HQL 语句，里面带宏，传入时不带order by
    
    protected MacrocodeQueryCondition condition;
 
    public PaginationQuery(EntityManager em, String ql, MacrocodeQueryCondition condition) {
        if ( em == null ) throw new BusinessException("em不能为空");
        if ( condition == null ) throw new BusinessException("分页条件查询对象不能为空");
        if ( EasyUtils.isNullOrEmpty(ql) ) throw new BusinessException("查询语句不能为空");
        
        this.em = em;
        this.ql = ql;
        this.condition = condition;
    }

    /**
     * <p>
     * 执行分页查询，获取分页结果及相关信息
     * </p>
     * @return
     */
    public PageInfo getResultList() {
        Set<String> ignores = condition.getIgnoreProperties();
        CollectionUtils.addAll(ignores, COMMON_IGNORE_PROPERTIES);
        Map<String, Object> properties = BeanUtil.getProperties(condition, ignores);
        
        // 过滤空参数、无效参数对应的宏代码 
        Map<String, Object> macrocodes = condition.getConditionMacrocodes();
        for (  Iterator<String> it = macrocodes.keySet().iterator(); it.hasNext(); ) {
            String key = it.next();
            if (key.startsWith("${") && key.endsWith("}")) {
                String name = key.substring(2, key.length() - 1);
                Object value = properties.get(name);
                if ( QueryCondition.isValueNullOrEmpty(value) ) {
                	it.remove();
                }
            }
        }
        
        // 解析带了宏定义的QL语句
        String queryQl = MacrocodeCompiler.run(ql, macrocodes);
 
        PageInfo page = condition.getPage();
        page.setTotalRows(getTotalRows(queryQl, properties));
        
        // 获取当前页数据记录集
        int firstResult = page.getFirstResult();
        if (firstResult >= 0) {
            // 添加HQL中order by 语句
            appendOrderBy();
            
            Query query = createQuery(queryQl);
            query.setFirstResult(firstResult);
            query.setMaxResults(page.getPageSize());
            
            // 为查询语句设置相应的参数
            setProperties4Query(query, properties);
            
            page.setItems( query.getResultList() );
        }

        return page;
    }
    
    /* 添加HQL中order by 语句 */
    private void appendOrderBy(){
    	if ( condition.getOrderByFields() == null ) return;
    	
    	String orderByFiledContent = "";
        for ( String field : condition.getOrderByFields() ) {
        	if( EasyUtils.isNullOrEmpty(field) ) continue;
        	
        	if ( orderByFiledContent.length() > 0 ) {
                orderByFiledContent += ", ";
            }
            orderByFiledContent += field;
        }
        
        if ( orderByFiledContent.length() > 0 ) {
            ql += " order by " + orderByFiledContent;
    	}
    }
    
    /**
     * <p>
     * 为查询语句设置相应的参数
     * </p>
     * @param query 查询
     * @param properties 参数集
     */
    protected void setProperties4Query(Query query, Map<String, Object> properties) {
        for (Map.Entry<String, Object> entry : properties.entrySet()) {
            Object value = entry.getValue();
            if ( !QueryCondition.isValueNullOrEmpty(value) ) {
            	query.setParameter( entry.getKey(), value );
            }
        }
    }

    /**
     * <p>
     * 获取总记录数
     * </p>
     * @param sumQl 统计QL语句
     * @param properties 参数集
     * @return Integer 总记录数
     */
    protected Integer getTotalRows(String ql, Map<String, Object> properties)  {
    	// 生成对应的总记录数统计QL语句
    	int fromIndex = ql.toLowerCase().indexOf("from ");
    	int toIndex = ql.toLowerCase().indexOf(" order by ");
    	if(toIndex <= 0) {
    	    toIndex = ql.length();
    	}
    	String sumHql = "select count(*) " + ql.substring(fromIndex, toIndex);
    	
        Query query = this.createQuery(sumHql); 
        setProperties4Query(query, properties);
        return EasyUtils.convertObject2Integer(query.getSingleResult());
    }

    /**
     * <p>
     * 通过QL语句创建对应的Query对象
     * </p>
     * @param ql 查询HQL/SQL语句
     * @return Query对象
     */
    protected abstract Query createQuery(String ql);

}