有這樣一個需求,根據姓名(fullname)、職位(position)、狀態(status)中的一個或者多個條件,查詢新員工信息。這裏的問題在於,用戶在查詢時,可能只輸入了fullname一個條件,這樣我們就不能簡單的將hql語句寫成下面這樣:
String hql = "from StaffVo as s where s.fullname = :fullname and s.position = :position and status = :status";
爲了滿足需求,可以寫成下面這樣,關鍵點在於使用了StringBuffer的append(String str)方法,拼接hql語句:
package com.entry_exit.dao.impl;
import java.util.Iterator;
import java.util.List;
import org.springframework.stereotype.Repository;
import com.entry_exit.dao.StaffDao;
import com.entry_exit.vo.StaffVo;
@Repository
public class StaffDaoImpl extends BasicDaoImpl<StaffVo> implements StaffDao {
@Override
public List<StaffVo> queryWithConditions(String fullname, String position, String status, int page, int rows) {
// TODO Auto-generated method stub
System.out.println("進入dao方法");
//String hql = "from StaffVo as s where s.fullname = :fullname and s.position.id = :position and status = :status";
StringBuffer hql1 = new StringBuffer();
hql1.append("from StaffVo where ");
if(fullname != null && fullname.length() > 0){
hql1.append("fullname like '%");
hql1.append(fullname);
hql1.append("%' and ");
}
if(position != null && position.length() > 0){
hql1.append("position.position = '");
hql1.append(position);
hql1.append("' and ");
}
if(status != null && status.length() > 0){
hql1.append("status = '");
hql1.append(status);
hql1.append("' and ");
}
//去除多出來的“' and ”,並返回字符串
String hql = hql1.substring(0, hql1.length()-5);
//List<StaffVo> staffList = getSession().createQuery(sql).setString("fullname", fullname).setString("status", status).setFirstResult((page-1)*rows).setMaxResults(rows).list();
List<StaffVo> staffList = getSession().createQuery(hql).setFirstResult((page-1)*rows).setMaxResults(rows).list();
if(!staffList.isEmpty()){
Iterator<StaffVo> it = staffList.iterator();
System.out.println("查詢到的結果如下:");
while(it.hasNext()){
System.out.println(it.next().getStaffid());
}
}
return staffList;
}
}