Hibernate的使用技巧②

Criteria?c?=?session.createCriteria(User.class.getName());??

?? ?

c.setProjection(Projections.rowCount());??

?? ?

CheckRowNumResponseBean?result?=?new?CheckRowNumResponseBean();??

result.setRowNum(Integer.parseInt(c.uniqueResult().toString()));??

setResult(result);?

package com.ntej.exam.model.vo;

?

/**

* 考试信息展示，显示在我的考试界面 和我的成绩界面

*

*/

public class ExamInfoVO {

?

????private String E_ID;

????private String E_Name;

????private Integer E_Score;

????private String MajorType;

????private String MajorName;

????private String ExamTitle;

????private Integer QuestionNumber;

????private Integer TotalTime;

????private String ExamBeginDateTime;

????private String ExamEndDateTime;

????private Integer ExamCode;

?

????public String getE_ID() {

????????return E_ID;

????}

?

????public void setE_ID(String e_ID) {

????????E_ID = e_ID;

????}

?

????public String getE_Name() {

????????return E_Name;

????}

?

????public void setE_Name(String e_Name) {

????????E_Name = e_Name;

????}

?

????public Integer getE_Score() {

????????return E_Score;

????}

?

????public void setE_Score(Integer e_Score) {

????????E_Score = e_Score;

????}

?

????public String getMajorType() {

????????return MajorType;

????}

?

????public void setMajorType(String majorType) {

????????MajorType = majorType;

????}

?

????public String getMajorName() {

????????return MajorName;

????}

?

????public void setMajorName(String majorName) {

????????MajorName = majorName;

????}

?

????public String getExamTitle() {

????????return ExamTitle;

????}

?

????public void setExamTitle(String examTitle) {

????????ExamTitle = examTitle;

????}

?

????public Integer getQuestionNumber() {

????????return QuestionNumber;

????}

?

????public void setQuestionNumber(Integer questionNumber) {

????????QuestionNumber = questionNumber;

????}

?

????public Integer getTotalTime() {

????????return TotalTime;

????}

?

????public void setTotalTime(Integer totalTime) {

????????TotalTime = totalTime;

????}

?

????public String getExamBeginDateTime() {

????????return ExamBeginDateTime;

????}

?

????public void setExamBeginDateTime(String examBeginDateTime) {

????????ExamBeginDateTime = examBeginDateTime;

????}

?

????public String getExamEndDateTime() {

????????return ExamEndDateTime;

????}

?

????public void setExamEndDateTime(String examEndDateTime) {

????????ExamEndDateTime = examEndDateTime;

????}

?

????public Integer getExamCode() {

????????return ExamCode;

????}

?

????public void setExamCode(Integer examCode) {

????????ExamCode = examCode;

????}

?

????@Override

????public String toString() {

????????return "ExamInfoVO [E_ID=" + E_ID + ", E_Name=" + E_Name + ", E_Score="

????????????????+ E_Score + ", MajorType=" + MajorType + ", MajorName="

????????????????+ MajorName + ", ExamTitle=" + ExamTitle + ", QuestionNumber="

????????????????+ QuestionNumber + ", TotalTime=" + TotalTime

????????????????+ ", ExamBeginDateTime=" + ExamBeginDateTime

????????????????+ ", ExamEndDateTime=" + ExamEndDateTime + ", ExamCode="

????????????????+ ExamCode + "]";

????}

?

}

public List<ExamInfoVO> getExamInfoVosByemp(Emp emp){

????????try {

???????????? String queryString = "???? SELECT e.E_ID,e.E_Name,s.E_Score,m.MajorType,m.MajorName,ei.ExamTitle,ei.QuestionNumber,ei.TotalTime,DATE_FORMAT(ei.ExamBeginDateTime,‘%Y-%m-%d %H:%i:%s‘) as ExamBeginDateTime,DATE_FORMAT(ei.ExamEndDateTime,‘%Y-%m-%d %H:%i:%s‘) as ExamEndDateTime, ei.ExamCode"

???????????? ????????+ " FROM emp e,score s,major m,examinfo ei WHERE????e.E_ID=s.E_ID AND e.D_No=ei.D_No AND s.MajorID=m.MajorID AND s.ExamCode=ei.ExamCode AND e.E_ID=‘"+emp.getEId()+"‘;";

???? Query query= getSession().createSQLQuery(queryString);

???? List<ExamInfoVO> list = query.setResultTransformer(Transformers.aliasToBean(ExamInfoVO.class)).list();

???? return list;

????????} catch (RuntimeException re) {

????????????throw re;

????????}

????}

Hibernate中共提供了三种检索方式：HQL(Hibernate Query Language)、QBC(Query By Criteria)、QBE(Query By Example)。而今天的这个查询方法属于QBC，

?
List list=getHibernateSession().createCriteria(MeterUser.class).add(Restrictions.eq("name", "11")).addOrder(Order.desc("userid")).list();

? ?

Restrictions的用法：

QBC常用限定方法

Restrictions.eq --> equal,等于.

Restrictions.allEq --> 参数为Map对象,使用key/value进行多个等于的比对,相当于多个Restrictions.eq的效果

Restrictions.gt --> great-than > 大于

Restrictions.ge --> great-equal >= 大于等于

Restrictions.lt --> less-than, < 小于

Restrictions.le --> less-equal <= 小于等于

Restrictions.between --> 对应SQL的between子句

Restrictions.like --> 对应SQL的LIKE子句

Restrictions.in --> 对应SQL的in子句

Restrictions.and --> and 关系

Restrictions.or --> or 关系

Restrictions.isNull --> 判断属性是否为空,为空则返回true

Restrictions.isNotNull --> 与isNull相反

Restrictions.sqlRestriction --> SQL限定的查询

Order.asc --> 根据传入的字段进行升序排序

Order.desc --> 根据传入的字段进行降序排序

MatchMode.EXACT --> 字符串精确匹配.相当于"like ‘value‘"

MatchMode.ANYWHERE --> 字符串在中间匹配.相当于"like ‘%value%‘"

MatchMode.START --> 字符串在最前面的位置.相当于"like ‘value%‘"

MatchMode.END --> 字符串在最后面的位置.相当于"like ‘%value‘"

例子
查询年龄在20-30岁之间的所有学生对象
List list = session.createCriteria(Student.class)
????? .add(Restrictions.between("age",new Integer(20),new Integer(30)).list();
查询学生姓名在AAA,BBB,CCC之间的学生对象
String[] names = {"AAA","BBB","CCC"};
List list = session.createCriteria(Student.class)
????? .add(Restrictions.in("name",names)).list();
查询年龄为空的学生对象
List list = session.createCriteria(Student.class)
????? .add(Restrictions.isNull("age")).list();
查询年龄等于20或者年龄为空的学生对象
List list = session.createCriteria(Student.class)
????? .add(Restrictions.or(Restrictions.eq("age",new Integer(20)),
???????????????? Restrictions.isNull("age")).list();

--------------------------------------------------------------------
使用QBC实现动态查询
public List findStudents(String name,int age){

Criteria criteria = session.createCriteria(Student.class);
if(name != null){
? criteria.add(Restrictions.like("name",name,MatchMode.ANYWHERE));
}
if(age != 0){
? criteria.add(Restrictions.eq("age",new Integer(age)));
}
criteria.addOrder(Order.asc("name"));//根据名字升序排列
return criteria.list();
}

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今天用了写hibernate高级查询时用了Restrictions(当然Expression也是可以以的)这个类.感觉不错.
下面的代码写的不易读.其实核心就是一句
Restrictions.or(Restrictions.like(),Restrictions.or(Restrictions.like,........))
里面的or可以无限加的.还是比较好用

Session session = getHibernateTemplate().getSessionFactory()
??????????????? .openSession();
??????? Criteria criteria = session.createCriteria(Film.class);
??????? List<Film> list = criteria.add(
??????????? Restrictions.or(Restrictions.like("description", key,MatchMode.ANYWHERE),
??????????? Restrictions.or(Restrictions.like("name", key,MatchMode.ANYWHERE),
??????????????? Restrictions.or(??? Restrictions.like("direct", key,MatchMode.ANYWHERE),
??????????????? Restrictions.or(Restrictions.like("mainplay",key,MatchMode.ANYWHERE),
??????????????????????? Restrictions.like("filearea", key,MatchMode.ANYWHERE)))))).list();

??????? session.close();
??????? return list;

窗体底端

public List<Question> getQuestions(int majorid,int num){

????????String majorType=new MajorDAO().getMajorType(majorid);

????????System.out.println("getQuestions==="+majorType);

????????try {

????????????if ("安全".equals(majorType)) {

????????????????log.debug("安全题库查找。。");

????????????????String hql="from Question q where q.majorId= 13 or q.majorId= "+majorid+"and q.isPass=‘是‘ order by rand()";

????????????????Query query = getSession().createQuery(hql);

????????????????query.setMaxResults(num);

????????????????List<Question>list=query.list();

????????????????return list;

????????????}else {

????????????????log.debug("质量题库查找。。");

????????????????String hql="from Question q where q.majorId= "+majorid+" and q.isPass=‘是‘ order by rand() ";

????????????????Query query = getSession().createQuery(hql);

????????????????query.setMaxResults(num);

????????????????List<Question>list=query.list();

????????????????return list;

????????????}

????????} catch (RuntimeException re) {

????????????log.error("查找失败", re);

????????????throw re;

????????}

????}