1. 查询整个映射对象所有字段
1. //直接from查询出来的是一个映射对象,即:查询整个映射对象所有字段
2. String hql = "from Users";
3. Query query = session.createQuery(hql);
4.
5. List<Users> users = query.list();
6. for(Users user : users){
7. System.out.println(user.getName() + " : " + user.getPasswd() + " : " + user.getId());
8. }
9.
10. 输出结果为:
11. name1 : password1 : 1
12. name2 : password2 : 2
13. name3 : password3 : 3
2.查询单个字段
1. //查询单个字段
2. String hql = " select name from Users";
3. Query query = session.createQuery(hql);
4.
5. List<String> list = query.list();
6. for(String str : list){
7. System.out.println(str);
8. }
9. 输出结果为:
10. name1
11. name2
12. name3
3.查询其中几个字段
1. //查询其中几个字段
2. String hql = " select name,passwd from Users";
3. Query query = session.createQuery(hql);
4. //默认查询出来的list里存放的是一个Object数组
5. List<Object[]> list = query.list();
6. for(Object[] object : list){
7. String name = (String)object[0];
8. String passwd = (String)object[1];
9.
10. System.out.println(name + " : " + passwd);
11. }
12. 输出结果为:
13. name1 : password1
14. name2 : password2
15. name3 : password3
4.修改默认查询结果(query.list())不以Object[]数组形式返回,以List形式返回
//查询其中几个字段,添加new list(),注意list里的l是小写的。也不需要导入包,这样通过query.list()出来的list里存放的不再是默认的Object数组了,而是List集合了
String hql = " select new list(name,passwd) from Users";
Query query = session.createQuery(hql);
//默认查询出来的list里存放的是一个Object数组,但是在这里list里存放的不再是默认的Object数组了,而是List集合了
List<List> list = query.list();
for(List user : list){
String name = (String)user.get(0);
String passwd = (String)user.get(1);
System.out.println(name + " : " + passwd);
}
/**
输出结果为:
name1 : password1
name2 : password2
name3 : password3
*/
5.修改默认查询结果(query.list())不以Object[]数组形式返回,以Map形式返回
1. //查询其中几个字段,添加new map(),注意map里的m是小写的。也不需要导入包,这样通过query.list()出来的list里存放的不再是默认的Object数组了,而是map集合了
2. String hql = " select new map(name,passwd) from Users";
3. Query query = session.createQuery(hql);
4. //默认查询出来的list里存放的是一个Object数组,但是在这里list里存放的不再是默认的Object数组了,而是Map集合了
5. List<Map> list = query.list();
6. for(Map user : list){
7. //一条记录里所有的字段值都是map里的一个元素,key是字符串0,1,2,3....,value是字段值
8. //如果将hql改为:String hql = " select new map(name as username,passwd as password) from Users";,那么key将不是字符串0,1,2...了,而是"username","password"了
9. String name = (String)user.get("0");//get("0");是get(key),注意:0,1,2...是字符串,而不是整形
10. String passwd = (String)user.get("1");
11.
12. System.out.println(name + " : " + passwd);
13. }
14. /**
15. 输出结果为:
16. name1 : password1
17. name2 : password2
18. name3 : password3
19. */
6.修改默认查询结果(query.list())不以Object[]数组形式返回,以Set形式返回,但是因为Set里是不允许有重复的元素,所以:username和password的值不能相同。只需将hql改为:String hql = " select new set(name,passwd) from Users";
7.修改默认查询结果(query.list())不以Object[]数组形式返回,以自定义类型返回
自定义类:
1. package com.domain;
2.
3. public class MyUser {
4.
5. private String username;
6. private String password;
7. //因为:String hql = " select new com.domain.MyUser(name,passwd) from Users";所以必须要有接受2个参数的构造函数
8. public MyUser(String username,String password){
9. this.username = username;
10. this.password = password;
11. }
12.
13. public String getUsername() {
14. return username;
15. }
16. public void setUsername(String username) {
17. this.username = username;
18. }
19. public String getPassword() {
20. return password;
21. }
22. public void setPassword(String password) {
23. this.password = password;
24. }
25. }
1. //通过query.list()出来的list里存放的不再是默认的Object数组了,而是自定义的类MyUser,必须加包名,String hql = "from Users";中的Users类也是必须加包名的,但是因为再Users.hbm.xml里<hibernate-mapping auto-import="true"> auto-import默认值为true(所以auto-import属性也可以不写),自动导入了
2. String hql = " select new com.domain.MyUser(name,passwd) from Users";
3. Query query = session.createQuery(hql);
4. //默认查询出来的list里存放的是一个Object数组,但是在这里list里存放的不再是默认的Object数组了,而是MyUser对象了
5. List<MyUser> myUsers = query.list();
6. for(MyUser myUser : myUsers){
7. String name = myUser.getUsername();
8. String passwd = myUser.getPassword();
9. System.out.println(name + " : " + passwd);
10. }
11. /**
12. 输出结果为:
13. name1 : password1
14. name2 : password2
15. name3 : password3
16. */
8:条件查询
1. //条件查询,参数索引值从0开始,索引位置。通过setString,setParameter设置参数
2. String hql = "from Users where name=? and passwd=?";
3. Query query = session.createQuery(hql);
4. //第1种方式
5. // query.setString(0, "name1");
6. // query.setString(1, "password1");
7. //第2种方式
8. query.setParameter(0, "name1",Hibernate.STRING);
9. query.setParameter(1, "password1",Hibernate.STRING);
10. List<Users> list = query.list();
11. for(Users users : list){
12. System.out.println(users.getId());
13. }
1. //条件查询,自定义索引名(参数名):username,:password.通过setString,setParameter设置参数
2. String hql = "from Users where name=:username and passwd=:password";
3. Query query = session.createQuery(hql);
4. //第1种方式
5. // query.setString("username", "name1");
6. // query.setString("password", "password1");
7. //第2种方式,第3个参数确定类型
8. query.setParameter("username", "name1",Hibernate.STRING);
9. query.setParameter("password", "password1",Hibernate.STRING);
10. List<Users> list = query.list();
11. for(Users users : list){
12. System.out.println(users.getId());
13. }
1. //条件查询,通过setProperties设置参数
2. String hql = "from Users where name=:username and passwd=:password";
3. Query query = session.createQuery(hql);
4. //MyUser类的2个属性必须和:username和:password对应
5. MyUser myUser = new MyUser("name1","password1");
6. query.setProperties(myUser);
7. List<Users> list = query.list();
8. for(Users users : list){
9. System.out.println(users.getId());
10. }