1.//查询整个对象
String hql="from Users";
Query query = session.createQuery(hql);
List
for(Users user: users){
System.out.print(user.getName()+" "+user.getPassword());
}
}
1输出结果为:
2name1 : password1 : 1
3name2 : password2 : 2
4name3 : password3 : 3
2.//查询几个字段String hql="select name , password from Users";
Query query = session.createQuery(hql);
List
//list 存放一个object数组
for(Object[] object: list){
String name =(String)object[0];
String password =(String)object[1];
System.out.print(name+": "+password);
}
5输出结果为:
6name1 : password1
7name2 : password2
8name3 : password3
3.//查询单个字段
String hql="select name from Users";
Query query = session.createQuery(hql);
List
//list 存放一个object数组
for(String object: list){
String name =object;
System.out.print(name);
}
9输出结果为:
10name1
11name2
12name3
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String hql="select new list(name,password)from Users";
Query query = session.createQuery(hql);
List list = query.list();
for(List user:list){
String name = (String)user.get(0);
String password = (String)user.get(1);
}
System.out.println(name+":"+password)//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
//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
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String hql="select new map(name,passwd) from Users";
Query query = session.createQuery(hql);
List
for(Map user: map){
String name = (String)user.get("0");
String password =(String) user.get("1");
System.out.println(name+":"+password)
}
13/**
14输出结果为:
15name1 : password1
16name2 : password2
17name3 : password3
18*/
//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
//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
19//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
20//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
21//get("0");是get(key),注意:0,1,2...是字符串,而不是整形
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[拓展]
自定义类:
22package com.domain;
23public class MyUser {
24private String username;
25private String password;
26//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
27public MyUser(String username,String password){
https://www.sodocs.net/doc/7411486264.html,ername = username;
29this.password = password;
30}
31public String getUsername() {
32return username;
33}
34public void setUsername(String username) {
https://www.sodocs.net/doc/7411486264.html,ername = username;
36}
37public String getPassword() {
38return password;
39}
40public void setPassword(String password) {
41this.password = password;
42}
43}
44//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
45String hql = " select new com.domain.MyUser(name,passwd) from Users";
46Query query = session.createQuery(hql);
47//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
48List
49for(MyUser myUser : myUsers){
50String name = myUser.getUsername();
51String passwd = myUser.getPassword();
52System.out.println(name + " : " + passwd);
53}
54/**
55输出结果为:
56name1 : password1
57name2 : password2
58name3 : password3
59*/
8:条件查询通过setString,setParameter设置参数
60//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
61String hql = "from Users where name=? and passwd=?";
62Query query = session.createQuery(hql);
63//第1种方式
64// query.setString(0, "name1");
65// query.setString(1, "password1");
66//第2种方式
67query.setParameter(0, "name1",Hibernate.STRING);
68query.setParameter(1, "password1",Hibernate.STRING);
69List
70for(Users users : list){
71System.out.println(users.getId());
72}
自定义索引名(参数名)
73//条件查询,自定义索引名(参数名):username,:password.通过
setString,setParameter设置参数
74String hql = "from Users where name=:username and
passwd=:password";
75Query query = session.createQuery(hql);
76//第1种方式
77// query.setString("username", "name1");
78// query.setString("password", "password1");
79//第2种方式,第3个参数确定类型
80query.setParameter("username", "name1",Hibernate.STRING);
81query.setParameter("password", "password1",Hibernate.STRING);
82List
83for(Users users : list){
84System.out.println(users.getId());
85}
通过setProperties设置参数
86//条件查询,通过setProperties设置参数
87String hql = "from Users where name=:username and passwd=:password";
88Query query = session.createQuery(hql);
89//MyUser类的2个属性必须和:username和:password对应90MyUser myUser = new MyUser("name1","password1"); 91query.setProperties(myUser);
92List
93for(Users users : list){
94System.out.println(users.getId());
95}