标签：分享 date ash log oct 索引 value onclick mpi
需求： 部门与员工
一个部门有多个员工; 【一对多】
多个员工，属于一个部门 【多对一】
1、javaBean
——Dept.java
package com.gqx.onetomany;
import java.util.HashSet;
import java.util.Set;
public class Dept {
private int deptId;
private String deptName;
//部门对应的多个员工 (一对多)
private Set<Employee> emps=new HashSet<Employee>();
public int getDeptId() {
return deptId;
}
public void setDeptId(int deptId) {
this.deptId = deptId;
}
public String getDeptName() {
return deptName;
}
public void setDeptName(String deptName) {
this.deptName = deptName;
}
public Set<Employee> getEmps() {
return emps;
}
public void setEmps(Set<Employee> emps) {
this.emps = emps;
}
}
——Employee.java
package com.gqx.onetomany;
public class Employee {
private int empId;
private String empName;
private double salary;
//员工与部门 （多对一）
private Dept dept;
public int getEmpId() {
return empId;
}
public void setEmpId(int empId) {
this.empId = empId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
public Dept getDept() {
return dept;
}
public void setDept(Dept dept) {
this.dept = dept;
}
}
2、一对多与多对一在映射文件中的表现
多个员工对应一个部门（Employee.hbm.xml）
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.gqx.onetomany"> <class name="Employee" table="t_Employee"> <id name="empId" > <generator class="native"></generator> </id> <property name="empName" length="20"></property> <property name="salary" type="double"></property> <!-- 多对一映射配置 Employee映射关键点 1、映射的部门属性 dept 2、映射的部门对象,对应的字段 dept_id 3、部门的类型 --> <many-to-one name="dept" column="dept_id" class="Dept"></many-to-one> </class> </hibernate-mapping>
一个部门对应多个员工（Dept.hbm.xml）
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.gqx.onetomany"> <class name="Dept" table="t_Dept" > <id name="deptId"> <generator class="native"></generator> </id> <property name="deptName" length="20"></property> <!-- 一对多关联映射配置（通过部门管理到员工） Dept 映射关键点 1、指定映射的集合属性： "emps" 2、集合属性对应的集和表 "t_employee" 3、集合表的外键字段 "t_employee中的dept_id 4、集合元素的类型 --> <set name="emps" table="t_Employee"> <key column="dept_id"></key> <one-to-many class="Employee"/> </set> </class> </hibernate-mapping>
3、写测试类进存储
package com.gqx.onetomany;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.Test;
public class Demo {
private static SessionFactory sf;
static{
sf=new Configuration().
configure().
addClass(Dept.class).addClass(Employee.class)
.buildSessionFactory();
}
/**
* 保存：部门方【一的一方】
*/
@Test
public void test() {
Session session=sf.openSession();
session.beginTransaction();
//部门对象
Dept dept=new Dept();
dept.setDeptName("前端组");
//员工对象
Employee emp1=new Employee();
emp1.setEmpName("张三");
Employee emp2=new Employee();
emp2.setEmpName("李四");
//关系
dept.getEmps().add(emp1);
dept.getEmps().add(emp2);
//保存
session.save(dept);
session.save(emp1);
session.save(emp2);
session.getTransaction().commit();
session.close();
/* 结果
*Hibernate: insert into t_Employee (empName, salary, dept_id) values (?, ?, ?)
*Hibernate: insert into t_Employee (empName, salary, dept_id) values (?, ?, ?)
*Hibernate: insert into t_Dept (deptName) values (?)
*Hibernate: update t_Employee set deptId=? where empId=?
*Hibernate: update t_Employee set deptId=? where empId=?
*
*为什么会有五条sql语句？
*开始的时候先插入员工，并没有部门，一旦部门加入后，通过update的语句维护两者的关系
*/
}
/**
* 保存：员工方【多的一方】
*/
@Test
public void test2() {
Session session=sf.openSession();
session.beginTransaction();
//部门对象
Dept dept=new Dept();
dept.setDeptName("运维组");
//员工对象
Employee emp1=new Employee();
emp1.setEmpName("王五");
Employee emp2=new Employee();
emp2.setEmpName("老刘");
//关系
emp1.setDept(dept);
emp2.setDept(dept);
//保存
session.save(emp1);
session.save(emp2);
session.save(dept);
session.getTransaction().commit();
session.close();
/* 结果
*Hibernate: insert into t_Dept (deptName) values (?)
*Hibernate: insert into t_Employee (empName, salary, dept_id) values (?, ?, ?)
*Hibernate: insert into t_Employee (empName, salary, dept_id) values (?, ?, ?)
*
*如果将session.save(dept)放到两个员工的下方 结果为：
* Hibernate: insert into t_Employee (empName, salary, dept_id) values (?, ?, ?)
Hibernate: insert into t_Employee (empName, salary, dept_id) values (?, ?, ?)
Hibernate: insert into t_Dept (deptName) values (?)
Hibernate: update t_Employee set empName=?, salary=?, dept_id=? where empId=?
Hibernate: update t_Employee set empName=?, salary=?, dept_id=? where empId=?
*/
}
}
存储之后，如果要获取数据，则、
package com.gqx.onetomany;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.Test;
public class DemoGet {
private static SessionFactory sf;
static{
sf=new Configuration().
configure().
addClass(Dept.class).addClass(Employee.class)
.buildSessionFactory();
}
@Test
public void test() {
Session session=sf.openSession();
session.beginTransaction();
//通过部门方获取另外一方
Dept dept=(Dept)session.get(Dept.class, 1);
System.out.println(dept.getDeptName());
Set<Employee> set=dept.getEmps();
Iterator<Employee> iterators=set.iterator();
for (Iterator iterator = set.iterator(); iterator.hasNext();) {
Employee employee = (Employee) iterator.next();
System.out.println(employee.getEmpName());
}
session.getTransaction().commit();
session.close();
}
@Test
public void test2() {
Session session=sf.openSession();
session.beginTransaction();
//通过员工方获取另外一方
Employee employee=(Employee)session.get(Employee.class, 1);
System.out.println(employee.getEmpName());
System.out.println(employee.getDept().getDeptName());
session.getTransaction().commit();
session.close();
}
}
在一对多与多对一的关联关系中，保存数据最好的通过多的一方来维护关系，这样可以减少update语句的生成，从而提高hibernate的执行效率！
配置一对多与多对一，这种叫“双向关联”
只配置一对多， 叫“单项一对多”
只配置多对一， 叫“单项多对一”
注意：
配置了哪一方，哪一方才有维护关联关系的权限！
js：强大的splice
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
</head>
<body>
<input type="text">
<br>
<input type="checkbox" value="html">html
<br>
<input type="checkbox" value="js">js
<br>
<input type="checkbox" value="css">css
<br>
<input type="checkbox" value="jquery">jquery
<br>
<script>
/* array.splice(start, deleteCount[, item1[, item2[, ...]]])
哪一位开始修改内容 / 移除的数组元素的个数 / 要添加进数组的元素。如果不指定，则 splice() 只删除数组元素
var arr = [‘a‘,‘b‘,‘c‘,‘d‘,‘e‘,‘f‘];
var a = arr.splice( 1 , 2 , ‘x‘ , ‘y‘ ,‘z‘ );
console.log(arr);
会打印出["a", "x", "y", "z", "d", "e", "f"]
将arr中索引为1（从0开始）的后两位删除，同时添加‘x‘,‘y‘,‘z‘
*/
var aInput = document.getElementsByTagName(‘input‘);
for (var i = aInput.length - 1; i >= 0; i--) {
aInput[i].onclick = function() {
if (this.checked) {
if (aInput[0].value == ‘‘) {
aInput[0].value += this.value;
} else {
aInput[0].value += ‘,‘ + this.value;
}
} else {
var arr = aInput[0].value.split(‘,‘);
for (var i = arr.length - 1; i >= 0; i--) {
if (arr[i] == this.value) {
//第二个参数表示从数组中的第i个元素开始删除一个元素
console.log(arr);
arr.splice(1, 1);
console.log(arr);
}
}
aInput[0].value = arr;
}
}
}
</script>
</body>
</html>
标签：分享 date ash log oct 索引 value onclick mpi
原文地址：http://www.cnblogs.com/helloworldcode/p/6284118.html
