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Spring
官网:
理念:使现有技术更加实用,本身是大杂烩整合现有的框架技术
优点:
- 轻量级框架
- Ioc 容器-控制反转 inversion of Control
- Aop 面向切面编程
- 对事务支持
- 对框架的支持
一、Ioc 控制反转
Ioc 是一种编程思想,由主动编程变为被动接收
别名:依赖注入 dependency injection
控制:
指谁来控制对象的创建 传统的应用程序对象的创建是由程序本身控制的 使用 spring 之后,由 spring 创建对象反转:
正转指程序来创建对象 反转指程序本身不创建对象,而变成被动接受对象总结:
以前对象是由程序本身创建, 使用 spring 之后,程序变为接收 spring 创建好的对象简单示例
1、依赖 pom.xml
org.springframework spring-context-support 5.2.6.RELEASE org.springframework spring-context 5.2.6.RELEASE
2、Person.java
package com.pengshiyu.bean;public class Person { private String name; public void setName(String name) { this.name = name; } public void sayHello() { System.out.println("hello " + this.name); }}
3、beans.xml
此处是完整写法,之后将采用简写形式
4、Demo.java
package com.pengshiyu.spring;import com.pengshiyu.bean.Person;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Demo { public static void main(String[] args) { // 解析beans.xml 文件,生成对应的Bean对象 ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); Person person = (Person)context.getBean("person"); person.sayHello(); }}
二、Dao 管理示例
Ioc: 对象由 spring 来创建
1、UserDao
package com.spring.dao;public interface UserDao { public void getUser();}
2、UserDaoMysqlImpl
package com.spring.dao.impl;import com.spring.dao.UserDao;public class UserDaoMysqlImpl implements UserDao { @Override public void getUser() { System.out.println("Mysql 获取用户信息"); }}
3、UserDaoOracleImpl
package com.spring.dao.impl;import com.spring.dao.UserDao;public class UserDaoOracleImpl implements UserDao { @Override public void getUser() { System.out.println("Oracle 获取用户信息"); }}
4、UserService
package com.spring.service;public interface UserService { public void getUser();}
5、UserServiceImpl
package com.spring.service.impl;import com.spring.dao.UserDao;import com.spring.service.UserService;public class UserServiceImpl implements UserService { private UserDao userDao = null; public void setUserDao(UserDao userDao) { this.userDao = userDao; } @Override public void getUser() { this.userDao.getUser(); }}
6、beans.xml(简化版)
7、TestDemo
package com.spring.test;import com.spring.service.UserService;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class TestDemo { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); UserService service = (UserService)context.getBean("service"); service.getUser(); }}
三、使用 Ioc 来创建对象的 3 种方法
Person 类
package com.pengshiyu.bean;public class Person { private String name; public Person() { } public Person(String name) { this.name = name; } public void sayHello() { System.out.println("hello " + this.name); }}
创建对象
package com.spring.test;import com.pengshiyu.bean.Person;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Demo { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); Person person = (Person) context.getBean("person"); person.sayHello(); }}
beans.xml(简化版)
1、无参构造
2、有参构造
(1)根据参数下标设置
(2)根据参数名称设置
(3)根据参数类型设置
3、工厂方法创建
(1)静态工厂
package com.pengshiyu.factory;import com.pengshiyu.bean.Person;public class PersonFactory { public static Person newInstance(String name) { return new Person(name); }}
(2)动态工厂
package com.pengshiyu.factory;import com.pengshiyu.bean.Person;public class PersonFactory { public Person newInstance(String name) { return new Person(name); }}
注意静态工厂 static
四、Spring 配置文件
id 是 bean 的唯一标识符,如果没有配置 id,name 默认为标识符
如果配置了 id,又配置了 name,则 name 是别名
name 可以设置多个别名分隔符可以是空格、逗号、分号class 是 bean 的全限定名=包名+类名
如果不配置 id 和 name,那么可以可以使用如下方式获取对象applicationContext.getBean(class)
配置如下
获取方式
Person person = (Person) context.getBean("person1");// 或者Person person = (Person) context.getBean("user");// 或者Person person = (Person) context.getBean(Person.class);
导入文件
五、Spring 依赖注入 DI
dependency injection
依赖:指 bean 对象创建依赖于容器,bean 对象的依赖资源注入:指 bean 对象依赖的资源由容器来设置和装配
spring 注入
测试
package com.spring.test;import com.pengshiyu.bean.Person;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Demo { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml"); Person person = (Person) context.getBean("person"); person.sayHello(); }}
- 构造器注入
package com.pengshiyu.bean;public class Person { private String name; public Person(String name) { this.name = name; } public void sayHello() { System.out.println("hello " + this.name); }}
- setter 注入
(1)常量注入
package com.pengshiyu.bean;public class Person { private String name; public void setName(String name) { this.name = name; } public void sayHello() { System.out.println("hello " + this.name); }}
(2)bean 注入
package com.pengshiyu.bean;public class Address { private String address; public void setAddress(String address) { this.address = address; } public String getAddress() { return address; }}
package com.pengshiyu.bean;public class Person { private String name; private Address address; public void setAddress(Address address) { this.address = address; } public void setName(String name) { this.name = name; } public void sayHello() { System.out.println("hello " + this.name + this.address.getAddress()); }}
(3)数组注入
package com.pengshiyu.bean;public class Book { private String name; public Book(String name){ this.name = name; } @Override public String toString() { return "《" + this.name + "》"; }}
package com.pengshiyu.bean;import java.util.Arrays;public class Person { private Book[] books; public void setBooks(Book[] books) { this.books = books; } @Override public String toString() { return "Person{" + "books=" + Arrays.toString(books) + '}'; }}
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(4)List 注入
package com.pengshiyu.bean;import java.util.Arrays;import java.util.List;public class Person { private List[] books; public void setBooks(List [] books) { this.books = books; } @Override public String toString() { return "Person{" + "books=" + Arrays.toString(books) + '}'; }}
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(5)Map 注入
package com.pengshiyu.bean;import java.util.Map;public class Person { private Mapcards; public void setCards(Map cards) { this.cards = cards; } @Override public String toString() { return cards.toString(); }}
(6)Set 注入
package com.pengshiyu.bean;import java.util.Set;public class Person { private Setgames; public void setGames(Set games) { this.games = games; } @Override public String toString() { return games.toString(); }}
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(7)null 注入
package com.pengshiyu.bean;public class Person { public void setWife(String wife) { this.wife = wife; } private String wife; @Override public String toString() { return wife; }}
(8) Properties 注入
package com.pengshiyu.bean;import java.util.Properties;public class Person { private Properties props; public void setProps(Properties props) { this.props = props; } @Override public String toString() { return this.props.toString(); }}
Tom Man
(9) p 命名空间注入
需要有对应的 set 方法package com.pengshiyu.bean;public class Person { private String name; private int age; public void setName(String name) { this.name = name; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + '}'; }}
头文件需要引入
xmlns:p="http://www.springframework.org/schema/p"
(10)c 命名空间注入
要求有对应的构造方法package com.pengshiyu.bean;public class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + '}'; }}
头文件需要引入
xmlns:c="http://www.springframework.org/schema/c"
六、bean 的作用域
spring
桥梁轻量级易学ioc diapp事务整合框架
scope:
- singleton 单例 整个容器只有一个对象实例(默认)
- prototype 原型 每次获取 Bean 都产生一个新对象
- request 每次请求时创建一个新的对象
- session 会话范围内有一个对象
- global session 只在 portlet 下有用,表示 applicatio
- application 在应用范围中有一个对象
Bean 自动装配
autowire
- byName
- byType
- constructor
不推荐使用自动装配
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