Spring是一個開源框架,Spring是於2003 年興起的一個輕量級的Java 開發框架,由Rod Johnson創建。簡單來說,Spring是一個分層的JavaSE/EEfull-stack(一站式) 輕量級開源框架。 總的來說spring有兩個主要功能:
ioc+aop:容器+切片
Spring—ioc容器
Spring通過Spring自身配置容器,將java中的類製作成bean(咖啡豆)放入ioc中,通過配置讓這些bean具有關聯,而不需要再通過代碼實現類與類之間的關係
下面來實現如何通過容器來控制類之間關係:
首先使用spring需要一些必要導入的包:
第一步建立一個含有空參構造和setter,getter的類:
package cn.hncu.domain;
public class Person {
private String name;
private String age;
public Person() {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + "]";
}
}
第二步建立spring配置文件:bean中id是類的屬性值,property是類中屬性參數,通過value賦值,scope中有四類參數:prototype可視爲多例 singleton視爲單例 session爲單用戶範圍 request即request的存儲空間 如果scope不填,默認爲singleton–單例
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/aop" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="p1" class="cn.hncu.domain.Person">
<property name="name" value="jack"></property>
<property name="age" value="22"></property>
</bean>
<!-- scope="prototype"將該bean設爲原型,則是多例 -->
<bean id="p2" class="cn.hncu.domain.Person" scope="prototype">
<property name="name" value="jack"></property>
<property name="age" value="22"></property>
</bean>
</beans>
第三步調用bean:通過ApplicationContext context = new ClassPathXmlApplicationContext(new String(“applicationContext.xml”));得到context 再從context得到bean,得到的bean就是一個類的實例對象
package cn.hncu.Demo1;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import cn.hncu.domain.Person;
public class Demo1 {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
new String("applicationContext.xml"));
// 第一個參數爲xml中配置bean的id,第二個參數是告訴xml將new好的對象強轉成什麼類型
Person p1 = context.getBean("p1", Person.class);
System.out.println(p1.toString());
Person p3 = context.getBean("p1", Person.class);
// spring默認是單例
System.out.println(p3.equals(p1));
Person p2 = context.getBean("p2", Person.class);
Person p4 = context.getBean("p2", Person.class);
System.out.println(p2.toString());
System.out.println(p2.equals(p4));
}
}
我們也可以在配置文件中爲一個bean關聯另一個類或者map,list,Object[]數組,Set:
User:
package cn.hncu.demo2;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class User {
private String name;
private String age;
private Cat cat;
private List<String> addr;
private Map<String, Object> map;
private Set<String> set;
private Object[] obj;
public Object[] getObj() {
return obj;
}
public void setObj(Object[] obj) {
this.obj = obj;
}
public Set<String> getSet() {
return set;
}
public void setSet(Set<String> set) {
this.set = set;
}
public Map<String, Object> getMap() {
return map;
}
public void setMap(Map<String, Object> map) {
this.map = map;
}
public List<String> getAddr() {
return addr;
}
public void setAddr(List<String> addr) {
this.addr = addr;
}
public Cat getCat() {
return cat;
}
public void setCat(Cat cat) {
this.cat = cat;
}
public User() {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
@Override
public String toString() {
return "User [name=" + name + ", age=" + age + ", cat=" + cat
+ ", addr=" + addr + ", map=" + map + ", set=" + set + ", obj="
+ Arrays.toString(obj) + "]";
}
}
Cat:
package cn.hncu.demo2;
public class Cat {
private String name;
private String age;
public Cat() {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
@Override
public String toString() {
return "Cat [name=" + name + ", age=" + age + "]";
}
}
配置文件:ref一般就是用來引用其他bean
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/aop" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="user" class="cn.hncu.demo2.User">
<property name="name" value="tom"></property>
<property name="age" value="22"></property>
<!-- 屬性變量是一個bean -->
<property name="cat" ref="cat2"></property>
<!-- 屬性變量是一個List -->
<property name="addr">
<list>
<value>益陽</value>
<value>長沙</value>
<value>上海</value>
<value>北京</value>
</list>
</property>
<!-- 屬性變量是一個map -->
<property name="map">
<map>
<entry key="name" value="aaa" />
<entry key="age" value="22" />
</map>
</property>
<!-- 屬性變量是一個set -->
<property name="set">
<set>
<value>111</value>
<value>222</value>
<value>333</value>
</set>
</property>
<!-- 屬性變量是一個Object數組 -->
<property name="obj">
<array>
<value>一個字符串</value>
<ref bean="cat2" />
<list>
<value>益陽</value>
<value>長沙</value>
<value>上海</value>
<value>北京</value>
</list>
<map>
<entry key="name" value="aaa" />
<entry key="age" value="22" />
</map>
<!-- 內部匿名bean -->
<bean class="cn.hncu.domain.Person">
<property name="name" value="張三"></property>
<property name="age" value="22"></property>
</bean>
</array>
</property>
</bean>
<!-- 導入其他配置文件 -->
<import resource="cat.xml" />
</beans>