Spring入门

本文主要包括以下内容

1. 控制反转（IOC)
2. springDI
3. springIOC与DI实现MVC实例

控制反转

即把对象的创建交给spring容器来做

• spring容器创建对象的方式
  1、默认是调用默认的构造函数
  2、利用静态工厂方法创建
  spring调用工厂方法产生对象，但是真正创建对象还是由程序员来完成的
  3、实例工厂方法
  说明：
  spring配置文件中，只要是一个bean就会为该bean创建对象

• spring容器创建对象的时机
  在单例的情况下
  1、在默认的情况下，启动spring容器创建对象
  2、在spring的配置文件bean中有一个属性lazy-init=”default/true/false”
  1、如果lazy-init为”default/false”在启动spring容器时创建对象
  2、如果lazy-init为”true”,在context.getBean时才要创建对象
  意义：
  在第一种情况下可以在启动spring容器的时候，检查spring容器配置文件的正确性，如果再结合tomcat,
  如果spring容器不能正常启动，整个tomcat就不能正常启动。但是这样的缺点是把一些bean过早的放在了
  内存中，如果有数据，则对内存来是一个消耗
  在第二种情况下，可以减少内存的消耗，但是不容易发现错误
  在多例的情况下
  就是一种情况：在context.getBean时才创建对象

• spring的bean中的scope
  1、由spring产生的bean默认是单例的
  2、可以在spring的配置文件中，scope的值进行修改 =”singleton/prototype/request/session/global session”
  3、如果spring的配置文件的scope为”prototype”，则在得到该bean时才创建对象

• spring容器对象的生命周期：
  1、spring容器创建对象
  2、执行init方法
  3、调用自己的方法
  4、当spring容器关闭的时候执行destroy方法

spring容器创建对象实例

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       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-2.5.xsd">
    <bean id="helloWorld_C_M" class="cn.itcast.spring.sh.createobject.method.HelloWorld"></bean>
    <!-- 
        factory-method
          工厂方法
     -->
    <bean id="helloFactory" class="cn.itcast.spring.sh.createobject.method.HelloWorldFactory"></bean>

    <bean id="aa" factory-bean="helloFactory" factory-method="getIns"></bean>
</beans>

springDI

通过依赖注入给属性赋值

有两种方法

set方法赋值

package cn.itcast.spring.sh.di.set;

import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;


public class Person {
    private Long pid;
    private String pname;
    private Student student;

    private Set sets;

    public Long getPid() {
        return pid;
    }

    public void setPid(Long pid) {
        this.pid = pid;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

    public Set getSets() {
        return sets;
    }

    public void setSets(Set sets) {
        this.sets = sets;
    }

    public List getLists() {
        return lists;
    }

    public void setLists(List lists) {
        this.lists = lists;
    }

    public Map getMap() {
        return map;
    }

    public void setMap(Map map) {
        this.map = map;
    }

    public Properties getProperties() {
        return properties;
    }

    public void setProperties(Properties properties) {
        this.properties = properties;
    }

    private List lists;

    private Map map;

    private Properties properties;
}

XML文件中的配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    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-2.5.xsd">
    <!-- 
        把person和student放入到spring容器中
     -->
     <!-- 
        property是用来描述一个类的属性
           基本类型的封装类、String等需要值的类型用value赋值
          引用类型用ref赋值
      -->
    <bean id="person" class="cn.itcast.spring.sh.di.set.Person">
        <property name="pid" value="1"></property>
        <property name="pname" value="aaa"></property>
        <property name="student">
            <ref bean="student"/>
        </property>
        <property name="lists">
            <list>
                <value>list1</value>
                <ref bean="student"/>
                <value>list2</value>
            </list>
        </property>
        <property name="sets">
            <set>
                <value>set1</value>
                <ref bean="student"/>
                <value>set2</value>
            </set>
        </property>
        <property name="map">
            <map>
                <entry key="m1">
                    <value>map1</value>
                </entry>
                <entry key="m2">
                    <ref bean="student"/>
                </entry>
            </map>
        </property>
        <property name="properties">
            <props>
                <prop key="prop1">
                    prop1
                </prop>
                <prop key="prop2">
                    prop2
                </prop>
            </props>
        </property>
    </bean>

    <bean id="student" class="cn.itcast.spring.sh.di.set.Student"></bean>
</beans>

构造函数方法赋值

1、如果spring的配置文件中的bean中没有该元素，则调用默认的构造函数
2、如果spring的配置文件中的bean中有该元素，则该元素确定唯一的构造函数
index 代表参数的位置 从0开始计算
type 指的是参数的类型
value 给基本类型赋值
ref 给引用类型赋值

package cn.itcast.spring.sh.di.constructor;

import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class Person {
    private Long pid;
    private String pname;
    private Student student;

    private Set sets;

    public Person(String pname,Student student){
        this.pname = pname;
        this.student = student;
    }

    public Person(Long pid,String pname,Student student){
        this.pid = pid;
        this.pname = pname;
        this.student = student;
    }

    public Person(){}

    public Long getPid() {
        return pid;
    }

    public void setPid(Long pid) {
        this.pid = pid;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

    public Set getSets() {
        return sets;
    }

    public void setSets(Set sets) {
        this.sets = sets;
    }

    public List getLists() {
        return lists;
    }

    public void setLists(List lists) {
        this.lists = lists;
    }

    public Map getMap() {
        return map;
    }

    public void setMap(Map map) {
        this.map = map;
    }

    public Properties getProperties() {
        return properties;
    }

    public void setProperties(Properties properties) {
        this.properties = properties;
    }

    private List lists;

    private Map map;

    private Properties properties;
}

配置文件的配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    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-2.5.xsd">
    <!-- 

     -->
    <bean id="person_Con" class="cn.itcast.spring.sh.di.constructor.Person">
        <constructor-arg index="0" type="java.lang.Long" value="1"></constructor-arg>
        <constructor-arg index="1" value="aaa"></constructor-arg>
        <constructor-arg index="2" ref="student_Con"></constructor-arg>
    </bean>

    <bean id="student_Con" class="cn.itcast.spring.sh.di.constructor.Student"></bean>
</beans>

SPringIOC和DC实现MVC实例

PersonAction

package cn.itcast.spring.sh.mvc;

public class PersonAction {
    private PersonService personService;

    public PersonService getPersonService() {
        return personService;
    }

    public void setPersonService(PersonService personService) {
        this.personService = personService;
    }

    public void savePerson(){
        this.personService.savePerson();
    }
}

PersonService

package cn.itcast.spring.sh.mvc;

public interface PersonService {
    public void savePerson();
}

PersonServiceImpl

package cn.itcast.spring.sh.mvc;

public class PersonServiceImpl implements PersonService{

    private PersonDao personDao;
    public PersonDao getPersonDao() {
        return personDao;
    }
    public void setPersonDao(PersonDao personDao) {
        this.personDao = personDao;
    }
    @Override
    public void savePerson() {
        // TODO Auto-generated method stub
        this.personDao.savePerson();
    }

}

PersonDao

package cn.itcast.spring.sh.mvc;

public interface PersonDao {
    public void savePerson();
}

PersonDaoImpl

package cn.itcast.spring.sh.mvc;

public class PersonDaoImpl implements PersonDao{

    @Override
    public void savePerson() {
        // TODO Auto-generated method stub
        System.out.println("save person dao");
    }

}

配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    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-2.5.xsd">
    <bean id="personDao" class="cn.itcast.spring.sh.mvc.PersonDaoImpl"></bean>

    <bean id="personService" class="cn.itcast.spring.sh.mvc.PersonServiceImpl">
        <property name="personDao">
            <ref bean="personDao"/>
        </property>
    </bean>

    <bean id="personAction" class="cn.itcast.spring.sh.mvc.PersonAction">
        <property name="personService">
            <ref bean="personService"/>
        </property>
    </bean>
</beans>

完成