Spring之bean一基础

在前面得博客依赖注入与控制反转中演示了应用spring实现ioc，在ApplicationContext.xml中有bean的配置，里面只是bean简单的应用。这篇主要是进一步学习使用bean。

一、定义

<?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.xsd">
<bean id="DaoImpl" class="Cuiyw.Spring.Dao.DaoImpl"></bean>
<bean id="ServiceImpl" class="Cuiyw.Spring.Service.ServiceImpl" scope="singleton">
<property name="dao" ref="DaoImpl"></property>
</bean>
</beans>

上面的代码是之前博客配置的，可以看到bean的基本构成。<beans/>是Sring配置文件的根节点，一个<beans/>节点里面可以有多个<bean>节点。在bean中常用两个属性:ID,Class. ID是一唯一标识，来确定是哪个bean，可以让其他bean中使用id引用。class用来指定是哪个class。同时还可以设置scope属性，scope有两种:singleton，non-singelton。singleton：单实例模式（默认，构造方法为private），整个Spring的容器中只有一个共享实例存在(singleton)。non-singelton:每次请求该bean,Spring容器都会新建立一个bean实例，然后返回给程序（request,session,prototype）。
二、创建

Bean的命名机制

id 当在Spring的窗口当中，查找某个Bean对象时，首先根据id进行查找，将其余作为Bean的默认名称，如果ID属性不存在，则根据Name属性进行查找（将其中的第一个名称作为默认的名称），如果ID和NAME都不存在根据类的名称进行查找。id---------->name--------------->类名。

Bean的别名:可以使用alias来为bean指定别名.

下面的配置文件还是在上面的xml基础上修改的。这里配置了ID为ServiceImpl的bean设置了别名。我们可以使用它的name、id、alias来获取service。

<?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.xsd">
<bean id="DaoImpl" class="Cuiyw.Spring.Dao.DaoImpl"></bean>
<bean id="ServiceImpl" class="Cuiyw.Spring.Service.ServiceImpl" scope="singleton" name="ServiceA">
<property name="dao" ref="DaoImpl"></property>
</bean>
<alias name="ServiceA" alias="ServiceA1"/>
</beans>

package Cuiyw.SpringAop;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import Cuiyw.Spring.IService.IService;

public class App 
{
    public static void main( String[] args )
    {
        ApplicationContext context=new ClassPathXmlApplicationContext(new String[]{"ApplicationContext.xml"});
        BeanFactory factory=context;
        IService service=(IService)factory.getBean("ServiceA1");
        service.service("Cuiyw ServiceA1"); 
        service=(IService)factory.getBean("ServiceA");
        service.service("Cuiyw ServiceA"); 
        service=(IService)factory.getBean("ServiceImpl");
        service.service("Cuiyw ServiceImpl"); 
    }

}

三、注入

1.基本类型和string

可以使用value元素来设置,在上面的代码基础上稍作修改

<property name="baseProperty" value="222"></property>

package Cuiyw.Spring.Service;

import Cuiyw.Spring.IDao.IDao;
import Cuiyw.Spring.IService.IService;

public class ServiceImpl implements  IService{

    private IDao dao;
    private int baseProperty;
    public IDao getDao() {
        return dao;
    }
    public void setDao(IDao dao) {
        this.dao = dao;
    }
    public void service(String name) {
        System.out.println(dao.sayHello(name)+" baseProperty:"+getBaseProperty());
    }
    public int getBaseProperty() {
        return baseProperty;
    }
    public void setBaseProperty(int baseProperty) {
        this.baseProperty = baseProperty;
    }
}

对于string类型，XML解析器以String类型解析出数据,如果属性不是String类型，属性值会通过PropertyEditors转换为其他类型，比如时间类型.

2.注入bean

上面的代码中就注入了bean,在ServiceImpl中注入DaoImpl。可以使用ref来进行配置。

3.注入集合

常见的集合有list、map、set、property等，下面的代码是在ServiceImpl中定义了几个属性，然后在上下文中通过属性注入进去。为了测试，在DaoImpl中也增加了一个属性s。

package Cuiyw.Spring.Dao;

import java.util.Calendar;

import Cuiyw.Spring.IDao.IDao;

public class DaoImpl implements IDao{

    public String s;
    public String getS() {
        return s;
    }
    public void setS(String s) {
        this.s = s;
    }
    public String sayHello(String name) {
        int hour=Calendar.getInstance().get(Calendar.HOUR_OF_DAY);
        if(hour<6) return "凌晨早,"+name;
        if(hour<12)return "早上好,"+name;
        if(hour<13)return "中午好,"+name;
        if(hour<18)return "下午好,"+name;
        return "晚上好,"+name+", s="+s;
            
    }    
}

package Cuiyw.Spring.Service;

import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import Cuiyw.Spring.IDao.IDao;
import Cuiyw.Spring.IService.IService;

public class ServiceImpl implements  IService{

    private IDao dao;
    private int baseProperty;
    private List<Object> lists;
    private Set<Object> sets;
    private Map<Object, Object> maps;
    private Properties pros;
    public IDao getDao() {
        return dao;
    }
    public void setDao(IDao dao) {
        this.dao = dao;
    }
    public void service(String name) {
        System.out.println(dao.sayHello(name)+",baseProperty:"+getBaseProperty());
        for(int i=0;i<lists.size();i++)
        {
            Object obj=lists.get(i);
            System.out.println(obj.getClass().getName());
        }
        for(Object obj : sets)
        {
            System.out.println(obj.getClass().getName());
        }
        //遍历maps中的key
        for (Object key : maps.keySet()) {
            System.out.println("Key = " + key);
        }
        //遍历maps中的值
        for (Object value : maps.values()) {
            System.out.println("Value = " + value);
        }
         Set<String> pro=pros.stringPropertyNames();
         Iterator<String> it=pro.iterator();
         while(it.hasNext()){
             Object key=it.next();
             System.out.println(key+"----"+pros.getProperty((String) key));
             }
    }
    public int getBaseProperty() {
        return baseProperty;
    }
    public void setBaseProperty(int baseProperty) {
        this.baseProperty = baseProperty;
    }
    public List<Object> getLists() {
        return lists;
    }
    public void setLists(List<Object> lists) {
        this.lists = lists;
    }
    public Set<Object> getSets() {
        return sets;
    }
    public void setSets(Set<Object> sets) {
        this.sets = sets;
    }
    public Map<Object, Object> getMaps() {
        return maps;
    }
    public void setMaps(Map<Object, Object> maps) {
        this.maps = maps;
    }
    public Properties getPros() {
        return pros;
    }
    public void setPros(Properties pros) {
        this.pros = pros;
    }
}

主要是注入的配置，在list、map、set属性中都是配置了一个基础类型value=1，两个DaoImpl类型。

<?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.xsd">
<bean id="DaoImpl" class="Cuiyw.Spring.Dao.DaoImpl">
  <property name="s" value="cyw"></property>
</bean>
<bean id="ServiceImpl" class="Cuiyw.Spring.Service.ServiceImpl" scope="singleton" name="ServiceA">
    <property name="dao" ref="DaoImpl"></property>
    <property name="baseProperty" value="222"></property>
    <property name="lists">
         <list>
            <value>1</value>
            <ref bean="DaoImpl" />
            <bean class="Cuiyw.Spring.Dao.DaoImpl">
                <property name="s" value="cuiywlists" />
            </bean>
        </list>
    </property>
    <property name="sets">
         <set>
            <value>1</value>
            <ref bean="DaoImpl" />
            <bean class="Cuiyw.Spring.Dao.DaoImpl">
                <property name="s" value="cuiywsets" />
            </bean>
        </set>
    </property>
    <property name="maps">
         <map>
            <entry key="key1" value="1"></entry>
            <entry key="key2" value-ref="DaoImpl"></entry>
            <entry key="key3" >
            <bean class="Cuiyw.Spring.Dao.DaoImpl">
                <property name="s" value="cuiywmaps" />
            </bean>
            </entry>
        </map>
    </property>
    <property name="pros">
        <props>
            <prop key="prokey1">prokeyA</prop>
            <prop key="prokey2">prokeyB</prop>
        </props>
    </property>
</bean>
<alias name="ServiceA" alias="ServiceA1"/>
</beans>

执行main方法可以看到属性都注入进去了。

4.自定义属性编辑器

对于有一些属性是没法注入的，此时就需要自定义，比如上面说的日期类型。

首先是要定义一个继承PropertyEditorSupport的类，重写setAsText方法。

package Cuiyw.Spring.Service;

import java.beans.PropertyEditorSupport;
import java.text.ParseException;
import java.text.SimpleDateFormat;

public class CustomerProperty extends PropertyEditorSupport {

    private String format="yyyy-MM-dd";
    public String getFormat() {
        return format;
    }
    public void setFormat(String format) {
        this.format = format;
    }
    @Override
    public void setAsText(String text) throws IllegalArgumentException {
        // TODO Auto-generated method stub
        SimpleDateFormat sdf=new SimpleDateFormat(format);
        //super.setAsText(text);
        try {
            //转换对象，能过setValue方法重新赋值
            this.setValue(sdf.parse(text));
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }

}

然后在配置文件配置这个类

<bean id="customEditorConfigurer" class="org.springframework.beans.factory.config.CustomEditorConfigurer">
 <property name="customEditors">
  <map>
   <entry key="java.util.Date" value="Cuiyw.Spring.Service.CustomerProperty"/>
  </map>
 </property>
</bean>

这里还是在ServiceImpl中增加了一个java.util.Date类型的date属性。并在配置文件注入值。

    <property name="date" value="2017-12-10"/>

 四、注入方式

package Cuiyw.Spring.Service;

import Cuiyw.Spring.IDao.IDao;

public class IOCWay {

    /*public IOCWay(IDao dao, String name) {
        
        this.dao = dao;
        this.name = name;
        System.out.println("调用构造函数实例化参数");
    }
    */

    private IDao dao;
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public IDao getDao() {
        return dao;
    }

    public void setDao(IDao dao) {
        this.dao = dao;
    }
    
    public void print()
    {
        System.out.println(dao.sayHello(name));
    }
    
    

}

上面创建了一个IOCWay类，构造函数主要是为了用来测试构造函数注入。

1.属性注入

上面用的都是属性注入。

<bean id="DaoImpl" class="Cuiyw.Spring.Dao.DaoImpl">
  <property name="s" value="cyw"></property>
</bean>

2.构造函数注入  这里可以用index来设置是参数的位置

<bean id="IOCWay" class="Cuiyw.Spring.Service.IOCWay">
<constructor-arg type="java.lang.String" index="1">
<value>cuiyw</value>
</constructor-arg>
<constructor-arg ref="DaoImpl" index="0"></constructor-arg>
</bean>

3.静态工厂方式

这里先创建一个工厂类

package Cuiyw.Spring.Service;

import Cuiyw.Spring.Dao.DaoImpl;

public class IOCFactory {

    public static final DaoImpl getStaticFactoryDaoImpl(){ 
        return new DaoImpl("cuiyw"); 
    }
}

在配置bean时使用下面的配置，可以看到在配置属性doa时是指向了daofactory，在daofactory中配置了factory-method

<bean id="IOCWay1" class="Cuiyw.Spring.Service.IOCWay">
<property name="dao" ref="daofactory"></property>
<property name="name" value="cyw"></property>
</bean>
<bean name="daofactory" class="Cuiyw.Spring.Service.IOCFactory" factory-method="getStaticFactoryDaoImpl"></bean>

4.实例工厂方式

在上面工厂类中增加一个实例化方法。

package Cuiyw.Spring.Service;

import Cuiyw.Spring.Dao.DaoImpl;

public class IOCFactory {

    public static final DaoImpl getStaticFactoryDaoImpl(){ 
        return new DaoImpl("cuiyw"); 
    }
    
    public  final DaoImpl getInstanceFactoryDaoImpl(){ 
        return new DaoImpl("cuiyw"); 
    }
}

这里还是往IOCWay注入dao和name。前面的静态工厂方法是不需要实例化工厂类的，而实例化工厂方法是需要实例化工厂类的。所以在配置factorydao时需要设置factory-bean。

<bean id="IOCWay2" class="Cuiyw.Spring.Service.IOCWay">
<property name="dao" ref="factorydao"></property>
<property name="name" value="cyw"></property>
</bean>
<bean name="daofactory" class="Cuiyw.Spring.Service.IOCFactory"></bean>
<bean name="factorydao" factory-bean="daofactory" factory-method="getInstanceFactoryDaoImpl"></bean>

上面算是把常见的4种注入方式学习了下，其实还有其他几种，已经通过注解来注入等，这里只学习了xml的注入，而且一般只有属性和构造函数常用。