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");
} }

Spring之bean一基础

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=""></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;
}
}

Spring之bean一基础

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。

Spring之bean一基础

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"/>

Spring之bean一基础

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。

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