一.從XML文件中獲取Bean的方法
1.采用BeanFactory方式
????????Resource?rs?=?new?FileSystemResource("beans-config.xml");
????????BeanFactory?factory?=?new?XmlBeanFactory(rs);
????????HelloBean?helloBean?=?(HelloBean)factory.getBean("helloBean");
采用BeanFactory方式，可以利用XmlBeanFactory從xml配置文件中獲得bean，也可以使用其它方式，比如利用PropertiesFactoryBean從.property文件中獲得。
2.采用ApplicationContext方式
采用BeanFactory對簡單的應用程序來說就夠了，可以獲得對象管理上的便利性。
但是要獲取一些特色和高級的容器功能，可以采用ApplicationContext。
ApplicationContext提供了一些高級的功能，比如：
1.提供取得資源文件更方便的方法
2.提供文字消息解析的方法
3.支持國際化(i18n)消息
4.可以發布事件，對事件感興趣的Bean可以接收這些事件
Spring創始者建議采用ApplicationContext取代BeanFactory。
在實現ApplicationContext借口的類中，常用的幾個：
FileSystemXmlApplicationContext：
可以指定XML定義文件的相對路徑或者絕對路徑來讀取定義文件。
ClassPathXmlApplicationCOntext:
可以從classpath中讀取XML文件
XmlWebApplicationCOntext:
從Web應用程序的文件架構中，指定相對位置來讀取定義文件。
一個簡單的例子：
package?cn.blogjava.hello;
import?org.springframework.context.ApplicationContext;
import?org.springframework.context.support.FileSystemXmlApplicationContext;
public?class?SpringDemo?{
????public?static?void?main(String[]?args)?{
????????ApplicationContext?context?=?
????????????new?FileSystemXmlApplicationContext("beans-config.xml");????????
????????HelloBean?helloBean?=?(HelloBean)context.getBean("helloBean");
????????System.out.print("Name:?");
????????System.out.println(helloBean.getName());
????????System.out.print("Word:?");
????????System.out.println(helloBean.getHelloWord());
????}
}
二.Type 2 IoC, Type 3 IoC
Type2是利用setter方法完成依賴注入，這是Spring鼓勵的。但也允許使用Type 3注入，也就是利用構造函數完成注入。
例如：
package?cn.blogjava.hello;
public?class?HelloBean?{
????
????private?String?helloWord;
????private?String?name;
????
????public?HelloBean()?{
????????
????}
????public?HelloBean(String?helloWord,?String?name)?{
????????this.helloWord?=?helloWord;
????????this.name?=?name;
????}????
????
????public?String?getHelloWord()?{
????????return?helloWord;
????}
????public?void?setHelloWord(String?helloword)?{
????????this.helloWord?=?helloword;
????}
????public?String?getName()?{
????????return?name;
????}
????public?void?setName(String?name)?{
????????this.name?=?name;
????}
????
}
配置文件：
beans-config.xml
<?xml?version="1.0"?encoding="UTF-8"?>
<!DOCTYPE?beans?PUBLIC?"-//SPRING/DTD?BEAN/EN"
????"http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
????<bean?id="helloBean"?class="cn.blogjava.hello.HelloBean"?>
????????<constructor-arg?index="0">
????????????<value>YYY!</value>
????????</constructor-arg>
????????<constructor-arg?index="1">
????????????<value>Hello!</value>
????????</constructor-arg>
????</bean>
</beans>
三.屬性參考
如果在Bean文件中已經有一個定義的Bean實例，可以讓某個屬性直接參考這個實例。
package?cn.blogjava.hello;
import?java.util.Date;
public?class?HelloBean?{
????
????private?String?helloWord;
????private?Date?date;
????
????public?HelloBean()?{
????????
????}
?
????
????public?String?getHelloWord()?{
????????return?helloWord;
????}
????public?void?setHelloWord(String?helloword)?{
????????this.helloWord?=?helloword;
????}
????
????public?Date?getDate()?{
????????return?date;
????}
????public?void?setDate(Date?date)?{
????????this.date?=?date;
????}
}
配置文件
beans-config.xml
<?xml?version="1.0"?encoding="UTF-8"?>
<!DOCTYPE?beans?PUBLIC?"-//SPRING/DTD?BEAN/EN"
????"http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
????<bean?id="dateBean"?class="java.util.Date"/>
????<bean?id="helloBean"?class="cn.blogjava.hello.HelloBean"?>
????????<property?name="helloWord">
????????????<value>Hello!</value>
????????</property>
?
????????<property?name="date">
????????????<ref?bean="dateBean"?/>
????????</property>????????????????
????</bean>
</beans>
如果某個Bean的實例只被參考一次，可以直接在屬性定義時使用<bean>標簽，并僅需要指定其"class"屬性即可。
????????<property?name="date">
????????????<bean?class="java.util.Date"?/>
????????</property>??????????????
四.自動綁定
byType
<?xml?version="1.0"?encoding="UTF-8"?>
<!DOCTYPE?beans?PUBLIC?"-//SPRING/DTD?BEAN/EN"
????"http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
????<bean?id="dateBean"?class="java.util.Date"/>
????<bean?id="helloBean"?class="cn.blogjava.hello.HelloBean" ?autowire="byType">
????????<property?name="helloWord">
????????????<value>Hello!</value>
????????</property>
????????<property?name="name">
????????????<value>YYY!</value>
????????</property>?????????????
????</bean>
</beans>
這里并沒有指定helloBean的data屬性，而是通過自動綁定，指定了"byType",所以會根據helloBean的setDate()方法所接受的類型，來判斷定義文件中是否有類似的對象，并將之設定給helloBean的setDate()，如果無法完成綁定，會拋異常。
byName
根據id屬性上指定的別名是否與setter名稱一致來綁定。無法綁定，僅維持未綁定狀態，不拋異常。
<?xml?version="1.0"?encoding="UTF-8"?>
<!DOCTYPE?beans?PUBLIC?"-//SPRING/DTD?BEAN/EN"
????"http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
????<bean?id="date"?class="java.util.Date"/>
????<bean?id="helloBean"?class="cn.blogjava.hello.HelloBean"??autowire="byName">
????????<property?name="helloWord">
????????????<value>Hello!</value>
????????</property>
????????<property?name="name">
????????????<value>YYY!</value>
????????</property>?????????????
????</bean>
</beans>
?autowire="constructor"
根據構造方法上的參數類型，來匹配。無法綁定拋異常。
autowire="autodetect"
會試著用constructor，byType等方式來建立依賴關系。
加入依賴檢查
依賴檢查有4種方式：
simple只檢查簡單的屬性，例如int或者String類型對象是否完成依賴。
objects檢查對象類型的屬性是否完成依賴。
all檢查所有的屬性，none是默認值，不檢查依賴性。
????<bean?id="helloBean"?class="cn.blogjava.hello.HelloBean"??autowire="autodetect" dependency-check="all">
????????<property?name="helloWord">
????????????<value>Hello!</value>
????????</property>
????????<property?name="name">
????????????<value>YYY!</value>
????????</property>?????????????
????</bean>
五.集合對象的注入
對于像數組、List、Set、Map等集合對象，在注入前若必須填充一些對象到集合中，然后再將集合對象注入到Bean中時，可以交給Spring的IoC容器自動維護或者生成集合對象，并完成依賴注入。
SomeBean.java
package?cn.blogjava.hello;
import?java.util.List;
import?java.util.Map;
public?class?SomeBean?{
????
????private?String[]?someStrArray;
????private?Some[]?someObjectArray;
????private?List?someList;
????private?Map?someMap;
????public?List?getSomeList()?{
????????return?someList;
????}
????public?void?setSomeList(List?someList)?{
????????this.someList?=?someList;
????}
????public?Map?getSomeMap()?{
????????return?someMap;
????}
????public?void?setSomeMap(Map?someMap)?{
????????this.someMap?=?someMap;
????}
????public?Some[]?getSomeObjectArray()?{
????????return?someObjectArray;
????}
????public?void?setSomeObjectArray(Some[]?someObjectArray)?{
????????this.someObjectArray?=?someObjectArray;
????}
????public?String[]?getSomeStrArray()?{
????????return?someStrArray;
????}
????public?void?setSomeStrArray(String[]?someStrArray)?{
????????this.someStrArray?=?someStrArray;
????}
????
????
}
Some.java
package?cn.blogjava.hello;
public?class?Some?{
????private?String?name;
????public?String?getName()?{
????????return?name;
????}
????public?void?setName(String?name)?{
????????this.name?=?name;
????}????
????
????public?String?toString(){
????????return?name;
????}
}
beans-config.xml
<?xml?version="1.0"?encoding="UTF-8"?>
<!DOCTYPE?beans?PUBLIC?"-//SPRING/DTD?BEAN/EN"
????"http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
????<bean?id="some1"?class="cn.blogjava.hello.Some">
????????<property?name="name">
????????????<value>YYY</value>
????????</property>
????</bean>
????
????<bean?id="some2"?class="cn.blogjava.hello.Some">
????????<property?name="name">
????????????<value>BYF</value>
????????</property>
????</bean>
????
????<bean?id="someBean"?class="cn.blogjava.hello.SomeBean">
????????<property?name="someStrArray">
????????????<list>
????????????????<value>Hello!</value>
????????????????<value>Welcome!</value>
????????????</list>
????????</property>
????????
????????<property?name="someObjectArray">
????????????<list>
????????????????<ref?bean="some1"/>
????????????????<ref?bean="some2"/>
????????????</list>
????????</property>
????????
????????<property?name="someList">
????????????<list>
????????????????<ref?bean="some1"/>
????????????????<ref?bean="some2"/>????????????
????????????</list>
????????</property>
????????
????????<property?name="someMap">
????????????<map>
????????????????<entry?key="MapTest">
????????????????????<value>Hello?YYY!</value>
????????????????</entry>
????????????????<entry?key="someKey1">
????????????????????<ref?bean="some1"?/>
????????????????</entry>
????????????</map>
????????</property>
????</bean>
????????
????<bean?id="helloBean"?class="cn.blogjava.hello.HelloBean"?>
????</bean>
</beans>
測試類：SpringDemo.java
package?cn.blogjava.hello;
import?java.util.List;
import?java.util.Map;
import?org.springframework.context.ApplicationContext;
import?org.springframework.context.support.FileSystemXmlApplicationContext;
public?class?SpringDemo?{
????public?static?void?main(String[]?args)?{
????????ApplicationContext?context?=?
????????????new?FileSystemXmlApplicationContext("beans-config.xml");????????
????????SomeBean?someBean?=?(SomeBean)context.getBean("someBean");
????????//取得數組類型依賴注入對象
????????String[]?strs?=?(String[])someBean.getSomeStrArray();
????????Some[]?somes?=?(Some[])someBean.getSomeObjectArray();
????????for(int?i=0;?i?<?strs.length;?i++){
????????????System.out.println(strs[i]?+?","?+?somes[i].getName());
????????}
????????
????????System.out.println();
????????//取得List類型依賴注入對象
????????List?someList?=?someBean.getSomeList();
????????for(int?i=0;?i?<?someList.size();?i++)?{
????????????System.out.println(someList.get(i));
????????}
????????
????????System.out.println();
????????//取得Map類型依賴注入對象
????????Map?someMap?=?someBean.getSomeMap();
????????System.out.println(someMap.get("MapTest"));
????????System.out.println(someMap.get("someKey1"));
????}
}
posted on 2006-07-26 11:24
knowhow 閱讀(5148)
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