一.从XML文件中获取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从xml配置文件中获得bean,也可以使用其它方式,比如利用PropertiesFactoryBean从.property文件中获得。
2.采用ApplicationContext方式
采用BeanFactory对简单的应用程序来说就够了,可以获得对象管理上的便利性。
但是要获取一些特色和高级的容器功能,可以采用ApplicationContext。
ApplicationContext提供了一些高级的功能,比如:
1.提供取得资源文件更方便的方法
2.提供文字消息解析的方法
3.支持国际化(i18n)消息
4.可以发布事件,对事件感兴趣的Bean可以接收这些事件
Spring创始者建议采用ApplicationContext取代BeanFactory。
在实现ApplicationContext借口的类中,常用的几个:
FileSystemXmlApplicationContext:
可以指定XML定义文件的相对路径或者绝对路径来读取定义文件。
ClassPathXmlApplicationCOntext:
可以从classpath中读取XML文件
XmlWebApplicationCOntext:
从Web应用程序的文件架构中,指定相对位置来读取定义文件。
一个简单的例子:
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方法完成依赖注入,这是Spring鼓励的。但也允许使用Type 3注入,也就是利用构造函数完成注入。
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.属性参考
如果在Bean文件中已经有一个定义的Bean实例,可以让某个属性直接参考这个实例。
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
>
如果某个Bean的实例只被参考一次,可以直接在属性定义时使用<bean>标签,并仅需要指定其"class"属性即可。
<
property
name
="date"
>
<
bean
class
="java.util.Date"
/>
</
property
>
四.自动绑定
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
>
这 里并没有指定helloBean的data属性,而是通过自动绑定,指定了"byType",所以会根据helloBean的setDate()方法所接 受的类型,来判断定义文件中是否有类似的对象,并将之设定给helloBean的setDate(),如果无法完成绑定,会抛异常。
byName
根据id属性上指定的别名是否与setter名称一致来绑定。无法绑定,仅维持未绑定状态,不抛异常。
<?
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"
根据构造方法上的参数类型,来匹配。无法绑定抛异常。
autowire="autodetect"
会试着用constructor,byType等方式来建立依赖关系。
加入依赖检查
依赖检查有4种方式:
simple只检查简单的属性,例如int或者String类型对象是否完成依赖。
objects检查对象类型的属性是否完成依赖。
all检查所有的属性,none是默认值,不检查依赖性。
<
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.集合对象的注入
对于像数组、List、Set、Map等集合对象,在注入前若必须填充一些对象到集合中,然后再将集合对象注入到Bean中时,可以交给Spring的IoC容器自动维护或者生成集合对象,并完成依赖注入。
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
>
测试类: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 " );
// 取得数组类型依赖注入对象
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类型依赖注入对象
List someList = someBean.getSomeList();
for ( int i = 0 ; i < someList.size(); i ++ ) {
System.out.println(someList.get(i));
}
System.out.println();
// 取得Map类型依赖注入对象
Map someMap = someBean.getSomeMap();
System.out.println(someMap.get( " MapTest " ));
System.out.println(someMap.get( " someKey1 " ));
}
}