转自:https://www.cnblogs.com/wxgblogs/p/6849782.html
spring中InitializingBean接口使用理解
InitializingBean接口为bean提供了初始化方法的方式,它只包括afterPropertiesSet方法,凡是继承该接口的类,在初始化bean的时候会执行该方法。
测试程序如下:
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import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;
public
class
InitBean implements InitializingBean{
public
void
afterPropertiesSet() throws Exception {
System.
out
.println(
"启动时自动执行 afterPropertiesSet..."
);
}
public
void
init(){
System.
out
.println(
"init method..."
);
}
}
|
配置文件如下:
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<?xml version=
"1.0"
encoding=
"UTF-8"
?>
<beans xmlns=
"http://www.springframework.org/schema/beans"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
xmlns:context=
"http://www.springframework.org/schema/context"
xmlns:dubbo=
"http://code.alibabatech.com/schema/dubbo"
xmlns:mvc=
"http://www.springframework.org/schema/mvc"
xmlns:aop=
"http://www.springframework.org/schema/aop"
xmlns:tx=
"http://www.springframework.org/schema/tx"
xsi:schemaLocation=
"http:
//www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http:
//www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http:
//www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http:
//www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http:
//www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http:
//code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd"
default
-lazy-init=
"true"
>
<bean id=
"initBean"
class
=
"com.netease.nsip.spring.InitBean"
init-method=
"init"
> </bean>
</beans>
|
Main主程序如下:
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import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
public
class
Main {
public
static
void
main(String[] args) {
ApplicationContext context =
new
FileSystemXmlApplicationContext(
"classpath:/applicationContext-core.xml"
);
context.getBean(
"initBean"
);
}
}
|
运行Main程序,打印如下结果:
1
2
|
启动时自动执行 afterPropertiesSet...
init method...
|
这说明在spring初始化bean的时候,如果bean实现了InitializingBean接口,会自动调用afterPropertiesSet方法。
问题:实现InitializingBean接口与在配置文件中指定init-method有什么不同?由结果可看出,在spring初始化bean的时候,如果该bean是实现了InitializingBean接口,并且同时在配置文件中指定了init-method,系统则是先调用afterPropertiesSet方法,然后在调用init-method中指定的方法。这方式在spring中是怎么实现的?通过查看spring的加载bean的源码类(AbstractAutowireCapableBeanFactory)可看出其中奥妙AbstractAutowireCapableBeanFactory类中的invokeInitMethods讲解的非常清楚,源码如下:
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protected
void
invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
throws Throwable {
//判断该bean是否实现了实现了InitializingBean接口,如果实现了InitializingBean接口,则只掉调用bean的afterPropertiesSet方法
boolean isInitializingBean = (bean instanceof InitializingBean);
if
(isInitializingBean && (mbd ==
null
|| !mbd.isExternallyManagedInitMethod(
"afterPropertiesSet"
))) {
if
(logger.isDebugEnabled()) {
logger.debug(
"Invoking afterPropertiesSet() on bean with name '"
+ beanName +
"'"
);
}
if
(System.getSecurityManager() !=
null
) {
try
{
AccessController.doPrivileged(
new
PrivilegedExceptionAction<Object>() {
public
Object run() throws Exception {
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
return
null
;
}
},getAccessControlContext());
}
catch
(PrivilegedActionException pae) {
throw
pae.getException();
}
}
else
{
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
}
}
if
(mbd !=
null
) {
String initMethodName = mbd.getInitMethodName();
//判断是否指定了init-method方法,如果指定了init-method方法,则再调用制定的init-method
if
(initMethodName !=
null
&& !(isInitializingBean &&
"afterPropertiesSet"
.
equals
(initMethodName)) &&
!mbd.isExternallyManagedInitMethod(initMethodName)) {
//进一步查看该方法的源码,可以发现init-method方法中指定的方法是通过反射实现
invokeCustomInitMethod(beanName, bean, mbd);
}
}
}
|
总结:
- spring为bean提供了两种初始化bean的方式,实现InitializingBean接口,实现afterPropertiesSet方法,或者在配置文件中同过init-method指定,两种方式可以同时使用
- 实现InitializingBean接口是直接调用afterPropertiesSet方法,比通过反射调用init-method指定的方法效率相对来说要高点。但是init-method方式消除了对spring的依赖
- 如果调用afterPropertiesSet方法时出错,则不调用init-method指定的方法。
spring中InitializingBean接口使用理解
InitializingBean接口为bean提供了初始化方法的方式,它只包括afterPropertiesSet方法,凡是继承该接口的类,在初始化bean的时候会执行该方法。
测试程序如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
|
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;
public
class
InitBean implements InitializingBean{
public
void
afterPropertiesSet() throws Exception {
System.
out
.println(
"启动时自动执行 afterPropertiesSet..."
);
}
public
void
init(){
System.
out
.println(
"init method..."
);
}
}
|
配置文件如下:
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2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
<?xml version=
"1.0"
encoding=
"UTF-8"
?>
<beans xmlns=
"http://www.springframework.org/schema/beans"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
xmlns:context=
"http://www.springframework.org/schema/context"
xmlns:dubbo=
"http://code.alibabatech.com/schema/dubbo"
xmlns:mvc=
"http://www.springframework.org/schema/mvc"
xmlns:aop=
"http://www.springframework.org/schema/aop"
xmlns:tx=
"http://www.springframework.org/schema/tx"
xsi:schemaLocation=
"http:
//www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http:
//www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http:
//www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http:
//www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http:
//www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http:
//code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd"
default
-lazy-init=
"true"
>
<bean id=
"initBean"
class
=
"com.netease.nsip.spring.InitBean"
init-method=
"init"
> </bean>
</beans>
|
Main主程序如下:
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10
|
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
public
class
Main {
public
static
void
main(String[] args) {
ApplicationContext context =
new
FileSystemXmlApplicationContext(
"classpath:/applicationContext-core.xml"
);
context.getBean(
"initBean"
);
}
}
|
运行Main程序,打印如下结果:
1
2
|
启动时自动执行 afterPropertiesSet...
init method...
|
这说明在spring初始化bean的时候,如果bean实现了InitializingBean接口,会自动调用afterPropertiesSet方法。
问题:实现InitializingBean接口与在配置文件中指定init-method有什么不同?由结果可看出,在spring初始化bean的时候,如果该bean是实现了InitializingBean接口,并且同时在配置文件中指定了init-method,系统则是先调用afterPropertiesSet方法,然后在调用init-method中指定的方法。这方式在spring中是怎么实现的?通过查看spring的加载bean的源码类(AbstractAutowireCapableBeanFactory)可看出其中奥妙AbstractAutowireCapableBeanFactory类中的invokeInitMethods讲解的非常清楚,源码如下:
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protected
void
invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
throws Throwable {
//判断该bean是否实现了实现了InitializingBean接口,如果实现了InitializingBean接口,则只掉调用bean的afterPropertiesSet方法
boolean isInitializingBean = (bean instanceof InitializingBean);
if
(isInitializingBean && (mbd ==
null
|| !mbd.isExternallyManagedInitMethod(
"afterPropertiesSet"
))) {
if
(logger.isDebugEnabled()) {
logger.debug(
"Invoking afterPropertiesSet() on bean with name '"
+ beanName +
"'"
);
}
if
(System.getSecurityManager() !=
null
) {
try
{
AccessController.doPrivileged(
new
PrivilegedExceptionAction<Object>() {
public
Object run() throws Exception {
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
return
null
;
}
},getAccessControlContext());
}
catch
(PrivilegedActionException pae) {
throw
pae.getException();
}
}
else
{
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
}
}
if
(mbd !=
null
) {
String initMethodName = mbd.getInitMethodName();
//判断是否指定了init-method方法,如果指定了init-method方法,则再调用制定的init-method
if
(initMethodName !=
null
&& !(isInitializingBean &&
"afterPropertiesSet"
.
equals
(initMethodName)) &&
!mbd.isExternallyManagedInitMethod(initMethodName)) {
//进一步查看该方法的源码,可以发现init-method方法中指定的方法是通过反射实现
invokeCustomInitMethod(beanName, bean, mbd);
}
}
}
|
总结:
- spring为bean提供了两种初始化bean的方式,实现InitializingBean接口,实现afterPropertiesSet方法,或者在配置文件中同过init-method指定,两种方式可以同时使用
- 实现InitializingBean接口是直接调用afterPropertiesSet方法,比通过反射调用init-method指定的方法效率相对来说要高点。但是init-method方式消除了对spring的依赖
- 如果调用afterPropertiesSet方法时出错,则不调用init-method指定的方法。
InitializingBean接口为bean提供了初始化方法的方式,它只包括afterPropertiesSet方法,凡是继承该接口的类,在初始化bean的时候会执行该方法。
测试程序如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
|
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;
public
class
InitBean implements InitializingBean{
public
void
afterPropertiesSet() throws Exception {
System.
out
.println(
"启动时自动执行 afterPropertiesSet..."
);
}
public
void
init(){
System.
out
.println(
"init method..."
);
}
}
|
配置文件如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
<?xml version=
"1.0"
encoding=
"UTF-8"
?>
<beans xmlns=
"http://www.springframework.org/schema/beans"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
xmlns:context=
"http://www.springframework.org/schema/context"
xmlns:dubbo=
"http://code.alibabatech.com/schema/dubbo"
xmlns:mvc=
"http://www.springframework.org/schema/mvc"
xmlns:aop=
"http://www.springframework.org/schema/aop"
xmlns:tx=
"http://www.springframework.org/schema/tx"
xsi:schemaLocation=
"http:
//www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http:
//www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http:
//www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http:
//www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http:
//www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http:
//code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd"
default
-lazy-init=
"true"
>
<bean id=
"initBean"
class
=
"com.netease.nsip.spring.InitBean"
init-method=
"init"
> </bean>
</beans>
|
Main主程序如下:
1
2
3
4
5
6
7
8
9
10
|
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
public
class
Main {
public
static
void
main(String[] args) {
ApplicationContext context =
new
FileSystemXmlApplicationContext(
"classpath:/applicationContext-core.xml"
);
context.getBean(
"initBean"
);
}
}
|
运行Main程序,打印如下结果:
1
2
|
启动时自动执行 afterPropertiesSet...
init method...
|
这说明在spring初始化bean的时候,如果bean实现了InitializingBean接口,会自动调用afterPropertiesSet方法。
问题:实现InitializingBean接口与在配置文件中指定init-method有什么不同?由结果可看出,在spring初始化bean的时候,如果该bean是实现了InitializingBean接口,并且同时在配置文件中指定了init-method,系统则是先调用afterPropertiesSet方法,然后在调用init-method中指定的方法。这方式在spring中是怎么实现的?通过查看spring的加载bean的源码类(AbstractAutowireCapableBeanFactory)可看出其中奥妙AbstractAutowireCapableBeanFactory类中的invokeInitMethods讲解的非常清楚,源码如下:
1
2
3
4
5
6
7
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17
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protected
void
invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
throws Throwable {
//判断该bean是否实现了实现了InitializingBean接口,如果实现了InitializingBean接口,则只掉调用bean的afterPropertiesSet方法
boolean isInitializingBean = (bean instanceof InitializingBean);
if
(isInitializingBean && (mbd ==
null
|| !mbd.isExternallyManagedInitMethod(
"afterPropertiesSet"
))) {
if
(logger.isDebugEnabled()) {
logger.debug(
"Invoking afterPropertiesSet() on bean with name '"
+ beanName +
"'"
);
}
if
(System.getSecurityManager() !=
null
) {
try
{
AccessController.doPrivileged(
new
PrivilegedExceptionAction<Object>() {
public
Object run() throws Exception {
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
return
null
;
}
},getAccessControlContext());
}
catch
(PrivilegedActionException pae) {
throw
pae.getException();
}
}
else
{
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
}
}
if
(mbd !=
null
) {
String initMethodName = mbd.getInitMethodName();
//判断是否指定了init-method方法,如果指定了init-method方法,则再调用制定的init-method
if
(initMethodName !=
null
&& !(isInitializingBean &&
"afterPropertiesSet"
.
equals
(initMethodName)) &&
!mbd.isExternallyManagedInitMethod(initMethodName)) {
//进一步查看该方法的源码,可以发现init-method方法中指定的方法是通过反射实现
invokeCustomInitMethod(beanName, bean, mbd);
}
}
}
|
总结:
- spring为bean提供了两种初始化bean的方式,实现InitializingBean接口,实现afterPropertiesSet方法,或者在配置文件中同过init-method指定,两种方式可以同时使用
- 实现InitializingBean接口是直接调用afterPropertiesSet方法,比通过反射调用init-method指定的方法效率相对来说要高点。但是init-method方式消除了对spring的依赖
- 如果调用afterPropertiesSet方法时出错,则不调用init-method指定的方法。
InitializingBean接口为bean提供了初始化方法的方式,它只包括afterPropertiesSet方法,凡是继承该接口的类,在初始化bean的时候会执行该方法。
测试程序如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
|
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Service;
public
class
InitBean implements InitializingBean{
public
void
afterPropertiesSet() throws Exception {
System.
out
.println(
"启动时自动执行 afterPropertiesSet..."
);
}
public
void
init(){
System.
out
.println(
"init method..."
);
}
}
|
配置文件如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
<?xml version=
"1.0"
encoding=
"UTF-8"
?>
<beans xmlns=
"http://www.springframework.org/schema/beans"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
xmlns:context=
"http://www.springframework.org/schema/context"
xmlns:dubbo=
"http://code.alibabatech.com/schema/dubbo"
xmlns:mvc=
"http://www.springframework.org/schema/mvc"
xmlns:aop=
"http://www.springframework.org/schema/aop"
xmlns:tx=
"http://www.springframework.org/schema/tx"
xsi:schemaLocation=
"http:
//www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http:
//www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http:
//www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http:
//www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http:
//www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http:
//code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd"
default
-lazy-init=
"true"
>
<bean id=
"initBean"
class
=
"com.netease.nsip.spring.InitBean"
init-method=
"init"
> </bean>
</beans>
|
Main主程序如下:
1
2
3
4
5
6
7
8
9
10
|
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
public
class
Main {
public
static
void
main(String[] args) {
ApplicationContext context =
new
FileSystemXmlApplicationContext(
"classpath:/applicationContext-core.xml"
);
context.getBean(
"initBean"
);
}
}
|
运行Main程序,打印如下结果:
1
2
|
启动时自动执行 afterPropertiesSet...
init method...
|
这说明在spring初始化bean的时候,如果bean实现了InitializingBean接口,会自动调用afterPropertiesSet方法。
问题:实现InitializingBean接口与在配置文件中指定init-method有什么不同?由结果可看出,在spring初始化bean的时候,如果该bean是实现了InitializingBean接口,并且同时在配置文件中指定了init-method,系统则是先调用afterPropertiesSet方法,然后在调用init-method中指定的方法。这方式在spring中是怎么实现的?通过查看spring的加载bean的源码类(AbstractAutowireCapableBeanFactory)可看出其中奥妙AbstractAutowireCapableBeanFactory类中的invokeInitMethods讲解的非常清楚,源码如下:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
protected
void
invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
throws Throwable {
//判断该bean是否实现了实现了InitializingBean接口,如果实现了InitializingBean接口,则只掉调用bean的afterPropertiesSet方法
boolean isInitializingBean = (bean instanceof InitializingBean);
if
(isInitializingBean && (mbd ==
null
|| !mbd.isExternallyManagedInitMethod(
"afterPropertiesSet"
))) {
if
(logger.isDebugEnabled()) {
logger.debug(
"Invoking afterPropertiesSet() on bean with name '"
+ beanName +
"'"
);
}
if
(System.getSecurityManager() !=
null
) {
try
{
AccessController.doPrivileged(
new
PrivilegedExceptionAction<Object>() {
public
Object run() throws Exception {
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
return
null
;
}
},getAccessControlContext());
}
catch
(PrivilegedActionException pae) {
throw
pae.getException();
}
}
else
{
//直接调用afterPropertiesSet
((InitializingBean) bean).afterPropertiesSet();
}
}
if
(mbd !=
null
) {
String initMethodName = mbd.getInitMethodName();
//判断是否指定了init-method方法,如果指定了init-method方法,则再调用制定的init-method
if
(initMethodName !=
null
&& !(isInitializingBean &&
"afterPropertiesSet"
.
equals
(initMethodName)) &&
!mbd.isExternallyManagedInitMethod(initMethodName)) {
//进一步查看该方法的源码,可以发现init-method方法中指定的方法是通过反射实现
invokeCustomInitMethod(beanName, bean, mbd);
}
}
}
|
总结:
- spring为bean提供了两种初始化bean的方式,实现InitializingBean接口,实现afterPropertiesSet方法,或者在配置文件中同过init-method指定,两种方式可以同时使用
- 实现InitializingBean接口是直接调用afterPropertiesSet方法,比通过反射调用init-method指定的方法效率相对来说要高点。但是init-method方式消除了对spring的依赖
- 如果调用afterPropertiesSet方法时出错,则不调用init-method指定的方法。