本文实例讲述了Spring Bean基本管理。分享给大家供大家参考,具体如下:
一、使用setter方式完成依赖注入
下面是Bean和beans-config.xml文件。
1
2
3
4
|
public class HelloBean {
private String helloWord;
//...省略getter、setter方法
}
|
1
2
3
4
5
6
7
8
9
10
11
|
<? 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 = "onlyfun.caterpillar.HelloBean" >
< property name = "helloWord" >
< value >Hello!Justin!</ value >
</ property >
</ bean >
</ beans >
|
1
2
3
4
5
6
7
8
|
public class SpringDemo {
public static void main(String[] args) {
Resource rs = new FileSystemResource( "beans-config.xml" );
BeanFactory factory = new XmlBeanFactory(rs);
HelloBean hello = (HelloBean) factory.getBean( "helloBean" );
System.out.println(hello.getHelloWord());
}
}
|
二、使用constructor方式完成注入
1
2
3
4
5
6
7
8
9
10
11
12
|
public class HelloBean {
private String name;
private String helloWord;
// 建议有要无参数建构方法
public HelloBean() {
}
public HelloBean(String name, String helloWord) {
this .name = name;
this .helloWord = helloWord;
}
//...省略getter、setter方法
}
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
<? 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 = "onlyfun.caterpillar.HelloBean" >
< constructor-arg index = "0" >
< value >Justin</ value >
</ constructor-arg >
< constructor-arg index = "1" >
< value >Hello</ value >
</ constructor-arg >
</ bean >
</ beans >
|
1
2
3
4
5
6
7
8
9
10
11
|
public class SpringDemo {
public static void main(String[] args) {
ApplicationContext context =
new FileSystemXmlApplicationContext( "beans-config.xml" );
HelloBean hello = (HelloBean) context.getBean( "helloBean" );
System.out.print( "Name: " );
System.out.println(hello.getName());
System.out.print( "Word: " );
System.out.println(hello.getHelloWord());
}
}
|
三、属性参考
1
2
3
4
5
|
public class HelloBean {
private String helloWord;
private Date date;
//...省略getter、setter方法
}
|
1
2
3
4
5
6
7
8
9
10
11
|
< beans >
< bean id = "dateBean" class = "java.util.Date" />
< bean id = "helloBean" class = "onlyfun.caterpillar.HelloBean" >
< property name = "helloWord" >
< value >Hello!</ value >
</ property >
< property name = "date" >
< ref bean = "dateBean" />
</ property >
</ bean >
</ beans >
|
1
2
3
4
5
6
7
8
9
10
11
|
public class SpringDemo {
public static void main(String[] args) {
ApplicationContext context =
new FileSystemXmlApplicationContext( "beans-config.xml" );
HelloBean hello = (HelloBean) context.getBean( "helloBean" );
System.out.print(hello.getHelloWord());
System.out.print( " It's " );
System.out.print(hello.getDate());
System.out.println( "." );
}
}
|
四、“byType”自动绑定
将“三”中的配置文件改为下面,即可完成bean属性的按类型自动绑定。
1
2
3
4
5
6
7
8
|
< beans >
< bean id = "dateBean" class = "java.util.Date" />
< bean id = "helloBean" class = "onlyfun.caterpillar.HelloBean" autowire = "byType" >
< property name = "helloWord" >
< value >Hello!</ value >
</ property >
</ bean >
</ beans >
|
五、“byName”自动绑定
将“三”中的配置文件改为下面,即可完成bean属性的按名称自动绑定。
1
2
3
4
5
6
7
8
|
< beans >
< bean id = "dateBean" class = "java.util.Date" />
< bean id = "helloBean" class = "onlyfun.caterpillar.HelloBean" autowire = "byName" >
< property name = "helloWord" >
< value >Hello!</ value >
</ property >
</ bean >
</ beans >
|
六、“constructor”自动绑定
将“三”中的配置文件改为下面,即可完成bean属性的按构造方法自动绑定。在建立依赖关系时,Srping容器会试图比对容器中的Bean实例类型,及相关的构造方法上的参数类型,看看在类型上是否符合,如果有的话,则选用该构造方法来建立Bean实例。如果无法绑定,则抛出org.springframework.beans.factory.UnsatisfiedDependencyException异常。
1
2
3
4
5
6
7
8
|
< beans >
< bean id = "dateBean" class = "java.util.Date" />
< bean id = "helloBean" class = "onlyfun.caterpillar.HelloBean" autowire = "constructor" >
< property name = "helloWord" >
< value >Hello!</ value >
</ property >
</ bean >
</ beans >
|
六、“autodetect”自动绑定
将“三”中的配置文件改为下面,即可完成bean属性的自动绑定,这个自动绑定是Spring会尝试用入constructor来处理依赖关系的建立,如果不行,则再尝试用byType类建立依赖关系。
1
2
3
4
5
6
7
8
|
< beans >
< bean id = "dateBean" class = "java.util.Date" />
< bean id = "helloBean" class = "onlyfun.caterpillar.HelloBean" autowire = "autodetect" >
< property name = "helloWord" >
< value >Hello!</ value >
</ property >
</ bean >
</ beans >
|
七、依赖检查方式
在自动绑定中,由于没办法从定义文件中,清楚地看到是否每个属性都完成设定,为了确定某些依赖关系确实建立,您可以假如依赖检查,在<bean>标签使用时设定"dependency-check",可以有四种依赖检查方式:simple、objects、all、none。
simple:只检查简单的类型(像原生数据类型或字符串对象)属性是否完成依赖关系,。
objects:检查对象类型的属性是否完成依赖关系。
all:则检查全部的属性是否完成依赖关系。
none:设定是默认值,表示不检查依赖性。
1
2
3
4
5
6
7
8
|
< beans >
< bean id = "dateBean" class = "java.util.Date" />
< bean id = "helloBean" class = "onlyfun.caterpillar.HelloBean" autowire = "autodetect" dependeny-check = "all" >
< property name = "helloWord" >
< value >Hello!</ value >
</ property >
</ bean >
</ beans >
|
八、集合对象注入
对于像数组、List、Set、Map等集合对象,在注入前必须填充一些对象至集合中,然后再将集合对象注入至所需的Bean时,也可以交由Spring的IoC容器来自动维护或生成集合对象,并完成依赖注入。
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
38
39
40
41
42
|
public class SomeBean {
private String[] someStrArray;
private Some[] someObjArray;
private List someList;
private Map someMap;
public String[] getSomeStrArray() {
return someStrArray;
}
public void setSomeStrArray(String[] someStrArray) {
this .someStrArray = someStrArray;
}
public Some[] getSomeObjArray() {
return someObjArray;
}
public void setSomeObjArray(Some[] someObjArray) {
this .someObjArray = someObjArray;
}
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 class Some {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this .name = name;
}
public String toString() {
return name;
}
}
|
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
38
39
40
41
42
43
44
45
46
|
<? 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 = "onlyfun.caterpillar.Some" >
< property name = "name" >
< value >Justin</ value >
</ property >
</ bean >
< bean id = "some2" class = "onlyfun.caterpillar.Some" >
< property name = "name" >
< value >momor</ value >
</ property >
</ bean >
< bean id = "someBean" class = "onlyfun.caterpillar.SomeBean" >
< property name = "someStrArray" >
< list >
< value >Hello</ value >
< value >Welcome</ value >
</ list >
</ property >
< property name = "someObjArray" >
< list >
< ref bean = "some1" />
< ref bean = "some2" />
</ list >
</ property >
< property name = "someList" >
< list >
< value >ListTest</ value >
< ref bean = "some1" />
< ref bean = "some2" />
</ list >
</ property >
< property name = "someMap" >
< map >
< entry key = "MapTest" >
< value >Hello!Justin!</ value >
</ entry >
< entry key = "someKey1" >
< ref bean = "some1" />
</ entry >
</ map >
</ property >
</ bean >
</ beans >
|
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
|
public class SpringDemo {
public static void main(String[] args) {
ApplicationContext context =
new FileSystemXmlApplicationContext(
"beans-config.xml" );
SomeBean someBean =
(SomeBean) context.getBean( "someBean" );
// 取得数组型态依赖注入对象
String[] strs =
(String[]) someBean.getSomeStrArray();
Some[] somes =
(Some[]) someBean.getSomeObjArray();
for ( int i = 0 ; i < strs.length; i++) {
System.out.println(strs[i] + ","
+ somes[i].getName());
}
// 取得List型态依赖注入对象
System.out.println();
List someList = (List) someBean.getSomeList();
for ( int i = 0 ; i < someList.size(); i++) {
System.out.println(someList.get(i));
}
// 取得Map型态依赖注入对象
System.out.println();
Map someMap = (Map) someBean.getSomeMap();
System.out.println(someMap.get( "MapTest" ));
System.out.println(someMap.get( "someKey1" ));
}
}
|
希望本文所述对大家Java程序设计有所帮助。