Spring Beans 自动装配 使用XML配置列子（带源码）

原文地址：http://websystique.com/spring/spring-beans-auto-wiring-example-using-xml-configuration/

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Bean 装配是为了提供需要完成任务所依赖bean。Spring中，bean可以通过手动和自动两种方式装配。

手动装配 : 通过 <property> 或者 <constructor> 标签中的ref 属性

<!-- default example (autowire="no") --><bean id="driver" class="com.websystique.spring.domain.Driver">    <property name="license" ref="license"/></bean> <bean id="license" class="com.websystique.spring.domain.License" >    <property name="number" value="123456ABCD"/></bean>

自动装配：使用<bean> 标签中的autowire

<bean id="application" class="com.websystique.spring.domain.Application" autowire="byName"/>

在此例中，bean将会通过Spring自动装配特性自动的装配。

有4种方式：

• autowire="byName" : 根据属性名自动装配。如果另外一个bean属性名于此相同则自动装配。
• autowire="byType" : 根据bean的类型进行自动装配。
• autowire="constructor" : 根据构造方法装自动装配。如果其他bean的构造参数和此相同则此bean将被装配到其他bean的构造方法。
• autowire="no" : 不自动装配。和通过ref指定一样。

1. autowire=”byName” 例子

package com.websystique.spring.domain; public class Application {     private ApplicationUser applicationUser;     public ApplicationUser getApplicationUser() {        return applicationUser;    }     public void setApplicationUser(ApplicationUser applicationUser) {        this.applicationUser = applicationUser;    }     @Override    public String toString() {        return "Application [applicationUser=" + applicationUser + "]";    }}

package com.websystique.spring.domain; public class ApplicationUser {     private String name;     public String getName() {        return name;    }     public void setName(String name) {        this.name = name;    }     @Override    public String toString() {        return "ApplicationUser [name=" + name + "]";    }}

<?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"    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">     <!-- byName example -->    <bean id="application" class="com.websystique.spring.domain.Application" autowire="byName"/>     <bean id="applicationUser" class="com.websystique.spring.domain.ApplicationUser" >        <property name="name" value="superUser"/>    </bean>  </beans>

application类的applicationUser属性 和 ApplicationUser bean的id相同。

package com.websystique.spring; import org.springframework.context.support.AbstractApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext; import com.websystique.spring.domain.Application; public class AppMain {    public static void main(String args[]){        AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");         //autowire=byName         Application application = (Application)context.getBean("application");        System.out.println("Application Details : "+application);    }}

运行结果：

Application Details : Application [applicationUser=ApplicationUser [name=superUser]]

2. autowire=”byType”例子

package com.websystique.spring.domain; public class Employee {     private EmployeeAddress address;     public EmployeeAddress getAddress() {        return address;    }     public void setAddress(EmployeeAddress address) {        this.address = address;    }     @Override    public String toString() {        return "Employee [address=" + address + "]";    }}

package com.websystique.spring.domain; public class EmployeeAddress {     private String Street;    private String city;     public String getStreet() {        return Street;    }     public void setStreet(String street) {        Street = street;    }     public String getCity() {        return city;    }     public void setCity(String city) {        this.city = city;    }     @Override    public String toString() {        return "EmployeeAddress [Street=" + Street + ", city=" + city + "]";    }}

<?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"    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">     <!-- byType example -->    <bean id="employee" class="com.websystique.spring.domain.Employee" autowire="byType"/>     <bean id="employeeAddress" class="com.websystique.spring.domain.EmployeeAddress" >        <property name="street" value="112/223,SantaVila"/>        <property name="city" value="Nebraska"/>    </bean> </beans>

Employee 类中 EmployeeAddress address 和employeeAddress 并不相同，但是是按照类型注入。所以可以装配进去。

运行：

package com.websystique.spring; import org.springframework.context.support.AbstractApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext; import com.websystique.spring.domain.Employee; public class AppMain {    public static void main(String args[]){        AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");         //autowire=byType        Employee employee = (Employee)context.getBean("employee");        System.out.println("Employee Details : "+employee);    }}

输出：

Employee Details : Employee [address=EmployeeAddress [Street=112/223,SantaVila, city=Nebraska]]

3. autowire=”constructor”

package com.websystique.spring.domain; public class Performer {         private Instrument instrument;         public Performer(Instrument instrument){        this.instrument = instrument;    }     @Override    public String toString() {        return "Performer [instrument=" + instrument + "]";    }}

package com.websystique.spring.domain; public class Instrument {     private String name;     public String getName() {        return name;    }     public void setName(String name) {        this.name = name;    }     @Override    public String toString() {        return "Instrument [name=" + name + "]";    }}

注意：Performer类有一个接收Instrument类型的参数的构造方法。

XML配置文件：

<?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"    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">     <!-- constructor example -->    <bean id="performer" class="com.websystique.spring.domain.Performer" autowire="constructor"/>     <bean id="instrument" class="com.websystique.spring.domain.Instrument" >        <property name="name" value="PIANO"/>    </bean> </beans>

Performer<span style="font-weight: bold;"><span style="font-family:Consolas, Bitstream Vera Sans Mono, Courier New, Courier, monospace;"><span style="font-size: 13px; line-height: 14.3px; white-space: pre; background-color: rgb(245, 245, 245);"><span style="color:#0000ff;"><span style="color: rgb(64, 64, 64); font-family: 'Open Sans', sans-serif; font-size: 15px; line-height: 22.5px;">类有一个接收Instrument类型的参数的构造方法。将在Spring 定义的id为instrument的装配进去，。</span></span></span></span></span>

<pre name="code" class="java">package com.websystique.spring; import org.springframework.context.support.AbstractApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext; import com.websystique.spring.domain.Performer; public class AppMain {    public static void main(String args[]){        AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");         //autowire=constructor        Performer performer = (Performer)context.getBean("performer");        System.out.println("Performer Details : "+performer);    } }

运行结果：

<pre name="code" class="plain">Performer Details : Performer [instrument=Instrument [name=PIANO]]

3. autowire=”no”

<pre name="code" class="java">package com.websystique.spring.domain; public class Driver {     private License license;         public void setLicense(License license) {        this.license = license;    }     public License getLicense() {        return license;    }     @Override    public String toString() {        return "Driver [license=" + license + "]";    }}

package com.websystique.spring.domain; public class License {     private String number;     public String getNumber() {        return number;    }     public void setNumber(String number) {        this.number = number;    }     @Override    public String toString() {        return "License [number=" + number + "]";    }     }

配置文件：

<?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"    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">     <!-- default example (autowire="no") -->    <bean id="driver" class="com.websystique.spring.domain.Driver" autowire="no">        <property name="license" ref="license"/>    </bean>     <bean id="license" class="com.websystique.spring.domain.License" >        <property name="number" value="123456ABCD"/>    </bean> </beans>

autowire="no" 没有什么作用。可以不写。只是不自动装载。

运行：

package com.websystique.spring; import org.springframework.context.support.AbstractApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext; import com.websystique.spring.domain.Driver; public class AppMain {    public static void main(String args[]){        AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");         //autowire=default        Driver driver = (Driver)context.getBean("driver");        System.out.println("Driver Details : "+driver);          }}

结果：

Driver Details : Driver [license=License [number=123456ABCD]]

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