spring源码分析之FactoryBean

上文中描述spring加载bean的过程中，有一段关于FactoryBean的处理。所以今天讲一下FactoryBean。从名字上直译就是bean工厂,用来创建bean的。从Spring 3.0 开始， FactoryBean开始支持泛型，即接口声明改为FactoryBean 的形式：

package org.Springframework.beans.factory;    public interface FactoryBean<T> {     /** * 返回由FactoryBean创建的bean实例，如果isSingleton()返回true，则该实          例会放到Spring容器中单实例缓存池中。 */   T getObject() throws Exception;     /**   *返回FactoryBean创建的bean类型。   */   Class<?> getObjectType();   /***返回由FactoryBean创建的bean实例的作用域是singleton还是prototype。*/    boolean isSingleton();    } 

下面就开始写今天要演示的2个例子

import org.apache.commons.lang.builder.ToStringBuilder;import org.apache.commons.lang.builder.ToStringStyle;public class Student {    private String name;    private String classname;    private String age;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getClassname() {        return classname;    }    public void setClassname(String classname) {        this.classname = classname;    }    public String getAge() {        return age;    }    public void setAge(String age) {        this.age = age;    }    @Override    public String toString(){         return ToStringBuilder.reflectionToString(this,ToStringStyle.MULTI_LINE_STYLE);    }}

import org.apache.commons.lang.builder.ToStringBuilder;import org.apache.commons.lang.builder.ToStringStyle;import org.springframework.beans.factory.FactoryBean;public class StudentFactoryBean implements FactoryBean<Student> {    private String studentInfo;    @Override    public Student getObject() throws Exception {        Student s=new Student();        String[] studentInfos=studentInfo.split(",");        s.setName(studentInfos[0]);        s.setClassname(studentInfos[1]);        s.setAge(studentInfos[2]);        return s;    }    @Override    public Class<Student> getObjectType() {        return Student.class;    }    @Override    public boolean isSingleton() {        return false;    }    public String getStudentInfo() {        return studentInfo;    }    public void setStudentInfo(String studentInfo) {        this.studentInfo = studentInfo;    }    @Override    public String toString(){         return ToStringBuilder.reflectionToString(this,ToStringStyle.MULTI_LINE_STYLE);    }}

bean id="studentFactoryBean" class="com.eroadsf.springdemo.factorybean.StudentFactoryBean">        <property name="studentInfo" value="测试1,JAVA班,18"></property>    </bean>

public class Test {    @SuppressWarnings("deprecation")    public static void main(String[] args) {        XmlBeanFactory f=new XmlBeanFactory(new ClassPathResource("spring-context.xml"));        Student s=(Student) f.getBean("studentFactoryBean");        System.out.println("获取student:\n"+s);        StudentFactoryBean sf=(StudentFactoryBean) f.getBean("&studentFactoryBean");//spring就是用&这个来判断获取的是bean还是FactoryBean        System.out.println("获取StudentFactoryBean:\n"+sf);    }}

结果
获取student:
com.eroadsf.springdemo.factorybean.Student@9d63e96[
name=测试1
classname=JAVA班
age=18
]
获取StudentFactoryBean:
com.eroadsf.springdemo.factorybean.StudentFactoryBean@4d50a1ac[
studentInfo=测试1,JAVA班,18
]