spring源码分析之FactoryBean

2023年4月2日 416次阅读 来源: Spring Cloud

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
]

    原文作者：Spring Cloud
    原文地址: https://blog.csdn.net/hepei120/article/details/78129431
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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