Unlock Spring Boot 3: Master MethodLocatingFactoryBean & MethodInvokingFactoryBean

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The tutorial focuses on two powerful Spring classes: MethodLocatingFactoryBean and MethodInvokingFactoryBean . Both are FactoryBean implementations that allow dynamic method lookup and invocation.

1. Environment

Spring Boot version 3.4.2 is used.

2. MethodLocatingFactoryBean (method lookup)

This class returns a java.lang.reflect.Method object based on a bean name and method name.

@Component("ps")
public class PersonService {
    public void save() {
        System.out.println("PersonService save method invoke...");
    }
    public void query(Integer id) {
        System.out.printf("PersonService query method id: %d%n", id);
    }
}

public class MethodLocatingFactoryBean implements FactoryBean<Method>, BeanFactoryAware {
    private String targetBeanName;
    private String methodName;
    private Method method;
    public Method getObject() throws Exception {
        return this.method;
    }
    public Class<Method> getObjectType() {
        return Method.class;
    }
    // ... other required methods
}

@Configuration
public class AppConfig {
    @Bean
    MethodLocatingFactoryBean methodLocatingFactoryBean() {
        MethodLocatingFactoryBean fb = new MethodLocatingFactoryBean();
        fb.setMethodName("save");
        fb.setTargetBeanName("ps");
        return fb;
    }
}

Inject the Method into another bean and invoke it:

@Component
public class BeanMethod {
    @Resource
    private Method method;
    @Resource
    private PersonService target;
    public Object invoke(Object... params) throws Exception {
        return method.invoke(target, params);
    }
}

@Resource
private BeanMethod bm;
@Test
public void testSave() {
    bm.invoke();
}
// Output: PersonService save method invoke...

3. Configuring Method Parameters

When the target method has parameters, the full qualified name must be used, e.g., fb.setMethodName("query(java.lang.Integer)"). Primitive types can be specified directly, such as query(int).

4. MethodInvokingFactoryBean (method invocation)

public class MethodInvokingFactoryBean extends MethodInvokingBean implements FactoryBean<Object> {
    private Object singletonObject;
    public void afterPropertiesSet() throws Exception {
        prepare();
        if (this.singleton) {
            this.initialized = true;
            this.singletonObject = invokeWithTargetException();
        }
    }
    public Object getObject() throws Exception {
        if (this.singleton) {
            return this.singletonObject;
        }
        return null;
    }
}

Static method example:

public class PersonFactory {
    public static PersonService getPs() {
        return new PersonService();
    }
    public PersonService getInstance() {
        return new PersonService();
    }
}

@Configuration
public class AppConfig {
    @Bean
    MethodInvokingFactoryBean methodInvokingFactoryBean() {
        MethodInvokingFactoryBean fb = new MethodInvokingFactoryBean();
        fb.setTargetClass(PersonFactory.class);
        fb.setTargetMethod("getPs");
        return fb;
    }
}

@Resource
private PersonService ps;
@Test
public void testSave() {
    ps.query(10);
}
// Output: PersonService query method id: 10

Non‑static method configuration:

MethodInvokingFactoryBean fb = new MethodInvokingFactoryBean();
fb.setTargetObject(new PersonFactory());
fb.setTargetMethod("getInstance");

The article ends by asking readers if they can think of scenarios for using these two classes and encourages likes, shares, and follows.