Java 通过反射动态调用对象方法

       业务场景：不具体方法调用，根据方法名和方法入参来调用对应的方法

1. 被调用对象        

import com.alibaba.fastjson.JSON;

public class Demo {

    // 测试传入不同类型参数
    public static String test1(String name,Integer age){
        System.out.println("入參打印：name:"+name+",age:"+age);
        return "test1执行成功！";
    }

    // 测试传入对象
    public static String test2(User user){
        System.out.println("入參打印：user:"+ JSON.toJSONString(user));
        return "test2执行成功！";
    }
}

       对象参数：        

public class User {

    private String name;

    private Integer age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

2.反射工具类 

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.util.ArrayList;
import java.util.List;

public class ReflectionUtils {

    public static void main(String args[]){
        JSONObject reParams = new JSONObject();
        reParams.put("name","张三");
        reParams.put("age","23");

        System.out.println("==============测试test1调用==============");
        invokeMethod("test1",reParams);
        System.out.println("==============测试test2调用==============");
        invokeMethod("test2",reParams);
    }

    public static Object invokeMethod(String methodName,JSONObject reqParams){

        Class<?> clazz;
        ReflectionUtils utils = new ReflectionUtils();
        ObjectMapper objectMapper = new ObjectMapper();

        try {
            clazz = Class.forName("com.example.demo.util.Demo");
            Method[] methods = clazz.getDeclaredMethods();
            for(Method method:methods){
                if(methodName.equals(method.getName())){
                    Parameter[] parameters = method.getParameters();
                    List<Object> paramsValue = new ArrayList<>();
                    for(Parameter parameter:parameters){
                        System.out.println("参数类型："+parameter.getType().getName());
                        if(parameter.getType().getName()!=null&&parameter.getType().getName().contains("com.example.demo.util.User")){
                            Class<?> beanClazz = Class.forName(parameter.getType().getName());
                            Object obj = beanClazz.newInstance();
                            Field[] fields = beanClazz.getDeclaredFields();
                            for(Field field:fields){
                                Class<?> type = field.getType();
                                String fieldName = field.getName();
                                // 类型转换
                                Object value = objectMapper.convertValue(reqParams.get(fieldName), type);
                                if(value != null){
                                    String methodNm = "set"+fieldName.substring(0, 1).toUpperCase()+fieldName.substring(1);
                                    Method methodField = obj.getClass().getMethod(methodNm,type);
                                    methodField.invoke(obj,value);
                                }
                            }
                            System.out.println("对象参数："+ JSON.toJSONString(obj));
                            paramsValue.add(obj);
                        }else{
                            Class<?> type = parameter.getType();
                            String name = parameter.getName();
                            Object value = objectMapper.convertValue(reqParams.get(name), type);
                            paramsValue.add(value);
                        }
                    }
                    Object[] array = paramsValue.toArray();
                    Object invoke = method.invoke(utils, array);
                    System.out.println("反射调用结果:"+ JSON.toJSONString(invoke));
                    return invoke;
                }
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
        return null;
    }
}

3.pom 添加依赖和插件

  <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.31</version>
        </dependency>

  通过com.fastxml.jackson的ObjectMapper对象进行转换,用于转换参数类型

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.2</version>
</dependency>

 反射获取真实参数名，参考：https://blog.youkuaiyun.com/lvhu123/article/details/98873473

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <compilerArgs>
                        <arg>-parameters</arg>
                    </compilerArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>

4.打印结果