java 使用反射转换对象 Object to Map

Object to Map 转换的三种方法
就是把对象以及其对应的属性名 和属性值， 映射到一个Map中

import java.beans.BeanInfo;  
import java.beans.IntrospectionException;  
import java.beans.Introspector;  
import java.beans.PropertyDescriptor;  
import java.lang.reflect.Field;  
import java.lang.reflect.InvocationTargetException;  
import java.lang.reflect.Method;  
import java.util.HashMap;  
import java.util.Map;  


public class ObjectToMap {  

    public static void main(String[] args) throws IntrospectionException, InvocationTargetException, IllegalAccessException {  
        TestObject o = new TestObject();  
        o.setCity("beijing");  
        o.setName("bj");  
        o.setOrder("ASC");  

        ObjectToMap objectToMap = new ObjectToMap();  
        System.out.println("=========== Invoke objectToMapViaBeanInfo ===========");  
        objectToMap.objectToMapViaBeanInfo(o);  
        System.out.println("=========== Invoke objectToMapViaFields ===========");  
        objectToMap.objectToMapViaFields(o);  
        System.out.println("=========== Invoke objectToMapViaApacheTools ===========");  
        objectToMapViaApacheTools(o);  
    }  


    /** 
     * 通过Introspector 的方式复制属性值 
     * */  
    private static void objectToMapViaBeanInfo(TestObject o) throws IntrospectionException, InvocationTargetException, IllegalAccessException {  
        Map<String, Object> result = new HashMap<String, Object>();  
        BeanInfo info = Introspector.getBeanInfo(o.getClass());  
        for (PropertyDescriptor pd : info.getPropertyDescriptors()) {  
            Method reader = pd.getReadMethod();  
            //内容为null的过滤掉  
            if (reader == null || reader.invoke(o) == null) {  
                continue;  
            }  
           //默认继承Object类的属性，过滤掉  
            if (pd.getName().equalsIgnoreCase("class")) {  
                continue;  
            }  
            result.put(pd.getName(), reader.invoke(o));  
        }  

        for (String key : result.keySet()) {  
            System.out.println("Key:" + key + ";Value:" + result.get(key));  
        }  

    }  


    /** 
     * 通过getDeclaredFields 的方式复制属性值 
     *  getDeclaredFields方式不会返回父类的属性 
     * */  
    private static void objectToMapViaFields(TestObject o) throws IllegalAccessException {  
        Map<String, Object> resMap = new HashMap<String, Object>();  
        Field[] declaredFields = o.getClass().getDeclaredFields();  
        for (Field field : declaredFields) {  
            field.setAccessible(true);  
            //过滤内容为空的  
            if (field.get(o) == null) {  
                continue;  
            }  
            resMap.put(field.getName(), field.get(o));  
        }  
        printOut(resMap);  
    }  


    /** 
     * 通过Apache beanUtils的方式复制属性值 
     * 其内部实现方式同 方法1 
     * */  
    private static void objectToMapViaApacheTools(TestObject o) {  
        Map<String, Object> resMap = new org.apache.commons.beanutils.BeanMap(o);  
        printOut(resMap);  
    }  


    /** 
     * 打印结果 
     * */  
    private static void printOut(Map<String, Object> resMap) {  
        for (String key : resMap.keySet()) {  
            System.out.println("Key:" + key + ";Value:" + resMap.get(key));  
        }  
    }  


    /** 
     * 测试类 
     * */  
    public static class TestObject {  
        String city;  
        String name;  
        String order;  

        public String getOrder() {  
            return order;  
        }  

        public void setOrder(String order) {  
            this.order = order;        }  


        public String getName() {  
            return name;  
        }  

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

        public String getCity() {  
            return city;  
        }  

        public void setCity(String city) {  
            this.city = city;  
        }  
    }  
}

===================更新===================：

突然想不起来这种情况的应用场景了。那么是否可以转成JSONObject呢。

Student student = new Student();
JSONObject jsonObject =(JSONObject) JSONObject.toJSON(student);
System.out.print(jsonObject.toJSONString());

1、是为了转成字符串输出或存储？