常用的map转bean互转方法

今天药忘吃喽~ 2024-03-26 17:12 78阅读 0赞

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#### 常用的map转bean互转方法 ####

*  一、hutool工具类
 *  二、fastjson工具类
 *  三、beanutils\_BeanUtils工具类 不太好用
 *  四、cglib BeanMap工具类 不太好用
 *  五、reflect 反射来玩 不太好玩
 *  六、Introspector类 不太好用
 *  总结

## 一、hutool工具类 ##

这个很常用，还支持将蛇形转成驼，如：apply\_time 会赋值到applyTime上

LTDemo ltDemo = BeanUtil.mapToBean(map, LTDemo.class, true, CopyOptions.create());
            Map<String, Object> demoMap = BeanUtil.beanToMap(ltDemo);
            
            System.out.println("输出map -> bean: " + ltDemo.toString());
            System.out.println("输出bean -> map : " + demoMap);
            System.out.println(ltDemo.getApplyTime());
            System.out.println(ltDemo.getChildren());
            ltDemo.getChildren().forEach(children -> System.out.println(children.toString()));
            ltDemo.getChildren().forEach(children -> System.out.println(children.getAddress()));

输出原生map: {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:21:01 CST 2023, age=2}], name=张三, apply_time=Fri Mar 03 17:21:01 CST 2023, age=20}
    输出map -> bean: LTDemo(name=张三, age=20, address=上海市, applyTime=Fri Mar 03 17:21:01 CST 2023, children=[LTDemo(name=小张, age=2, address=上海市, applyTime=Fri Mar 03 17:21:01 CST 2023, children=[])])
    输出bean -> map : {
        name=张三, age=20, address=上海市, applyTime=Fri Mar 03 17:21:01 CST 2023, children=[LTDemo(name=小张, age=2, address=上海市, applyTime=Fri Mar 03 17:21:01 CST 2023, children=[])]}
    Fri Mar 03 17:21:01 CST 2023
    [LTDemo(name=小张, age=2, address=上海市, applyTime=Fri Mar 03 17:21:01 CST 2023, children=[])]
    LTDemo(name=小张, age=2, address=上海市, applyTime=Fri Mar 03 17:21:01 CST 2023, children=[])
    上海市

## 二、fastjson工具类 ##

这个也很常用，也支持将蛇型转成驼峰，  
如：`apply_time` 会赋值到`applyTime`上

LTDemo ltDemo = JSONObject.parseObject(JSONObject.toJSONString(map), LTDemo.class);
            Map demoMap = JSONObject.parseObject(JSONObject.toJSONString(ltDemo), Map.class);
            
            System.out.println("输出map -> bean: " + ltDemo.toString());
            System.out.println("输出bean -> map : " + demoMap);
            System.out.println(ltDemo.getApplyTime());
            System.out.println(ltDemo.getChildren());
            ltDemo.getChildren().forEach(children -> System.out.println(children.toString()));
            ltDemo.getChildren().forEach(children -> System.out.println(children.getAddress()));

输出原生map: {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:21:59 CST 2023, age=2}], name=张三, apply_time=Fri Mar 03 17:21:59 CST 2023, age=20}
    输出map -> bean: LTDemo(name=张三, age=20, address=上海市, applyTime=Fri Mar 03 17:21:59 CST 2023, children=[LTDemo(name=小张, age=2, address=上海市, applyTime=Fri Mar 03 17:21:59 CST 2023, children=[])])
    输出bean -> map : {
        address=上海市, children=[{
        "address":"上海市","children":[],"name":"小张","applyTime":1677835319813,"age":2}], name=张三, applyTime=1677835319813, age=20}
    Fri Mar 03 17:21:59 CST 2023
    [LTDemo(name=小张, age=2, address=上海市, applyTime=Fri Mar 03 17:21:59 CST 2023, children=[])]
    LTDemo(name=小张, age=2, address=上海市, applyTime=Fri Mar 03 17:21:59 CST 2023, children=[])
    上海市

## 三、beanutils\_BeanUtils工具类 不太好用 ##

嵌套型map，转换会有问题，且`不支持蛇型转成驼峰`

//-------------------    beanutils_BeanUtils  -----------------
        //map转java对象
        public static <T> T beanUtils_mapToObject(Map<String, Object> map, Class<T> clazz) throws Exception {
        
            if (map == null) {
        
                return null;
            }
            T bean = clazz.newInstance();
            BeanUtils.populate(bean, map);
            return bean;
        }

LTDemo ltDemo = beanUtils_mapToObject(map, LTDemo.class);
            System.out.println("输出map -> bean: " + ltDemo.toString());
            System.out.println(ltDemo.getApplyTime());
            System.out.println(ltDemo.getChildren().get(0).getApplyTime());

输出map -> bean: LTDemo(name=张三, age=20, address=上海市, applyTime=Fri Mar 03 17:04:38 CST 2023, children=[{
        address=上海市, name=小张, applyTime=Fri Mar 03 17:04:38 CST 2023, age=2}])
    Fri Mar 03 17:04:38 CST 2023
    Exception in thread "main" java.lang.ClassCastException: java.util.HashMap cannot be cast to com.example.demo.map2bean.LTDemo
    	at com.example.demo.map2bean.MapToBean.main(MapToBean.java:73)

## 四、cglib BeanMap工具类 不太好用 ##

这个也很常用，也支持将蛇形转成驼，如：apply\_time 会赋值到applyTime上

import net.sf.cglib.beans.BeanMap;
    
        // -------------------   cglib BeanMap  -------------------
        //map对象转java
        public static <T> T BeanMapMapToObject(Map<String, Object> map, Class<T> beanClass) throws Exception {
        
            T object = beanClass.newInstance();
            BeanMap beanMap = BeanMap.create(object);
            beanMap.putAll(map);
            return object;
        }
    
        //java对象转map
        public static Map<String, Object> BeanMapObjectToMap(Object obj) {
        
            Map<String, Object> map = Maps.newHashMap();
            if (obj != null) {
        
                BeanMap beanMap = BeanMap.create(obj);
                for (Object key : beanMap.keySet()) {
        
                    map.put(key + "", beanMap.get(key));
                }
            }
            return map;
        }

LTDemo ltDemo = beanMapMapToObject(map, LTDemo.class);
            Map demoMap = beanMapObjectToMap(ltDemo);
            System.out.println("输出map -> bean: " + ltDemo.toString());
            System.out.println("输出bean -> map : " + demoMap);
            System.out.println(ltDemo.getApplyTime());
            System.out.println(ltDemo.getChildren());
            ltDemo.getChildren().forEach(children -> System.out.println(children.toString()));

输出原生map: {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:12:45 CST 2023, age=2}], name=张三, apply_time=Fri Mar 03 17:12:45 CST 2023, age=20}
    输出map -> bean: LTDemo(name=张三, age=20, address=上海市, applyTime=null, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:12:45 CST 2023, age=2}])
    输出bean -> map : {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:12:45 CST 2023, age=2}], name=张三, applyTime=null, age=20}
    null
    [{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:12:45 CST 2023, age=2}]
    Exception in thread "main" java.lang.ClassCastException: java.util.HashMap cannot be cast to com.example.demo.map2bean.LTDemo
    	at java.util.ArrayList.forEach(ArrayList.java:1259)
    	at com.example.demo.map2bean.MapToBean.main(MapToBean.java:75)

## 五、reflect 反射来玩 不太好玩 ##

//-------------------   reflect     -------------------
        //map转java对象
        public static Object reflectMapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
        
            if (map == null) {
        
                return null;
            }
            Object object = beanClass.newInstance();
            Field[] fields = beanClass.getDeclaredFields();
            for (Field field : fields) {
        
                int mod = field.getModifiers();
                if (Modifier.isFinal(mod) || Modifier.isStatic(mod)) {
        
                    continue;
                }
                field.setAccessible(true);
                field.set(object, map.get(field.getName()));
            }
            return object;
        }
    
        //java对象转map
        public static Map<String, Object> reflectObjectToMap(Object obj) throws Exception {
        
            if (obj == null) {
        
                return null;
            }
            Map<String, Object> map = new HashMap<String, Object>();
            Field[] declaredFields = obj.getClass().getDeclaredFields();
            for (Field field : declaredFields) {
        
                field.setAccessible(true);
                map.put(field.getName(), field.get(obj));
            }
            return map;
        }

LTDemo ltDemo = reflectMapToObject(map,LTDemo.class);
            Map demoMap = reflectObjectToMap(ltDemo);
            System.out.println("输出map -> bean: " + ltDemo.toString());
            System.out.println("输出bean -> map : " + demoMap);
            System.out.println(ltDemo.getApplyTime());
            System.out.println(ltDemo.getChildren());
            ltDemo.getChildren().forEach(children -> System.out.println(children.toString()));

输出原生map: {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:16:35 CST 2023, age=2}], name=张三, apply_time=Fri Mar 03 17:16:35 CST 2023, age=20}
    输出map -> bean: LTDemo(name=张三, age=20, address=上海市, applyTime=null, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:16:35 CST 2023, age=2}])
    输出bean -> map : {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:16:35 CST 2023, age=2}], name=张三, applyTime=null, age=20}
    null
    [{
        address=上海市, name=小张, apply_time=Fri Mar 03 17:16:35 CST 2023, age=2}]
    Exception in thread "main" java.lang.ClassCastException: java.util.HashMap cannot be cast to com.example.demo.map2bean.LTDemo
    	at java.util.ArrayList.forEach(ArrayList.java:1259)
    	at com.example.demo.map2bean.MapToBean.main(MapToBean.java:84)

## 六、Introspector类 不太好用 ##

这个用起来，只能转换第一层，而且不支持蛇型转驼峰

import java.beans.BeanInfo;
    import java.beans.Introspector;
    import java.beans.PropertyDescriptor;
    
     //----------------- Introspector    ------------------
    
        //map转java对象
        public static <T> T introspector_mapToObject(Map<String, Object> map, Class<T> clazz) throws Exception {
        
            if (map == null) {
        
                return null;
            }
            T bean = clazz.newInstance();
            BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass());
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            for (PropertyDescriptor property : propertyDescriptors) {
        
                Method setter = property.getWriteMethod();
                if (setter != null) {
        
                    setter.invoke(bean, map.get(property.getName()));
                }
            }
            return bean;
        }
    
        //java对象转map
        public static Map<String, Object> introspector_objectToMap(Object obj) throws Exception {
        
            if (obj == null) {
        
                return null;
            }
            Map<String, Object> map = new HashMap<String, Object>();
            BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
            PropertyDescriptor[] propertyDescriptors = beanInfo
                    .getPropertyDescriptors();
            for (PropertyDescriptor property : propertyDescriptors) {
        
                String key = property.getName();
                if (key.compareToIgnoreCase("class") == 0) {
        
                    continue;
                }
                Method getter = property.getReadMethod();
                Object value = getter != null ? getter.invoke(obj) : null;
                map.put(key, value);
            }
            return map;
        }

LTDemo ltDemo = introspector_mapToObject(map, LTDemo.class);
            Map demoMap = introspector_objectToMap(ltDemo);
            System.out.println("输出map -> bean: " + ltDemo.toString());
            System.out.println("输出bean -> map : " + demoMap);
    
            System.out.println(ltDemo.getApplyTime());
    
            System.out.println(ltDemo.getChildren());
    
            System.out.println(ltDemo.getChildren().get(0).toString());

输出原生map: {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 16:56:37 CST 2023, age=2}], name=张三, apply_time=Fri Mar 03 16:56:37 CST 2023, age=20}
    输出map -> bean: LTDemo(name=张三, age=20, address=上海市, applyTime=null, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 16:56:37 CST 2023, age=2}])
    输出bean -> map : {
        address=上海市, children=[{
        address=上海市, name=小张, apply_time=Fri Mar 03 16:56:37 CST 2023, age=2}], name=张三, applyTime=null, age=20}
    null
    [{
        address=上海市, name=小张, apply_time=Fri Mar 03 16:56:37 CST 2023, age=2}]
    Exception in thread "main" java.lang.ClassCastException: java.util.HashMap cannot be cast to com.example.demo.map2bean.LTDemo
    	at com.example.demo.map2bean.MapToBean.main(MapToBean.java:65)

## 总结 ##

不想说啥…看着用吧