提示：文章写完后，目录可以自动生成，如何生成可参考右边的帮助文档

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.LTDemoat 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javapublic 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mappublic 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.LTDemoat 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mappublic 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.LTDemoat 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mappublic 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.LTDemoat com.example.demo.map2bean.MapToBean.main(MapToBean.java:65)

总结

不想说啥…看着用吧