Métodos de conversão de mapa em feijão comumente usados

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1. classe de ferramenta hutool

Isto é muito comumente usado. Ele também suporta a conversão de uma forma de cobra em forma de camelo. Por exemplo: apply_time será atribuído a applyTime.

        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

2. Classe de ferramenta Fastjson

Isso também é muito comumente usado. Ele também suporta a conversão da forma de cobra em caixa de camelo.
Por exemplo: apply_timeserá atribuído ao applyTimeacima

        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

3. A classe de ferramenta beanutils_BeanUtils não é muito fácil de usar.

Mapa aninhado, haverá problemas com a conversão e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)

4. A classe de ferramenta cglib BeanMap não é fácil de usar

Isso também é muito comumente usado. Ele também suporta a conversão de uma forma de cobra em forma de camelo. Por exemplo: apply_time será atribuído a applyTime.

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)

5. Refletir Não é divertido brincar com a reflexão.

    //-------------------   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)

6. A classe Introspector não é fácil de usar

Ao usar isso, ele só pode converter a primeira camada e não suporta conversão em forma de cobra em forma de corcunda.

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)

Resumir

Não quero dizer nada... apenas use.