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java中實(shí)現(xiàn)map與對(duì)象相互轉(zhuǎn)換的方法有哪些

發(fā)布時(shí)間:2020-07-11 10:46:00 來源:億速云 閱讀:2856 作者:清晨 欄目:開發(fā)技術(shù)

這篇文章主要介紹java中實(shí)現(xiàn)map與對(duì)象相互轉(zhuǎn)換的方法有哪些,文中介紹的非常詳細(xì),具有一定的參考價(jià)值,感興趣的小伙伴們一定要看完!

最近,研究map與java對(duì)象之間的相互轉(zhuǎn)換,總結(jié)了5種方法:

第一種:使用org.apache.commons.beanutils轉(zhuǎn)換

用到的主要jar包:commons-beanutils-1.9.3.jar

//map轉(zhuǎn)java對(duì)象
public static Object mapToObject(Map<String, Object> map, Class<&#63;> beanClass)
  throws Exception {
 if (map == null) {
  return null;
 }
 Object obj = beanClass.newInstance();
 BeanUtils.populate(obj, map);
 return obj;
 }
 
//java對(duì)象轉(zhuǎn)map
public static Map<&#63;, &#63;> objectToMap(Object obj) {
 if (obj == null)
  return null;
 return new BeanMap(obj);
 }

在使用該方法進(jìn)行java對(duì)象轉(zhuǎn)map時(shí),可能會(huì)發(fā)生以下錯(cuò)誤:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/collections/Transformer
 at java.lang.ClassLoader.defineClass1(Native Method)
 at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
 at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
 at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
 at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
 at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
 at org.apache.commons.beanutils.BeanMap.createTypeTransformers(BeanMap.java:132)
 at org.apache.commons.beanutils.BeanMap.<clinit>(BeanMap.java:68)
 at com.example2.pojo.PojoToMap.objectToMap(PojoToMap.java:23)
 at com.example2.pojo.PojoToMap.main(PojoToMap.java:16)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.collections.Transformer
 at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
 ... 16 more

解決方法見本人的另一篇文章:https://www.jb51.net/article/190471.htm

第二種:使用Introspector轉(zhuǎn)換

//map轉(zhuǎn)java對(duì)象
public static Object mapToObject(Map<String, Object> map, Class<&#63;> beanClass) throws Exception {
    if (map == null)
      return null;
    Object obj = beanClass.newInstance();
    BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
    PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
    for (PropertyDescriptor property : propertyDescriptors) {
      Method setter = property.getWriteMethod();
      if (setter != null) {
        setter.invoke(obj, map.get(property.getName()));
      }
    }
    return obj;
  }
 
//java對(duì)象轉(zhuǎn)map
public static Map<String, Object> 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 &#63; getter.invoke(obj) : null;
 map.put(key, value);
 }
 return map;
}

第三種:使用reflect轉(zhuǎn)換

//map轉(zhuǎn)java對(duì)象
public static Object mapToObject(Map<String, Object> map, Class<&#63;> 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對(duì)象轉(zhuǎn)map
public static Map<String, Object> objectToMap(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;
}

第四種:使用net.sf.cglib.beans.BeanMap轉(zhuǎn)換

用到的主要jar包:cglib-2.2.2.jar

//map轉(zhuǎn)java對(duì)象
public static Object mapToObject(Map<String, Object> map, Class<&#63;> beanClass) throws Exception {
  Object object = beanClass.newInstance();
  BeanMap beanMap = BeanMap.create(object);
  beanMap.putAll(map);
  return object;
}
 
//java對(duì)象轉(zhuǎn)map
public static Map<String, Object> objectToMap(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;
}

在使用本方法進(jìn)行map轉(zhuǎn)java對(duì)象時(shí),可能會(huì)發(fā)生以下錯(cuò)誤:

Exception in thread "main" java.lang.NoClassDefFoundError: org/objectweb/asm/Type
 at net.sf.cglib.core.TypeUtils.parseType(TypeUtils.java:184)
 at net.sf.cglib.core.KeyFactory.<clinit>(KeyFactory.java:66)
 at net.sf.cglib.beans.BeanMap$Generator.<clinit>(BeanMap.java:64)
 at net.sf.cglib.beans.BeanMap.create(BeanMap.java:56)
 at com.example2.pojo.MapToPojo.mapToBean(MapToPojo.java:27)
 at com.example2.pojo.MapToPojo.main(MapToPojo.java:18)
Caused by: java.lang.ClassNotFoundException: org.objectweb.asm.Type
 at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
 at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
 ... 6 more

解決方法見本人的另一篇文章:https://www.jb51.net/article/190474.htm

第五種:使用json轉(zhuǎn)換

用到的主要jar包:fastjson-1.2.54.jar

//map轉(zhuǎn)java對(duì)象
public static Object mapToObject(Map<String, Object> map, Class<&#63;> beanClass) throws Exception {
  String jsonStr = JSONObject.toJSONString(map);
  return JSONObject.parseObject(jsonStr, beanClass);
}
 
//java對(duì)象轉(zhuǎn)map
public static Map<String, Object> objectToMap(Object obj) {
  String jsonStr = JSONObject.toJSONString(obj);
  return JSONObject.parseObject(jsonStr);
}

以上是java中實(shí)現(xiàn)map與對(duì)象相互轉(zhuǎn)換的方法有哪些的所有內(nèi)容,感謝各位的閱讀!希望分享的內(nèi)容對(duì)大家有幫助,更多相關(guān)知識(shí),歡迎關(guān)注億速云行業(yè)資訊頻道!

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