Java code realizes mutual conversion between Map and Object and between Map and Json

/**
* 使用org.apache.commons.beanutils进行转换
*/
class A {
public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
if (map == null)
return null;
Object obj = beanClass.newInstance();
org.apache.commons.beanutils.BeanUtils.populate(obj, map);
return obj;
}
public static Map<?, ?> objectToMap(Object obj) {
if(obj == null)
return null;
return new org.apache.commons.beanutils.BeanMap(obj);
}
}
/**
* 使用Introspector进行转换
*/
class B {
public static Object mapToObject(Map<String, Object> map, Class<?> 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;
}
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 ? getter.invoke(obj) : null;
map.put(key, value);
}
return map;
}
}
/**
* 使用reflect进行转换
*/
class C {
public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) throws Exception {
if (map == null)
return null;
Object obj = beanClass.newInstance();
Field[] fields = obj.getClass().getDeclaredFields();
for (Field field : fields) {
int mod = field.getModifiers();
if(Modifier.isStatic(mod) || Modifier.isFinal(mod)){
continue;
}
field.setAccessible(true);
field.set(obj, map.get(field.getName()));
}
return obj;
}
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;
}
<p>} </p><p>
</p><p>from：http://www.open-open.com/code/view/1423280939826</p>

Map<String,Object> map = new HashMap<String,Object>();
map.put("method","json");
map.put("param",null);
map.put("time","2015-01-23 10:54:55");
ObjectMapper mapper = new ObjectMapper();
mapper.writeValueAsString(map);

public static void readJson2Map(String json) {
ObjectMapper objectMapper = new ObjectMapper();
try {
//将json字符串转成map结合解析出来，并打印(这里以解析成map为例)
Map<String, Map<String, Object>> maps = objectMapper.readValue(
json, Map.class);
System.out.println(maps.size());
Set<String> key = maps.keySet();
Iterator<String> iter = key.iterator();
while (iter.hasNext()) {
String field = iter.next();
System.out.println(field + ":" + maps.get(field));
}
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
readJson2Map(json);