java 自定义map_Java的map自定义工具类MapUtils

public class MapUtil {

public static final char UNDERLINE = '_';

/**

* 下划线方式转驼峰

* @param

*/

public static Map underlineToCamel(Map param) {

if (param == null) {

return null;

}

Map retMap = new HashMap();

Set list = param.keySet();

for (String string : list) {

String str = string.toLowerCase();

int len = str.length();

StringBuilder sb = new StringBuilder(len);

for (int i = 0; i < len; i++) {

char c = str.charAt(i);

if (c == UNDERLINE) {

if (++i < len) {

sb.append(Character.toUpperCase(str.charAt(i)));

}

} else {

sb.append(c);

}

}

String key = sb.toString();

retMap.put(key, param.get(string));

}

return retMap;

}

/**

* map转javabean

* @param

*/

public static T convertMap(Class type, Map map)

throws IntrospectionException, IllegalAccessException,

InstantiationException, InvocationTargetException {

BeanInfo beanInfo = Introspector.getBeanInfo(type); // 获取类属性

T obj = (T) type.newInstance(); // 创建 JavaBean 对象

// 给 JavaBean 对象的属性赋值

PropertyDescriptor[] propertyDescriptors = beanInfo

.getPropertyDescriptors();

for (int i = 0; i < propertyDescriptors.length; i++) {

PropertyDescriptor descriptor = propertyDescriptors[i];

String propertyName = descriptor.getName();

if (map.containsKey(propertyName)) {

// 下面一句可以 try 起来，这样当一个属性赋值失败的时候就不会影响其他属性赋值。

Object value = map.get(propertyName);

Object[] args = new Object[1];

args[0] = value;

descriptor.getWriteMethod().invoke(obj, args);

}

}

return obj;

}

public static Map sumMapForString(Map a,

Map b) {

/**

* @Return java.util.Map

* @Description 将两个Map拼接成一个

* @param a

* @param b

*/

Map res = new HashMap();

for (Map.Entry aMap : a.entrySet()) {

res.put(aMap.getKey(), aMap.getValue());

}

for (Map.Entry bMap : b.entrySet()) {

if (res.containsKey(bMap.getKey())) {

String key = bMap.getKey();

int aValue = Integer.valueOf(res.get(key));

int bValue = Integer.valueOf(bMap.getValue());

int temp = aValue + bValue;

res.put(key, temp + "");

} else {

res.put(bMap.getKey(), bMap.getValue());

}

}

return b;

}

public static Map sumMapForInteger(Map a,

Map b) {

/**

* @Return java.util.Map

* @Description 将两个Map拼接成一个

* @param a

* @param b

*/

Map res = new HashMap();

for (Map.Entry aMap : a.entrySet()) {

res.put(aMap.getKey(), aMap.getValue());

}

for (Map.Entry bMap : b.entrySet()) {

if (res.containsKey(bMap.getKey())) {

String key = bMap.getKey();

int aValue = res.get(key);

int bValue = bMap.getValue();

int temp = aValue + bValue;

res.put(key, temp);

} else {

res.put(bMap.getKey(), bMap.getValue());

}

}

return res;

}

/**

* Map转换成Map

*

* @param map

* @return

*/

public static Map objectToString(Map map) {

Map res = new HashMap();

for (Map.Entry iterable : map.entrySet()) {

if(!(iterable.getValue() ==null)){

res.put(iterable.getKey(), iterable.getValue().toString());

}else {

res.put(iterable.getKey(), "");

}

}

return res;

}

/**

* 将Map中的value取出存入List

*

* @param map

* @return

*/

public static List mapToList(Map map) {

List list = new ArrayList<>();

for (Map.Entry string : map.entrySet()) {

list.add(string.getValue());

}

return list;

}

/**

* MODULE : sortMapByValue

* ABSTRACT : 将map的值从大到小排序

* @author : BJ

* @param ：HashMap

* @return ：TreeMap

* @note : 将map的值从大到小排序

*/

public static TreeMap sortMapByValue(HashMap map){

Comparator comparator = new ValueComparator(map);

//TreeMap is a map sorted by its keys.

//The comparator is used to sort the TreeMap by keys.

TreeMap result = new TreeMap(comparator);

result.putAll(map);

return result;

}

}

class ValueComparator implements Comparator{

HashMap map = new HashMap();

public ValueComparator(HashMap map){

this.map.putAll(map);

}

@Override

public int compare(String s1, String s2) {

if(map.get(s1) >= map.get(s2)){

return -1;

}else{

return 1;

}

}

}