java Map常用方法封装
CreationTime--2018年7月16日15点59分
Author:Marydon
1.准备工作
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import org.apache.log4j.Logger;
/**
* Map数据处理工具类
* @explain
* @author Marydon
* @creationTime 2018年7月9日上午9:17:37
* @version 1.0
* @since
* @email [email protected]
*/
public class MapUtils {
private static Logger log = Logger.getLogger(MapUtils.class);
}
2.无序Map转换成有序Map
/**
* 将无序Map转换成有序Map
* @explain 将参数按照第一个字符的键值 ASCII 码递增排序（字母升序排序），如果遇到相同字符则按照第二个字符的键值 ASCII 码递增排序，
* 以此类推通过SortedMap可以实现
* @param paramsMap
* @return Map 按ASCII码升序排列
*/
public static Map<String, Object> toSortedMap(Map<String, Object> paramsMap) {
// 用于存储接收到的key:value，并按key以ASCII码进行升序排列组合
SortedMap<String, Object> data = new TreeMap<String, Object>();
// 获取Map对象中的键值对对象
Set<Entry<String, Object>> entrySet = paramsMap.entrySet();
Entry<String, Object> entry = null;
String key = "";
Object value = null;
// 遍历paramsMap数据，添加到SortedMap对象
for (Iterator<Entry<String, Object>> iterator = entrySet.iterator(); iterator.hasNext();) {
entry = iterator.next();
key = entry.getKey();
value = entry.getValue();
data.put(key, value);
}
log.info("Map-->SortedMap：" + data);
return data;
}
3.将map的value转化成String类型
/**
* Map<String, Object>-->Map<String, String>
* @explain 前提：value必须为String类型
* @param paramsMap
* @return
* @throws Exception
*/
public static Map<String, String> toStringMap(Map<String, Object> paramsMap) throws Exception{
Map<String, String> data = new HashMap<String, String>();
// 获取Map对象中的键值对对象
Set<Entry<String, Object>> entrySet = paramsMap.entrySet();
Entry<String, Object> entry = null;
String key = "";
String value = null;
for (Iterator<Entry<String, Object>> iterator = entrySet.iterator(); iterator.hasNext();) {
entry = iterator.next();
key = entry.getKey();
if (key instanceof String) {
value = (String) entry.getValue();
data.put(key, value);
} else {
log.error("Map中含有非String类型的值，对应的key=" + key);
throw new Exception("Map中含有非String类型的值，对应的key=" + key);
}
}
log.info("Map<String, Object>-->Map<String, String>：" + data);
return data;
}
4.将map的value转化成Object类型
/**
* Map<String, String>-->Map<String, Object>
* @explain 将value转换成Object类型
* @param paramsMap
* @return
*/
public static Map<String, Object> toObjectMap(Map<String, String> paramsMap){
Map<String, Object> data = new HashMap<String, Object>();
// 获取Map对象中的键值对对象
Set<Entry<String, String>> entrySet = paramsMap.entrySet();
Entry<String, String> entry = null;
String key = "";
Object value = null;
for (Iterator<Entry<String, String>> iterator = entrySet.iterator(); iterator.hasNext();) {
entry = iterator.next();
key = entry.getKey();
value = entry.getValue();
data.put(key, value);
}
log.info("Map<String, String>-->Map<String, Object>：" + data);
return data;
}
5.将map的key小写转换成大写
/**
* key 小写-->大写
* @explain 将key改为大写
* @param paramsMap
* @return
*/
public static Map<String, Object> toUpperMap(Map<String, Object> paramsMap){
Map<String, Object> data = new HashMap<String, Object>();
// 获取Map对象中的键值对对象
Set<Entry<String, Object>> entrySet = paramsMap.entrySet();
Entry<String, Object> entry = null;
String key = "";
Object value = null;
for (Iterator<Entry<String, Object>> iterator = entrySet.iterator(); iterator.hasNext();) {
entry = iterator.next();
key = entry.getKey().toUpperCase();
value = entry.getValue();
data.put(key, value);
}
log.info("Map 小写-->大写：" + data);
return data;
}