1，取key
Map<String,String> map=new HashMap<String,String>();
for(String key:map.keySet()){
map.get(key);
}
2，取value
Map<String,String> map=new HashMap<String,String>();
for(String value:map.values){
System.out.println("value = "+value);
}
3，最常用
Map<String, String> map = new HashMap<String, String>();
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}
4，iterator
Map<String, String> map = new HashMap<String, String>();
Iterator<Map.Entry<String, String>> entries = map.entrySet().iterator();
while (entries.hasNext()) {
Map.Entry<String, String> entry = entries.next();
System.out.println("Key = " + entry.getKey() + ", Value = " + entry.getValue());
}