假设有数据在Map中：
Map<Integer, String> wordsByKey = new HashMap<>();
wordsByKey.put(1, "one");
wordsByKey.put(2, "two");
wordsByKey.put(3, "three");
wordsByKey.put(4, "four");
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希望输出成字符串：
{1=one, 2=two, 3=three, 4=four}
Java Stream实现：
public String convertWithStream(Map<Integer, ?> map) {
String mapAsString = map.keySet().stream()
.map(key -> key + "=" + map.get(key))
.collect(Collectors.joining(", ", "{", "}"));
return mapAsString;
}
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现在，反过来，将上述字符串转换到Map中：
public Map<String, String> convertWithStream(String mapAsString) {
Map<String, String> map = Arrays.stream(mapAsString.split(","))
.map(entry -> entry.split("="))
.collect(Collectors.toMap(entry -> entry[0], entry -> entry[1]));
return map;
}
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展示了Collectors的joining和toMap方法使用。