java 如何在java中将两个json字符串合并为一个

How to merge two json Strings into one in java

提问by Prashant Thorat

If we have given 2 Strings of type json, how can we merge them into single json String in java?

如果我们给出了 2 个 json 类型的字符串，我们如何在 java 中将它们合并为单个 json 字符串？

e.g. 

    String json1 = {
        "glossary": {
            "title": "example glossary",
            "GlossDiv": {
                "title": "S"
            }
        }
    }

String json2 = {
        "glossary": {
            "title": "person name",
            "age":  "25"
        }
    }  

Should produce

应产生

String mergedJson = {
   "glossary": {
            "title": "example glossary",
            "GlossDiv": {
                "title": "S"
            },
            "age":  "25"
        }
}

采纳答案by Prashant Thorat

Here is the code which recursively merges two jsons. This outputs as excepted:

这是递归合并两个json的代码。此输出除外：

private static JsonObject merge(JsonObject json1Obj, JsonObject json2Obj) {

        Set<Entry<String, JsonElement>> entrySet1 = json1Obj.entrySet();
        for (Entry<String, JsonElement> entry : entrySet1) {
            String key1 = entry.getKey();
            if (json2Obj.get(key1) != null) {
                JsonElement tempEle2 = json2Obj.get(key1);
                JsonElement tempEle1 = entry.getValue();
                if (tempEle2.isJsonObject() && tempEle1.isJsonObject()) {
                    JsonObject mergedObj = merge(tempEle1.getAsJsonObject(),
                            tempEle2.getAsJsonObject());
                    entry.setValue(mergedObj);
                }
            }
        }

        Set<Entry<String, JsonElement>> entrySet2 = json2Obj.entrySet();
        for (Entry<String, JsonElement> entry : entrySet2) {
            String key2 = entry.getKey();
            if (json1Obj.get(key2) == null) {
                json1Obj.add(key2, entry.getValue());
            }
        }
        return json1Obj;
    }

回答by Darshan Mehta

Below code should do it, with a couple of assumptions:

下面的代码应该这样做，有几个假设：

• You are using ObjectMapper of Hymanson library (com.fasterxml.Hymanson.databind.ObjectMapper) to serialise/deserialise json

• fields of json1 will always overwrite json2 while merging

  ObjectMapper mapper = new ObjectMapper();
  Map<String, Object> map1 = mapper.readValue("json1", Map.class);
  Map<String, Object> map2 = mapper.readValue("json2", Map.class);
  Map<String, Object> merged = new HashMap<String, Object>(map2);
  merged.putAll(map1);
  System.out.println(mapper.writeValueAsString(merged));
  

• 您正在使用 Hymanson 库 ( com.fasterxml.Hymanson.databind.ObjectMapper) 的ObjectMapper来序列化/反序列化 json

• 合并时 json1 的字段将始终覆盖 json2

  ObjectMapper mapper = new ObjectMapper();
  Map<String, Object> map1 = mapper.readValue("json1", Map.class);
  Map<String, Object> map2 = mapper.readValue("json2", Map.class);
  Map<String, Object> merged = new HashMap<String, Object>(map2);
  merged.putAll(map1);
  System.out.println(mapper.writeValueAsString(merged));
  

回答by T8xi

So I'm quite late to the party but I wanted to share my solution if anybody stumbles across this. You can deeply merge two json strings with com.fasterxml.Hymanson.core:Hymanson-databindObjectMapper.readerForUpdating().

所以我参加聚会已经很晚了，但如果有人偶然发现这个问题，我想分享我的解决方案。您可以将两个 json 字符串与com.fasterxml.Hymanson.core:Hymanson-databindObjectMapper.readerForUpdating().

In this scenario you pass in two Json as String and merge them via readerForUpdating (untested code):

在这种情况下，您将两个 Json 作为字符串传递并通过 readerForUpdating（未经测试的代码）合并它们：

public String mergeJsonStrings(String json1, String json2) {
    ObjectMapper mapper = new ObjectMapper();
    ObjectReader reader = mapper.readerForUpdating(json1);
    String result = reader.readValue(json2);
    return result;
}

I used similar code to merge a property into an existing dataset. In this example the SomePropertiesclass contains a hashmap which holds the properties for a specific user. The passed in propertiesStringis a single dot separated property e.g. some.random.property=value. The property will be transformed into a JsonNodewith com.fasterxml.Hymanson.dataformat:Hymanson-dataformat-properties.

我使用类似的代码将属性合并到现有数据集中。在此示例中，SomeProperties该类包含一个哈希图，其中包含特定用户的属性。传入的propertiesString是一个单点分隔的属性，例如some.random.property=value. 该属性将转换为JsonNodewith com.fasterxml.Hymanson.dataformat:Hymanson-dataformat-properties。

public SomeProperties mergeProperties(SomeProperties someProperties, String propertiesString) {
    JavaPropsMapper javaPropsMapper = new JavaPropsMapper();
    ObjectMapper objectMapper = new ObjectMapper();
    JsonNode jsonNode = javaPropsMapper.readTree(propertiesString);
    ObjectReader objectReader = mapper.readerForUpdating(someProperties.getProperties());
    HashMap<String, Object> mergedProperties = objectReader.readValue(jsonNode);
    someProperties.setProperties(mergedProperties);
    return someProperties;
}

In both cases everything passed into objectReader.readValue()will override existing keys.

在这两种情况下，传入的所有内容都objectReader.readValue()将覆盖现有的键。