将json串以标准格式输出到文件中友好显示

1 使用阿里的FastJson

1.1 项目的pom.xml依赖

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>fastjson</artifactId>
  <version>1.2.58</version>
</dependency>

public static void main(String[] args) {

    String jsonString = "{\"_index\":\"book_shop\",\"_type\":\"it_book\",\"_id\":\"1\",\"_score\":1.0," +
            "\"_source\":{\"name\": \"Java编程思想（第4版）\",\"author\": \"[美] Bruce Eckel\",\"category\": \"编程语言\"," +
            "\"price\": 109.0,\"publisher\": \"机械工业出版社\",\"date\": \"2007-06-01\",\"tags\": [ \"Java\", \"编程语言\" ]}}";

    JSONObject object = JSONObject.parseObject(jsonString);
    String pretty = JSON.toJSONString(object, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue, 
            SerializerFeature.WriteDateUseDateFormat);

    System.out.println(pretty);
}

 格式化输出后的结果:

说明: FastJson通过Tab键进行换行后的格式化.

{
    "_index":"book_shop",
    "_type":"it_book",
    "_source":{
        "date":"2007-06-01",
        "author":"[美] Bruce Eckel",
        "price":109.0,
        "name":"Java编程思想（第4版）",
        "publisher":"机械工业出版社",
        "category":"编程语言",
        "tags":[
            "Java",
            "编程语言"
        ]
    },
    "_id":"1",
    "_score":1.0
}

1.2 使用谷歌GSON

public static void main(String[] args) {
    
    String jsonString = "{\"_index\":\"book_shop\",\"_type\":\"it_book\",\"_id\":\"1\",\"_score\":1.0," +
            "\"_source\":{\"name\": \"Java编程思想（第4版）\",\"author\": \"[美] Bruce Eckel\",\"category\": \"编程语言\"," +
            "\"price\": 109.0,\"publisher\": \"机械工业出版社\",\"date\": \"2007-06-01\",\"tags\": [ \"Java\", \"编程语言\" ]}}";
    
    String pretty = toPrettyFormat(jsonString)
    
    System.out.println(pretty);
}

/**
 * 格式化输出JSON字符串
 * @return 格式化后的JSON字符串
 */
private static String toPrettyFormat(String json) {
    JsonParser jsonParser = new JsonParser();
    JsonObject jsonObject = jsonParser.parse(json).getAsJsonObject();
    Gson gson = new GsonBuilder().setPrettyPrinting().create();
    return gson.toJson(jsonObject);
}

说明: Gson使用2个空格作为换行后的格式转换.

{
  "_index": "book_shop",
  "_type": "it_book",
  "_id": "1",
  "_score": 1.0,
  "_source": {
    "name": "Java编程思想（第4版）",
    "author": "[美] Bruce Eckel",
    "category": "编程语言",
    "price": 109.0,
    "publisher": "机械工业出版社",
    "date": "2007-06-01",
    "tags": [
      "Java",
      "编程语言"
    ]
  }
}