Java如何实现两种格式化输出JSON字符串的方法？

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1. 使用阿里巴巴的FastJson库

1.1 在项目的pom.xml文件中添加依赖：

xml com.alibaba fastjson 1.2.58

1.2 Java示例代码（1）：

导入的包：com.alibaba.fastjson.JSONjavaimport com.alibaba.fastjson.JSON;

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>

1.2 Java示例代码

(1) 导入的包:

com.alibaba.fastjson.JSON; import com.alibaba.fastjson.JSONObject; import com.alibaba.fastjson.serializer.SerializerFeature;

(2) 测试代码:

其中JSON字符串为:

{"_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" ]}}

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); }

(3) 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 }

2 使用谷歌的Gson

2.1 项目的pom.xml依赖

<dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>2.2.4</version> </dependency>

2.2 Java示例代码

(1) 导入的包:

import com.google.gson.Gson; import com.google.gson.GsonBuilder; import com.google.gson.JsonArray; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonParser;

(2) 测试代码:

JSON字符串与上述测试代码相同.

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); }

(3) 格式化输出后的结果:

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" ] } }

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