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