我有以下JSON文本。我如何解析它以获得pageName, pagePic, post_id等的值?
{
"pageInfo": {
"pageName": "abc",
"pagePic": "http://example.com/content.jpg"
},
"posts": [
{
"post_id": "123456789012_123456789012",
"actor_id": "1234567890",
"picOfPersonWhoPosted": "http://example.com/photo.jpg",
"nameOfPersonWhoPosted": "Jane Doe",
"message": "Sounds cool. Can't wait to see it!",
"likesCount": "2",
"comments": [],
"timeOfPost": "1234567890"
}
]
}
Quick-json解析器非常简单,灵活,快速,可定制。试一试
特点:
Compliant with JSON specification (RFC4627)
High-Performance JSON parser
Supports Flexible/Configurable parsing approach
Configurable validation of key/value pairs of any JSON Hierarchy
Easy to use # Very small footprint
Raises developer friendly and easy to trace exceptions
Pluggable Custom Validation support - Keys/Values can be validated by configuring custom validators as and when encountered
Validating and Non-Validating parser support
Support for two types of configuration (JSON/XML) for using quick-JSON validating parser
Requires JDK 1.5
No dependency on external libraries
Support for JSON Generation through object serialisation
Support for collection type selection during parsing process
它可以这样使用:
JsonParserFactory factory=JsonParserFactory.getInstance();
JSONParser parser=factory.newJsonParser();
Map jsonMap=parser.parseJson(jsonString);
Gson很容易学习和实现,我们需要知道的是以下两种方法
toJson() -将Java对象转换为JSON格式
fromJson() -将JSON转换为Java对象
`
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import com.google.gson.Gson;
public class GsonExample {
public static void main(String[] args) {
Gson gson = new Gson();
try {
BufferedReader br = new BufferedReader(
new FileReader("c:\\file.json"));
//convert the json string back to object
DataObject obj = gson.fromJson(br, DataObject.class);
System.out.println(obj);
} catch (IOException e) {
e.printStackTrace();
}
}
}
`
几乎所有给出的答案都要求在访问感兴趣的属性中的值之前,将JSON完全反序列化为Java对象。另一种不走这条路的替代方法是使用JsonPATH,它类似于JSON的XPath,允许遍历JSON对象。
它是一个规范,JayWay的优秀人员已经为该规范创建了一个Java实现,您可以在这里找到:https://github.com/jayway/JsonPath
所以基本上要使用它,把它添加到你的项目中,例如:
<dependency>
<groupId>com.jayway.jsonpath</groupId>
<artifactId>json-path</artifactId>
<version>${version}</version>
</dependency>
并使用:
String pageName = JsonPath.read(yourJsonString, "$.pageInfo.pageName");
String pagePic = JsonPath.read(yourJsonString, "$.pageInfo.pagePic");
String post_id = JsonPath.read(yourJsonString, "$.pagePosts[0].post_id");
等等……
查看JsonPath规范页面,了解横向JSON的其他方法的更多信息。
本页的热门答案使用了太简单的例子,比如只有一个属性的对象(例如{name: value})。我认为这个简单但真实的例子可以帮助到一些人。
这是谷歌Translate API返回的JSON:
{
"data":
{
"translations":
[
{
"translatedText": "Arbeit"
}
]
}
}
我想检索“translatedText”属性的值。“Arbeit”使用谷歌的Gson。
两种可能的方法:
Retrieve just one needed attribute
String json = callToTranslateApi("work", "de");
JsonObject jsonObject = new JsonParser().parse(json).getAsJsonObject();
return jsonObject.get("data").getAsJsonObject()
.get("translations").getAsJsonArray()
.get(0).getAsJsonObject()
.get("translatedText").getAsString();
Create Java object from JSON
class ApiResponse {
Data data;
class Data {
Translation[] translations;
class Translation {
String translatedText;
}
}
}
...
Gson g = new Gson();
String json =callToTranslateApi("work", "de");
ApiResponse response = g.fromJson(json, ApiResponse.class);
return response.data.translations[0].translatedText;