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"
}
]
}
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。
为了便于示例,让我们假设您有一个只有名称的Person类。
private class Person {
public String name;
public Person(String name) {
this.name = name;
}
}
谷歌GSON (Maven)
我个人最喜欢的JSON对象序列化/反序列化。
Gson g = new Gson();
Person person = g.fromJson("{\"name\": \"John\"}", Person.class);
System.out.println(person.name); //John
System.out.println(g.toJson(person)); // {"name":"John"}
更新
如果你想获取单个属性,你可以很容易地使用谷歌库:
JsonObject jsonObject = new JsonParser().parse("{\"name\": \"John\"}").getAsJsonObject();
System.out.println(jsonObject.get("name").getAsString()); //John
Org。JSON (Maven)
如果您不需要对象反序列化,而只是获得一个属性,您可以尝试org。json(或查看上面的GSON示例!)
JSONObject obj = new JSONObject("{\"name\": \"John\"}");
System.out.println(obj.getString("name")); //John
杰克逊(Maven)
ObjectMapper mapper = new ObjectMapper();
Person user = mapper.readValue("{\"name\": \"John\"}", Person.class);
System.out.println(user.name); //John
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();
}
}
}
`
{
"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"
}
]
}
Java code :
JSONObject obj = new JSONObject(responsejsonobj);
String pageName = obj.getJSONObject("pageInfo").getString("pageName");
JSONArray arr = obj.getJSONArray("posts");
for (int i = 0; i < arr.length(); i++)
{
String post_id = arr.getJSONObject(i).getString("post_id");
......etc
}