使用Jackson API解析Java中的JSON文件

Question

I have the following JSON file and wish to parse it to create tweet objects.

the tweet objects should contain user id, username, text, coordinates, and timestamp through the definition of POJO class.

{"text": "I think this would be good. Would hopefully light the fire in the later rounds if you knew you were losing", "user": {"id": "39455201", "name": "Elvis Sinosic"}, "lang": "en","created_at": "Mon Mar 06 22:48:07 +0000 2017"}

{"text": "@Night_0f_Fire He's stuck in the alimony machine,, bust him out", "user": {"id": "2744192965", "name": "Mitch L"}, "lang": "en","created_at": "Mon Mar 06 22:47:53 +0000 2017"}

this is what i did

import com.fasterxml.jackson.databind.*;

import java.util.Arrays;
import java.util.List;
import java.util.Map;



public class Tweets {
    private long userID;
    private String userName;
    private String text;
    private List<int> coordinates;
    private String timestamp;
}

ObjectMapper mapper = new ObjectMapper();
ObjectMapper mapper = new ObjectMapper();
Tweets tweets = mapper.readValue(new("/Users/YusufNing/IdeaProjects/comp6700-2017/ass1/parsing/Tweets.java"), Tweets.class);

Answer 1

Jackson is pretty straight forward. Create your .java classes with user id, username, text, coordinates, and timestamp. You can make them all string variables (makes it super easy to map). You can always parse out later once the data is mapped

ParsedTweets.class:

public class ParsedTweets
{
    private String id;
    private String username;
    private String text; 
    private String coordinates;
    private String timestamp;
}

Implementation:

ObjectMapper mapper = new ObjectMapper();
String jsonTweeterString = "{'text': 'I think this would be good. Would hopefully light the fire in the later rounds if you knew you were losing', 'user': {'id': '39455201', 'name': 'Elvis Sinosic'}, 'lang': 'en','created_at': 'Mon Mar 06 22:48:07 +0000 2017'}";

ParsedTweets tweets = mapper.readValue(jsonTweeterString, ParsedTweets.class);

To read from file you do:

ParsedTweets tweets = mapper.readValue(new File("/Users/Kutam/IdeaProjects/comp6700-2017/ass1/tweets.js‌​on"), ParsedTweets.class);