如何阅读在Java中使用Gson的Json [英] How to read Json using Gson in java

问题描述

我需要使用Java中的Gson库来读取Json文件。首先，我不明白Json文件是什么，我有以下内容：（抱歉缺少空格，就是它被粘贴的方式）

  {
initialStorage：[
 {shoeType：red-boots，amount：10}，
 {shoeType：green-flip-flops，金额：7} 
]，
服务：{
时间：{
速度：1000，
持续时间：24 
}，
经理：{
 discountSchedule：[
 {shoeType：red-boots，amount：1，tick：3}，
 {shoeType：green-flip-flops，amount：3， tick：10} 
] 
}，
工厂：3，
卖家：2，
 customers：[
 {
 name： Bruria，
 wishlist：[green-flip-flops]，
 purchaseSchedule：[
 {shoeType：red-boots，tick：3} 
] 
 $，
 {
 name：Shraga，
 wishList：[]，
 purchaseSchedule：[
 {shoeType：green-flip-flops， tick：12} 
] 
} 
] 
} 
} 
  

1. 我只是把它放在java中作为字符串json =-pasting it here-？什么是Json文件，它是一种我必须读作nameoffile.json的文件吗？


2. 如何使用Gson来读取它？我对从解释它的youtube视频中了解不多。
舒适的方式： http://i.stack.imgur.com/r0cTs.png


解决方案

JSON 是JavaScript Object Notation的缩写，是一种存储信息以有组织，易于访问的方式进行。简而言之，它为我们提供了一个可读的数据集合，我们可以通过一种非常合理的方式访问这些数据。





作为一个简单的例子，关于我的信息可能会写入如下所示：



  {
age：24，
hometown： Missoula，MT，
gender：male
} 
  

要使用 Gson 读取java中的 Json 文件，您需要使用 Gson lib。





Gson是一个Java库，可用于将Java对象转换为他们的JSON表示。它也可以用来将JSON字符串转换为等效的Java对象。 Gson可以使用任意Java对象，包括您没有源代码的预先存在的对象。


$ b 演示：从 file.json，转换回对象并显示它。

  package com.mkyong.core; 
 
 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））; 
 
 //将json字符串转换回对象
 DataObject obj = gson.fromJson（br，DataObject.class）; 
 
 System.out.println（obj）; 
 
} catch（IOException e）{
 e.printStackTrace（）; 
} 
 
} 
} 
  




I'm required to read a Json file, using the Gson library, in Java. First I don't understand what a Json file is, what I have is the following: (sorry for the lack of spaces, that's how it was pasted)

{
"initialStorage": [
{shoeType: "red-boots", amount: 10},
{shoeType: "green-flip-flops", amount: 7}
],
services: {
time: {
speed: 1000,
duration: 24
},
manager: {
discountSchedule: [
{shoeType: "red-boots", amount: 1, tick: 3},
{shoeType: "green-flip-flops", amount: 3, tick:10}
]
},
factories: 3,
sellers: 2,
customers: [
{
name: "Bruria",
wishList: ["green-flip-flops"],
purchaseSchedule: [
{shoeType: "red-boots", tick: 3}
]
},
{
name: "Shraga",
wishList: [],
purchaseSchedule: [
{shoeType: "green-flip-flops", tick: 12}
]
}
]
}
}

1. Do I just put it in java as.. String json = "-pasting it here-"? What is a "Json" file, is it some sort of a file I have to read as nameoffile.json?
2. How do I use Gson to read it? I didn't understand much from the youtube videos explaining it.

The following link shows the given Json input in a more comfortable way: http://i.stack.imgur.com/r0cTs.png

解决方案

JSON is short for JavaScript Object Notation, and is a way to store information in an organized, easy-to-access manner. In a nutshell, it gives us a human-readable collection of data that we can access in a really logical manner.

As a simple example, information about me might be written in JSON as follows:

{
    "age" : "24",
    "hometown" : "Missoula, MT",
    "gender" : "male"
}

To Read the Json file in java using Gson you need to use Gson lib.

Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.

Demo : Read data from "file.json", convert back to object and display it.

package com.mkyong.core;

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();
    }

    }
}

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