java - Java GSON 错误：JSON 文档未完全使用
问题描述
所以我有一个 JSON 文档，我想用不同的值读取它，包括下面的数组
{ "name": "MacBook", "price": 1299, "stock": 10, "picture": "macbook.jpeg", "categories": [{"id": 1,"name": "macbook"},{"id": 2, "name":"notebook"}]}
我创建了几个 POJO java 类来阅读它们：
1 - 类（Product.java）
package models;
import java.util.ArrayList;
public class Product {
String name;
int price;
int stock;
String picture;
public ArrayList<Categories> categories;
public Product(String name, int price, int stock, String picture) {
this.name = name;
this.price = price;
this.stock = stock;
this.picture = picture;
this.categories = new ArrayList<>();
}
public void setName(String name) {
this.name = name;
}
public void setPrice(int price) {
this.price = price;
}
public void setStock(int stock) {
this.stock = stock;
}
public void setPicture(String picture) {
this.picture = picture;
}
public void setCategories(ArrayList<Categories> categories) {
this.categories = categories;
}
public String getName() {
return name;
}
public int getPrice() {
return price;
}
public int getStock() {
return stock;
}
public String getPicture() {
return picture;
}
public ArrayList<Categories> getCategories() {
return categories;
}
@Override
public String toString() {
return "Product{" +
"productName='" + name + '\'' +
", productPrice=" + price +
", productStock=" + stock +
", productPicture='" + picture + '\'' +
", categories=" + categories +
'}';
}
}
2 类（Categories.java）读取数组
package models;
public class Categories {
private int id;
private String description;
public int getId() {
return id;
}
public String getDescription() {
return description;
}
public void setId(int id) {
this.id = id;
}
public void setDescription(String description) {
this.description = description;
}
public Categories(int id, String description) {
this.id = id;
this.description = description;
}
@Override
public String toString() {
return "Category{" + "id=" + id + ", description=" + description + '}';
}
}
这是主要的
package p3;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import models.Product;
import com.google.gson.Gson;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.lang.reflect.Type;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;
public class Main {
public static void main(String[] args) {
Gson gson = new GsonBuilder()
.setLenient()
.create();
String fichero = "";
try (BufferedReader br = new BufferedReader(new FileReader("src/res/FitxersJSON/products.json"))) {
String linea;
while ((linea = br.readLine()) != null) {
fichero += linea;
}
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
Product productObject = gson.fromJson(fichero.toString(), Product.class);
System.out.println(productObject);
}
}
由于某种原因，当我执行 main 时出现此错误
Exception in thread "main" com.google.gson.JsonIOException: JSON document was not fully consumed.
at com.google.gson.Gson.assertFullConsumption(Gson.java:861)
at com.google.gson.Gson.fromJson(Gson.java:854)
at com.google.gson.Gson.fromJson(Gson.java:802)
at com.google.gson.Gson.fromJson(Gson.java:774)
at p3.Main.main(Main.java:42)
我尝试格式化 JSON 文档，但看起来一切正常，因为我可以清楚地读取它在每个循环中打印“linea”值。
先感谢您。
[编辑]
我通过在 JSON 文件的开头和结尾添加“[”和“]”以及在除最后一行之外的所有行中添加“，”来解决问题。
package p3;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import models.Categories;
import models.Product;
import java.io.*;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
public class Main {
public static void main(String[] args) {
ex2_readProducts();
ex3_addProducts();
}
private static void ex2_readProducts() {
Gson gson = new Gson();
Type collectionType = new TypeToken<Collection<Product>>() {
}.getType();
String file = "";
try (BufferedReader br = new BufferedReader(new FileReader("src/resources/products.json"))) {
String linea;
System.out.println("***************************** Reading the JSON file *********************************");
while ((linea = br.readLine()) != null) {
file += linea;
}
Collection<Product> enums = gson.fromJson(file, collectionType);
int counter = 0;
for (Product r : enums) {
counter++;
System.out.println("Product nº: " + counter );
System.out.println(r);
}
System.out.println("Result: " + counter + " products read from the file" );
System.out.println("***************************** Finished reading the JSON file *********************************");
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
}
public static void ex3_addProducts() {
Gson gson = new Gson();
Categories c1 = new Categories(1, "tablet");
Categories c2 = new Categories(2, "game");
Categories c3 = new Categories(3, "phone");
Categories c4 = new Categories(5, "smartwatch");
Categories c5 = new Categories(9, " scooter");
Product p1 = new Product("ipad32", 1200, 23, "ipad32.jpg");
Product p2 = new Product("soccer 3000", 100, 500, "soccer.jpg");
Product p3 = new Product("pixel", 900, 900, "pixel.jpg");
Product p4 = new Product("mi watch", 300, 23, "miwatch.jpg");
Product p5 = new Product("mi scooter 365", 365, 23, "miscooter.jpg");
ArrayList<Categories> categoriesArrayList1;
categoriesArrayList1 = new ArrayList<>(Arrays.asList(c1, c3));
ArrayList<Categories> categoriesArrayList2;
categoriesArrayList2 = new ArrayList<>(Arrays.asList(c1, c2, c3));
ArrayList<Categories> categoriesArrayList3;
categoriesArrayList3 = new ArrayList<>(Arrays.asList(c1, c4, c3));
ArrayList<Categories> categoriesArrayList4;
categoriesArrayList4 = new ArrayList<>(Arrays.asList(c1, c3));
ArrayList<Categories> categoriesArrayList5;
categoriesArrayList5 = new ArrayList<>(Arrays.asList(c5, c1));
p1.setCategories(categoriesArrayList1);
p2.setCategories(categoriesArrayList2);
p3.setCategories(categoriesArrayList3);
p4.setCategories(categoriesArrayList4);
p5.setCategories(categoriesArrayList5);
Product[] productsArray = {p1, p2, p3, p4, p5};
try (BufferedWriter br = new BufferedWriter(new FileWriter("src/resources/products2.json"))) {
System.out.println("********************** Adding products to a new file: *********************************");
br.write("[");
br.newLine();
int counter = 0;
for (int i = 0; i < productsArray.length; i++) {
System.out.println("Product nº: " + (i+1) + '\n' + productsArray[i]);
String json = gson.toJson(productsArray[i]);
br.write(json);
if (i != productsArray.length - 1) {
br.write(",");
}
br.newLine();
counter = (i+1);
}
br.write("]");
System.out.println("Result: " + counter + " products added to the file" );
System.out.println("**************************** Finished adding products *****************************");
} catch (IOException ex) {
System.out.println(ex.getMessage());
}
}
}
解决方案
首先，您在 java 类中使用Department而不是Categories 。如我所见，它包含不同的字段。我相信您的问题出在读取文件的 json 文件或 Main 类中。使用 Guava 可以让您更轻松地阅读文件。查看我的代码：
产品.json
{
"name": "MacBook",
"price": 1299,
"stock": 10,
"picture": "macbook.jpeg",
"categories": [
{
"id": 1,
"name": "macbook"
},
{
"id": 2,
"name": "notebook"
}
]
}
主类
package com.test;
import com.google.common.io.Resources;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.nio.charset.StandardCharsets;
public class Main {
public static void main(String[] args) throws Exception {
Gson gson = new GsonBuilder()
.create();
String products = Resources.toString(Resources.getResource("products.json"), StandardCharsets.UTF_8).trim();
Product productObject = gson.fromJson(products, Product.class);
System.out.println(productObject);
}
}
输出是
Product{name='MacBook', price=1299, stock=10, picture='macbook.jpeg', categories=[Category{id=1, name='macbook'}, Category{id=2, name='notebook'}]}
推荐阅读
- javascript - 当属性是可选的时，如何在 Typescript 中描述对象？
- reactjs - 显示加载微调器
- php - 统计数据库中特定数据的数量，如果有空白或空值，则显示 0。PHP
- azure-devops - 通知 - 过滤掉服务帐户
- javascript - 如何对值类仅元素显示可见的jQuery求和
- python - 什么是在 Python 中迭代 numpy 数组的更快方法
- python - Django：获取下拉值并为基于类的视图选择动态表单字段
- javascript - 结果没有进入 vueJS 中的分页页面
- regex - 正则表达式查找数字，但如果它是十进制数的一部分则不查找
- chatbot - 自动重启上下文变量