Json解析多个对象 [英] Json Parsing through multiple object

问题描述

我有一个json文件名：test.json

  {books：{name：XXXXX ISBN：98892}} 
 {书：{ 名： YYYYY， ISBN：64728}} 
 {书：{ 名： ZZZZZ， ISBN ：19837}} 
  

这是我的bean类

  class Books {
 private String name; 
 private int isbn; 
 // getter和setter方法
  

我的主类

  Gson gson = new Gson（）; 
 try {
 BufferedReader br = new BufferedReader（new FileReader（C：\\test.json））; 
 
书籍m = gson.fromJson（br，Books.class）; 
 
 System.out.printf（％s，m.getName（））; 
 System.out.printf（\t％d，m.getIsbn（））; 
  

我只能打印第一行，如果必须解析其他行，我该怎么办？

解决方案

test.json中的JSON格式错误。它不应该能够解析它，因为它是。名称应该是字符串，所以数据应该如下所示：

  {books：{name：XXXXX ISBN：98892}} 
 { 书：{ 名： YYYYY， ISBN：64728}} 
 { 书：{ 名： ZZZZZ ，isbn：19837}} 
  

但它仍然是一个好奇的数据结构。它是你自己的格式，还是你得到的东西？看起来好像它可能想成为一个数组，例如：

  {books：[{name： XXXXX，isbn：98892}，
 {name：YYYYY，isbn：64728}，
 {name：ZZZZZ，isbn：19837}如果是这样，你可以使用Gson解析整个文件，给定你的书类，如下所示： 
 
 
  Books booksArray []; 
 booksArray = Gson.fromGson（br，Books []。class）; 
  
否则，考虑到数据结构与您的问题一样 - 假设 book 属性名称被引用 - 您需要考虑额外的对象级别，例如：
  class BooksWrapper 
 {
私人图书书籍; 
 
 public Books getBooks（）
 {
返还书籍; 
 
 
 $ / code> 
你可以循环 BufferedReader 并收集所有对象，如下所示： 
 
 
  ArrayList< Books> books = new ArrayList< Books>（）; 
 BufferedReader br = new BufferedReader（new FileReader（test.json））; 
字符串行; 
 
 BooksWrapper包装; $（b 
 
）（（line = 
 books.add（wrapper.getBooks（））; 
 
 
（Books book：books）
 {
 System.out.print（book.getName（））; 
 System.out.println（\t+ book.getIsbn（））; 
} 
  
 
I have a json in a file name: test.json
{books:{"name":"XXXXX","isbn":98892}}
{books:{"name":"YYYYY","isbn":64728}}
{books:{"name":"ZZZZZ","isbn":19837}}
this is my bean class
    class Books{
        private String name;
        private int isbn;
//getter and setter methods
my main class
Gson gson = new Gson();
    try {
        BufferedReader br= new BufferedReader(new FileReader("C:\\test.json"));

                Books m = gson.fromJson(br, Books.class);

                System.out.printf("%s",m.getName());
                System.out.printf("\t%d",m.getIsbn());
I am able to print only the first line, if I have to parse other line what should I do ?
解决方案
The JSON in your test.json is malformed. It gson shouldn't be able to parse it as it is. Names should be strings, so the data should look like this:
{"books":{"name":"XXXXX","isbn":98892}}
{"books":{"name":"YYYYY","isbn":64728}}
{"books":{"name":"ZZZZZ","isbn":19837}}
But it's a curious data structure anyway. Is it your own format, or something that you've been given? It seems as if it may want to be an array, such as:
{"books":[{"name":"XXXXX","isbn":98892},
          {"name":"YYYYY","isbn":64728},
          {"name":"ZZZZZ","isbn":19837}]}
If so, you could parse the entire file using Gson, given your Books class, like this:
Books booksArray[];
booksArray = Gson.fromGson(br, Books[].class);
Otherwise, given the data structure as it is in your question - assuming that the books attribute names are quoted - you'll need to account for the additional level of object, for example:
class BooksWrapper
{
    private Books books;

    public Books getBooks()
    {
       return books;
    }
}
And you can loop over the lines in your BufferedReader and collect all the objects like so:
ArrayList<Books> books = new ArrayList<Books>();
BufferedReader br = new BufferedReader(new FileReader("test.json"));
String line;

BooksWrapper wrapper;

while ((line = br.readLine()) != null)
{
   wrapper = gson.fromJson(line, BooksWrapper.class);
   books.add(wrapper.getBooks());
}

for (Books book : books)
{
   System.out.print(book.getName());
   System.out.println("\t" + book.getIsbn());
}


                        
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