在java中顯示用GSON決議的字串物件時如何擺脫“\”

我正在嘗試使用 GSON 獲得清晰的 JSON 物件（書籍）陣列。但是每當我運行以下代碼時：

public class Book {
    private int id;
    private String name;
    private String type;
    private boolean available;
    
    public Book(int id, String name, String type, boolean available) {
        super();
        this.id = id;
        this.name = name;
        this.type = type;
        this.available = available;
    }

    @Override
    public String toString() {
        return "{id="   id   ", name="   name   ", type="   type   ", available="   available   "},";
    }

    
}

import org.springframework.stereotype.Component;

import com.google.gson.Gson;

@Component
public class BookService {

    private int size = 0;
    public  int len = 6;
    public Book Allbooks[] = new Book[len];

    public Book AddBook(int id, String name, String type, boolean available) {
        if(id == len)
            return null;
        this.size  ;
        return Allbooks[this.size - 1] = createBook(id, name, type, available);


    }
    private Book createBook(int id, String name, String type, boolean available) {
        return new Book(id, name, type, available);
    }
    public Book[] bookRepo() {
        
        Allbooks[0] = AddBook(1, "One", "fiction", false);
        Allbooks[1] = AddBook(2, "Two", "non-fiction", true);
        Allbooks[2] = AddBook(3, "Three", "fiction", true);
        Allbooks[3] = AddBook(4, "Four", "fiction", false);
        Allbooks[4] = AddBook(5, "Five", "non-fiction", true);
        Allbooks[5] = AddBook(6, "Six", "non-fiction", true);

        return Allbooks;
    }
    public String[] showAll() {
        String[] arr = new String[Allbooks.length];
        for (int i = 0; i < arr.length; i  ) {
            arr[i] = new Gson().toJson(Allbooks[i], Book.class);
        }return arr;

    }
}

@RestController
class ControllerGET {

    @Autowired Status status;
    @Autowired BookService bookRepository;

    @GetMapping(path = {"/", ""})
    public String mainPage() {
        return "Welcome to Mile's simple book-API";
    }
    @GetMapping(path = "/status")
    public Status getStatus() {
        status.value = "OK";
        return status;
    }
    @GetMapping(path = "/books")
    public String[] getAllBooks() {
         bookRepository.bookRepo();
         return bookRepository.showAll();
    }
    //@GetMapping(path = "/books/:bookid")
    
}

我在本地主機（郵遞員）上得到以下輸出：

[
    "{\"id\":1,\"name\":\"One\",\"type\":\"fiction\",\"available\":false}",
    "{\"id\":2,\"name\":\"Two\",\"type\":\"non-fiction\",\"available\":true}",
    "{\"id\":3,\"name\":\"Three\",\"type\":\"fiction\",\"available\":true}",
    "{\"id\":4,\"name\":\"Four\",\"type\":\"fiction\",\"available\":false}",
    "{\"id\":5,\"name\":\"Five\",\"type\":\"non-fiction\",\"available\":true}",
    "null"
]

我的目標是讓它看起來像這樣：

 {"id":1,
  "name":"One",
  "type":"fiction",
  "available":false}",
}

其他書也一樣。如果您知道方法，請幫助我。我將不勝感激！……………………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………… ………………

uj5u.com熱心網友回復：

在回傳 springboot 之前，您不需要決議為 json。Spring boot 會為你做這件事（默認使用 jackson lib）

嘗試這個：

  @GetMapping(path = "/books")
    public Book[] getAllBooks() { // return Book[] instead of String []
         bookRepository.bookRepo();
         return bookRepository.bookRepo(); // return all list of books
    }

uj5u.com熱心網友回復：

洗掉@Override toString()函式。直接回傳gson().toJson()字串。

然而這并不好。您可以定義ArrayList而不是原始陣列。所以，

ArrayList<Book> AllBooks;
AllBooks.add(new Book(// add book 1));
AllBooks.add(new Book(// add book 2));
AllBooks.add(new Book(// add book 3));

然后在 repo 上你可以回傳

return new Gson.toJson(AllBooks);

然而

這不是最佳做法，因為您的書籍存盤在服務器的RAM 上。所以，重新考慮建立一個資料庫來輔助資料關系。事實上，spring 提供了 jpa@Entity來幫助你處理這種事情。當您將圖書宣告為物體時，例如

@Entity
public class Book {
    private int id;
    private String name;
    private String type;
    private boolean available;
}

您可以創建一個JpaRepository來檢索所有資料，例如

@Repository
public interface BookRepository extends JpaRepository<Book, Long> {
}

然后只需呼叫控制器上的存盤庫

@GetMapping(path = "/books")
public List<book> getAllBooks() {
    BookRepository bookRepo = new BookRepository();
    List<book> books = bookRepo.findAll();
    return books;
}

標籤：爪哇 春天 行家 格森

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