[SpringMVC笔记] SpringMVC-13-表现层与前端数据传输数据协议实现

SpringMVC-13-SSM整合-表现层与前端数据传输数据协议实现

为了使前端更加方便地处理后端传来的数据，通常对返回结果数据进行统一化，可以将数据封装在一个 Result 类中，类中包含数据本体 data，操作代码 code，提示信息 message 等属性，前后端自行协商，达成一致即可

Result 类示例：

public class Result {
    private Integer code;
    private Object data;
    private String message;
    
    // 成员方法省略
}
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操作码的值可以放在类中作为常量，提高可读性：

public class Code {
    public static final Integer SAVE_OK = 20011;
    public static final Integer DELETE_OK = 20021;
    public static final Integer UPDATE_OK = 20031;
    public static final Integer GET_OK = 20041;

    public static final Integer SAVE_ERR = 20010;
    public static final Integer DELETE_ERR = 20020;
    public static final Integer UPDATE_ERR = 20030;
    public static final Integer GET_ERR = 20040;
}
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Controller 类示例：

@RestController
@RequestMapping("/books")
public class BookController {
    @Autowired
    private BookService bookService;

    @GetMapping("/{id}")
    public Result getById(@PathVariable Integer id) {
        Book book = bookService.getById(id);
        Integer code = (book == null) ? Code.GET_ERR : Code.GET_OK;
        String message = (book == null) ? "数据查询失败，请重试！" : null;
        return new Result(code, book, message);
    }

    @GetMapping
    public Result getAll() {
        List<Book> books = bookService.getAll();
        Integer code = (books == null) ? Code.GET_ERR : Code.GET_OK;
        String message = (books == null) ? "数据查询失败，请重试！" : null;
        return new Result(code, books, message);
    }
}
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