java - 数据库注释 - 重复注释

Question

作为我类(class)项目的一部分，我们被要求注释我们的代码。

对于下面的代码

import java.lang.annotations.*;
@Target({ElementType.LOCAL_VARIABLE})
@Retention(RetentionPolicy.RUNTIME)
public @interface DBAnnotation {
 String variable () default "";
 String table () default "";
 String column () default "";
 boolean isSource () default false; 
}


public static void addFileToDB(String fileName, String fileLocation, int offerID){
    @DBAnnotation (variable = "fileName",  table = "files", column = "FileName", isSource = true)
    @DBAnnotation (variable = "fileLocation",  table = "files", column = "fileLocation", isSource = true)




    String SQLFileSelect = "SELECT FileName FROM files WHERE OfferID = ? AND FileLocation = ?;";
.
.
.
}

我收到以下错误。

Duplicate annotation @File.DBAnnotation. Repeated annotations are allowed only at source level 1.8 or above

但是如果我把它改成...

public @interface DBAnnotation {
     String[] variable () default "";
     String table () default "";
     String[] column () default "";
     boolean[] isSource () default false; 
    }
.
.
.
@DBAnnotation (
            variable = {"fileName","fileLocation"},  
            table = "files", 
            column = {"FileName","fileLocation"}, 
            isSource = true)

然后它不会给出任何错误。

我关心的是，对于变量 fileLocation，te DBAnnotation 会被认为是 variable = "fileLocation", table = "files", column = "fileLocation",isSource = true

或者会被认为是 变量 = "文件位置", 表 = "", 列 = "文件位置",isSource =

Answer 1

如果你这样设置:

variable = {"fileName","fileLocation"},  
            table = "files", 
            column = {"FileName","fileLocation"}, 
            isSource = true

那么变量和列将是两个值，因为您将它们定义为字符串数组。

这里重要的是，您对自定义注解的操作完全取决于您(您在运行时对其进行的操作)，因此:

  getAnnotation(DBAnnotation.class).variable(); // will return the String array with both values.