[英]TYPE_USE annotations on generic type not being compiled into class file
我想為具有多個@Valid
元素的有效負載定義一個通用類, @Validated
由我的 Spring Boot 應用程序進行@Validated
。 班級要去圖書館。
如果我定義一個看起來像的泛型類:
class GroupPayload<T> {
@Size(min = 1) List<@Valid T> data;
}
編譯后,類文件如下所示:
class GroupPayload<T> {
@Size(
min = 1
)
private List<T> data; // T is not @Valid !?
}
盡管@Size
使得它的類文件時, @Valid
annnotation(包括anotations有@Retention(RUNTIME)
T
不與輸入@Valid
在編譯的類。
如果我使用MyGroupPayload extends GroupPayload<MyType>
,驗證不火的元素,但如果我使用硬編碼(非通用)類List<@Valid MyType> data
驗證工作。
如何將泛型類型的 TYPE_USE 注釋添加到編譯類中,以便我可以將其用作直接項目之外的庫類。
注釋被編譯到類文件中。 我懷疑您用來檢查類文件的任何工具都有問題。
這是一個 MWE:
import java.util.List;
import java.lang.annotation.ElementType;
import java.lang.annotation.Target;
@Target(ElementType.TYPE_USE)
@interface Valid{}
public class GroupPayload<T> {
List<@Valid T> data;
}
的輸出
javac GroupPayload.java
javap -v GroupPayload.class
出現在下方。 您可以從這些片段中看到:
...
#9 = Utf8 LValid;
...
java.util.List<T> data;
...
RuntimeInvisibleTypeAnnotations:
0: #9(): FIELD, location=[TYPE_ARGUMENT(0)]
@Valid
注釋在.class
文件中。
這是javap -v GroupPayload.class
的完整輸出:
Classfile /home/mernst/GroupPayload.class
Last modified Jan 16, 2020; size 515 bytes
MD5 checksum 3db07417a8da20b35032650b64e9ffce
Compiled from "GroupPayload.java"
public class GroupPayload<T extends java.lang.Object> extends java.lang.Object
minor version: 0
major version: 52
flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
#1 = Methodref #3.#22 // java/lang/Object."<init>":()V
#2 = Class #23 // GroupPayload
#3 = Class #24 // java/lang/Object
#4 = Utf8 data
#5 = Utf8 Ljava/util/List;
#6 = Utf8 Signature
#7 = Utf8 Ljava/util/List<TT;>;
#8 = Utf8 RuntimeInvisibleTypeAnnotations
#9 = Utf8 LValid;
#10 = Utf8 <init>
#11 = Utf8 ()V
#12 = Utf8 Code
#13 = Utf8 LineNumberTable
#14 = Utf8 LocalVariableTable
#15 = Utf8 this
#16 = Utf8 LGroupPayload;
#17 = Utf8 LocalVariableTypeTable
#18 = Utf8 LGroupPayload<TT;>;
#19 = Utf8 <T:Ljava/lang/Object;>Ljava/lang/Object;
#20 = Utf8 SourceFile
#21 = Utf8 GroupPayload.java
#22 = NameAndType #10:#11 // "<init>":()V
#23 = Utf8 GroupPayload
#24 = Utf8 java/lang/Object
{
java.util.List<T> data;
descriptor: Ljava/util/List;
flags:
Signature: #7 // Ljava/util/List<TT;>;
RuntimeInvisibleTypeAnnotations:
0: #9(): FIELD, location=[TYPE_ARGUMENT(0)]
public GroupPayload();
descriptor: ()V
flags: ACC_PUBLIC
Code:
stack=1, locals=1, args_size=1
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: return
LineNumberTable:
line 8: 0
LocalVariableTable:
Start Length Slot Name Signature
0 5 0 this LGroupPayload;
LocalVariableTypeTable:
Start Length Slot Name Signature
0 5 0 this LGroupPayload<TT;>;
}
Signature: #19 // <T:Ljava/lang/Object;>Ljava/lang/Object;
SourceFile: "GroupPayload.java"
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