Java 使用 jackson 反序列化 List<Interface>
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Deserialize List<Interface> with Hymanson
提问by varunl
I want to deserialize json to class Foo:
我想将 json 反序列化为 Foo 类：
class Foo {
List<IBar> bars;
}
interface IBar {
...
}
class Bar implements IBar {
...
}
IBar has two implementations, but when deserializing I always want to use the first implementation. (This should ideally make the problem easier, because there is no runtime type checking required)
IBar 有两个实现，但是在反序列化时我总是想使用第一个实现。（理想情况下，这应该使问题更容易，因为不需要运行时类型检查）
I am sure I can write custom deserializers, but felt there must be something easier.
我确信我可以编写自定义反序列化器，但觉得一定有更简单的方法。
I found this annotation, which works perfectly when there is no list.
我找到了这个注释，当没有列表时它可以完美地工作。
@JsonDeserialize(as=Bar.class)
IBar bar;
List<IBar> bars; // Don't know how to use the annotation here.
采纳答案by varunl
@JsonDeserialize(contentAs=Bar.class)
List<IBar> bars;
回答by Mena
Why don't you just use a TypeReference?
你为什么不只使用一个TypeReference？
For instance...
例如...
Json file test.jsonin /your/path/:
Json 文件test.json位于/your/path/：
[{"s":"blah"},{"s":"baz"}]
Main class in package test:
包中的主类test：
public class Main {
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
try {
List<IBar> actuallyFoos = mapper.readValue(
new File("/your/path/test.json"), new TypeReference<List<Foo>>() {
});
for (IBar ibar : actuallyFoos) {
System.out.println(ibar.getClass());
}
}
catch (Throwable t) {
t.printStackTrace();
}
}
static interface IBar {
public String getS();
public void setS(String s);
}
static class Foo implements IBar {
protected String s;
public String getS() {
return s;
}
public void setS(String s) {
this.s = s;
}
}
static class Bar implements IBar {
protected String s;
public String getS() {
return s;
}
public void setS(String s) {
this.s = s;
}
}
}
Output of the mainmethod:
该main方法的输出：
class test.Main$Foo
class test.Main$Foo
回答by HiJon89
Put the annotation on the IBarinterface declaration rather than the field, ie:
将注解放在IBar接口声明而不是字段上，即：
@JsonDeserialize(as=Bar.class)
interface IBar {
...
}
