我正在編寫一個網絡類，并希望能夠解析對不同類的不同響應（仍然存在一對一的關系，但我希望有一個單一的來parseResponse()處理來自不同端點的所有響應，并endpoint.className具有預期的類類型我應該映射到）：private Class<?> parseResponse(StringBuilder responseContent, Endpoint endpoint) { ObjectMapper mapper = new ObjectMapper(); try { Class<?> object = mapper.readValue(responseContent.toString(), endpoint.className); // endpoint.className has Class<?> type if (object instanceof endpoint.className) { } } catch (IOException e) { // handle errors }}但是如果我寫的話就會出錯if (object instanceof endpoint.className)更新：可能更好的選擇是向類添加parse()方法Endpoint：public Class<?> parseResponse(String responseContent) { // this.className has Class<?> type (e.g., Foo.class).}public enum Endpoint { FOO (Foo.class), BAR (Bar.class); private Class<?> classType;}但是仍然存在相同類型的錯誤。
1 回答
月關寶盒
TA貢獻1772條經驗 獲得超5個贊
您應該將JSON反序列化與應用程序的其他部分分開。您不能為所有響應實現一種方法，但您的響應數量可能有限，您可以為每個類聲明一些簡單的方法。通常，您只能使用一種聲明如下的方法：
public <T> T deserialise(String payload, Class<T> expectedClass) {
Objects.requireNonNull(payload);
Objects.requireNonNull(expectedClass);
try {
return mapper.readValue(payload, expectedClass);
} catch (IOException e) {
throw new IllegalStateException("JSON is not valid!", e);
}
}
現在，您可以反序列化您想要的所有有效負載。您需要提供要接收的JSON負載和類。POJO
顯示該概念的簡單工作解決方案：
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import java.io.IOException;
import java.util.Objects;
public class JsonMapper {
private final ObjectMapper mapper = new ObjectMapper();
public JsonMapper() {
// configure mapper instance if required
mapper.enable(SerializationFeature.INDENT_OUTPUT);
mapper.enable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
// etc...
}
public String serialise(Object value) {
try {
return mapper.writeValueAsString(value);
} catch (JsonProcessingException e) {
throw new IllegalStateException("Could not generate JSON!", e);
}
}
public <T> T deserialise(String payload, Class<T> expectedClass) {
Objects.requireNonNull(payload);
Objects.requireNonNull(expectedClass);
try {
return mapper.readValue(payload, expectedClass);
} catch (IOException e) {
throw new IllegalStateException("JSON is not valid!", e);
}
}
public Foo parseResponseFoo(String payload) {
return deserialise(payload, Foo.class);
}
public Bar parseResponseBar(String payload) {
return deserialise(payload, Bar.class);
}
public static void main(String[] args) {
JsonMapper jsonMapper = new JsonMapper();
String bar = "{\"bar\" : 2}";
System.out.println(jsonMapper.parseResponseBar(bar));
String foo = "{\"foo\" : 1}";
System.out.println(jsonMapper.parseResponseFoo(foo));
System.out.println("General method:");
System.out.println(jsonMapper.deserialise(foo, Foo.class));
System.out.println(jsonMapper.deserialise(bar, Bar.class));
}
}
class Foo {
public int foo;
@Override
public String toString() {
return "Foo{" +
"foo=" + foo +
'}';
}
}
class Bar {
public int bar;
@Override
public String toString() {
return "Bar{" +
"bar=" + bar +
'}';
}
}
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