我在以下架构中有json对象：
{
name: "foo",
timestamp: 1475840608763,
payload:
{
foo: "bar"
}
}
此处，该字段包含一个嵌入式 json 对象，并且此对象的架构是动态的，并且每次都不同。payload
对象是从不同的 API 服务以及不同 API 服务的不同方法获得的原始输出。无法将其映射到所有可能的值。payload
是否可以拥有如下所示的 Java 类：
public class Event
{
public String name;
public long timestamp;
public JsonObject payload;
}
或者沿着这些路线的东西，所以我可以接收基本模式并处理它，然后将其发送到相关类，该类将转换为其适当的预期类？payload
JsonNode
你可以使用 com.fasterxml.jackson.databind package 中的 JsonNode：
public class Event {
public String name;
public long timestamp;
public JsonNode payload;
// Getters and setters
}
然后使用以下方法解析它：
String json = "{\"name\":\"foo\",\"timestamp\":1475840608763,"
+ "\"payload\":{\"foo\":\"bar\"}}";
ObjectMapper mapper = new ObjectMapper();
Event event = mapper.readValue(json, Event.class);
JsonNode例如，假设您要将 JsonNode 实例映射到以下类：
public class Payload {
private String foo;
// Getters and setters
}
这可以通过以下代码段实现：
Payload payload = mapper.treeToValue(event.getPayload(), Payload.class);
Map<String, Object>
根据您的要求，您可以使用一个代替JsonNode：Map<String, Object>
public class Event {
public String name;
public long timestamp;
public Map<String, Object> payload;
// Getters and setters
}
如果需要将 a 转换为 POJO，请使用：Map<String, Object>
Payload payload = mapper.convertValue(event.getPayload(), Payload.class);
根据 Jackson 文档，该方法在功能上类似于首先将给定值序列化为 JSON，然后将 JSON 数据绑定到给定类型的值，但应该更有效，因为不会（需要）发生完全序列化。但是，将使用与数据绑定相同的转换器（序列化程序和解串器），这意味着相同的对象映射器配置工作正常。convertValue()
这有帮助吗？
import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
public class Payload {
private final Map<String, Object> other = new HashMap<>();
@JsonAnyGetter
public Map<String, Object> any() {
return other;
}
@JsonAnySetter
public void set(final String name, final Object value) {
other.put(name, value);
}
public Map<String, Object> getOther() {
return other;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = (prime * result) + ((other == null) ? 0 : other.hashCode());
return result;
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (!(obj instanceof Payload)) {
return false;
}
Payload other = (Payload) obj;
if (this.other == null) {
if (other.other != null) {
return false;
}
} else if (!this.other.equals(other.other)) {
return false;
}
return true;
}
@Override
public String toString() {
return "Payload [other=" + other + "]";
}
}
那么这个拥有类
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
public class Outer {
private final String name;
private final long timestamp;
private final Payload payload;
@JsonCreator
public Outer(@JsonProperty("name") final String name, @JsonProperty("timestamp") final long timestamp, @JsonProperty("payload") final Payload payload) {
super();
this.name = name;
this.timestamp = timestamp;
this.payload = payload;
}
public String getName() {
return name;
}
public long getTimestamp() {
return timestamp;
}
public Payload getPayload() {
return payload;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = (prime * result) + ((name == null) ? 0 : name.hashCode());
result = (prime * result) + ((payload == null) ? 0 : payload.hashCode());
result = (prime * result) + (int) (timestamp ^ (timestamp >>> 32));
return result;
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (!(obj instanceof Outer)) {
return false;
}
Outer other = (Outer) obj;
if (name == null) {
if (other.name != null) {
return false;
}
} else if (!name.equals(other.name)) {
return false;
}
if (payload == null) {
if (other.payload != null) {
return false;
}
} else if (!payload.equals(other.payload)) {
return false;
}
if (timestamp != other.timestamp) {
return false;
}
return true;
}
@Override
public String toString() {
return "Outer [name=" + name + ", timestamp=" + timestamp + ", payload=" + payload + "]";
}
}
然后进行测试
public class Main {
private static final ObjectMapper mapper = new ObjectMapper();
public static void main(final String... args) throws JsonParseException, JsonMappingException, IOException {
final Outer outer = mapper.readValue(new File("test.json"), Outer.class);
System.out.println(outer);
}
}
提供控制台输出
Outer [name=foo, timestamp=1475840608763, payload=Payload [other={foo=bar}]]
