使用键作为值反序列化Jackson

我有一个类似于这样的JSON结构：

"teams": { "team1Id": "team1Name", "team2Id": "team2Name" } 

我想将它反序列化为这些Java类：

 class Teams { Team team1; Team team2; } class Team { String id; String name; } 

正如您所见，team1Id和team2Id（它们是JSON密钥）应该转换为Java字段的值。 此外，第一个teamId / teamName对应该归因于存储在team1中的对象，而第二个对应存储在team2字段中。

是否有任何本地JACKSON映射器可以执行此操作，还是需要为此创建自己的自定义反序列化器？

Answer 1

你可以为这个类实现自定义反序列化器，但是，我认为，更简单的解决方案是使用@JsonAnySetter注释。

 class Teams { Team team1 = new Team(); Team team2 = new Team(); @JsonAnySetter public void anySetter(String key, String value) { if (key.startsWith("team1")) { team1.setId(key); team1.setName(value); } else if (key.startsWith("team2")) { team2.setId(key); team2.setName(value); } } //getters, setterr, toString() } 

用法示例：

 import java.io.File; import java.io.IOException; import com.fasterxml.jackson.annotation.JsonAnySetter; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonProgram { public static void main(String[] args) throws IOException { ObjectMapper mapper = new ObjectMapper(); Wrapper wrapper = mapper.readValue(new File("X:/json"), Wrapper.class); System.out.println(wrapper.getTeams()); } } class Wrapper { private Teams teams; public Teams getTeams() { return teams; } public void setTeams(Teams teams) { this.teams = teams; } } 

以上程序打印：

 Teams [team1=Team [id=team1Id, name=team1Name], team2=Team [id=team2Id, name=team2Name]] 

对于这个JSON：

 { "teams": { "team1Id": "team1Name", "team2Id": "team2Name" } } 

###编辑1 ###

如果您的JSON看起来像这样：

 { "teams": { "12345": "Chelsea", "67890": "Tottenham" } } 

我建议将它反序列化为LinkedHashMap ，然后将其转换为Teams对象。 示例程序：

 import java.io.File; import java.io.IOException; import java.util.ArrayList; import java.util.LinkedHashMap; import java.util.List; import java.util.Map.Entry; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonProgram { public static void main(String[] args) throws IOException { ObjectMapper mapper = new ObjectMapper(); Wrapper wrapper = mapper.readValue(new File("X:/json"), Wrapper.class); System.out.println(wrapper.toTeams()); } } class Wrapper { private LinkedHashMap teams; public LinkedHashMap getTeams() { return teams; } public void setTeams(LinkedHashMap teams) { this.teams = teams; } public Teams toTeams() { List teamList = toTeamList(); Teams result = new Teams(); result.setTeam1(teamList.get(0)); result.setTeam2(teamList.get(1)); return result; } private List toTeamList() { List teamList = new ArrayList(teams.size()); for (Entry entry : teams.entrySet()) { Team team = new Team(); team.setId(entry.getKey()); team.setName(entry.getValue()); teamList.add(team); } return teamList; } } 

以上程序打印：

 Teams [team1=Team [id=12345, name=Chelsea], team2=Team [id=67890, name=Tottenham]]