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Jackson：String转object反序列化失败

news 2025/7/12 9:41:45

场景

消费mq时String转Object

代码

for (MessageExt msg : msgs) {String msgBody = new String(msg.getBody(), StandardCharsets.UTF_8);BinlogEvent binlogEvent = JsonUtil.silentString2Object(msgBody, BinlogEvent.class);binlogEvent.setPort(Long.valueOf(port));tConsumer.consume(binlogEvent);}

binlogEvent.setPort空指针，说明binlogEvent为空

debug报错信息

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `java.lang.String` from Object value (token `JsonToken.START_OBJECT`)at [Source: (String)"{ "before": {}, "after": { "id": 1019, "name": "ababababab", "score": 99 }, "source": { "version": "zzcdc:", "connector": "mysql", "name": "zzcdc:task:5017", "ts_ms": 1686193967, "db": "cdc", "table": "t1", "server_id": 192215017, "gtid": "", "file": "", "pos": 0, "row": 0, "partition_key": "5017:cdc:t1:1019" }, "op": "u", "ts_ms": 1686193967808, "transaction": null, "timestamp": "2023-06-08T11:12:47.808178366+08:00", "ts_u_ms": 1686193967808178}"; line: 1, column: 13] (through reference chain: com.zhuanzhuan.datasync.helper.mq.event.BinlogEvent["before"])

原因分析

Cannot deserialize value of type `java.lang.String` from Object value (token `JsonToken.START_OBJECT`)

报错信息：意思是Object反序列化为String失败

String：

{"before": {},"after": {"id": 1019,"name": "ababababab","score": 99},"source": {"version": "zzcdc:","connector": "mysql","name": "zzcdc:task:5017","ts_ms": 1686193967,"db": "cdc","table": "t1","server_id": 192215017,"gtid": "","file": "","pos": 0,"row": 0,"partition_key": "5017:cdc:t1:1019"},"op": "u","ts_ms": 1686193967808,"transaction": null,"timestamp": "2023-06-08T11:12:47.808178366+08:00","ts_u_ms": 1686193967808178
}

承接实体Object：

public class BinlogEvent {private String before;private String after;private String source;private String op;private Long tsMs;private String transaction;private String timestamp;private Long tsUMs;
}

发现原因：JSON/Object数据不能用String承接

解决

方法1：使用Object承接

public class BinlogEvent {private Object before;private Object after;private Object sourceprivate String op;private Long tsMs;private Object transaction;private String timestamp;private Long tsUMs;
}

方法2：新建JSON对应实体类承接

 public class BinlogEvent {private Object before;private Object after;private BinlogSourceEvent sourceprivate String op;private Long tsMs;private Object transaction;private String timestamp;private Long tsUMs;
}public class BinlogSourceEvent {private String version;private String connector;private String name;private Long tsMs;private String db;private String table;private Long serverId;private String gtid;private String file;private Long pos;private Long row;private String partitionKey;
}