java - 在 Java 中使用公共(public)键合并两个列表

Question

我从 AS400 查询中获取一个列表，从 SQL Server 查询中获取另一个列表。我需要将这两个列表合并为一个列表。第一个列表是我们库存中的每项 Assets ，如下所示:

[
    {
        "assetId": 0,
        "type": "OV",
        "truckNumber": "L122",
        "longitude": 0,
        "latitude": 0,
        "id": 0
    },
    {
        "assetId": 0,
        "type": "PO",
        "truckNumber": "SQ46",
        "longitude": 0,
        "latitude": 0,
        "id": 0
    }
]

第二个列表有更多的细节，看起来像这样，两个列表有一个共同的字段，truckNumber:

[
   {
        "trailerGroup": "C",
        "assetId": 308,
        "loaded": false,
        "dedicated": false,
        "intermodal": false,
        "sealed": false,
        "truckNumber": "L122",
        "companyOwned": true,
        "onSite": false,
        "customerId": "KTPH",
        "id": 308,
        "modified": {
            "when": 1546498401156
        },
        "created": {
            "when": 1546498401156
        }
    },
    {
        "trailerGroup": "C",
        "assetId": 309,
        "loaded": false,
        "dedicated": false,
        "intermodal": false,
        "sealed": false,
        "truckNumber": "SQ46",
        "companyOwned": true,
        "onSite": true,
        "customerId": "KTPH",
        "id": 309,
        "modified": {
            "when": 1546498401156
        },
        "created": {
            "when": 1546498401156
        }
    }
]

我需要更新任何现有值(如经度)，同时添加任何不在第一个查询中的值。

我尝试了一些合并示例，但根本不起作用，或者其他示例只是将第一个列表附加到第二个列表。

---

可能的解决方案:

有人看到这方面的问题吗？

List<Trailer> trailers = null;
List<Trailer> trailersAS400 = null;
List<Trailer> trailersSQLServer = null;

try {
    trailersAS400 = getTrailerAS400Proxy().getTrailers();
    trailersSQLServer = getTrailerSQLServerProxy().getTrailers();           

    Map<String, Trailer> map = new HashMap<>();
    for (Trailer t : trailersAS400) {
        map.put(t.getNumber(), t);
    }
    for (Trailer t : trailersSQLServer) {
        String key = t.getNumber();
        if (map.containsKey(key)) {
            map.get(key).setNumber(t.getNumber());
        } else {
            map.put(key, t);
        }
    }
    trailers = new ArrayList<>(map.values());

}

Answer 1

如果您使用的是 Jackson(最流行的 JSON 库之一)，您可以按如下方式简单地实现:

代码片段

ObjectMapper mepper = new ObjectMapper();
List<Map<String, Object>> listAs400 = mepper.readValue(jsonStrAs400, List.class);
List<Map<String, Object>> listSqlServer = mepper.readValue(jsonStrSqlServer, List.class);
listAs400.forEach(e1 -> {
    listSqlServer.forEach(e2 -> {
        if (e1.get("truckNumber").toString().equals(e2.get("truckNumber").toString())) {
            e2.forEach((k, v) -> {
                e1.put(k, v);
            });
        }
    });
});
System.out.println(mapper.writeValueAsString(listAs400));

控制台输出

[ 
  { 
    "assetId":308,
    "type":"OV",
    "truckNumber":"L122",
    "longitude":0,
    "latitude":0,
    "id":308,
    "trailerGroup":"C",
    "loaded":false,
    "dedicated":false,
    "intermodal":false,
    "sealed":false,
    "companyOwned":true,
    "onSite":false,
    "customerId":"KTPH",
    "modified":{ 
      "when":1546498401156
    },
    "created":{ 
      "when":1546498401156
    }
  },
  { 
    "assetId":309,
    "type":"PO",
    "truckNumber":"SQ46",
    "longitude":0,
    "latitude":0,
    "id":309,
    "trailerGroup":"C",
    "loaded":false,
    "dedicated":false,
    "intermodal":false,
    "sealed":false,
    "companyOwned":true,
    "onSite":true,
    "customerId":"KTPH",
    "modified":{ 
      "when":1546498401156
    },
    "created":{ 
      "when":1546498401156
    }
  }
]