在java中展平三层嵌套的JSON字符串
要求是为输入 JSON 对象创建一个通用的扁平化实用程序以扁平化 JSON 对象。
示例 JSON 如下所示
{
"Source": "source-1",
"Rows": [
{
"Keys": {
"device-id": "BC04-EBH-N3K-01",
"interface-name": "TenGigE0/0/0/39",
"node-name": "0/0/CPU0"
},
"Timestamp": 1567621527656,
"inner": {
"donm": {
"id": "0062",
"mol": {
"rem": 30,
"len": 11,
"org": {
"ldp": [
{
"t": 486,
"o": 322
},
{
"t": 487,
"o": 32,
"twss": 1,
"tlv": "00:01"
}
]
},
"chlen": 14,
"poe": 5,
"combs": 10,
"chaype": 4,
"rek": 0,
"rem-um": 67
},
"detail": {
"enas": "B,R",
"systes": "B,R",
"timng": 91,
"syn": "C",
"met-type": 0,
"neses": {
"lldEDIT": [
{
"ium": 830,
"m": 1,
"ass": {
"ape": "ipv4",
"ipvs": "94"
}
}
]
},
"pess": "0008",
"por]d": 0,
"pon": "BCtive",
"sysme": "BC1"
},
"reme": "Bu1",
"hean": 0,
"porl": "Et1"
}
}
}
],
"Tey": {
"epath": "Cgetail",
"sustr": "MX",
"coime": 1567621527653,
"msp": 1567621527653,
"come": 1567621527660,
"nor": "BC5",
"cid": 14789654
}
}
我一直在尝试将其扁平化为 3 个级别，并提出了以下实用程序。但是，当我必须处理数组和 String、long、Timestamp 等类型的值时，事情变得复杂。此外，我无法理解如何维护嵌套键的唯一性。
任何帮助是极大的赞赏。
Cats萌萌浏览 183回答 4
4回答
-
交互式爱情
您可以查看json-flattener。 -
慕哥9229398
为了避免与键名称冲突，您可以使用JSON 指针规范来创建它们。它也受到Jackson库的支持，因此您可以稍后使用它们来遍历JsonNode节点。简单的实现如下所示：import com.fasterxml.jackson.databind.JsonNode;import com.fasterxml.jackson.databind.ObjectMapper;import com.fasterxml.jackson.databind.node.ArrayNode;import com.fasterxml.jackson.databind.node.ObjectNode;import java.io.File;import java.util.LinkedHashMap;import java.util.Map;import java.util.Objects;import java.util.concurrent.atomic.AtomicInteger;public class JsonApp { public static void main(String[] args) throws Exception { File jsonFile = new File("./test.json"); ObjectMapper mapper = new ObjectMapper(); JsonNode root = mapper.readTree(jsonFile); Map<String, JsonNode> map = new JsonFlattener(root).flatten(); System.out.println("Use key-value pairs:"); map.forEach( (k, v) -> { System.out.println(k + " => " + v); }); System.out.println(); System.out.println("Use pointers:"); map.forEach( (k, v) -> { System.out.println(k + " => " + root.at(k)); }); }}class JsonFlattener { private final Map<String, JsonNode> json = new LinkedHashMap<>(64); private final JsonNode root; JsonFlattener(JsonNode node) { this.root = Objects.requireNonNull(node); } public Map<String, JsonNode> flatten() { process(root, ""); return json; } private void process(JsonNode node, String prefix) { if (node.isObject()) { ObjectNode object = (ObjectNode) node; object .fields() .forEachRemaining( entry -> { process(entry.getValue(), prefix + "/" + entry.getKey()); }); } else if (node.isArray()) { ArrayNode array = (ArrayNode) node; AtomicInteger counter = new AtomicInteger(); array .elements() .forEachRemaining( item -> { process(item, prefix + "/" + counter.getAndIncrement()); }); } else { json.put(prefix, node); } }}上面的代码打印：Use key-value pairs:/Source => "source-1"/Rows/0/Keys/device-id => "BC04-EBH-N3K-01"/Rows/0/Keys/interface-name => "TenGigE0/0/0/39"/Rows/0/Keys/node-name => "0/0/CPU0"/Rows/0/Timestamp => 1567621527656/Rows/0/inner/donm/id => "0062"/Rows/0/inner/donm/mol/rem => 30/Rows/0/inner/donm/mol/len => 11/Rows/0/inner/donm/mol/org/ldp/0/t => 486/Rows/0/inner/donm/mol/org/ldp/0/o => 322/Rows/0/inner/donm/mol/org/ldp/1/t => 487/Rows/0/inner/donm/mol/org/ldp/1/o => 32/Rows/0/inner/donm/mol/org/ldp/1/twss => 1/Rows/0/inner/donm/mol/org/ldp/1/tlv => "00:01"/Rows/0/inner/donm/mol/chlen => 14/Rows/0/inner/donm/mol/poe => 5/Rows/0/inner/donm/mol/combs => 10/Rows/0/inner/donm/mol/chaype => 4/Rows/0/inner/donm/mol/rek => 0/Rows/0/inner/donm/mol/rem-um => 67/Rows/0/inner/donm/detail/enas => "B,R"/Rows/0/inner/donm/detail/systes => "B,R"/Rows/0/inner/donm/detail/timng => 91/Rows/0/inner/donm/detail/syn => "C"/Rows/0/inner/donm/detail/met-type => 0/Rows/0/inner/donm/detail/neses/lldEDIT/0/ium => 830/Rows/0/inner/donm/detail/neses/lldEDIT/0/m => 1/Rows/0/inner/donm/detail/neses/lldEDIT/0/ass/ape => "ipv4"/Rows/0/inner/donm/detail/neses/lldEDIT/0/ass/ipvs => "94"/Rows/0/inner/donm/detail/pess => "0008"/Rows/0/inner/donm/detail/por]d => 0/Rows/0/inner/donm/detail/pon => "BCtive"/Rows/0/inner/donm/detail/sysme => "BC1"/Rows/0/inner/donm/reme => "Bu1"/Rows/0/inner/donm/hean => 0/Rows/0/inner/donm/porl => "Et1"/Tey/epath => "Cgetail"/Tey/sustr => "MX"/Tey/coime => 1567621527653/Tey/msp => 1567621527653/Tey/come => 1567621527660/Tey/nor => "BC5"/Tey/cid => 14789654Use pointers:/Source => "source-1"/Rows/0/Keys/device-id => "BC04-EBH-N3K-01"/Rows/0/Keys/interface-name => "TenGigE0/0/0/39"/Rows/0/Keys/node-name => "0/0/CPU0"/Rows/0/Timestamp => 1567621527656/Rows/0/inner/donm/id => "0062"/Rows/0/inner/donm/mol/rem => 30/Rows/0/inner/donm/mol/len => 11/Rows/0/inner/donm/mol/org/ldp/0/t => 486/Rows/0/inner/donm/mol/org/ldp/0/o => 322/Rows/0/inner/donm/mol/org/ldp/1/t => 487/Rows/0/inner/donm/mol/org/ldp/1/o => 32/Rows/0/inner/donm/mol/org/ldp/1/twss => 1/Rows/0/inner/donm/mol/org/ldp/1/tlv => "00:01"/Rows/0/inner/donm/mol/chlen => 14/Rows/0/inner/donm/mol/poe => 5/Rows/0/inner/donm/mol/combs => 10/Rows/0/inner/donm/mol/chaype => 4/Rows/0/inner/donm/mol/rek => 0/Rows/0/inner/donm/mol/rem-um => 67/Rows/0/inner/donm/detail/enas => "B,R"/Rows/0/inner/donm/detail/systes => "B,R"/Rows/0/inner/donm/detail/timng => 91/Rows/0/inner/donm/detail/syn => "C"/Rows/0/inner/donm/detail/met-type => 0/Rows/0/inner/donm/detail/neses/lldEDIT/0/ium => 830/Rows/0/inner/donm/detail/neses/lldEDIT/0/m => 1/Rows/0/inner/donm/detail/neses/lldEDIT/0/ass/ape => "ipv4"/Rows/0/inner/donm/detail/neses/lldEDIT/0/ass/ipvs => "94"/Rows/0/inner/donm/detail/pess => "0008"/Rows/0/inner/donm/detail/por]d => 0/Rows/0/inner/donm/detail/pon => "BCtive"/Rows/0/inner/donm/detail/sysme => "BC1"/Rows/0/inner/donm/reme => "Bu1"/Rows/0/inner/donm/hean => 0/Rows/0/inner/donm/porl => "Et1"/Tey/epath => "Cgetail"/Tey/sustr => "MX"/Tey/coime => 1567621527653/Tey/msp => 1567621527653/Tey/come => 1567621527660/Tey/nor => "BC5"/Tey/cid => 14789654 -
阿波罗的战车
试试这个代码：public static void flattenJson(JsonNode node, String parent, Map<String, ValueNode> map) { if (node instanceof ValueNode) { map.put(parent, (ValueNode)node); } else { String prefix = parent == null ? "" : parent + "."; if (node instanceof ArrayNode) { ArrayNode arrayNode = (ArrayNode)node; for(int i = 0; i < arrayNode.size(); i++) { flattenJson(arrayNode.get(i), prefix + i, map); } } else if (node instanceof ObjectNode) { ObjectNode objectNode = (ObjectNode) node; for (Iterator<Map.Entry<String, JsonNode>> it = objectNode.fields(); it.hasNext(); ) { Map.Entry<String, JsonNode> field = it.next(); flattenJson(field.getValue(), prefix + field.getKey(), map); } } else { throw new RuntimeException("unknown json node"); } }}public static Map<String, ValueNode> flattenJson(JsonNode input) { Map<String, ValueNode> map = new LinkedHashMap<>(); flattenJson(input, null, map); return map;}然后你可以打电话 ObjectMapper om = new ObjectMapper(); JsonNode jsonNode = om.readTree(json); Map<String, ValueNode> m = flattenJson(jsonNode); for (Map.Entry<String, ValueNode> kv : m.entrySet()) { System.out.println(kv.getKey() + "=" + kv.getValue().asText()); }输出：Source=source-1Rows.0.Keys.device-id=BC04-EBH-N3K-01Rows.0.Keys.interface-name=TenGigE0/0/0/39Rows.0.Keys.node-name=0/0/CPU0Rows.0.Timestamp=1567621527656Rows.0.inner.donm.id=0062Rows.0.inner.donm.mol.rem=30Rows.0.inner.donm.mol.len=11Rows.0.inner.donm.mol.org.ldp.0.t=486Rows.0.inner.donm.mol.org.ldp.0.o=322Rows.0.inner.donm.mol.org.ldp.1.t=487Rows.0.inner.donm.mol.org.ldp.1.o=32Rows.0.inner.donm.mol.org.ldp.1.twss=1Rows.0.inner.donm.mol.org.ldp.1.tlv=00:01Rows.0.inner.donm.mol.chlen=14Rows.0.inner.donm.mol.poe=5Rows.0.inner.donm.mol.combs=10Rows.0.inner.donm.mol.chaype=4Rows.0.inner.donm.mol.rek=0Rows.0.inner.donm.mol.rem-um=67Rows.0.inner.donm.detail.enas=B,RRows.0.inner.donm.detail.systes=B,RRows.0.inner.donm.detail.timng=91Rows.0.inner.donm.detail.syn=CRows.0.inner.donm.detail.met-type=0Rows.0.inner.donm.detail.neses.lldEDIT.0.ium=830Rows.0.inner.donm.detail.neses.lldEDIT.0.m=1Rows.0.inner.donm.detail.neses.lldEDIT.0.ass.ape=ipv4Rows.0.inner.donm.detail.neses.lldEDIT.0.ass.ipvs=94Rows.0.inner.donm.detail.pess=0008Rows.0.inner.donm.detail.por]d=0Rows.0.inner.donm.detail.pon=BCtiveRows.0.inner.donm.detail.sysme=BC1Rows.0.inner.donm.reme=Bu1Rows.0.inner.donm.hean=0Rows.0.inner.donm.porl=Et1Tey.epath=CgetailTey.sustr=MXTey.coime=1567621527653Tey.msp=1567621527653Tey.come=1567621527660Tey.nor=BC5Tey.cid=14789654 -
墨色风雨
只需将每个级别的键附加到更高级别的键中即可创建键的命名空间。换句话说，你的扁平 JSON 的键将是：{ "L1key::L2key": "L2val", "L1key": "L1val", "L1key::L2key::L3key": "L3val"}这样你就可以保证唯一性，而且你也可以从中创建原始的 json。最后确保级别分隔符（此处::）不会出现在您的密钥中。
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