我有一個 Java 對象，如下所示。我需要遍歷這個嵌套對象并獲取一個字段的所有值。下面的java對象的前'時間'。如果是列表，我可以使用 java 8 過濾器。但是如何在對象上執(zhí)行此操作？另外，我需要以通用的方式來做。 { "dataType": "Node", "totalCount": 1, "count": 1, "startIndex": 0, "data": [ { "id": "a4b7a825f67930965747445709011120-Node-6f638b5e71debd5807ec7fb73b9dc20b", "refObjects": {}, "tid": "a4b7a825f67930965747445709011120", "creationDate": "2018-09-20T06:55:36.742+0000", "lmd": "2018-09-20T06:55:36.799+0000", "exceptions": [ { "name": "projectedInventory", "status": "Stockout", "severity": "High", "time": "2018-09-20T00:00:00.000+0000" } ], "criticalities": [ "HotItem" ], "customerName": "Best Buys", "supplierName": "Samsung", "customerItemName": "Ship to item name", "nodeType": "inventory", "supplierItemName": "Ship from item name", "shipToSiteName": "IT06", "shipFromSiteName": "IT07", "status": "Active", "lob": "HC", "processType": "demandSupply", "measures": { "maxInventory": [ { "refObjects": {}, "time": "2018-09-26T00:00:00.000+0000", "quantity": 0 }, { "refObjects": {}, "time": "2018-09-27T00:00:00.000+0000", "quantity": 0 } ], "maxDistribution": [ { "refObjects": {}, "time": "2018-09-28T00:00:00.000+0000", "quantity": 0 }, { "refObjects": {}, "time": "2018-09-29T00:00:00.000+0000", "quantity": 0 },現(xiàn)在我想檢索“時間”字段的所有值并將其保存在列表中。這樣做的最佳方法是什么？輸出應(yīng)該是這樣的：{ "time": [ "2018-12-30T00:00:00.000+0000", "2018-08-24T12:00:00.000+0000" ]}
2 回答
蝴蝶不菲
TA貢獻1810條經(jīng)驗 獲得超4個贊
您也可以使用反射，但 apache-commons 使它更容易。我在下面編寫的方法有兩個參數(shù)，一個是您的 POJO 對象，另一個是空列表。"time"即使存在嵌套對象，它也會通過填充輸入對象中的所有屬性值來返回相同的列表。在else if我添加了一個條件，我正在檢查 className 是否包含“com.your.packageName”，這是因為在這里我假設(shè)您的所有 POJO（可以嵌套在您的輸入對象中）都存儲在一個包中“ com.your.packageName”，因此如果您將所有 POJO 存儲在一個位置，那么您可以將其替換為您的包名稱。為 common-beanutils 添加以下依賴項。
<groupId>commons-beanutils</groupId>
<artifactId>commons-beanutils</artifactId>
<version>1.9.2</version>
import org.apache.commons.beanutils.BeanMap;
import org.apache.commons.beanutils.PropertyUtilsBean;
private static List<String> getPropertyValue(Object myObj, List<String> timeList) {
final BeanMap beanMap = new BeanMap(myObj);
PropertyUtilsBean pp = new PropertyUtilsBean();
beanMap.keySet().stream().forEach(x -> {
try {
String propertyName= ""+x;
//GET THE CLASS TYPE OF PROPERTY
String proprtyTypeClassName=""+pp.getPropertyType((Object)myObj,propertyName);
System.out.println(propertyName+" "+proprtyTypeClassName);
if(propertyName.equals("time")) {
//GET THE VALUE OF A propertyName FROM object myObj
timeList.add((String)pp.getProperty(myObj, propertyName));
}
else if(proprtyTypeClassName.contains("com.your.packageName")) {
//recursively call same method if value is another POJO object nested inside
getPropertyValue(pp.getProperty(myObj, propertyName),timeList);
}
} catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
e.printStackTrace();
}
});
return timeList;
}
如果您有任何疑問，請告訴我。
30秒到達戰(zhàn)場
TA貢獻1828條經(jīng)驗 獲得超6個贊
非常感謝。我正在嘗試一些解決方案，并在下面找到了一個。如果這看起來也正確，請告訴我：
package com.company.dct.exec.lib.relationships.util;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.jayway.jsonpath.JsonPath;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
@Component("objectPathValuesExtractor")
public class ObjectPathValuesExtractor {
private static final Logger LOGGER = LoggerFactory.getLogger(ObjectPathValuesExtractor.class);
/**
* Extract values for a given path from current object.
*
* @param object the object
*/
public <T extends Object> T extractValues(Object object, String pathExpression) {
T values = null;
if (object == null) {
return values;
}
try {
ObjectMapper mapper = new ObjectMapper();
mapper.setDefaultPropertyInclusion(JsonInclude.Value.construct(JsonInclude.Include.ALWAYS, JsonInclude.Include.NON_NULL));
Map<String, Object> mappedObject = mapper.convertValue(object, Map.class);
values = JsonPath.read(mappedObject, pathExpression);
} catch (Exception e) {
LOGGER.error("Failed to load alert referenced object.", e);
}
return values;
}
}
在這里我使用
compile group: 'com.jayway.jsonpath', name: 'json-path', version: '2.4.0' 來自 apache
然后我調(diào)用這個函數(shù)
List<Map<String, Extensible>> refObjects = objectPathValuesExtractor.extractValues(object, "$..time");
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