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如何在 Java 中将复杂的 JSON 对象展平或不展平为平面和类似地图的结构？

已发表: 2020-09-02
如何在 Java 中将复杂的 JSON 对象展平或不展平为平面和类似地图的结构？

如何将嵌套的 JSON 反序列化为扁平的、类似 Map 的结构？

几天前，我收到了一个关于如何展平可能结构简单或复杂的 JSON 对象的问题？

JsonFlattener是一个非常强大的 maven 实用程序，完全一样。 我们来看一个例子。

您需要将以下 Maven 依赖项导入到您的项目中。 将以下内容添加到项目的 pom.xml 文件中。

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< dependency >
< groupId > com . github . wnameless < / groupId >
< artifactId > json - flattener < / artifactId >
< version > 0.2.2 < / version >
< / dependency >
 
< dependency >
     < groupId > com . github . wnameless . json < / groupId >
     < artifactId > json - flattener < / artifactId >
     < version > 0.12.0 < / version >
< / dependency >

如果您没有在 Eclipse 工作区中看到pom.xml文件，因为您没有 maven 项目，那么您可以简单地隐藏您的项目 maven 项目。

side note ：很高兴看到谷歌搜索结果页面中的 Crunchify 文章

很高兴看到 Google 搜索页面上精选的 Crunchify 文章

让我们开始吧

第1步

  • 创建 java 类CrunchifyJSONFlattenerTutorial .java
  • 希望您已将上述json-flattener依赖项添加到您的pom.xml文件中

第2步

如果您在 Macbook 上，请创建文件crunchify.txt并将其放在~/Document文件夹下。 根据您的需要修改路径。

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{
"Name" : "crunchify.com" ,
"Author" : "App Shah" ,
"Address" : "New York" ,
"Company Services" : [ {
"Service" : "Site SEO Review" ,
"Link" : "https://pro.crunchify.com/#seo"
} , {
"Service" : "Full Website Design Service" ,
"Link" : "https://pro.crunchify.com/#full-design"
} , {
"Service" : "WordPress Optimization & Consultation" ,
"Link" : "https://pro.crunchify.com/#consultant"
} ]
}

我们将在 java 中读取 crunchify.txt JSON 文件。

第三步

将 java 代码复制到 Eclipse：

Java
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package crunchify . com . tutorials ;
 
import com . github . wnameless . json . flattener . JsonFlattener ;
import com . github . wnameless . json . unflattener . JsonUnflattener ;
import org . json . simple . JSONObject ;
import org . json . simple . parser . JSONParser ;
 
import java . io . FileReader ;
import java . util . Map ;
 
/**
* @author Crunchify.com
* How to Flatten or Unflatten Complex JSON objects into Flat & Map-Like Structure in Java?
*
*/
 
public class CrunchifyJSONFlattenerTutorial {
public static void main ( String [ ] args ) {
JSONParser parser = new JSONParser ( ) ;
try {
 
/* crunchify.txt file content
{
"Name": "crunchify.com",
"Author": "App Shah",
"Address": "New York",
"Company Services": [{
"Service": "Site SEO Review",
"Link": "https://crunchify.com/services/site-seo-review-service/"
}, {
"Service": "Full Website Design Service",
"Link": "https://crunchify.com/services/full-website-design-service/"
}, {
"Service": "WordPress Optimization & Consultation",
"Link": "https://crunchify.com/services/wordpress-optimization-service/"
}]
}
*/
 
// Put above JSON content to crunchify.txt file and change path location
Object obj = parser . parse ( new FileReader ( "/Users/appshah/Documents/crunchify.txt" ) ) ;
JSONObject jsonObject = ( JSONObject ) obj ;
 
// JsonFlattener: A Java utility used to FLATTEN nested JSON objects
// The String class represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class.
String flattenedJson = JsonFlattener . flatten ( jsonObject . toString ( ) ) ;
log ( "\n========== Simple Flatten ========== \n" + flattenedJson ) ;
 
Map < String , Object > flattenedJsonMap = JsonFlattener . flattenAsMap ( jsonObject . toString ( ) ) ;
 
log ( "\n=====Flatten As Map=====\n" + flattenedJson ) ;
// We are using Java8 forEach loop. More info: http://crunchify.me/1VIwm0l
flattenedJsonMap . forEach ( ( k , v ) - > log ( k + " : " + v ) ) ;
 
// Unflatten it back to original JSON
String nestedJson = JsonUnflattener . unflatten ( flattenedJson ) ;
System . out . println ( "\n===== Unflatten it back to original JSON ===== \n" + nestedJson ) ;
} catch ( Exception e ) {
e . printStackTrace ( ) ;
}
}
 
private static void log ( String flattenedJson ) {
System . out . println ( flattenedJson ) ;
 
}
}

就是这样。 只需运行程序，您将看到 JSONObject 的Flatten和Unflatten格式。

Eclipse 控制台输出：

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===== Simple Flatten =====
{ "Address" : "New York" , "Author" : "App Shah" , "Company Services[0].Service" : "Site SEO Review" , "Company Services[0].Link" : "https:\/\/crunchify.com\/services\/site-seo-review-service\/" , "Company Services[1].Service" : "Full Website Design Service" , "Company Services[1].Link" : "https:\/\/crunchify.com\/services\/full-website-design-service\/" , "Company Services[2].Service" : "WordPress Optimization & Consultation" , "Company Services[2].Link" : "https:\/\/crunchify.com\/services\/wordpress-optimization-service\/" , "Name" : "crunchify.com" }
 
===== Flatten As Map =====
{ "Address" : "New York" , "Author" : "App Shah" , "Company Services[0].Service" : "Site SEO Review" , "Company Services[0].Link" : "https:\/\/crunchify.com\/services\/site-seo-review-service\/" , "Company Services[1].Service" : "Full Website Design Service" , "Company Services[1].Link" : "https:\/\/crunchify.com\/services\/full-website-design-service\/" , "Company Services[2].Service" : "WordPress Optimization & Consultation" , "Company Services[2].Link" : "https:\/\/crunchify.com\/services\/wordpress-optimization-service\/" , "Name" : "crunchify.com" }
Address : New York
Author : App Shah
Company Services [ 0 ] . Service : Site SEO Review
Company Services [ 0 ] . Link : https : //pro.crunchify.com/#seo
Company Services [ 1 ] . Service : Full Website Design Service
Company Services [ 1 ] . Link : https : //pro.crunchify.com/#full-design
Company Services [ 2 ] . Service : WordPress Optimization & Consultation
Company Services [ 2 ] . Link : https : //pro.crunchify.com/#consultant
Name : crunchify . com
 
===== Unflatten it back to original JSON =====
{
"Name" : "crunchify.com" ,
"Author" : "App Shah" ,
"Address" : "New York" ,
"Company Services" : [ {
"Service" : "Site SEO Review" ,
"Link" : "https://crunchify.com/services/site-seo-review-service/"
} , {
"Service" : "Full Website Design Service" ,
"Link" : "https://crunchify.com/services/full-website-design-service/"
} , {
"Service" : "WordPress Optimization & Consultation" ,
"Link" : "https://crunchify.com/services/wordpress-optimization-service/"
} ]
}