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Java 在DataWeave中递归遍历并展平JSON对象

java json

Java 在DataWeave中递归遍历并展平JSON对象,java,json,transformation,dataweave,mulesoft,Java,Json,Transformation,Dataweave,Mulesoft,我想遍历并展平一个大JSON文件，该文件具有以下显示产品层次结构的结构（将其视为在线商店中的导航）： 我想用这样的格式将它们展平： { "hierarchieSet": [ { "Nodeid": "00000001", # Number in this json "Nodename": "child 1",

我想遍历并展平一个大JSON文件，该文件具有以下显示产品层次结构的结构（将其视为在线商店中的导航）：

我想用这样的格式将它们展平：

{
    "hierarchieSet": [
        {
            "Nodeid": "00000001", # Number in this json
            "Nodename": "child 1",
            "Tlevel": "01", # First child of product group
            "Parentid": "00000000", # Parent is null
            "Childid": "00000002", # Child node number
            "Nextid": "00000008" # Node number on the same level (child 2)
        }, 
        {
            "Nodeid": "00000002",
            "Nodename": "child 1.1",
            "Tlevel": "02",
            "Parentid": "00000001",
            "Childid": "00000003",
            "Nextid": "00000003"
        }, 
        {
            "Nodeid": "00000003",
            "Nodename": "child 1.2",
            "Tlevel": "02",
            "Parentid": "00000002",
            "Childid": "00000005",
            "Nextid": "00000007"
        }, 
        {
            "Nodeid": "00000004",
            "Nodename": "child 1.2.1",
            "Tlevel": "03",
            "Parentid": "00000003",
            "Childid": "0000005",
            "Nextid": "00000006"
        }
        , 
        {
            "Nodeid": "00000005",
            "Nodename": "child 1.2.1.1",
            "Tlevel": "04",
            "Parentid": "00000004",
            "Childid": "0000000", #No more children
            "Nextid": "00000000"
        }, 
        {
            "Nodeid": "00000006",
            "Nodename": "child 1.2.2",
            "Tlevel": "03",
            "Parentid": "00000003",
            "Childid": "0000000",
            "Nextid": "00000000"
        }, 
        {
            "Nodeid": "00000007",
            "Nodename": "child 1.3",
            "Tlevel": "02",
            "Parentid": "00000001",
            "Childid": "0000000",
            "Nextid": "00000000"
        }, 
        {
            "Nodeid": "00000008",
            "Nodename": "child 2",
            "Tlevel": "01",
            "Parentid": "00000000",
            "Childid": "0000009", # 00000009 not shown
            "Nextid": "00000014" # 
        }, 
        ...
        {
            "Nodeid": "000000014",
            "Nodename": "child 3",
            "Tlevel": "01",
            "Parentid": "00000000",
            "Childid": "00000015",
            "Nextid": "00000000" # 00000010 does not exist
        }
    ]
}
因此，我确定了一些主要问题：

  • 树结构的递归
  • 变换元素
  • 扁平化结构
  • 跟踪父母、兄弟姐妹和孩子
  • 跟踪递归级别
  • 格式化数字
我试图通过两种不同的方法来解决这个问题：

  • 使用DataWeave转换所有元素
  • 使用Java遍历结构
由于我对函数式编程相当陌生，所以我更加关注Java实现，但遇到了许多问题。

Java方法

读取json>Init Tree var，并为
Tree.Java中的顶级数组invoke
transverse（data，level）
中的每个元素分配Java实例>
Tree.java:


import org.json.JSONObject;

public class Tree {
    private int id = 0;
    private List<Node> nodes = new ArrayList<Node>();
    
    public Tree() {
        nodes.add(new Node("01", "00000001", "HOME", "01", "00000000", "00000002", "00000000"));
    }
    
    public void traverse(String data, int level) {
        System.out.println(data);
        // TODO parse json
    }
    
    private void visit(JSONObject parent, JSONObject node, int level) {
        id++;
        nodes.add(new Node("01", String.valueOf(id), node.getString("key"), String.valueOf(level), "", "", ""));
    }
    
    public List<Node> getNodes() {
        return nodes;
    }

    private static class Node {
        private String zshop, nodename, parentid, childid, nextid, nodeid, tlevel;
        
        public Node(String zshop, String nodeid, String nodename, String tlevel, String parentid, String childid, String nextid) {
            this.zshop = zshop;
            this.nodeid = nodeid;
            this.nodename = nodename;
            this.tlevel = tlevel;
            this.parentid = parentid;
            this.childid = childid;
            this.nextid = nextid;
        }
    }
}


但这会产生以下错误：

无法强制对象{编码：UTF-8，媒体类型：text/json；
charset=UTF-8，mimeType:text/json，原始：
org.mule.weave.v2.el。SeekableCursorStream@50ecee52 }
（org.mule.weave.v2.el。MuleTypedValue@511ba9cc)串

5 |数据：vars.rootMessage.payload作为字符串，
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Trace:at main（第5行第7列）“计算表达式：”%dw2.0输出应用程序/java
---{data:vars.rootMessage.payload作为字符串，级别：1}”

我尝试了很多方法：


    

  • 将其转换为我用Java编写的
    ProductGroup
    对象
    • 

  • 尝试将检索到的对象强制转换为
    org.json.JSONObject
    • 

  • 尝试缓冲并读取
    vars.rootMessage.payload（二进制）
    • 


但我无法解决这些问题。

数据编织方法
My.dw脚本


%dw 2.0
fun append
(item: Object, acc: Object = {
}) = acc ++ item

fun mapper(item: Object) = 
{
    Zshop: "01",
    Nodeid: "00000000",
    Nodename: item.key as Number as String {format: ""},
    Tlevel: "02",
    Parentid: "00000000",
    Childid: "00000000",
    Nextid: "00000000"
}
    
fun traverse(a: Array, level: Number) = 
    a map $ flatMap(value, index) -> value
    
output application/json
---
{
    test: payload.productGroups reduce (item, acc) -> append(mapper(item), acc)
}


在那里我试图解决一些问题
mapper（item）
应该创建json对象，我可以使用
appender（item，acc）
将其附加到最终输出中。递归已经画好了，但还不是我主要关心的问题。

这将产生以下结果：


(original payload),
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "800",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "110",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "720",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "710",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
...


我想知道为什么在没有任何对象结构的情况下得到平坦的结果。


我的问题是:


    

  • Java：为什么我不能转换字符串，或者如何正确地转换
    • 

  • DataWeave：有没有一个我看不到的简单解决方案
    • 

  • 为什么它是一个简单的结果而不是一个对象
    • 

  • reduce
    和
    flatMap
    功能的使用是否正确
    • 


欢迎提供任何帮助和/或反馈

Java：为什么我不能转换字符串，或者如何正确地转换

JSON不是字符串。使用write（有效负载，'application/json'）生成字符串

DataWeave：有没有一个我看不到的简单解决方案

只需传递对象，它就是Java中的映射。因为它是树-每个分支都是这个映射中的另一个映射

为什么它是一个简单的结果而不是一个对象

它总是客观的。Java世界中没有其他东西

reduce和flatMap函数的用法是否正确


不。mapObject和递归应该是很好的方法。
基于我收到的帮助，我可以设计这个解决方案：


public class Tree implements Serializable {
    private int id = 0;
    private List<Node> nodes = new ArrayList<Node>();
    
    public Tree() {
        nodes.add(new Node("01", "00000001", "HOME", "0", "00000000", "00000002", "00000000"));
    }
    
    public void enter(String jsonString, Integer level) {
        JSONObject json = new JSONObject(jsonString);
        traverse(json, level);
    }
    
    public void traverse(JSONObject json, int level) {
        visit(json, level);
        
        JSONArray arr = json.getJSONArray("childProductGroups");
        if(arr != null) {
            for(int i = 0; i < arr.length(); i++) {
                traverse(arr.getJSONObject(i), level + 1);
            }
        }       
    }
    
    private void visit(JSONObject object, int level) {
        id++;
        nodes.add(new Node("01", String.valueOf(id), object.getString("name_de"), String.valueOf(level), "", "", ""));
    }
    
    public Node[] getNodes() {
        assignParentIds();
        assignNextIds();
        assignChildIds();
            
        Node[] nodeArr = new Node[nodes.size()];
        for(int i = 0; i < nodes.size(); i++) {
            nodeArr[i] = nodes.get(i);
        }
        return nodeArr;
    }
    
    private void assignParentIds() {
        Map<String, Node> lastNodesWithHigherLevel = new HashMap<String, Node>();
        for(Node node : nodes) {
            Node higher = lastNodesWithHigherLevel.get(String.valueOf(Integer.valueOf(node.tlevel) - 1));
            if(higher != null) {
                node.parentid = higher.nodeid;
            }   
            lastNodesWithHigherLevel.put(node.tlevel, node);
        }
    }
    
    private void assignNextIds() {
        Map<String, Node> lastNodeOnSameLevel = new HashMap<String, Node>();
        for(Node node : nodes) {
            Node last = lastNodeOnSameLevel.get(node.tlevel);
            if(last != null) {
                if(last.parentid.equals(node.parentid)) {
                    // If the last and this node have the same parent
                    last.nextid = node.nodeid;
                }
            }   
            lastNodeOnSameLevel.put(node.tlevel, node);
        }
    }

    private void assignChildIds() {
        Iterator<Node> parentIterator = nodes.iterator();
        Iterator<Node> childIterator = nodes.iterator();
        
        // Init child iterator one further
        if(childIterator.hasNext()) {
            childIterator.next();
        }
        
        do {
            Node parent = parentIterator.next();
            Node child = childIterator.next();
            // If level of parent is higher (<) set the value
            if(Integer.valueOf(parent.tlevel) < Integer.valueOf(child.tlevel)) {
                parent.childid = child.nodeid;
            }
        } while (childIterator.hasNext());
        // Because childIterator will first be done, but parentIterator might need one more reference, we need do while
    }
    
    private static class Node implements Serializable {
        public String zshop, nodename, parentid, childid, nextid, nodeid, tlevel;
        
        public Node(String zshop, String nodeid, String nodename, String tlevel, String parentid, String childid, String nextid) {
            this.zshop = zshop;
            this.nodeid = nodeid;
            this.nodename = nodename;
            this.tlevel = tlevel;
            this.parentid = parentid;
            this.childid = childid;
            this.nextid = nextid;
        }
        
        @Override
        public String toString() {
            return "{zshop:" + zshop + ", nodename:" + nodename + ", parentid:" + parentid + ", childid:" + childid
                    + ", nextid:" + nextid + ", nodeid:" + nodeid + ", tlevel:" + tlevel + "}";
        }
    }
}



公共类树实现可序列化{
私有int id=0；
私有列表节点=新的ArrayList（）；
公树（）{
添加（新节点（“01”、“00000001”、“HOME”、“0”、“00000000”、“00000002”、“00000000”）；
}
public void enter（字符串jsonString，整数级别）{
JSONObject json=新的JSONObject（jsonString）；
遍历（json，级别）；
}
公共void遍历（JSONObject json，int级别）{
访问（json，级别）；
JSONArray arr=json.getJSONArray（“childProductGroups”）；
如果（arr！=null）{
对于（int i=0；i(original payload),
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "800",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "110",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "720",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
"Zshop": "01",
"Nodeid": "00000000",
"Nodename": "710",
"Tlevel": "02",
"Parentid": "00000000",
"Childid": "00000000",
"Nextid": "00000000",
...



public class Tree implements Serializable {
    private int id = 0;
    private List<Node> nodes = new ArrayList<Node>();
    
    public Tree() {
        nodes.add(new Node("01", "00000001", "HOME", "0", "00000000", "00000002", "00000000"));
    }
    
    public void enter(String jsonString, Integer level) {
        JSONObject json = new JSONObject(jsonString);
        traverse(json, level);
    }
    
    public void traverse(JSONObject json, int level) {
        visit(json, level);
        
        JSONArray arr = json.getJSONArray("childProductGroups");
        if(arr != null) {
            for(int i = 0; i < arr.length(); i++) {
                traverse(arr.getJSONObject(i), level + 1);
            }
        }       
    }
    
    private void visit(JSONObject object, int level) {
        id++;
        nodes.add(new Node("01", String.valueOf(id), object.getString("name_de"), String.valueOf(level), "", "", ""));
    }
    
    public Node[] getNodes() {
        assignParentIds();
        assignNextIds();
        assignChildIds();
            
        Node[] nodeArr = new Node[nodes.size()];
        for(int i = 0; i < nodes.size(); i++) {
            nodeArr[i] = nodes.get(i);
        }
        return nodeArr;
    }
    
    private void assignParentIds() {
        Map<String, Node> lastNodesWithHigherLevel = new HashMap<String, Node>();
        for(Node node : nodes) {
            Node higher = lastNodesWithHigherLevel.get(String.valueOf(Integer.valueOf(node.tlevel) - 1));
            if(higher != null) {
                node.parentid = higher.nodeid;
            }   
            lastNodesWithHigherLevel.put(node.tlevel, node);
        }
    }
    
    private void assignNextIds() {
        Map<String, Node> lastNodeOnSameLevel = new HashMap<String, Node>();
        for(Node node : nodes) {
            Node last = lastNodeOnSameLevel.get(node.tlevel);
            if(last != null) {
                if(last.parentid.equals(node.parentid)) {
                    // If the last and this node have the same parent
                    last.nextid = node.nodeid;
                }
            }   
            lastNodeOnSameLevel.put(node.tlevel, node);
        }
    }

    private void assignChildIds() {
        Iterator<Node> parentIterator = nodes.iterator();
        Iterator<Node> childIterator = nodes.iterator();
        
        // Init child iterator one further
        if(childIterator.hasNext()) {
            childIterator.next();
        }
        
        do {
            Node parent = parentIterator.next();
            Node child = childIterator.next();
            // If level of parent is higher (<) set the value
            if(Integer.valueOf(parent.tlevel) < Integer.valueOf(child.tlevel)) {
                parent.childid = child.nodeid;
            }
        } while (childIterator.hasNext());
        // Because childIterator will first be done, but parentIterator might need one more reference, we need do while
    }
    
    private static class Node implements Serializable {
        public String zshop, nodename, parentid, childid, nextid, nodeid, tlevel;
        
        public Node(String zshop, String nodeid, String nodename, String tlevel, String parentid, String childid, String nextid) {
            this.zshop = zshop;
            this.nodeid = nodeid;
            this.nodename = nodename;
            this.tlevel = tlevel;
            this.parentid = parentid;
            this.childid = childid;
            this.nextid = nextid;
        }
        
        @Override
        public String toString() {
            return "{zshop:" + zshop + ", nodename:" + nodename + ", parentid:" + parentid + ", childid:" + childid
                    + ", nextid:" + nextid + ", nodeid:" + nodeid + ", tlevel:" + tlevel + "}";
        }
    }
}



<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:java="http://www.mulesoft.org/schema/mule/java" xmlns:ee="http://www.mulesoft.org/schema/mule/ee/core"
    xmlns:file="http://www.mulesoft.org/schema/mule/file"
    xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/file http://www.mulesoft.org/schema/mule/file/current/mule-file.xsd
http://www.mulesoft.org/schema/mule/ee/core http://www.mulesoft.org/schema/mule/ee/core/current/mule-ee.xsd
http://www.mulesoft.org/schema/mule/java http://www.mulesoft.org/schema/mule/java/current/mule-java.xsd">
    <http:listener-config name="HTTP_Listener_config" doc:name="HTTP Listener config" doc:id="e31dc867-3f9f-457b-8013-cd50a74c0af1" >
        <http:listener-connection host="0.0.0.0" port="8081" />
    </http:listener-config>
    <file:config name="File_Config" doc:name="File Config" doc:id="3279487e-61ca-4845-89a2-5332e7c02638" />
    <flow name="java-flow" doc:id="3c036218-560d-44f0-aef5-0c7f0ef4d776" >
        <http:listener doc:name="Listener" doc:id="265a1691-4f9b-40e2-a280-592daf719002" config-ref="HTTP_Listener_config" path="java">
            <http:response >
                <http:body ><![CDATA[#[output application/json ---
payload]]]></http:body>
            </http:response>
        </http:listener>
        <file:read doc:name="Copy_of_Read" doc:id="9f8b3c6f-f674-45f7-80fe-756f64602b30" config-ref="File_Config" path="response.json" />
        <set-variable doc:name="Set Variable" doc:id="ecff267b-3b73-45d1-924e-227a01a99e4e" variableName="Tree" value="#[null]" />
        <java:new doc:name="New Tree" doc:id="764d60bf-da41-4f17-8e13-c8bf31f141dc" class="valion.Tree" constructor="Tree()" target="Tree" />
        <foreach doc:name="For Each" doc:id="e612fd8b-636e-41c2-b603-e6861514306b" collection="#[payload.productGroups]">
            <java:invoke doc:name="Traverse" doc:id="96da4743-00d3-4970-a9e5-712877bcf2a9" class="valion.Tree" instance="#[vars.Tree]" method="enter(java.lang.String,java.lang.Integer)">
                <java:args><![CDATA[#[%dw 2.0
output application/java
---
{
    jsonString: write( payload,'application/json'),
    level: 1
}]]]></java:args>
            </java:invoke>
        </foreach>
        <java:invoke doc:name="Get Nodes" doc:id="999d5f4c-80b4-4793-9188-e17725ad030b" instance="#[vars.Tree]" class="valion.Tree" method="getNodes()">
        </java:invoke>
        <ee:transform doc:name="Transform Message" doc:id="b078bef3-45aa-4821-b7d1-720c2c7d0580">
            <ee:message>
                <ee:set-payload><![CDATA[%dw 2.0
output application/json
---
{
    hierarchieSet: payload map ( item , index ) -> {
        zshop: item.zshop,
        nodeid: item.nodeid,
        nodename: item.nodename,
        tlevel: item.tlevel,
        parentid: item.parentid,
        childid: item.childid,
        nextid: item.nextid
    }
}]]></ee:set-payload>
            </ee:message>
        </ee:transform>
    </flow>
</mule>