【java/Json】用Java对象构建Json语法树

本文后续：https://www.cnblogs.com/xiandedanteng/p/11973129.html

编译第一步：将文本解析成Java对象构成的语法树

第二步：将语法树输出整形好的Json新文本。

下面完成的是第二步：

package com.hy;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

import org.apache.log4j.Logger;

public class Json implements Comparable<Json>{
    private static Logger log = Logger.getLogger(Json.class);

    // There are value types
    private int Type_String=1;
    private int Type_Array=2;
    private int Type_List=3;

    // Key always is String
    private String key;

    // There are three types of value
    private int valueType;
    private String valueString;
    private List<Json> valueArray;// 本质一致，表现不同
    private List<Json> valueList;

    // indent depth
    private int depth;

    /**
     * Contructor1
     */
    public Json(String key,String value) {
        this.key=key;
        this.valueType=Type_String;
        this.valueString=value;
        this.depth=0;
    }

    public Json(String key,int type) {
        this.key=key;

        if(type==Type_List) {
            this.valueType=Type_List;
            this.valueList=new LinkedList<Json>();
        }else if(type==Type_Array) {
            this.valueType=Type_Array;
            this.valueArray=new LinkedList<Json>();
        }
    }

    public void addJsonToList(Json json) {
        if(valueList!=null) {
            valueList.add(json);

            adjustDepth();
        }
    }

    public void addJsonToArray(Json json) {
        if(valueArray!=null) {
            valueArray.add(json);

            adjustDepth();
        }
    }

    private void adjustDepth() {
        if(valueType==Type_List) {
            for(Json json:valueList) {
                json.depth=this.depth+1;
                json.adjustDepth();
            }

        }

        if(valueType==Type_Array) {
            for(Json json:valueArray) {
                json.depth=this.depth+1;
                json.adjustDepth();
            }
        }
    }

    public String toString() {
        StringBuilder sb=new StringBuilder();

        // key
        String tabs=getIndentSpace();
        sb.append(tabs);
        //sb.append("\""+(key==null?"":key)+"\"");

        if(key!=null) {
            sb.append("\""+key+"\"");
            sb.append(":");
        }else {

        }

        // value
        if(valueType==Type_String) {
            sb.append("\""+valueString+"\"");
        }else if(valueType==Type_Array) {
            sb.append("[\n");

            /*for(Json json:valueArray) {
                sb.append(json.toString()+"\n");
            }*/

            int n=valueArray.size();
            for(int i=0;i<n;i++) {
                Json json=valueArray.get(i);
                if(i!=n-1) {
                    sb.append(json.toString()+",\n");
                }else {
                    sb.append(json.toString()+"\n");
                }
            }

            sb.append(tabs+"]");
        }else if(valueType==Type_List) {
            sb.append("{\n");

            Collections.sort(valueList);

            /*for(Json json:valueList) {
                sb.append(json.toString()+"\n");
            }*/

            int n=valueList.size();
            for(int i=0;i<n;i++) {
                Json json=valueList.get(i);
                if(i!=n-1) {
                    sb.append(json.toString()+",\n");
                }else {
                    sb.append(json.toString()+"\n");
                }
            }

            sb.append(tabs+"}");
        }

        //sb.append(",");

        return sb.toString();
    }

    public int compareTo(Json other) {
        return this.key.compareTo(other.key);
    }

    private String getIndentSpace() {
        return String.join("", Collections.nCopies(this.depth, "    "));
    }

    public static void main(String[] args) {
        Json id1=new Json("id","001");
        Json name1=new Json("name","白菜");

        Json title=new Json("title",3);
        title.addJsonToList(id1);
        title.addJsonToList(name1);

        Json empty1=new Json(null,3);
        empty1.addJsonToList(new Json("id","001"));
        empty1.addJsonToList(new Json("id","你好白菜"));

        Json empty2=new Json(null,3);
        empty2.addJsonToList(new Json("id","001"));
        empty2.addJsonToList(new Json("id","你好萝卜"));

        Json content=new Json("content",2);
        content.addJsonToArray(empty1);
        content.addJsonToArray(empty2);

        Json data=new Json("data",3);
        data.addJsonToList(title);
        data.addJsonToList(content);

        Json status=new Json("status","0000");
        Json message=new Json("message","success");

        Json root=new Json(null,3);
        root.addJsonToList(status);
        root.addJsonToList(message);
        root.addJsonToList(data);

        System.out.println(root.toString());
    }
}

输出：

{
    "data":{
        "content":[
            {
                "id":"001",
                "value":"你好白菜"
            },
            {
                "id":"002",
                "value":"你好萝卜"
            }
        ],
        "title":{
            "id":"001",
            "name":"白菜"
        }
    },
    "message":"success",
    "status":"0000"
}

可以看到，子对象都是按字母序排列的，这也是制作此类的最终目的之一。

--END-- 2019年12月1日11:26:39