【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("[
");
            
            /*for(Json json:valueArray) {
                sb.append(json.toString()+"
");
            }*/
            
            int n=valueArray.size();
            for(int i=0;i<n;i++) {
                Json json=valueArray.get(i);
                if(i!=n-1) {
                    sb.append(json.toString()+",
");
                }else {
                    sb.append(json.toString()+"
");
                }
            }
            
            sb.append(tabs+"]");
        }else if(valueType==Type_List) {
            sb.append("{
");
            
            Collections.sort(valueList);
            
            
            /*for(Json json:valueList) {
                sb.append(json.toString()+"
");
            }*/
            
            int n=valueList.size();
            for(int i=0;i<n;i++) {
                Json json=valueList.get(i);
                if(i!=n-1) {
                    sb.append(json.toString()+",
");
                }else {
                    sb.append(json.toString()+"
");
                }
            }
            
            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