java读写json文件

骑猪看日落 2021-09-21 21:30 451阅读 0赞

先下载一个 json.jar 库

[下载地址][Link 1]

下载完后就加到工程里，然后才可以使用别人已封装好的方法，下载这个jar后，就不需要添加其他的依赖了。

![20210323150249594.png][]

代码如下：

package MenuTreePack;
    
    import org.json.JSONArray;
    import org.json.JSONException;
    import org.json.JSONObject;
    
    import java.io.*;
    import java.util.ArrayList;
    
    public class json_do {
        public static void Test() {
            ArrayList<String> list = new ArrayList<String>();
            list.add("admin");
    
            JSONObject dataJson = ReadJson("test.json");//new JSONObject(data);
            JSONArray features=dataJson.getJSONArray("features");
            for (int i = 0; i < features.length(); i++) {
                JSONObject info = features.getJSONObject(i);// 获取features数组的第i个json对象
                JSONObject properties = info.getJSONObject("properties");// 找到properties的json对象
                String name = properties.getString("name");// 读取properties对象里的name字段值
                System.out.println(name);
    
                properties.put("NAMEID", list.get(i));// 添加NAMEID字段
                // properties.append("name", list.get(i));
                System.out.println(properties.getString("NAMEID"));
    
                properties.remove("ISO");// 删除ISO字段
    
                WriteJson("newFile.json", dataJson);
            }
        }
    
    
        public static JSONObject ReadJson(String Path){
            JSONObject dataJson = null;
            //读取json文件
            try {
                BufferedReader br = new BufferedReader(new FileReader(Path));
                String str=null;
                String data="";
                while((str=br.readLine())!=null) {
                    data=data+str+"\n";
                }
                dataJson = new JSONObject(data);
                br.close();
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }// 读取原始json文件
            catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return dataJson;
        }
    
        public static void WriteJson(String Path, JSONObject dataJson) {
            //读取json文件
            try {
                BufferedWriter bw=new BufferedWriter(new FileWriter(Path));
                String ws=dataJson.toString();
                System.out.println(ws);
                bw.write(ws);
                // bw.newLine();
                bw.flush();
                bw.close();
    
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }// 读取原始json文件
            catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    
    }

对应的测试用json文件为:

{
    	"type": "FeatureCollection",  
        "features": 
    	[
    		{  
    			"type": "Feature",  
    			"properties": 
    			{  
    				"name": "Yuen Long",  
    				"ID_0": 102,  
    				"ISO": "HKG"  
    			},  
    			"geometry": 
    			{  
    				"type": "Polygon",  
    				"coordinates": 
    				[
    					[
    						[
    							114.084511, 
    							22.519991
    						], 
    						[
    							114.075668, 
    						], 
    					]
    				]  
    			}  
    		}
    	]
    }

本文参考： [https://blog.csdn.net/qq\_23335979/article/details/81668604?utm\_medium=distribute.pc\_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control&dist\_request\_id=1328680.64143.16164822381121313&depth\_1-utm\_source=distribute.pc\_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control][https_blog.csdn.net_qq_23335979_article_details_81668604_utm_medium_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control_dist_request_id_1328680.64143.16164822381121313_depth_1-utm_source_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control]

[Link 1]: https://search.maven.org/search?q=g:org.json%20AND%20a:json&core=gav
[20210323150249594.png]: /images/20210920/640eafc8e39849fda2f1818736e7629a.png
[https_blog.csdn.net_qq_23335979_article_details_81668604_utm_medium_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control_dist_request_id_1328680.64143.16164822381121313_depth_1-utm_source_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control]: https://blog.csdn.net/qq_23335979/article/details/81668604?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control&dist_request_id=1328680.64143.16164822381121313&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-3.control