net.sf.json.JSONObject，将MySQL数据库的数据读出转化为json数据

maven依赖：

1     <dependency>
2       <groupId>net.sf.json-lib</groupId>
3       <artifactId>json-lib</artifactId>
4       <version>2.2.3</version>
5       <classifier>jdk13</classifier>
6     </dependency>

源代码：

 1 package com.reliable.service;
 2 import net.sf.json.JSONArray;
 3 import net.sf.json.JSONObject;
 4 import com.reliable.dao.ReadDB;
 5 import com.reliable.util.JDBCUtil;
 6 import java.sql.Connection;
 7 import java.sql.PreparedStatement;
 8 import java.sql.ResultSet;
 9 import java.sql.SQLException;
10 import java.util.*;
11
12 public class ReadDBImpl implements ReadDB {
13     private PreparedStatement preparedStatement=null;
14     private Connection conn =null;
15     private ResultSet resultSet=null;
16     @Override
17     public void getAllDbData() throws SQLException {
18         HashMap<String, String> map = new HashMap<>();
19         ArrayList<String> list = new ArrayList<String>();
20         conn= JDBCUtil.getConnection();
21         if(conn!=null)
22         {
23             System.out.println("数据库连接成功！");
24         }
25         preparedStatement=conn.prepareStatement("select * from hello;");
26         resultSet = preparedStatement.executeQuery();
27         while(resultSet.next()) {
28             String name= resultSet.getString(1);
29             String sex =resultSet.getString(2);
30             String age= resultSet.getString(3);
31             list.add(name+","+sex+" "+age);
32         }
33         for (int i=0;i<list.size();i++)
34         {
35             map.put(String.valueOf(i),list.get(i));
36         }
37         JSONObject jo = JSONObject.fromObject(map);
38 //        System.out.println(jo);
39
40         //遍历 01
41         Set<String> keys = map.keySet();  //map.keySet()返回key的集合
42         for(String key:keys) {
43             System.out.println(key+":"+map.get(key));  //map.get(key)返回key所对应的value值
44         }
45         System.out.println("--------------------------");
46         //遍历 02
47         Iterator<String> it02 = keys.iterator();
48         String key;
49         while (it02.hasNext()) {
50             key = it02.next();
51             System.out.println(key+":"+map.get(key));
52         }
53         System.out.println("--------------------------");
54         //遍历 03
55         Set<Map.Entry<String,String>> entrySet = map.entrySet();  //map.entrySet()返回<key,value>键值对的集合
56         for (Map.Entry<String,String> entry:entrySet) {
57             System.out.println(entry.getKey()+":"+entry.getValue());  //entry.getKey()返回key,entry.getValue()返回value
58         }
59         //遍历 04
60         System.out.println("--------------------------");
61         Iterator<Map.Entry<String,String>> it04 = entrySet.iterator();
62         Map.Entry<String,String> entry;
63         while (it04.hasNext()) {
64             entry = it04.next();
65             System.out.println(entry.getKey()+":"+entry.getValue());
66         }
67         JDBCUtil.release(conn,preparedStatement);
68     }
69 }

运行结果：