将数据从mysql内部的json拉到java

Posted 2023-02-26

【中文标题】将数据从mysql内部的json拉到java

【英文标题】：Pulling data from json inside mysql to java

【发布时间】：2021-08-11 19:49:45

【问题描述】：

所以我有一个我正在尝试整理的声明脚本，用于在购买后声明该产品。该程序是在 Java 内部构建的。我遇到的问题是他们在购买时输入了一个自定义字段，而商店本身将其插入到 JSON 格式中。所以我需要执行一个查询，将自定义字段拉入 WHERE 语句，如下所示：

public class StoreClaim implements Runnable 

    public static final String HOST = "104.161.43.58"; // website ip address 
    public static final String USER = "eseezjte_forum";
    public static final String PASS = "Fishsticks123";
    public static final String DATABASE = "eseezjte_forum";

    private Player player;
    private Connection conn;
    private Statement stmt;

    
    public StoreClaim(Player player) 
        this.player = player;
    
    
    

    public void run() 
        try 
            if (!connect(HOST, DATABASE, USER, PASS)) 
                return;
            

            
            String name = player.getUsername().replace("_", " ");
            ResultSet connect = executeQuery("SELECT ps_claimed, ps_item_id, ps_custom_fields->$.1 AS claimed FROM nexus_purchases WHERE ps_custom_fields->$.1 = '"+name+"' AND ps_claimed='0'");
            while (connect.next()) 
                player.sm("WORKING!");
                return;
                
            
            

            destroy();
         catch (Exception e) 
            e.printStackTrace();
        
    

/**
     *
     * @param host the host ip address or url
     * @param database the name of the database
     * @param user the user attached to the database
     * @param pass the users password
     * @return true if connected
     */
    public boolean connect(String host, String database, String user, String pass) 
        try 
            this.conn = DriverManager.getConnection("jdbc:mysql://"+host+":3306/"+database, user, pass);
            return true;
         catch (SQLException e) 
            System.out.println("Failing connecting to database!");
            return false;
        
    

    /**
     * Disconnects from the MySQL server and destroy the connection
     * and statement instances
     */
    public void destroy() 
        try 
            conn.close();
            conn = null;
            if (stmt != null) 
                stmt.close();
                stmt = null;
            
         catch(Exception e) 
            e.printStackTrace();
        
    

    /**
     * Executes an update query on the database
     * @param query
     * @see @link Statement#executeUpdate
     */
    public int executeUpdate(String query) 
        try 
            this.stmt = this.conn.createStatement(1005, 1008);
            int results = stmt.executeUpdate(query);
            return results;
         catch (SQLException ex) 
            ex.printStackTrace();
        
        return -1;
    

    /**
     * Executres a query on the database
     * @param query
     * @see @link Statement#executeQuery(String)
     * @return the results, never null
     */
    public ResultSet executeQuery(String query) 
        try 
            this.stmt = this.conn.createStatement(1005, 1008);
            ResultSet results = stmt.executeQuery(query);
            return results;
         catch (SQLException ex) 
            ex.printStackTrace();
        
        return null;
    

所以我需要将我试图从中提取的 JSON 插入到此结果集中。 这是我试图从数据库中提取并作为名称插入以验证哪个用户购买了要声明的产品。

我得到了错误：

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '>$.1 AS claimed FROM nexus_purchases WHERE ps_custom_fields->$.1 = 'quantum' ...' at line 1
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.Util.getInstance(Util.java:386)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1052)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3609)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3541)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2618)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2568)
    at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1557)
    at quantum.site.StoreClaim.executeQuery(StoreClaim.java:139)
    at quantum.site.StoreClaim.run(StoreClaim.java:45)
    at java.lang.Thread.run(Thread.java:748)
java.lang.NullPointerException
    at quantum.site.StoreClaim.run(StoreClaim.java:46)
    at java.lang.Thread.run(Thread.java:748)

指向：

ResultSet connect = executeQuery("SELECT ps_claimed, ps_item_id, ps_custom_fields->$.1 AS claimed FROM nexus_purchases WHERE ps_custom_fields->$.1 = '"+name+"' AND ps_claimed='0'");

我需要执行来检查数据库，找到其中名称 == 自定义字段“1”：变量和声明 == 0 的行，我需要从该行中提取 ps_item_id 来执行在另一个文件中。如何正确访问数组并检查玩家名称是否 == 到 "1": 变量？

【问题讨论】：

你忘了问问题。

试图从 mysql 中的 json 中提取测试，作为 WHERE 语句中的名称执行查询，如上所述。

这不是问题。这是一个声明。

虽然嘲笑学习开发者在业界很常见，但您不需要连词来发起问题，也不需要问号。很明显，我的问题是如何从 mysql 内部的数组中提取测试，以在上面列出的执行查询中标记为名称，如上所述。看来我需要不识字。

你没有问任何问题，你只是陈述了你想要实现的目标。我们不知道实际问题是什么，也不知道您在苦苦挣扎的概念是什么。您提供了一个执行某些操作的 sql 语句，可能没有达到预期的效果，但我们不知道它与预期效果的不同之处。所以不，没有明确的问题。

【参考方案1】：

在尝试了多种不同的方法后，我通过 JSON 对象找到了如何解析数据。我必须启动第一个 ResultSet，然后从该结果集中提取 custom_field，然后将其拉入 JSON 对象，将“1”解析为字符串，然后使用另一个带有该字符串的 ResultSet 来获取该行

String name = player.getUsername().replace("_", " ");
            ResultSet connect = executeQuery("SELECT * FROM nexus_purchases WHERE ps_claimed='0'");
            
            while (connect.next()) 
                String str = connect.getString("ps_custom_fields");
                JSONObject obj = new JSONObject(str);
                String n = obj.getString("1");
                ResultSet check = executeQuery("SELECT * FROM nexus_purchases WHERE '"+n+"' = '"+name+"' AND ps_claimed='0'");
                
                while (check.next()) 
                    
                    player.sm("WORKING!");
                    return;