Java字符串用拉丁字符随机替换字符

我正在用Java创建一个程序，将PostgreSQL表中的一些数据移动到另一个表中。每次程序读取一行时，它都会将数据存储在一个SQL查询中，该查询存储在一个字符串对象中

数据将在每读取500行后插入。我遇到的问题是，有时字符串中的字符会被随机替换为拉丁字符，如ȶ、Ȭ、ǎ等，这在查询到数据库时会导致错误。有人知道如何解决这个问题吗

读+写查询：

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可能是编码问题。请检查数据库中的编码设置以及更改环境的任何地方，例如客户端/服务器通信、数据库连接检索等。转换发生在某个地方，而不是JVM本身。@Ray我检查了数据库的编码，它们是UTF-8。这种查询是一个非常糟糕的主意。您应该将准备好的语句与addBatch一起使用，而不是玩弄字符串。更好的是，如果您不在Java中处理数据，请使用直接插入。。。仅使用数据源id进行选择，是Java的已删除标志。我认为您正在对结果字符串进行的字符串替换之一就是原因，或者数据库中已经存在非ASCII字符。很难说。

        dat = statement.getResultSet(); //grabbing the data
        int index = 0;
        while(dat.next())
        {
            if(index == 0 || index%500 == 0)                                  //check if it's the start of data or already 500 rows read
                { 
                    if(index > 0) 
                    {                      
                        stm = stm.substring(0, stm.length()-2);               // removing the space and comma at the end of final data
                        sql = new String(stm.getBytes("UTF-8"), "UTF-8");     // this is my attempt at trying to remove the latin char..
                        statementUnified.execute(sql);
                    }
                    stm = "INSERT INTO table (data_source_id, is_deleted_flag,"+columnlist+") values ");
                }

                stm = stm.concat(" ("+sourceid+",\'0\'");
                for(int i = 0;i<columnsize;i++)
                {
                    stm = stm.concat(",");
                    temp = dat.getString(columnlist.get(i));          //grabbing the data based on the column name
                    if(temp != null)                                                     //replacing escaped char in java and postgresql and removing leading / trailing whitespaces 
                    {
                        temp = temp.replace("\\", "\\\\\\\\");
                        temp = temp.replaceAll("\"", "\\\\\\\"");
                        temp = temp.replaceAll("\'", "\'\'");
                        temp = temp.replaceAll("%", "%%");
                        temp = temp.trim();
                    }

                    if(temp == null) stm = stm.concat("NULL");               // if data from table or after trimming the whitespaces is NULL, then append NULL to query
                    // after this there are some validation for email, gender, date of birth, etc.
                    else                   //if validation goes well, then the program will go into this ELSE
                    {
                        stm = stm.concat("\'"+temp+"\'");                      //inserting the data into query
                    }
                }
                stm = stm.concat(") , ");
                index++;
        }

        if(stm.endsWith(" , "))                                      //if the final query didn't reach 500 rows
        {
            stm = stm.substring(0, stm.length()-2);
                sql = new String(stm.getBytes("UTF-8"), "UTF-8");
                statementUnified.execute(sql);
        }