(int)(Math.random()这种方式，生成18位随机字符

好的，那么以下是修改后的代码，将生成18位随机字符： private static void insertData(Connection conn, int threadNo) throws SQLException { PreparedStatement ps = conn.prepareStatement("INSERT INTO " + TABLE_NAME + " VALUES(?, ?, ?, ?, ?)"); Set taskIdSet = new HashSet<>(); while(taskIdSet.size() < 100000){ StringBuilder sb = new StringBuilder(); for(int i=0; i<18; i++){ int randomNum = (int)(Math.random() * 36); char c = (randomNum < 10) ? (char)('0' + randomNum) : (char)('a' + randomNum - 10); sb.append(c); } taskIdSet.add(sb.toString()); } int taskState1Count = 20000; int taskState3Count = 20000; int taskState5Count = 30000; int taskState7Count = 20000; int taskState9Count = 10000; List taskStates = new ArrayList<>(); for (int i = 0; i < taskState1Count; i++) { taskStates.add(1); } for (int i = 0; i < taskState3Count; i++) { taskStates.add(3); } for (int i = 0; i < taskState5Count; i++) { taskStates.add(5); } for (int i = 0; i < taskState7Count; i++) { taskStates.add(7); } for (int i =