public class JSqlParserItem {
 private CCJSqlParser parser;
 public JSqlParserManager() {
 // init
 CCJSqlParser parser = new CCJSqlParser(new StreamProvider(new StringReader("select 1")));
 try {
 // Since the first parsing takes a long time, it is therefore advisable to perform an unnecessary parsing during initialization.
 parser.Statement();
 } catch (ParserException e){
 e.printStackTrace();
 }
 this.parser = parser;
 }
 public CCJSqlParser getParser() {
 return parser;
 }
 public void reInit(String sql) {
 this.parser.ReInit(new StreamProvider(new StringReader(sql)));
 }
}

public class JSqlParserUtils {
 public static void main(String[] args) {
 ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
 // Regardless of how many threads are used, the parsing speed remains the same.
 executor.setCorePoolSize(20);
 executor.setMaxPoolSize(30);
 executor.setThreadNamePrefix("JSqlParserThread-->");
 executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardOldestPolicy());
 ArrayBlockingQueue<JSqlParserManager> queue = new ArrayBlockingQueue<>(20);
 for (int i = 0; i <20;i++){
 JSqlParserManager manager = new JSqlParserManager();
 queue.add(manager);
 }
 // test SQL
 List<String> sqlList = genSqlList();
 
 for (int i = 0; i<10;i++) {
 exec(sqlList,executor,queue);
 }
 }
 public static void exec(List<String> sqlList,ThreadPoolTaskExecutor executor,ArrayBlockingQueue<JSqlParserManager> queue){
 long startTime = System.currentTimeMillis();
 for (int i = 0; i < sqlList.size(); i++) {
 String drSQL = sql.get(i);
 int drIndex = i;
 executor.execute(() -> {
 JSqlParserManager drQueue = null;
 try {
 drQueue = queue.take();
 drQueue.reInit(drSQL);
 
 Statement statement = drQueue.getParser().Statement();
 
 map.put(drIndex, statement);
 } catch (InterruptedException | ParseException e) {
 e.printStackTrace();
 } finally {
 countDownLatch.countDown();
 try {
 queue.put(drQueue);
 } catch (InterruptedException e) {
 e.printStackTrace();
 }
 }
 });
 }
 try {
 countDownLatch.await();
 } catch (InterruptedException e) {
 e.printStackTrace();
 }
 long endTime = System.currentTimeMillis();
 System.out.println( "usedTime:" + (endTime - startTime ));
 }
 public static List<String> genSqlList(){
 List<String> list = new ArrayList<>();
 for (int i = 0; i < 100; i++) {
 String sql = "select " + getRandomParam() + " = round(isnull(case when " + getRandomParam() + "=1 or " + getRandomParam() + "=3 then " + getRandomParam() + " when " + getRandomParam() + "=10 or " + getRandomParam() + "=11 then " + getRandomParam() + " end,0),4)";
 list.add(sql);
 }
 return list;
 }
 public static String getRandomParam() {
 String[] arr = new String[]{"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
 Random random = new Random();
 return arr[random.nextInt(26)];
 }
}