用于出现乐观锁重试的代码

gistfile1.java

package util.transaction;

import play.Logger;
import play.db.jpa.JPA;

public class TransactionRetryUtil {
    private static final int MAX_TRIED_TIMES = 15;
    public static <T> T run(TransactionCallback<T> callback) {
        for (int i = 0; i < MAX_TRIED_TIMES; i++) {
            try {
                if (!JPA.em().getTransaction().isActive()) {
                    JPA.em().getTransaction().begin();
                }
                T result = callback.doInTransaction();
                if (JPA.em().getTransaction().isActive()) {
                    JPA.em().getTransaction().commit();
                }

                return result;
            } catch (RuntimeException e) {
                if (JPA.em().getTransaction().isActive()) {
                    JPA.em().getTransaction().rollback();
                }
                e.printStackTrace();
                Logger.info("Found Exception: " + e.getMessage());
                Logger.info("wait 1 seconds." + e.toString());
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException ie) {
                    //ignore
                }
            }
        }
        return null;
    }
}

gistfile2.java

package util.transaction;

public interface TransactionCallback<T> {
    /**
     * 事务回调，这个方法的操作是在事务中，如果返回false或抛出异常，都会重试；如果返回true，则成功提交.
     * @return
     */
    public T doInTransaction();
}