littlesuccess

摘要： 3.3.3 ThreadLocal3.3.3 ThreadLocalA more formal means of maintaining thread confinement is ThreadLocal,which allows you to associate a per-thread value with a value-holding object. ThreadLocal provides get and set accessor methods that maintain a separate copy of the value for each thread that use... 阅读全文

摘要： Explicit LocksExplicit LockBefore Java 5.0, the only mechanisms for coordinating access to shared data were synchronized and volatile. Java 5.0 adds another option: ReentrantLock.Contrary to what some have written, ReentrantLock is not a replacement for intrinsic locking, but rather an alternative w 阅读全文

摘要： 1.创建测试表和测试索性代码：CREATE TABLE "GSC"."UNIQUE_TEST"( "COL" VARCHAR2(20 BYTE));CREATE UNIQUE INDEX "GSC"."IDX_COL" ON "GSC"."UNIQUE_TEST" ("COL") 2.插入2条NULL数据INSERT INTO unique_test VALUES(NULL);SELECT * FROM unique_test;--显示 阅读全文