JAVA技能树（技术面试知识点汇总）_Java技能树

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JAVA 技术树总结

面试宝典

根据面试经历及网上面试题总结的 JAVA 各类知识

总结，深入实现原理，对面试及学习提供一定的帮

助。

orange

2017/11/2

集合 .................................................................................................................................................. 3

一、List: .................................................................................................................................... 3

1、ArrayList ...................................................................................................................... 3

2、LinkedList ..................................................................................................................... 4

3、Vector/Stack ................................................................................................................ 5

二、Map: .................................................................................................................................. 5

1、HashMap ..................................................................................................................... 5

2、ConcurrentHashMap ................................................................................................... 6

3、WeakHashMap ............................................................................................................ 8

4、HashTable .................................................................................................................... 8

5、Properties .................................................................................................................... 9

三、Set ..................................................................................................................................... 9

1、HashSet ....................................................................................................................... 9

2、TreeSet ........................................................................................................................ 9

3、EnumSet ...................................................................................................................... 9

四、总结比较 ......................................................................................................................... 10

1、有序性（sort） ..................................................................................................... 10

2、稳定性（order） ................................................................................................... 10

3、结构图 ....................................................................................................................... 10

同步机制......................................................................................................................................... 11

一、volatile ..................................................................................................................... 11

二、sychronized .............................................................................................................. 11

三、ThreadLocal 类 ........................................................................................................ 12

四、transient .................................................................................................................. 15

五、ReentrantLock 独占锁 ........................................................................................... 17

六、AbstractQueuedSynchronizer(AQS) ........................................................................ 23

七、共享锁 ReentrantReadWriteLock ........................................................................... 42

八、独占锁和共享锁 ..................................................................................................... 46

九、公平锁和非公平锁 ................................................................................................. 47

十、SynchronousQueue 直接提交队列 ....................................................................... 47

SynchronousQueue 实现原理 .................................................................................................. 51

公平模式下的模型： ..................................................................................................... 51

非公平模式下的模型： ................................................................................................. 55

总结 ................................................................................................................................................ 57

十一、LinkedBlockingQueue 无界队列 ........................................................................ 58

十二、ArrayBlockingQueue 有界队列 .......................................................................... 58

多线程 ............................................................................................................................................ 58

一、启动线程 ................................................................................................................. 58

启动一个线程的三种方式 ............................................................................................. 58

二、CountDownLatch 用法及原理 ........................................................................................ 58

使用场景 ......................................................................................................................... 58

使用方式 ......................................................................................................................... 58

原理 ................................................................................................................................. 59

三、Cyclicbarrier 用法及原理................................................................................................ 61

四、Semaphore 信号量的用法及原理 ................................................................................. 63

五、线程池 ............................................................................................................................. 65

线程池 ............................................................................................................................. 65

线程池为什么能维持线程不释放，随时运行各种任务 ............................................. 66

JVM.................................................................................................................................................. 80

什么是 Java 虚拟机？ .......................................................................................................... 80

为什么 Java 被称作是平台无关的编程语言？ .................................................................. 81

Java 虚拟机具体是怎样运行 Java 字节码的？ ................................................................. 81

Java 虚拟机是如何加载 Java 类的? ................................................................................... 82

内存泄漏检查 ......................................................................................................................... 82

GC ............................................................................................................................................ 84

一，什么是垃圾回收 ..................................................................................................... 84

二，了解 G1 .................................................................................................................. 86

G1 Young GC .............................................................................................................. 87

异常 ................................................................................................................................................ 92

反射 ................................................................................................................................................ 93

SPRING ............................................................................................................................................ 95

事务 ................................................................................................................................................ 95

一、事务的传播级别和数据隔离级别 ......................................................................... 95

二、脏读、不可重复读、幻读 ..................................................................................... 98

三、Spring 配置声明式事务........................................................................................ 100

四、事务不生效的场景及解决方案 ........................................................................... 101

五、Spring 的统一事务模型.............................................................错误!未定义书签。

数据库-mysql ................................................................................................................................ 103

存储引擎的选择 ................................................................................................................... 103

数据类型 ............................................................................................................................... 103

CHAR 和 VARCHAR ........................................................................................................ 103

TEXT 和 BOLG ................................................................................................................ 103

索引的设计和使用 ............................................................................................................... 104

事务控制 ............................................................................................................................... 104

REDIS ............................................................................................................................................. 104

MYCAT ........................................................................................................................................... 104

MYCAT 解决的问题 .............................................................................................................. 104

数据库分片的方式 ............................................................................................................... 120

MYCAT 原理 .......................................................................................................................... 120

主要配置文件 ....................................................................................................................... 121

JKD8 新特性 .................................................................................................................................. 121

一、 Lambda 表达式 ................................................................................................... 121

KAFKA ............................................................................................................................................ 122

一、Kafka 介绍 ..................................................................................................................... 122

1、................................................................................................................................. 122

2、................................................................................................................................. 122

3、................................................................................................................................. 122

二、消息术语 ....................................................................................................................... 122

三、消息存储结构 ............................................................................................................... 122

四、分布式 ........................................................................................................................... 123

五、生产者（Producers）和消费者（Consumers） ......................................................... 124

六、生产者（Producers）实例 ....................................................................................... 125

七、消费者（Consumers）实例 .................................................................................... 125

ACTIVEMQ ..................................................................................................................................... 126

一、ActiviteMQ 消息有 3 中形式 ....................................................................................... 126

2、ActiviteMQ 接收和发送消息基本流程 ......................................................................... 126

三、高可用方案 ................................................................................................................... 113

1、Master-Slave 部署方式 ........................................................................................... 128

2、Broker-Cluster 部署方式 ........................................................................................ 129

3、Master-Slave 与 Broker-Cluster 相结合的部署方式 .............................................. 131

KEY ................................................................................................................................................ 133

集合

iterator<--Collection

Collection<--List Set Map

一、List:

1、ArrayList

a、优点及原因：

有序的，根据下标查找快（数组结构可以按下标直接锁定位置，遍历的复杂度为 O(1)）

b、缺点及原因：

插入删除慢（每次插入都会检查数组大小是否满足，如果不满足扩充 1.5 倍+1，新建数组，把旧的数据拷

贝到新数组）

删除中间元素后，Shifts any subsequent elements to the left

新增源码解析：