【免费】校招Java工程师面试问题及答案（全）_java工程师面试问题

需积分: 0 103 浏览量更新于2023-05-04 1 收藏 13.04MB PDF 举报

身份认证购VIP最低享 7 折!

领优惠券(最高得80元）

资源详情

资源推荐

2020 秋招常见面试题型宝典

Mr.Leon

2020-10-22

武汉理工大学-RS2MLAB

1 
 
目录 
Git ................................................................................................................................................................................................................................ 13 
计算机网络 ............................................................................................................................................................................................................... 14 
TCP 与 UDP 区别 ........................................................................................................................................................................................... 14 
如何防止 UDP 丢包 ...................................................................................................................................................................................... 15 
TCP 粘包的原因及解决方法 ...................................................................................................................................................................... 15 
tcp 三次握手，为什么不可以两次握手？会有什么问题？ ............................................................................................................ 16 
TCP 协议-三次握手/四次挥手 .................................................................................................................................................................. 16 
TCP 协议如何保证可靠传输 ...................................................................................................................................................................... 17 
滑动窗口和流量控制 .......................................................................................................................................................................... 17 
拥塞控制 ................................................................................................................................................................................................. 17 
TCP、UDP、IP、以太网报文格式以及重要字段 ............................................................................................................................... 18 
HTTP 报文传递过程 ...................................................................................................................................................................................... 20 
浏览器输入 URL 并回车的过程以及相关协议，DNS 查询过程 ................................................................................................... 21 
HTTP1.0、HTTP1.1 和 HTTP2.0 的区别 ................................................................................................................................................. 21 
长连接 keep-alive 在 HTTP 还是在 TCP ................................................................................................................................................ 22 
HTTP 和 HTTPS 的区别 ................................................................................................................................................................................ 22 
HTTPS 建立连接的过程 ............................................................................................................................................................................... 23 
HTTP 请求有哪些？ ...................................................................................................................................................................................... 23 
GET 和 POST 区别 ......................................................................................................................................................................................... 23 
PUT 和 POST 的区别 .................................................................................................................................................................................... 24 
Session 与 Cookie 的区别 ........................................................................................................................................................................... 24 
状态码 ............................................................................................................................................................................................................... 24 
转发与重定向区别 ........................................................................................................................................................................................ 28 
操作系统 .................................................................................................................................................................................................................... 28 
常见问题 .......................................................................................................................................................................................................... 28 
进程与线程、协程的区别 ................................................................................................................................................................. 28 
用户态和内核态 ................................................................................................................................................................................... 29 
操作系统中断 ........................................................................................................................................................................................ 29 
进程间的通信方式 ............................................................................................................................................................................... 30 
共享内存 ................................................................................................................................................................................................. 30 
进程调度算法 ........................................................................................................................................................................................ 30 
操作系统内存管理是做什么的？ ................................................................................................................................................... 31 
逻辑（虚拟）地址和物理地址 ........................................................................................................................................................ 31 
内存管理机制？内存管理有哪几种方式？ ................................................................................................................................. 31 
快表和多级页表 ................................................................................................................................................................................... 31 
分页管理与分段管理的共同点和区别 .......................................................................................................................................... 31 
为什么要有虚拟地址空间 ................................................................................................................................................................. 32 
CPU 寻址？为什么需要虚拟地址空间 .......................................................................................................................................... 32 
虚拟内存是什么 ................................................................................................................................................................................... 32 
局部性原理 ............................................................................................................................................................................................. 32 
虚拟存储器 ............................................................................................................................................................................................. 32 
虚拟内存实现技术 ............................................................................................................................................................................... 33 
页面置换算法 ........................................................................................................................................................................................ 33 
如果有个 java 进程 cpu 占有率特别高，如何排查问题 ........................................................................................................ 33 
Linux ............................................................................................................................................................................................................................ 34 
常见操作及概念 ............................................................................................................................................................................................. 34 
快捷键 ...................................................................................................................................................................................................... 34 

2 
 
求助 .......................................................................................................................................................................................................... 34 
关机 .......................................................................................................................................................................................................... 34 
sudo .......................................................................................................................................................................................................... 35 
包管理工具（RPM/DPKG） ............................................................................................................................................................. 35 
发行版 ...................................................................................................................................................................................................... 35 
VIM  三个模式 ....................................................................................................................................................................................... 35 
分区 .................................................................................................................................................................................................................... 36 
分区表(MBR/GPT) ................................................................................................................................................................................ 36 
开机检测程序 ........................................................................................................................................................................................ 37 
文件系统 .......................................................................................................................................................................................................... 37 
分区与文件系统 ................................................................................................................................................................................... 37 
组成 .......................................................................................................................................................................................................... 37 
文件读取 ................................................................................................................................................................................................. 38 
磁盘碎片 ................................................................................................................................................................................................. 38 
block ......................................................................................................................................................................................................... 38 
目录 .......................................................................................................................................................................................................... 39 
日志 .......................................................................................................................................................................................................... 39 
挂载 .......................................................................................................................................................................................................... 39 
目录配置 ................................................................................................................................................................................................. 39 
文件 .................................................................................................................................................................................................................... 40 
文件属性 ................................................................................................................................................................................................. 40 
文件与目录的基本操作 ...................................................................................................................................................................... 40 
修改权限 ................................................................................................................................................................................................. 41 
文件默认权限 ........................................................................................................................................................................................ 42 
目录的权限 ............................................................................................................................................................................................. 42 
链接 .......................................................................................................................................................................................................... 42 
获取文件内容 ........................................................................................................................................................................................ 43 
指令与文件搜索 ................................................................................................................................................................................... 43 
压缩与打包 ...................................................................................................................................................................................................... 44 
压缩文件名 ............................................................................................................................................................................................. 44 
压缩指令 ................................................................................................................................................................................................. 44 
打包 .......................................................................................................................................................................................................... 45 
管道命令 .......................................................................................................................................................................................................... 45 
提取指令 ................................................................................................................................................................................................. 46 
排序指令 ................................................................................................................................................................................................. 46 
双向输出重定向 ................................................................................................................................................................................... 47 
字符转换指令 ........................................................................................................................................................................................ 47 
分区指令 ................................................................................................................................................................................................. 47 
正则表达式 ...................................................................................................................................................................................................... 48 
grep .......................................................................................................................................................................................................... 48 
printf ......................................................................................................................................................................................................... 48 
awk ............................................................................................................................................................................................................ 48 
进程管理 .......................................................................................................................................................................................................... 49 
查看进程 ................................................................................................................................................................................................. 49 
进程状态 ................................................................................................................................................................................................. 50 
SIGCHLD .................................................................................................................................................................................................. 50 
wait() ......................................................................................................................................................................................................... 50 
waitpid() ................................................................................................................................................................................................... 51 
孤儿进程 ................................................................................................................................................................................................. 51 

3 
 
僵尸进程 ................................................................................................................................................................................................. 51 
Linux 基本命令 ............................................................................................................................................................................................... 51 
查看系统性能 ........................................................................................................................................................................................ 51 
目录切换命令 ........................................................................................................................................................................................ 53 
目录的操作命令（增删改查） ........................................................................................................................................................ 53 
文件的操作命令（增删改查） ........................................................................................................................................................ 53 
压缩文件的操作命令 .......................................................................................................................................................................... 54 
其他常用命令 ........................................................................................................................................................................................ 54 
Java 基础 ................................................................................................................................................................................................................... 54 
JVM、JRE、JDK ............................................................................................................................................................................................. 54 
深拷贝 VS 浅拷贝 .......................................................................................................................................................................................... 54 
i++如何实现线程安全？ ............................................................................................................................................................................ 55 
Object 类中的方法 ........................................................................................................................................................................................ 55 
Equals()与== ................................................................................................................................................................................................... 55 
equals()与 hashcode() .................................................................................................................................................................................. 56 
String、StringBuffer、StringBuilder ....................................................................................................................................................... 56 
Public、protected、default 和 private .................................................................................................................................................. 57 
除了 new 还有哪些方式创建对象 ........................................................................................................................................................... 57 
try-catch-finally ............................................................................................................................................................................................. 58 
为什么需要有包装类 ................................................................................................................................................................................... 58 
8 种基本类型的包装类和常量池 ............................................................................................................................................................. 58 
装箱与拆箱 ...................................................................................................................................................................................................... 59 
封装 .................................................................................................................................................................................................................... 60 
继承 .................................................................................................................................................................................................................... 60 
多态 .................................................................................................................................................................................................................... 60 
多态概念 ................................................................................................................................................................................................. 60 
多态的条件 ............................................................................................................................................................................................. 61 
多态的运用 ............................................................................................................................................................................................. 61 
如何理解多态 ........................................................................................................................................................................................ 61 
哪里会使用多态 ................................................................................................................................................................................... 61 
运行时多态实现机制 .......................................................................................................................................................................... 61 
Exception 和 Error 的区别 .......................................................................................................................................................................... 61 
接口和抽象类的区别，各自的使用场景是什么 ................................................................................................................................. 61 
普通类和抽象类的区别 ............................................................................................................................................................................... 62 
泛型与泛型擦除 ............................................................................................................................................................................................. 62 
Java 异常体系 ................................................................................................................................................................................................. 63 
反射原理及使用场景 ................................................................................................................................................................................... 63 
内存泄漏与内存溢出 ................................................................................................................................................................................... 63 
内存溢出的场景 ................................................................................................................................................................................... 64 
内存泄漏的场景 ................................................................................................................................................................................... 65 
final 与 static 关键字..................................................................................................................................................................................... 66 
final 关键字 ............................................................................................................................................................................................ 66 
static 关键字 .......................................................................................................................................................................................... 66 
重载和重写的区别 ........................................................................................................................................................................................ 66 
Java 反射机制 ................................................................................................................................................................................................. 67 
序列化与反序列化 ........................................................................................................................................................................................ 67 
ArrayList 和 LinkedList 区别 ....................................................................................................................................................................... 67 
fail-fast 和 fail-safe ....................................................................................................................................................................................... 68 
ArrayList 与 LinkedList .................................................................................................................................................................................. 68 

4 
 
ArrayList 的扩容机制 .................................................................................................................................................................................... 68 
HashMap .......................................................................................................................................................................................................... 68 
HashMap 为什么线程不安全？ ...................................................................................................................................................... 69 
HashMap 的 put 方法过程 ................................................................................................................................................................ 69 
ConcurrentHashMap 的 put 方法过程 .......................................................................................................................................... 69 
HashMap 扩容 ...................................................................................................................................................................................... 69 
为什么是 2 的幂次方 .......................................................................................................................................................................... 70 
为什么会产生 Hash 碰撞 ................................................................................................................................................................... 70 
HashMap 和 TreeMap ........................................................................................................................................................................ 70 
HashMap 与 HashTable 的区别 ...................................................................................................................................................... 71 
HashMap 底层实现 ............................................................................................................................................................................. 71 
为什么使用红黑树，不使用其他的树 .......................................................................................................................................... 72 
为什么 JDK8 中 HashMap 底层使用红黑树？ ........................................................................................................................... 72 
为什么链表长度大于阈值 8 时才将链表转为红黑树？ .......................................................................................................... 72 
当长度减小的时候红黑树还会转换为链表吗 ............................................................................................................................ 72 
Hash 函数 ............................................................................................................................................................................................... 72 
HashMap 的长度为什么是 2 的幂次方 ........................................................................................................................................ 72 
ConcurrentHashMap 和 HashTable 的区别 ................................................................................................................................ 73 
线程安全的数据结构/并发容器 ............................................................................................................................................................... 74 
CopyOnWrite .................................................................................................................................................................................................. 74 
BlockingQueue ............................................................................................................................................................................................... 75 
Lamda 表达式 ................................................................................................................................................................................................. 75 
Servlet 和 Filter 的区别 ................................................................................................................................................................................ 75 
Java 如何获取环境变量 ............................................................................................................................................................................... 75 
Java 时间戳的长度 ........................................................................................................................................................................................ 76 
BIO、NIO、AIO ...................................................................................................................................................................................................... 76 
Tomcat 是 BIO 还是 NIO？ ........................................................................................................................................................................ 76 
同步与异步 ...................................................................................................................................................................................................... 76 
阻塞与非阻塞 ................................................................................................................................................................................................. 76 
BIO(Blocking I/O) ........................................................................................................................................................................................... 76 
传统 BIO .................................................................................................................................................................................................. 76 
伪异步 IO ................................................................................................................................................................................................ 77 
BIO 代码示例 ......................................................................................................................................................................................... 78 
总结 .......................................................................................................................................................................................................... 79 
NIO(New I/O) .................................................................................................................................................................................................. 79 
NIO 简介 ................................................................................................................................................................................................. 79 
NIO 的特性/NIO 与 IO 区别 ............................................................................................................................................................. 80 
NIO  读数据和写数据方式 ................................................................................................................................................................ 80 
NIO 核心组件简单介绍 ...................................................................................................................................................................... 81 
AIO(Asynchronous I/O) ............................................................................................................................................................................... 81 
JVM .............................................................................................................................................................................................................................. 81 
Java 内存模型（JMM） .............................................................................................................................................................................. 81 
主内存与工作内存 ............................................................................................................................................................................... 81 
工作内存与主内存的交互 ................................................................................................................................................................. 82 
JVM 运行时内存划分？............................................................................................................................................................................... 83 
Minor GC 和 Full GC ..................................................................................................................................................................................... 83 
堆内存分配策略 ............................................................................................................................................................................................. 83 
Full GC 触发条件 ........................................................................................................................................................................................... 84 
对象创建过程 ................................................................................................................................................................................................. 84 