项目用的容器是tomcat8, tomcat8 默认的是servlet 3.1的版本, 看了下 web.xml还是3.0的版本, 所以升级了下, 顺便贴一下2.5到3.1的schema头部声明。

前言

okhttp 介绍

HTTP is the way modern applications network. It’s how we exchange data & media. >Doing HTTP efficiently makes your stuff load faster and saves bandwidth.

OkHttp is an HTTP client that’s efficient by default:

• HTTP/2 support allows all requests to the same host to share a socket.
• Connection pooling reduces request latency (if HTTP/2 isn’t available).
• Transparent GZIP shrinks download sizes.
• Response caching avoids the network completely for repeat requests.

OkHttp perseveres when the network is troublesome: it will silently recover from > >common connection problems. If your service has multiple IP addresses OkHttp will >attempt alternate addresses if the first connect fails. This is necessary for IPv4+IPv6 >and for services hosted in redundant data centers. OkHttp initiates new connections >with modern TLS features (SNI, ALPN), and falls back to TLS 1.0 if the handshake fails.

Using OkHttp is easy. Its request/response API is designed with fluent builders and immutability. It supports both synchronous blocking calls and async calls with callbacks.

OkHttp supports Android 2.3 and above. For Java, the minimum requirement is 1.7. —摘自 https://square.github.io/okhttp/

spring4.0以后加入了对websocket技术的支持，目前项目用的是SSM（springMVC+spring+MyBatis）框架，所以选择了spring自带的websocket。

Hello, this world！