和CMD不同是: CMD 是可以被 docker run 指令覆盖的,而ENTRYPOINT不能覆盖。
比如,容器名字为tang 我们在Dockerfile中指定如下CMD:
CMD ["/bin/echo", "test"]
假如启动容器的命令是
docker run tang
则会输出 test
假如启动容器的命令是
docker run -it tang /bin/bash
则什么都不会输出
ENTRYPOINT不会被覆盖,而且会比CMD或者docker run指定的命令要靠前执行
ENTRYPOINT ["echo", "test"]
假如启动容器的命令是
docker run -it tang 123
则会输出 test 123 ,这相当于要执行命令 echo test 123
10)VOLUME 创建一个可以从本地主机或其他容器挂载的挂载点。
VOLUME ["/data"]
11)USER指定RUN、CMD或者ENTRYPOINT运行时使用的用户
USER tang
12)WORKDIR 为后续的RUN、CMD或者ENTRYPOINT指定工作目录
WORKDIR /tmp/
Dockerfile示例:
mkdir docker_test #创建一个目录
vi Dockerfile
FROM ubuntu
MAINTAINER tang peng yuan
RUN apt update
RUN apt install -y libpcre2-dev net-tools gcc zlib1g-dev make
ADD http://nginx.org/download/nginx-1.23.2.tar.gz .
RUN tar zxvf nginx-1.23.2.tar.gz
RUN mkdir -p /usr/local/nginx
RUN cd nginx-1.23.2 && ./configure --prefix=/usr/local/nginx && make && make install
COPY index.html /usr/local/nginx/html/index.html
# COPY index2.html /usr/local/nginx/html/2.html
EXPOSE 80
ENTRYPOINT /usr/local/nginx/sbin/nginx -g "daemon off;" #-g这个的意思是让程序在前台启动,不到后台,如果程序到后台运行了,容器也就自己关闭了
FROM centos:7
RUN yum install -y gcc pcre pcre-devel devel zlib-devel make
ADD nginx-1.12.2.tar.gz /mnt
WORKDIR /mnt/nginx-1.12.2
#关闭debug日志
RUN sed -i 's/CFLAGS="$CFLAGS -g"/#CFLAGS="$CFLAGS -g"/g' auto/cc/gcc
RUN ./configure --prefix=/usr/local/nginx
RUN make
RUN make install
EXPOSE 80
VOLUME ["/usr/local/nginx/html"]
CMD ["/usr/local/nginx/sbin/nginx","-g","daemon off;"]
FROM centos:7
RUN yum install -y gcc pcre pcre-devel devel zlib-devel make &> /dev/null && yum clean all
ADD nginx-1.21.6.tar.gz /mnt
WORKDIR /mnt/nginx-1.21.6
RUN sed -i 's/CFLAGS="$CFLAGS -g"/#CFLAGS="$CFLAGS -g"/g' auto/cc/gcc
RUN ./configure --prefix=/usr/local/nginx &> /dev/null
RUN make &> /dev/null
RUN make install &> /dev/null
EXPOSE 80
VOLUME ["/usr/local/nginx/html"]
CMD ["/usr/local/nginx/sbin/nginx","-g","daemon off;"]
优化二:减少RUN构建
RUM命令比较多得时候
FROM centos:7
ADD nginx-1.21.6.tar.gz /mnt
WORKDIR /mnt/nginx-1.21.6
RUN yum install -y gcc pcre pcre-devel devel zlib-devel make &> /dev/null && \
yum clean all && \
sed -i 's/CFLAGS="$CFLAGS -g"/#CFLAGS="$CFLAGS -g"/g' auto/cc/gcc && \
./configure --prefix=/usr/local/nginx &> /dev/null && \
make &> /dev/null && make install &> /dev/null &&\
rm -rf /mnt/nginx-1.21.6
EXPOSE 80
VOLUME ["/usr/local/nginx/html"]
CMD ["/usr/local/nginx/sbin/nginx","-g","daemon off;"]
优化三:多阶段构建
使用FRON命令生成多个镜像,将指定的镜像做为其他镜像的基础镜像环境来构建
FROM centos:7 as build
ADD nginx-1.21.6.tar.gz /mnt
WORKDIR /mnt/nginx-1.21.6
RUN yum install -y gcc pcre pcre-devel devel zlib-devel make &> /dev/null && \
yum clean all && \
sed -i 's/CFLAGS="$CFLAGS -g"/#CFLAGS="$CFLAGS -g"/g' auto/cc/gcc && \
./configure --prefix=/usr/local/nginx &> /dev/null && \
make &> /dev/null && make install &> /dev/null &&\
rm -rf /mnt/nginx-1.21.6
FROM centos:7
EXPOSE 80
VOLUME ["/usr/local/nginx/html"]
COPY --from=build /usr/local/nginx /usr/local/nginx
CMD ["/usr/local/nginx/sbin/nginx","-g","daemon off;"]
java的多态性是指main方法在调用属性的时候类可以对这一属性做出反应的情况
//package 1;
class A{
public void test(){
System.out.println("A");
}
}
class D extends A{
public void test(){
S
参考了网上的思路,写了个Java版的:
public class Fibonacci {
final static int[] A={1,1,1,0};
public static void main(String[] args) {
int n=7;
for(int i=0;i<=n;i++){
int f=fibonac
1、查看系统客户端,数据库,连接层的编码
查看方法: http://daizj.iteye.com/blog/2174993
进入mysql,通过如下命令查看数据库编码方式: mysql> show variables like 'character_set_%'; +--------------------------+------
public class MyQueue {
private long[] arr;
private int front;
private int end;
// 有效数据的大小
private int elements;
public MyQueue() {
arr = new long[10];
elements = 0;
front
A binary search tree (BST) is a binary tree where each node has a Comparable key (and an associated value) and satisfies the restriction that the key in any node is larger than the keys in all