第二章

• 1. 考虑用静态工厂方法代替构造器
• 2. 遇到多个构造器参数时要考虑用构造器
• 3. 用私有构造器或者枚举类强花Singleton属性
• 4. 通过私有构造器强化不可实例化的能力
• 5. 避免创建不必要的对象
• 6. 消除过期的对象引用
• 7. 避免使用终结方法

     第三章

• 8. 覆盖equals时请遵守通用约定
  • 在覆盖equals方法时，你必须要遵守他的通用约定。下面是约定内容，来自Object的规范[JavaSE6]:
      equals方法实现了等价关系(equivalence relation):
  • 自反性(reflexive)。对于任何非空的引用值x，x.equals(x)必须返回true。
  • 对称性(symmetric)。对于任何非空的引用值x和y，当且仅当y.equals(x)返回true时，x.equals(y)必须返回true。
  • 传递性(reansitive)。对于任何非null的引用值x、y和z，如果x.equals(y)返回true，并且y.equals(z)也返回true，那么x.equals(z)也必须返回true。
  • 一致性(consistent)。对于任何非null的引用值x和y，只要equals的比较操作在对象中所用的信息没有被修改， 多次调用x.equals(y)就会一致的返回true，或者一致的返回false。
  • 对于任何非null得引用值x，x.equals(null)必须返回false。

封阳台

*

安装Redis,但是不是最新的,笔者安装时大概是安装3.2

yum install redis

如果要安装最新的redis，需要安装Remi的软件源，官网地址：http://rpms.famillecollet.com/

yum install -y http://rpms.famillecollet.com/enterprise/remi-release-7.rpm
yum --enablerepo=remi install redis

首先 因为使用的CentOS 所以默认使用yum安装

• 首先安装snap https://snapcraft.io/docs/installing-snapd

1. 安装snap
   确认自己使用的CentOS版本
   cat /etc/centos-release
   如果使用的是CentOS8

   1 2	sudo dnf install epel-release sudo dnf upgrade

   如果使用的CentOS7
   sudo yum install epel-release
sudo yum install snapd
   如果出现

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   Error: Package: snapd-selinux-2.47.1-1.el7.noarch (epel) Requires: selinux-policy-base >= 3.13.1-268.el7 Installed: selinux-policy-targeted-3.13.1-266.el7_8.1.noarch (@updates) selinux-policy-base = 3.13.1-266.el7_8.1 Available: selinux-policy-minimum-3.13.1-266.el7.noarch (base) selinux-policy-base = 3.13.1-266.el7 Available: selinux-policy-minimum-3.13.1-266.el7_8.1.noarch (updates) selinux-policy-base = 3.13.1-266.el7_8.1 Available: selinux-policy-mls-3.13.1-266.el7.noarch (base) selinux-policy-base = 3.13.1-266.el7 Available: selinux-policy-mls-3.13.1-266.el7_8.1.noarch (updates) selinux-policy-base = 3.13.1-266.el7_8.1 Available: selinux-policy-targeted-3.13.1-266.el7.noarch (base) selinux-policy-base = 3.13.1-266.el7 You could try using --skip-broken to work around the problem You could try running: rpm -Va --nofiles --nodigest

   yumdownloader snapd-selinux-2.47.1-1.el7.noarch

rpm –force –nodeps -ivh

启动并且开启端口
sudo systemctl enable --now snapd.socket
为了支持旧模式,建立一个链接
sudo ln -s /var/lib/snapd/snap /snap
2. 安装CertBot
sudo snap install --classic certbot
为CertBot创建一个软链接
sudo ln -s /snap/bin/certbot /usr/bin/certbot
如果想要覆盖nginx配置
sudo certbot –nginx
如果不想覆盖nginx配置
sudo certbot certonly –nginx
测试自动更新证书功能
sudo certbot renew –dry-run
可以验证域名了

首先安装yum-utils

sudo yum install yum-utils

创建/etc/yum.repos.d/nginx.repo

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[nginx-stable]
name=nginx stable repo
baseurl=http://nginx.org/packages/centos/$releasever/$basearch/
gpgcheck=1
enabled=1
gpgkey=https://nginx.org/keys/nginx_signing.key
module_hotfixes=true

[nginx-mainline]
name=nginx mainline repo
baseurl=http://nginx.org/packages/mainline/centos/$releasever/$basearch/
gpgcheck=1
enabled=0
gpgkey=https://nginx.org/keys/nginx_signing.key
module_hotfixes=true

repo默认使用stable版本,如果想使用mainline开发版本

sudo yum-config-manager --enable nginx-mainline

安装nginx

sudo yum install nginx

如果有指纹效验 573B FD6B 3D8F BC64 1079 A6AB ABF5 BD82 7BD9 BF62 接受它就好了

服务管理

1 标题修饰符 ‘#’

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# 一级标题 h1

一级标题 h1

1

## 二级标题 h2

二级标题 h2

1

### 三级标题 h3

三级标题 h3

1

#### 四级标题 h4

四级标题 h4

1

##### 五级标题 h5

查询当前所有域名

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[root@iZj6cgoyl5x6opizfwaukrZ ~]# certbot certificates
Saving debug log to /var/log/letsencrypt/letsencrypt.log

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Found the following certs:
  Certificate Name: 123.com
    Serial Number: 44365432b76836764e9e41b30da3a4faaba
    Domains: 123.com
    Expiry Date: 2020-12-30 14:26:28+00:00 (VALID: 53 days)
    Certificate Path: /etc/letsencrypt/live/123.com/fullchain.pem
    Private Key Path: /etc/letsencrypt/live/123.com/privkey.pem
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

如果你想删除一个域名

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sudo certbot revoke --cert-name 123.com
sudo certbot revoke --cert-path /etc/letsencrypt/live/123.com/

如果你想增加一个域名的https

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sudo certbot -d your.new.tld --expand

卸装

1. yum检查安装方式
   查看yum是否安装过mysql
   yum list installed mysql*
   如或显示了列表，说明系统中有MySQL

• yum卸装

  1 2	yum remove mysql-community-client mysql-community-common mysql-community-libs mysql-community-libs-compat mysql-community-server mysql57-community-release

• rpm查看安装

  1	rpm -qa | grep -i mysql

  

• rpm卸装

  1 2 3 4 5 6

  rpm -e mysql57-community-release-el7-9.noarch rpm -e mysql-community-server-5.7.17-1.el7.x86_64 rpm -e mysql-community-libs-5.7.17-1.el7.x86_64 rpm -e mysql-community-libs-compat-5.7.17-1.el7.x86_64 rpm -e mysql-community-common-5.7.17-1.el7.x86_64 rpm -e mysql-community-client-5.7.17-1.el7.x86_64

• 清理残余

  1	whereis mysql或find / -name mysql 删除文件

• 删除配置

  1 2	rm –rf /usr/my.cnf rm -rf /root/.mysql_sercret

• 剩余配置检查

  1 2	chkconfig --list | grep -i mysql chkconfig --del mysqld

安装

• 安装repo

  1	https://dev.mysql.com/downloads/repo/yum/

  
• 下载并安装

  1 2	wget wget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpm yum localinstall mysql57-community-release-el7-8.noarch.rpm

• 检查mysql源是否安装成功
  yum repolist enabled | grep "mysql.*-community.*"

4. 修改 vim /etc/yum.repos.d/mysql-community.repo源 ，改变默认安装的mysql版本。比如要安装5.6版本，将5.7源的enabled=1改成enabled=0。然后再将5.6源的enabled=0改成enabled=1即可。改完后保存 按ESC 后 按 shift + ： 输入 wq 保存退出

• 安装MySQL
  yum install mysql-community-server
• 启动MySQL服务
  systemctl start mysqld
• 开机启动
  systemctl enable mysqld
• 修改root本地登录密码
  grep 'temporary password' /var/log/mysqld.log

今天还是决定使用AS 4.0

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Unable to find method 'org.gradle.api.tasks.TaskInputs.property(Ljava/lang/String;Ljava/lang/Object;)Lorg/gradle/api/tasks/TaskInputs;'.
Possible causes for this unexpected error include:
Gradle's dependency cache may be corrupt (this sometimes occurs after a network connection timeout.)
Re-download dependencies and sync project (requires network)

The state of a Gradle build process (daemon) may be corrupt. Stopping all Gradle daemons may solve this problem.
Stop Gradle build processes (requires restart)

Your project may be using a third-party plugin which is not compatible with the other plugins in the project or the version of Gradle requested by the project.

In the case of corrupt Gradle processes, you can also try closing the IDE and then killing all Java processes.

解决方法:降级gradle插件到3.6.3 降级gradle到5.6.4

也有greendao的问题

将
classpath ‘org.greenrobot:greendao-gradle-plugin:3.2.2’
升级至
classpath ‘org.greenrobot:greendao-gradle-plugin:3.3.0’
即可解决

修改生成apk的路径

修改输出的文件夹位置

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D:\Project\AS\Label\app\src\main\java\com\tscale\ttouch\label\di\component\AppComponent.java:36: 错误: [Dagger/MissingBinding] [dagger.android.AndroidInjector.inject(T)] com.tscale.ttouch.label.ui.function.FunctionActivity cannot be provided without an @Inject constructor or an @Provides-annotated method. This type supports members injection but cannot be implicitly provided.
public interface AppComponent {
       ^
  A binding with matching key exists in component: com.tscale.ttouch.label.di.builder.ActivityBuilder_BindFunctionActivity.FunctionActivitySubcomponent
      com.tscale.ttouch.label.ui.function.FunctionActivity is injected at
          com.tscale.ttouch.label.ui.fragment.setting.ad.video.ADVideoFragmentModule.provideGridLayoutManager(activity)
      androidx.recyclerview.widget.GridLayoutManager is injected at
          com.tscale.ttouch.label.ui.fragment.setting.ad.video.ADVideoFragment.mGridLayoutManager
      com.tscale.ttouch.label.ui.fragment.setting.ad.video.ADVideoFragment is injected at
          dagger.android.AndroidInjector.inject(T)

这个问题是因为FunctionActivity错误,应该为SettingActivity