Java客户端API
添加依赖
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.10</version>
</dependency>
创建会话
- 构造器方法
ZooKeeper(String connectString, int sessionTimeout, Watcher watcher)
ZooKeeper(String connectString, int sessionTimeout, Watcher watcher, boolean canBeReadOnly)
ZooKeeper(String connectString, int sessionTimeout, Watcher watcher, long sessionId, byte[] sessionPasswd)
ZooKeeper(String connectString, int sessionTimeout, Watcher watcher, long sessionId, byte[] sessionPasswd, boolean canBeReadOnly)
- 参数详解
| 参数名 | 描述 |
|---|---|
| connectString | 形如ip:port,ip:port/path1/path2,表示zk服务器列表,带path路径的表示基于此path操作 |
| sessionTimeout | 客户端会话超时时间,毫秒值,在sessionTimeout时间内没有进行有效的心跳检测,则认为会话超时 |
| watcher | 默认监听器,可以不设置,传null即可 |
| canBeReadOnly | boolean值,true表示只读,默认为false |
| sessionId和sessionPasswd | 会话id和会话的秘钥,当一个会话创建后,会自动生成对应的id和秘钥,主要用来恢复会话 |
- 例子
package com.banary.base;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import java.util.concurrent.CountDownLatch;
public class ZookeeperFactory {
private static CountDownLatch countDownLatch = new CountDownLatch(1);
public static void main(String[] args) throws Exception {
createZk2();
}
public static void createZk1() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
System.out.println(zooKeeper.getState());
countDownLatch.await();
System.out.println("zk实例创建成功");
}
public static void createZk2() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
System.out.println(zooKeeper.getState());
countDownLatch.await();
long sessionId = zooKeeper.getSessionId();
byte[] sessionPasswd = zooKeeper.getSessionPasswd();
//使用错的sessionId和sessionPasswd
zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher(), 1l, "test".getBytes());
//使用对的sessionId和sessionPasswd
zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher(), sessionId, sessionPasswd);
Thread.sleep(Integer.MAX_VALUE);
}
private static class DemoWatcher implements Watcher{
public void process(WatchedEvent watchedEvent) {
System.out.println("收到zk event:" + watchedEvent);
countDownLatch.countDown();
}
}
}
- 注意
创建zk对象的方法是异步的,此处采用CountDownLatch实现同步
创建节点
- 方法(不支持递归创建,如果该节点已存在,会抛出异常NodeExistsException)
#同步方法
public String create(String path, byte[] data, List<ACL> acl, CreateMode createMode) throws KeeperException, InterruptedException
#异步方法
public void create(String path, byte[] data, List<ACL> acl, CreateMode createMode, StringCallback cb, Object ctx)
- 参数详解
| 参数名 | 描述 |
|---|---|
| path | 要创建的数据节点的路径 |
| data | 字节数组,该节点的初始内容,需要自己序列化成字节数组 |
| acl | 节点的安全策略,详见ZooDefs.Ids |
| createMode | 枚举类型,相见CreateMode |
| cb | 异步创建时的回调函数,需要开发者自己实现对应的AsyncCallback子接口,如StringCallback,重写void processResult(int var1, String var2, Object var3, String var4)方法,当zk服务器创建完节点,客户端自动调用该方法 |
| ctx | 回调函数上下文,和回调函数一起使用 |
- 例子
package com.banary.base;
import org.apache.zookeeper.*;
import java.util.concurrent.CountDownLatch;
public class CreateDemo {
private static CountDownLatch countDownLatch = new CountDownLatch(1);
public static void main(String[] args) throws Exception{
asyncCreate();
}
/**
* 同步创建
* @throws Exception
*/
public static void syncCreate() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
//阻塞,直到zk链接成功
countDownLatch.await();
//创建临时节点,没有权限限制
String path1 = zooKeeper.create("/zk-test-ephemeral-", "1".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println("临时节点1创建成功:"+ path1);
//创建临时顺序节点,没有权限限制
String path2 = zooKeeper.create("/zk-test-ephemeral-", "1".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
System.out.println("临时节点2创建成功:" + path2);
}
/**
* 异步创建
* @throws Exception
*/
public static void asyncCreate() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
//阻塞,直到zk链接成功
countDownLatch.await();
//创建临时节点,没有权限限制
zooKeeper.create("/zk-test-ephemeral-", "1".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL,
new DemoCallback(), "path1");
//创建临时顺序节点,没有权限限制
zooKeeper.create("/zk-test-ephemeral-", "1".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL,
new DemoCallback(), "path2" );
Thread.sleep(Integer.MAX_VALUE);
}
private static class DemoWatcher implements Watcher{
public void process(WatchedEvent watchedEvent) {
if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
countDownLatch.countDown();
}
}
}
private static class DemoCallback implements AsyncCallback.StringCallback {
@Override
public void processResult(int rc, String path, Object ctx, String name) {
System.out.println("创建节点:[" + rc + ", " + path + ", " + ctx.toString() +
", 真实path:" + name + "]");
}
}
}
- 异步方法回调接口参数说明
| 参数名 | 描述 |
|---|---|
| rc | 服务端响应码:0 创建成功;-4 客户端和服务端的链接断开;-110 节点已存在;-112 会话过期 |
| path | 对应create方法中节点路径参数值 |
| ctx | 接口调用时传如API的ctx,即对应异步create方法中的ctx参数 |
| name | 创建成功后,对应节点的真是路径 |
- 同步方法和异步方法比较
- 同步方法会阻塞线程,异步方法不会
- 同步会抛出异常,异步方法不会,异常信息是通过状态码的方式传递到回调函数中
删除
- 方法(删除时不支持递归删除,也就是说某个节点如果存在子节点,则不能删除)
#同步删除
public void delete(String path, int version) throws InterruptedException, KeeperException
#异步删除
public void delete(String path, int version, VoidCallback cb, Object ctx)
- 参数说明
| 参数名 | 描述 |
|---|---|
| path | 要删除的节点对应的path |
| version | 数据节点的版本号,乐观锁 |
| cb | 异步删除时的回调函数 |
| ctx | 回调函数的参数 |
- 例子
package com.banary.base;
import org.apache.zookeeper.*;
import java.util.concurrent.CountDownLatch;
public class DeleteDemo {
private static CountDownLatch countDownLatch = new CountDownLatch(1);
public static void main(String[] args) throws Exception{
asyncDelete();
}
public static void syncDelete() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
String path = zooKeeper.create("/deleteDemo", "deleteDemo".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
Thread.sleep(10000);
zooKeeper.delete(path, 0);
}
public static void asyncDelete() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
String path = zooKeeper.create("/deleteDemo", "deleteDemo".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
Thread.sleep(5000);
zooKeeper.delete(path, 0, new DemoCallback(), "asyncDelete");
Thread.sleep(5000);
}
private static class DemoWatcher implements Watcher{
@Override
public void process(WatchedEvent watchedEvent) {
System.out.println("创建zk会话:" + watchedEvent.getState());
if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
System.out.println("zk会话创建成功");
countDownLatch.countDown();
}
}
}
public static class DemoCallback implements AsyncCallback.VoidCallback{
@Override
public void processResult(int rc, String path, Object ctx) {
System.out.println("删除节点成功:[" + rc + ", " + path + ", " + ctx.toString() + "]");
}
}
}
查询节点数据内容getData
- 方法
public byte[] getData(String path, Watcher watcher, Stat stat) throws KeeperException, InterruptedException
public byte[] getData(String path, boolean watch, Stat stat) throws KeeperException, InterruptedException
public void getData(String path, Watcher watcher, DataCallback cb, Object ctx)
public void getData(String path, boolean watch, DataCallback cb, Object ctx)
- 参数
| 参数名 | 描述 |
|---|---|
| path | 要获取数据的节点的路径 |
| watcher | 监听器 |
| watch | true表示使用默认的监听器,即创建zk对象时注册的监听器 |
| stat | 数据节点的状态信息,传入一个旧的stat变量,服务器响应后会用的新的stat变量替换 |
| cb | 异步方法的回调函数 |
| ctx | 回调函数上下文参数 |
- 例子
package com.banary.base;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import java.util.concurrent.CountDownLatch;
public class GetDataDemo {
private static CountDownLatch countDownLatch = new CountDownLatch(1);
public static void main(String[] args) throws Exception{
asyncGetData();
}
/**
* 同步获取数据
* @throws Exception
*/
public static void syncGetData() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
String path = zooKeeper.create("/syncGetData", "syncGetData".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println(new String(zooKeeper.getData(path,true, new Stat())));
}
/**
* 异步获取数据
*/
public static void asyncGetData() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
String path = zooKeeper.create("/asyncGetData", "asyncGetData".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
System.out.println(new String(zooKeeper.getData(path,true, new Stat())));
Thread.sleep(Integer.MAX_VALUE);
}
private static class DemoWatcher implements Watcher{
@Override
public void process(WatchedEvent watchedEvent) {
if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
countDownLatch.countDown();
}
}
}
private static class DemoCallback implements AsyncCallback.DataCallback{
@Override
public void processResult(int rc, String path, Object ctx, byte[] bytes, Stat stat) {
System.out.println("异步获取的数据内容为:" + new String(bytes));
}
}
}
查询子节点getChildren
- 方法
public List<String> getChildren(String path, Watcher watcher) throws KeeperException, InterruptedException
public List<String> getChildren(String path, boolean watch) throws KeeperException, InterruptedException
public void getChildren(String path, Watcher watcher, ChildrenCallback cb, Object ctx)
public void getChildren(String path, boolean watch, ChildrenCallback cb, Object ctx)
public List<String> getChildren(String path, Watcher watcher, Stat stat) throws KeeperException, InterruptedException
public List<String> getChildren(String path, boolean watch, Stat stat) throws KeeperException, InterruptedException
public void getChildren(String path, Watcher watcher, Children2Callback cb, Object ctx)
public void getChildren(String path, boolean watch, Children2Callback cb, Object ctx)
- 参数
| 参数名 | 描述 |
|---|---|
| path | 要查询的节点 |
| watcher | 注册一个监听器 |
| watch | 使用默认的监听器 |
| cb | 异步方法的回调函数 |
| ctx | 回调函数上下文参数 |
| stat | 闯入一个旧的Stat对象,查询后,会被服务端响应的新Stat对象替换 |
修改
- 方法
#同步方法
public Stat setData(String path, byte[] data, int version) throws KeeperException, InterruptedException
#异步方法
public void setData(String path, byte[] data, int version, StatCallback cb, Object ctx)
- 参数
| 参数名 | 描述 |
|---|---|
| path | 要修改的数据节点的路径 |
| data | 修改后的数据 |
| version | 数据修改时基于的版本号,即乐观锁 |
| cb | 异步方法的回调函数 |
| ctx | 回调函数上下文参数 |
- 例子
package com.banary.base;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import java.util.concurrent.CountDownLatch;
public class UpdateDemo {
public static CountDownLatch countDownLatch = new CountDownLatch(1);
public static void main(String[] args) throws Exception{
asyncUpdate();
}
/**
* 同步更新
*/
public static void syncUpdate() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
String path = zooKeeper.create("/syncUpdate", "syncUpdate".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
Stat stat = new Stat();
System.out.println(new String(zooKeeper.getData(path, true, stat)));
System.out.println(stat.getCzxid() + "," + stat.getMzxid() + "," + stat.getVersion());
//-1 表示不加乐观锁
zooKeeper.setData(path, "32123".getBytes(), -1);
System.out.println(new String(zooKeeper.getData(path, true, stat)));
System.out.println(stat.getCzxid() + "," + stat.getMzxid() + "," + stat.getVersion());
}
/**
* 异步更新
* @throws Exception
*/
public static void asyncUpdate() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
String path = zooKeeper.create("/asyncUpdate", "asyncUpdate".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
Stat stat = new Stat();
System.out.println(new String(zooKeeper.getData(path, true, stat)));
System.out.println(stat.getCzxid() + "," + stat.getMzxid() + "," + stat.getVersion());
zooKeeper.setData(path, "dsadsa".getBytes(), -1, new DemoCallback(), "回调");
Thread.sleep(Integer.MAX_VALUE);
}
private static class DemoWatcher implements Watcher{
@Override
public void process(WatchedEvent watchedEvent) {
if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
countDownLatch.countDown();
}else if(watchedEvent.getType() == Event.EventType.NodeDataChanged){
System.out.println("节点数据内容发生了变化");
}
}
}
private static class DemoCallback implements AsyncCallback.StatCallback{
@Override
public void processResult(int rc, String path, Object ctx, Stat stat) {
System.out.println("修改节点:[" + rc + ", " + path + ", " + ctx.toString() +
", stat:" + stat.toString() + "]");
}
}
}
判断节点是否存在
- 方法
public Stat exists(String path, Watcher watcher) throws KeeperException, InterruptedException
public Stat exists(String path, boolean watch) throws KeeperException, InterruptedException
public void exists(String path, Watcher watcher, StatCallback cb, Object ctx)
public void exists(String path, boolean watch, StatCallback cb, Object ctx)
- 参数
| 参数名 | 描述 |
|---|---|
| path | 要判断的节点路径 |
| watcher | 注册一个监听器,用来监听节点被创建,删除,更新 |
| watch | 是否使用默认的监听器 |
| cb | 异步方法的回调函数 |
| ctx | 回调函数上下文参数 |
- 例子
package com.banary.base;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import java.util.concurrent.CountDownLatch;
public class ExistsNodeDemo {
public static CountDownLatch countDownLatch = new CountDownLatch(1);
public static void main(String[] args) throws Exception{
asyncExists();
}
/**
* 同步
*/
public static void syncExists() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
//创建
String path = zooKeeper.create("/syncExists", "syncExists".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
Stat stat = zooKeeper.exists(path, true);
System.out.println(stat.toString());
//更新
stat = zooKeeper.setData(path, "3213".getBytes(), -1);
System.out.println(stat.toString());
//删除
zooKeeper.delete(path, -1);
Thread.sleep(Integer.MAX_VALUE);
}
/**
* 异步
*/
public static void asyncExists() throws Exception{
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
//创建
String path = zooKeeper.create("/asyncExists", "asyncExists".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
zooKeeper.exists(path, true, new DemoCallback(), "asyncExists");
Thread.sleep(Integer.MAX_VALUE);
}
private static class DemoWatcher implements Watcher {
@Override
public void process(WatchedEvent watchedEvent) {
if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
countDownLatch.countDown();
}else if(Event.EventType.NodeCreated == watchedEvent.getType()){
System.out.println("创建节点");
}else if(Event.EventType.NodeDataChanged == watchedEvent.getType()){
System.out.println("修改节点");
}else if(Event.EventType.NodeDeleted == watchedEvent.getType()){
System.out.println("删除节点");
}
}
}
public static class DemoCallback implements AsyncCallback.StatCallback{
@Override
public void processResult(int rc, String path, Object ctx, Stat stat) {
System.out.println("[" + rc + ", " + path + ", " + ctx.toString() +
", stat:" + stat.toString() + "]");
}
}
}
权限控制
- 方法
#zk会话对象的方法
public void addAuthInfo(String scheme, byte[] auth)
- 参数
| 参数名 | 描述 |
|---|---|
| scheme | 权限控制模式,枚举值:world,auth,digest,ip和super |
| auth | 权限信息 |
- 例子
package com.banary.base;
import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import java.util.concurrent.CountDownLatch;
public class AuthDemo {
private static CountDownLatch countDownLatch = null;
public static void main(String[] args) throws Exception{
authCreate();
}
public static void authCreate() throws Exception{
countDownLatch = new CountDownLatch(1);
ZooKeeper zooKeeper = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
zooKeeper.addAuthInfo("digest", "auth".getBytes());
String path = zooKeeper.create("/auth", "auth".getBytes(), ZooDefs.Ids.CREATOR_ALL_ACL, CreateMode.PERSISTENT);
countDownLatch = new CountDownLatch(1);
ZooKeeper zooKeeper2 = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
zooKeeper2.addAuthInfo("digest", "auth".getBytes());
System.out.println(new String(zooKeeper2.getData(path, true, new Stat())));
countDownLatch = new CountDownLatch(1);
ZooKeeper zooKeeper1 = new ZooKeeper("localhost:2181", 5000, new DemoWatcher());
countDownLatch.await();
System.out.println(new String(zooKeeper1.getData(path, true, new Stat())));
}
private static class DemoWatcher implements Watcher {
public void process(WatchedEvent watchedEvent) {
if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
countDownLatch.countDown();
}
}
}
}
总结
- 除了创建会话是异步的,其他操作都存在同步和异步方法,同步会抛出异常
- 创建会话、查询(包括查询该节点的数据和子节点和判断节点存在)都可以注册监听器,也可以使用会话的默认监听器
Java客户端API的更多相关文章
- JAVA客户端API调用memcached两种方式
1. memcached client for java客户端API:memcached client for java 引入jar包:java-memcached-2.6.2.jar package ...
- zookeeper的Java客户端API
zookeeper作为一个分布式服务框架,主要用来解决分布式数据一致性问题,对多种语言提供了API.这里主要记录下JAVA客户端API的使用. 1.创建会话 客户端可以通过创建一个ZooKeeper实 ...
- Zookeeper的java客户端API使用方法(五)
前面几篇博文,我们简单的介绍了一下zookeeper,如何安装zookeeper集群,以及如何使用命令行等.这篇博文我们重点来看下Zookeeper的java客户端API使用方式. 创建会话 客户端可 ...
- hadoop系列二:HDFS文件系统的命令及JAVA客户端API
转载请在页首明显处注明作者与出处 一:说明 此为大数据系列的一些博文,有空的话会陆续更新,包含大数据的一些内容,如hadoop,spark,storm,机器学习等. 当前使用的hadoop版本为2.6 ...
- 读《分布式一致性原理》JAVA客户端API操作2
创建节点 通过客户端API来创建一个数据节点,有一下两个接口: public String create(final String path, byte data[], List<ACL> ...
- [转载] ZooKeeper的Java客户端API
转载自 http://www.cnblogs.com/ggjucheng/p/3370359.html http://zookeeper.apache.org/doc/trunk/javaExampl ...
- 读《分布式一致性原理》JAVA客户端API操作3
更新数据 客户端可以通过zookeeper的API来更新一个节点的数据内容,有如下两个接口: public Stat setData(final String path, byte data[], i ...
- Zookeeper Java客户端API的使用
1. 原生api 具体查看下面github代码 2. ZkClient ZkClient是Github上一个开源的ZooKeeper客户端.ZkClient在ZooKeeper原生 A ...
- 读《分布式一致性原理》JAVA客户端API操作
创建会话 客户端可以通过创建一个Zookeeper实例来连接服务器.4种构造方法如下 ZooKeeper(connectString, sessionTimeout, watcher): ZooKee ...
随机推荐
- .net中如何实现多线程
l线程肯定也是要执行一段代码的.所以要产生一个线程,必须先为该线程写一个方法,这个方法中的代码就是该线程运行所要执行的代码.(找个人来做一件事情) l线程启动时,通过委托调用该方法. (委托的好处) ...
- 自动化测试辅助工具(Selenium IDE等)
本随表目录 Selenium IDE安装和使用 FireBug安装和使用 FirePath安装和使用 Selenium IDE安装 方式一:打开Firefox-->添加组件-->搜索出 ...
- maven jar包冲三种解决方式
初次启动应用,一直包如下错误,起初怀疑引入pandora 版本冲突. Exception in thread "main" java.lang.NoSuchMethodError: ...
- C#保留2位小数的做法
第一 算法实现 保留两位的话,就用一个浮点型先乘以100,然后取整,取整完了之后,再乘以1.0,然后再除以100. 上面这种做法是保留n位,不会四舍五入的.因为这 ...
- js设置元素class方法小结及classList相关
给DOM元素设置class是我们在项目中非常容易遇到的,网上的资料和总结也比较多,下面比较全面的整理一下,希望给到大家一些帮助!并引用两种成熟的classList的兼容方法 一.el.setA ...
- EditTable-V1.0--续集
上一个功能有点少,这个V1.0版本是最小集合的. ================================= 双击单元格编辑,可以添加,删除单元格.并且保持相邻单元格不同的背景色. 引用了“M ...
- 浅谈Vue模板的那些事儿
接触过vue的童鞋都知道,组件的模板一般都是在template选项内定义的,如 Vue.component('child-component', { template: '<h3>我是闰土 ...
- LindDotNetCore~Mock对实际应用中的意义
回到目录 Mock在单元测试里的意义 Mock测试就是在测试过程中,对于某些不容易构造或者不容易获取的对象,用一个虚拟的对象来创建以 便测试的测试方法.一个闹钟根据时间来进行提醒服务,如果过了下午5点 ...
- 设计模式(三)装饰者模式Decorator
装饰者模式针对的问题是:对一个结构已经确定的类,在不改变该类的结构的情况下,动态增加一些功能. 一般来说,都是对一些已经写好的架构增加自己的功能,或者应对多种情况,增加功能. 我们还是来玩一句红警,首 ...
- 常用Linux命令笔记
任何脱离业务的架构都是耍流氓 只记录实际常用的Linux命令 常用Linux命令 查找安装路径: whereis nginx 查询nginx进程: ps aux|grep nginx 查看 CentO ...