博主前些天发现了一个巨牛的人工智能学习网站,通俗易懂,风趣幽默,忍不住也分享一下给大家
前言:源码阅读基于okhttp:3.10.0
c
implementation 'com.squareup.okhttp3:okhttp:3.10.0'
1、首先回顾OkHttp的使用
c
public class MainActivity extends RxActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
/**
* OkHttp的使用
*/
private static void okHttpUseAction() {
//通过构建者设计模式得到OkHttpClient
OkHttpClient okHttpClient = new OkHttpClient.Builder().build();
//get请求 构建者模式拿到request
Request request = new Request.Builder().url("https://www.baidu.com/").get().build();
//Call call = RealCall
Call call = okHttpClient.newCall(request);
// call.cancel();//取消请求
//同步方法,我们需要自己开启子线程 耗时
// try {
// Response response = call.execute();
// String string = response.body().string();
// InputStream inputStream = response.body().byteStream();
// Reader reader = response.body().charStream();
// } catch (IOException e) {
// e.printStackTrace();
// }
//异步方法
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
System.out.println("请求失败...");
}
@Override
public void onResponse(Call call, Response response) throws IOException {
String string = response.body().string();
System.out.println("请求完成:" + string);
// InputStream inputStream = response.body().byteStream();
// Reader reader = response.body().charStream();
}
});
}
public static void main(String[] args) {
okHttpUseAction();
}
}
2、OkHttp源码阅读之线程池详解
c
/**
* @Author: ly
* @Date: 2023/9/3
* @Description: 线程池的使用
*/
public class MyThreadPool {
public static void main(String[] args) {
//比较耗性能,开启子线程,然后回收
new Thread() {
@Override
public void run() {
super.run();
}
}.start();
//java 1.5 线程如何复用 线程池复用
//子线程
//需要一份工作:招聘工作,员工完成工作后,解聘
//需要一份工作:招聘工作,员工完成工作后,解聘
//需要一份工作:招聘工作,员工完成工作后,解聘
//线程池相当于以下
//需要一份工作:招聘工作,员工完成工作后,继续执行其他工作,解雇
//java 1.5 线程池复用,线程池(线程,如何让这么多线程复用,线程管理工作)
//Executor
// --ExecutorService
// --AbstractExecutorService
// --ThreadPoolExecutor
//ThreadPoolExecutor 学习此类
//线程池里面,只有一个核心线程在跑任务
/**
* corePoolSize:核心线程数
* maximumPoolSize:线程池非核心线程数,线程池规定大小
* keepAliveTime:时间数值
* unit:时间单位
* 参数三和四作用:正在执行的任务Runnable 20 大于核心线程数 参数三和参数四才会起作用
* 作用:Runnable1执行完毕后闲置60s,如果过了闲置60s,会回收掉Runnable1,如果在闲置时间60s内,复用此线程Runnable1
* workQueue:队列
* 作用:会把超出的任务加入到队列中,缓存起来
*/
// ExecutorService executorService = new ThreadPoolExecutor(1, 1, 60, TimeUnit.SECONDS, new LinkedBlockingDeque<>());
//Exception in thread "main" java.lang.IllegalArgumentException 会崩溃
// ExecutorService executorService = new ThreadPoolExecutor(5,
// 1, 60, TimeUnit.SECONDS, new LinkedBlockingDeque<>());
// ExecutorService executorService = new ThreadPoolExecutor(5,
// 10, 60, TimeUnit.SECONDS, new LinkedBlockingDeque<>());
//想实现缓存,线程池方案
/**
* corePoolSize:核心线程数
* maximumPoolSize:最大线程数。线程池非核心线程数,线程池规定大小
* keepAliveTime:时间数值
* unit:时间单位
* 参数三和四作用:正在执行的任务Runnable 20 大于核心线程数 参数三和参数四才会起作用
* 作用:Runnable1执行完毕后闲置60s,如果过了闲置60s,会回收掉Runnable1,如果在闲置时间60s内,复用此线程Runnable1
* workQueue:队列
* 作用:会把超出的任务加入到队列中,缓存起来
*/
// ExecutorService executorService = new ThreadPoolExecutor(0,
// Integer.MAX_VALUE, 60, TimeUnit.SECONDS, new LinkedBlockingDeque<>());
ExecutorService executorService = new ThreadPoolExecutor(0,
Integer.MAX_VALUE, 60, TimeUnit.SECONDS, new SynchronousQueue<>(),
new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread thread = new Thread();
thread.setName("MyOkHttp Dispatcher");
thread.setDaemon(false);//不是守护线程
return thread;
}
});
for (int i = 0; i < 20; i++) { //循环第二次,闲置60s,复用上一次任务
executorService.execute(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(1000);
System.out.println("当前线程,执行耗时任务,线程是:" + Thread.currentThread().getName());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
}
/**************************************JAVA提供了API***********************************************/
//Java设计者考虑到了不用使用线程池的参数配置,提供了API
ExecutorService executorService1 = Executors.newCachedThreadPool();
executorService1.execute(new Runnable() {
@Override
public void run() {
}
});
//线程池里面只有一个核心线程,最大线程也只有一个
ExecutorService executorService2 = Executors.newSingleThreadExecutor();
Executors.newFixedThreadPool(5); //指定固定大小线程池
}
}
3、守护线程详解
c
/**
* @Author: ly
* @Date: 2023/9/3
* @Description: 守护线程的使用
*/
public class MyThread {
public static void main(String[] args) {
Thread thread = new Thread() {
@Override
public void run() {
super.run();
while (true) {
// try {
// Thread.sleep(10);
// } catch (Exception e) {
// e.printStackTrace();
// } finally {
// System.out.println("run...");
// }
System.out.println("run...");
}
}
};
//守护线程
thread.setDaemon(true);
thread.start();
//JVM main()所持有的进程该结束了
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
4、根据OkHttp中构建者模式写一个例子
1.定义一个类HomeParam
c
/**
* @Author: ly
* @Date: 2023/9/3
* @Description: 房子的图纸
*/
public class HomeParam {
private double width;
private double height;
private String color = "白色";
public HomeParam() {
}
public HomeParam(double width, double height, String color) {
this.width = width;
this.height = height;
this.color = color;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
@Override
public String toString() {
return "画出来的图纸:HomeParam{" +
"width=" + width +
", height=" + height +
", color='" + color + '\'' +
'}';
}
}
2.定义一个类House
c
/**
* @Author: ly
* @Date: 2023/9/3
* @Description: 真实存在的房子
*/
public class House {
private double width;
private double height;
private String color;
public House() {
}
public House(double width, double height, String color) {
this.width = width;
this.height = height;
this.color = color;
}
public double getWidth() {
return width;
}
public void setWidth(double width) {
this.width = width;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
@Override
public String toString() {
return "具体建造出来的房子:House{" +
"width=" + width +
", height=" + height +
", color='" + color + '\'' +
'}';
}
}
3、定义一个类Worker
c
/**
* @Author: ly
* @Date: 2023/9/3
* @Description: 工人开始建造房子
*/
public class Worker {
//拿到图纸
private HomeParam mHomeParam;
public void setHomeParam(HomeParam homeParam) {
mHomeParam = homeParam;
}
//工作,盖房子
public House buildHouse() {
House house = new House();
house.setHeight(mHomeParam.getHeight());
house.setWidth(mHomeParam.getWidth());
house.setColor(mHomeParam.getColor());
return house;
}
}
4、定义一个类DesignerPerson
c
/**
* @Author: ly
* @Date: 2023/9/3
* @Description: 设计师
*/
public class DesignerPerson {
private HomeParam mHomeParam;
private Worker mWorker;
public DesignerPerson() {
mHomeParam = new HomeParam();
mWorker = new Worker();
}
/**
* 增加楼层
*
* @param height 高度
*/
public DesignerPerson addHeight(double height) {
mHomeParam.setHeight(height);
return this;
}
/**
* 增加宽度
*
* @param width 宽度
*/
public DesignerPerson addWidth(double width) {
mHomeParam.setWidth(width);
return this;
}
/**
* 增加颜色
*
* @param color 颜色
*/
public DesignerPerson addColor(String color) {
mHomeParam.setColor(color);
return this;
}
/**
* 把图纸给工人
* 员工说房子盖好了
*
* @return
*/
public House build() {
mWorker.setHomeParam(mHomeParam);
return mWorker.buildHouse();
}
}
5.定义一个类UserClient
c
/**
* @Author: ly
* @Date: 2023/9/3
* @Description: 用户有一个需求盖房子
*/
public class UserClient {
// public static void main(String[] args) {
//第一版
//找到建筑公司
// DesignerPerson designerPerson = new DesignerPerson();
// designerPerson.addHeight(4);
// designerPerson.addWidth(120.0);
// designerPerson.addColor("绿色");
//
// designerPerson.addHeight(2);
// designerPerson.addWidth(100.0);
// designerPerson.addColor("红色");
//
// designerPerson.addHeight(3);
// designerPerson.addWidth(90.0);
// designerPerson.addColor("黄色");
//
// //复制的过程
//
// House house = designerPerson.build();
// System.out.println(house);
// }
public static void main(String[] args) {
//第二版,链式调用
House house = new DesignerPerson().addColor("白色")
.addWidth(100)
.addHeight(8)
.build();
System.out.println(house);
}
}
2、OkHttp主线流程源码阅读
c
1.OSI七层模型,TCP/IP模型(四层),HTTP格式
OSI七层参考模型 --> TCP/IP参考模型
TCP/IP参考模型四层:
应用层 --> HTTP,HTTPS
传输层 --> Socket
HTTP get(请求行,请求属性集) post(请求行,请求属性集,type(form表单提交,还是其他提交),len(长度)==请求体)
2.OkHttp源码的主线流程
OkHttp的使用
OkHttpClient 通过构建者设计模式得到OkHttpClient
Request 通过构建者设计模式得到Request
Call 实际得到的是final class RealCall implements Call
//异步方法
call.enqueue(new Callback()
//不能执行大于1次 enqueue 否则会抛出异常Exception in thread "main" java.lang.IllegalStateException: Already Executed
synchronized (this) {
if (executed) throw new IllegalStateException("Already Executed");
executed = true;
}
//拿到调度器dispatcher执行enqueue()方法
client.dispatcher().enqueue(new AsyncCall(responseCallback));
Dispatcher{
/** Ready async calls in the order they'll be run. */ 等待队列
private final Deque<AsyncCall> readyAsyncCalls = new ArrayDeque<>();
运行的队列
/** Running asynchronous calls. Includes canceled calls that haven't finished yet. */
private final Deque<AsyncCall> runningAsyncCalls = new ArrayDeque<>();
//最终会调用到Dispatcher类中的enqueue()方法
synchronized void enqueue(AsyncCall call) {
//同时运行的异步任务小于64&&同时访问(同一个)的服务器,不能超过5个 条件满足加入到运行队列中,然后执行
if (runningAsyncCalls.size() < maxRequests && runningCallsForHost(call) < maxRequestsPerHost) {
runningAsyncCalls.add(call);
executorService().execute(call); //执行
} else {
//加入到等待队列
readyAsyncCalls.add(call);
}
}
Deque双端队列:Deque(双端队列)是一种用于管理HTTP请求和响应拦截器的数据结构。
Deque是"Double-ended Queue"的缩写,表示它可以在两端进行元素的插入和删除操作。
AsyncCall 执行耗时任务
signalledCallback 为true:这个错误是用户造成的,和OkHttp没有关系
为false:这个错误是OkHttp造成的。 onFailure
}
梳理主线流程:
OkHttpClient --> Request -> newCall RealCall.enqueue(){不能重复执行} --> Dispatcher.enqueue(AsyncCall)-->
Dispatcher{if:先加入运行队列里面去,执行异步任务 else 直接加入等待队列} --> 异步任务 AsyncCall.execute()
分析OkHttp里面的线程池
executorService().execute(call);
public synchronized ExecutorService executorService() {
if (executorService == null) {
executorService = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 60, TimeUnit.SECONDS,
new SynchronousQueue<Runnable>(), Util.threadFactory("OkHttp Dispatcher", false));
}
return executorService;
}
分析结果:OkHttp里面的线程池,采用的是缓存方案+线程工厂 name 不是守护线程
总结:采用的是缓存方案+定义线程工程(设置线程名,设置不是守护线程)
缓存方案:参数1 == 0
参数2 == Integer.MAX_VALUE
参数3 == 60s闲置时间,只要Runnable > 大于参数1 起作用(60s 之内就会复用之前的任务,60s之内就会回收任务)
--------------------------------->
看OkHttp源码,发现OkHttp里面使用了构建者设计模式,所以才要学习构建者设计模式
OkHttpClient ---构建者模式
Request ---构建者模式
开始学习构建者设计模式 -->盖房子的例子(根据OkHttp源码中的链式调用优化)