在另一个线程中调用并将参数传递给方法

Question

我创建了这个小项目来展示我想要做什么，但实际上它将用于使用大约 60 个不同线程的大型应用程序中。

我有两节课

public class Main {

    public static void main(String[] args) {
        Http http = new Http();
        Thread threadHttp = new Thread(http, "httpThread1");
        threadHttp.start();

        http.getPage("http://google.com"); // <-- This gets called on 
                                           // the main thread, 
                                           //I want it to get called from the
                                            // "httpThread1" thread
    }
}

和

public class Http implements Runnable {
    volatile OkHttpClient client;

    @Override
    public void run() {
        client = new OkHttpClient.Builder().readTimeout(10, TimeUnit.SECONDS).retryOnConnectionFailure(true).build();

    }

    public void getPage(String url) {
        Request request = new Request.Builder().url(url).build();

        try {
            Response response = client.newCall(request).execute();
            System.out.println(response.body().string());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

我希望能够从主线程调用getPage 方法，但让它在我们启动和初始化的httpThread1 上执行OkHttpClient client

这可能吗？怎么办？

Answer 1

Runnable#run 是设计用于完成Runnable 对象的实际工作的方法。所以你必须让它做你目前在getPage做的事情。

您可以使用状态来存储url，并将响应保存在不同的字段中。请参阅有关如何重构它以进一步简化它的更多 cmets。但从目前的代码来看，最简单的改动可能是：

class Http implements Runnable {

    //initialize Http. This can be done better perhaps
    volatile OkHttpClient client = new OkHttpClient.Builder()
            .readTimeout(10, TimeUnit.SECONDS)
            .retryOnConnectionFailure(true).build();

    private Response response;

    private String url;

    public Http(String url) {
        this.url = url;
    }

    @Override
    public void run() {
        this.getPage(this.url);
    }

    public void getPage(String url) {
        Request request = new Request.Builder().url(url).build();

        try {
            this.response = client.newCall(request).execute();
            System.out.println(response.body().string());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

在你的main 方法中：

Http http = new Http("http://google.com");
Thread threadHttp = new Thread(http, "httpThread1");
threadHttp.start();
threadHttp.join();
Response resp = http.getResponse();

---

但是，这可以通过使用期货大大简化。例如，它可能看起来很简单：

class Http {
    volatile OkHttpClient client = new OkHttpClient.Builder()
            .readTimeout(10, TimeUnit.SECONDS)
            .retryOnConnectionFailure(true).build();

    public Response getPage(String url) {
        Request request = new Request.Builder().url(url).build();

        try {
            this.response = client.newCall(request).execute();
            System.out.println(response.body().string());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

而且，使用期货，您的主要方法可以看起来更简单：

public static void main(String[] args) throws Exception {
    Http http = new Http();
    CompletableFuture<Response> future = 
            CompletableFuture.supplyAsync(() -> http.getPage("http://google.com"));

    //the preceding statement will call `getPage` on a different thread.
    //So you can do other things before blocking with next statement

    Response resp = future.join();
}

如果您需要更多地控制异步任务的运行方式，您甚至可以使用带有supplyAsync 的线程池。

Answer 2

您可以像这样在Updater 类中调用test 方法：updater.test(yourVarHere)
要在单独的线程中调用方法，请参阅this question
您可能还想查看Java concurrency tutorial

Answer 3

根据您的问题，我认为您可能会这样做：

class HttpThread extends Thread {
     volatile OkHttpClient client;

     HttpThread(Runnable target, String name) {
        super(target, name);
     }

     @Override
     public void run() {
        client = new OkHttpClient.Builder().readTimeout(10, TimeUnit.SECONDS).retryOnConnectionFailure(true).build();
     }

     public void getPage(String url) {
        Request request = new Request.Builder().url(url).build();
        try {
            Response response = client.newCall(request).execute();
            System.out.println(response.body().string());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 }

在主类中：

public class Main {

   public static void main(String[] args) {
       Thread httpThread = new HttpThread(http, "httpThread1");
       httpThread.start();
       httpThread.getPage("http://google.com"); 
    }
}