有没有一种更有效的方法来编写这段Jsoup代码

Question

我正在用jsp做一个网站，用来比较不同购物网站的产品价格，我把代码写在一个jsp页面上，如下所示：

try
{
 jsoup.connect(first_website)
 /* code for fetching prices and images */
 /* Html code for displaying prices and images */     
} catch(){}

try
{
 jsoup.connect(second_website)
 /* code for fetching prices and images */
 /* Html code for displaying prices and images */
} catch(){}

try
{
 jsoup.connect(third_website)
 /* code for fetching prices and images */
 /* Html code for displaying prices and images */
} catch(){}

此代码在同一页面上显示来自三个网站的单个搜索查询的结果。但问题是，我的网站现在加载速度很慢，有时一个或另一个网站的结果不显示。它给出了以下错误：

org.jsoup.HttpStatusException: HTTP error fetching URL.Status=500,URL=/*websitename*/

Answer 1

最好使用多个线程来请求站点，这样您就可以同时向这些站点发送请求。

你可以通过java Task Executor Service这样做：

    FutureTask<Boolean> futureTask1 = new FutureTask<Boolean>(new Callable<Boolean>()
    {
        @Override
        public Boolean call() throws Exception
        {
            try
            {
                //jsoup.connect(second_website)
                 /* code for fetching prices and images */
                 /* Html code for displaying prices and images */
                return true;
            } catch(Exception e){
                return false;
            }

        }
    });

    FutureTask<Boolean> futureTask2 = new FutureTask<Boolean>(new Callable<Boolean>()
    {
        @Override
        public Boolean call() throws Exception
        {
            //Same as above
        }
    });

    FutureTask<Boolean> futureTask3 = new FutureTask<Boolean>(new Callable<Boolean>()
    {
        @Override
        public Boolean call() throws Exception
        {
            //Same as above
        }
    });

    ExecutorService executorService = Executors.newFixedThreadPool(3);

    executorService.execute(futureTask1);
    executorService.execute(futureTask2);
    executorService.execute(futureTask3);

    while (true){
        if(futureTask1.isDone() && futureTask2.isDone() && futureTask3.isDone()){
            //Here work is done
            try
            {
                if(futureTask1.get()){
                    //task 1 done it's work correctly
                }else {
                    //some problem in task 
                }
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }

        }

        try
        {
            Thread.sleep(100);
        }
        catch (InterruptedException e)
        {
            e.printStackTrace();
        }
    }

如果您在这些任务之间有共同的逻辑，您可以创建一个实现Callable接口的类，并将站点url传递给它的构造函数。