使用java的HttpClient实现多线程并发

使用Java的HttpClient实现多线程并发，包括以下步骤：

1.导入HttpClient库

使用HttpClient进行请求需要导入相应的库，具体可以使用Maven或直接下载jar包导入。

2.创建HttpClient对象

创建HttpClient对象用于发送请求。可以使用HttpClientBuilder类的build方法创建HttpClient对象。

HttpClient httpClient=HttpClientBuilder.create().build();

3.创建HttpGet/HttpPost请求

创建HttpGet/HttpPost请求对象，进行GET/POST请求，也可以添加请求参数、请求头等信息。

HttpGet httpGet = new HttpGet("http://example.com");
HttpResponse response = httpClient.execute(httpGet);

HttpPost httpPost = new HttpPost("http://example.com");
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("param1", "value1"));
params.add(new BasicNameValuePair("param2", "value2"));
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse response = httpClient.execute(httpPost);

4.发送请求并处理响应

发送请求获取响应，可以获取响应状态码、响应头、响应实体等相关信息。处理完响应后需要关闭HttpResponse和HttpClient对象。

int statusCode = response.getStatusLine().getStatusCode();
Header[] headers = response.getAllHeaders();
HttpEntity entity = response.getEntity();
String responseText = EntityUtils.toString(entity);
EntityUtils.consume(entity);
response.close();
httpClient.close();

5.创建线程池

为了多线程并发发送请求，使用线程池创建多个线程进行任务分发，具体可以使用ThreadPoolExecutor类来创建线程池，设置参数如corePoolSize、maximumPoolSize、keepAliveTime等。

ExecutorService executorService = new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>());

6.提交任务到线程池

将任务提交到线程池中，具体可以使用Callable或Runnable。

Callable<String> task = new Callable<String>() {
    @Override
    public String call() throws Exception {
        HttpClient httpClient = HttpClientBuilder.create().build();
        HttpGet httpGet = new HttpGet("http://example.com");
        HttpResponse response = httpClient.execute(httpGet);
        int statusCode = response.getStatusLine().getStatusCode();
        HttpEntity entity = response.getEntity();
        String responseText = EntityUtils.toString(entity);
        EntityUtils.consume(entity);
        response.close();
        httpClient.close();
        return responseText;
    }
};
Future<String> future = executorService.submit(task);
String responseText = future.get();

示例一（使用线程池执行多个请求）：

ExecutorService executorService = Executors.newFixedThreadPool(10);
List<Callable<String>> tasks = new ArrayList<>();
tasks.add(() -> {
    HttpGet httpGet = new HttpGet("http://example.com");
    CloseableHttpClient httpClient = HttpClientBuilder.create().build();
    CloseableHttpResponse response = httpClient.execute(httpGet);
    int statusCode = response.getStatusLine().getStatusCode();
    String responseText = EntityUtils.toString(response.getEntity());
    response.close();
    httpClient.close();
    return responseText;
});
tasks.add(() -> {
    HttpPost httpPost = new HttpPost("http://example.com");
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair("param1", "value1"));
    params.add(new BasicNameValuePair("param2", "value2"));
    httpPost.setEntity(new UrlEncodedFormEntity(params));
    CloseableHttpClient httpClient = HttpClientBuilder.create().build();
    CloseableHttpResponse response = httpClient.execute(httpPost);
    int statusCode = response.getStatusLine().getStatusCode();
    String responseText = EntityUtils.toString(response.getEntity());
    response.close();
    httpClient.close();
    return responseText;
});
List<Future<String>> futures = executorService.invokeAll(tasks);
for (Future<String> future : futures) {
    String responseText = future.get();
    // do something with responseText
}
executorService.shutdown();

示例二（使用线程池执行多个请求之后处理结果）：

ExecutorService executorService = Executors.newFixedThreadPool(10);
List<Callable<HttpResponse>> tasks = new ArrayList<>();
tasks.add(() -> {
    HttpGet httpGet = new HttpGet("http://example.com");
    CloseableHttpClient httpClient = HttpClientBuilder.create().build();
    CloseableHttpResponse response = httpClient.execute(httpGet);
    return response;
});
tasks.add(() -> {
    HttpPost httpPost = new HttpPost("http://example.com");
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair("param1", "value1"));
    params.add(new BasicNameValuePair("param2", "value2"));
    httpPost.setEntity(new UrlEncodedFormEntity(params));
    CloseableHttpClient httpClient = HttpClientBuilder.create().build();
    CloseableHttpResponse response = httpClient.execute(httpPost);
    return response;
});
List<Future<HttpResponse>> futures = executorService.invokeAll(tasks);
for (Future<HttpResponse> future : futures) {
    HttpResponse response = future.get();
    int statusCode = response.getStatusLine().getStatusCode();
    String responseText = EntityUtils.toString(response.getEntity());
    EntityUtils.consume(response.getEntity());
    response.close();
    // do something with statusCode and responseText
}
executorService.shutdown();