如何在HttpClient上阻止资源泄漏？

try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
    HttpGet httpGet = new HttpGet("http://www.example.com");
    try (CloseableHttpResponse response = httpClient.execute(httpGet)) {
        // 处理响应
        HttpEntity entity = response.getEntity();
        // ...
    }
}

CloseableHttpClient httpClient = HttpClients.createDefault();
try {
    HttpGet httpGet = new HttpGet("http://www.example.com");
    CloseableHttpResponse response = httpClient.execute(httpGet);
    try {
        // 处理响应
        HttpEntity entity = response.getEntity();
        // ...
    } finally {
        response.close();
    }
} finally {
    httpClient.close();
}

PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
CloseableHttpClient httpClient = HttpClients.custom().setConnectionManager(connectionManager).build();
try {
    HttpGet httpGet = new HttpGet("http://www.example.com");
    CloseableHttpResponse response = httpClient.execute(httpGet);
    try {
        // 处理响应
        HttpEntity entity = response.getEntity();
        // ...
    } finally {
        response.close();
    }
} finally {
    httpClient.close();
}