java httpclient 获取重定向地址

要获取重定向地址，可以使用Apache HttpClient的RedirectStrategy类。以下是一个示例代码：

CloseableHttpClient httpClient = HttpClients.createDefault();
HttpGet httpGet = new HttpGet("http://example.com");

RequestConfig requestConfig = RequestConfig.custom()
        .setRedirectsEnabled(false)
        .build();
httpGet.setConfig(requestConfig);

CloseableHttpResponse response = httpClient.execute(httpGet);

try {
    int statusCode = response.getStatusLine().getStatusCode();
    if (statusCode == HttpStatus.SC_MOVED_PERMANENTLY || statusCode == HttpStatus.SC_MOVED_TEMPORARILY) {
        Header locationHeader = response.getFirstHeader("Location");
        if (locationHeader != null) {
            String location = locationHeader.getValue();
            System.out.println("Redirect location: " + location);
        } else {
            System.out.println("Location header not found");
        }
    } else {
        System.out.println("Unexpected status code: " + statusCode);
    }
} finally {
    response.close();
}

在这个例子中，我们首先创建了一个HttpClient实例和一个HttpGet请求对象。然后，我们设置请求配置，禁用自动重定向。接下来，我们执行请求并检查响应状态码，如果是重定向状态码（301或302），我们获取Location头并输出重定向地址。否则，我们输出意外的状态码。最后，我们关闭响应对象。