commons-httpclient如何拦截或过滤请求，记录请求地址，请求入参，请求出参？

commons-httpclient可以通过自定义拦截器（Interceptor）来实现请求拦截、记录请求地址、请求入参和请求出参的功能。具体实现方式如下：

1. 自定义Interceptor类，实现org.apache.commons.httpclient.HttpMethodInterceptor接口，重写process方法。

2. 在process方法中，通过HttpMethod对象获取请求地址、请求入参和请求出参等信息，并进行记录。

3. 将自定义的Interceptor添加到HttpClient中，可以通过HttpClient的getHttpConnectionManager方法获取HttpConnectionManager对象，然后调用HttpConnectionManager的getParams方法获取HttpConnectionManagerParams对象，最后调用HttpConnectionManagerParams的addHttpMethodInterceptor方法将Interceptor添加到HttpClient中。

以下是一个简单的示例代码：

import java.io.IOException;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpConnectionManager;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.HttpMethodInterceptor;
import org.apache.commons.httpclient.HttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.SimpleHttpConnectionManager;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpConnectionManagerParams;
import org.apache.commons.httpclient.params.HttpMethodParams;

public class HttpClientTest {
    public static void main(String[] args) throws IOException {
        HttpClient httpClient = new HttpClient();
        HttpConnectionManager httpConnectionManager = new SimpleHttpConnectionManager();
        HttpConnectionManagerParams httpConnectionManagerParams = new HttpConnectionManagerParams();
        httpConnectionManagerParams.addHttpMethodInterceptor(new MyInterceptor());
        httpConnectionManager.setParams(httpConnectionManagerParams);
        httpClient.setHttpConnectionManager(httpConnectionManager);

        String url = "http://www.example.com";
        HttpMethod method = new PostMethod(url);
        method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new HttpMethodRetryHandler() {
            public boolean retryMethod(HttpMethod method, IOException exception, int executionCount) {
                if (executionCount >= 3) {
                    return false;
                }
                if (exception instanceof IOException) {
                    return true;
                }
                return false;
            }
        });

        NameValuePair[] params = new NameValuePair[2];
        params[0] = new NameValuePair("param1", "value1");
        params[1] = new NameValuePair("param2", "value2");
        method.setQueryString(params);

        int statusCode = httpClient.executeMethod(method);
        if (statusCode != HttpStatus.SC_OK) {
            System.err.println("Method failed: " + method.getStatusLine());
        }

        byte[] responseBody = method.getResponseBody();
        System.out.println(new String(responseBody));

        method.releaseConnection();
    }

    static class MyInterceptor implements HttpMethodInterceptor {
        public void process(HttpMethod method, HttpMethodParams params) {
            System.out.println("Request URL: " + method.getURI());
            System.out.println("Request Params: " + method.getQueryString());
            System.out.println("Response Status: " + method.getStatusCode());
            System.out.println("Response Body: " + new String(method.getResponseBody()));
        }
    }
}

在上述示例代码中，自定义了一个MyInterceptor类，实现了HttpMethodInterceptor接口，重写了process方法，在该方法中打印了请求地址、请求入参、请求出参等信息。然后通过HttpConnectionManagerParams的addHttpMethodInterceptor方法将Interceptor添加到HttpClient中。最后执行Post请求并输出结果。