Apache的httpclient的简单使用

由于httpclient的每个版本及每次更新都会有或多或少的改变，所以本人建议所有的使用httpclient的新手一定要仔细查看官方给出的examples，这会给我们省去很多麻烦，一般如果是二进制文件的话，examples在httpcomponents-client-4.5.2-bin\httpcomponents-client-4.5.2\examples\org\apache\http\examples\client这样类似的目录下，如果是源文件目录路径也基本不变，最基本的就是quickstart.java这个文件，基本内容大致如下：

package org.apache.http.examples.client;

import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

public class QuickStart {

    public static void main(String[] args) throws Exception {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        try {
            HttpGet httpGet = new HttpGet("http://httpbin.org/get");
            CloseableHttpResponse response1 = httpclient.execute(httpGet);
            // The underlying HTTP connection is still held by the response object
            // to allow the response content to be streamed directly from the network socket.
            // In order to ensure correct deallocation of system resources
            // the user MUST call CloseableHttpResponse#close() from a finally clause.
            // Please note that if response content is not fully consumed the underlying
            // connection cannot be safely re-used and will be shut down and discarded
            // by the connection manager.
            try {
                System.out.println(response1.getStatusLine());
                HttpEntity entity1 = response1.getEntity();
                // do something useful with the response body
                // and ensure it is fully consumed
                EntityUtils.consume(entity1);
            } finally {
                response1.close();
            }

            HttpPost httpPost = new HttpPost("http://httpbin.org/post");
            List  nvps = new ArrayList ();
            nvps.add(new BasicNameValuePair("username", "vip"));
            nvps.add(new BasicNameValuePair("password", "secret"));
            httpPost.setEntity(new UrlEncodedFormEntity(nvps));
            CloseableHttpResponse response2 = httpclient.execute(httpPost);

            try {
                System.out.println(response2.getStatusLine());
                HttpEntity entity2 = response2.getEntity();
                // do something useful with the response body
                // and ensure it is fully consumed
                EntityUtils.consume(entity2);
            } finally {
                response2.close();
            }
        } finally {
            httpclient.close();
        }
    }

}