httpClient学习整理

package com.httpclient;  
  
import java.io.IOException;  
import java.net.URI;  
import java.util.ArrayList;  
import java.util.List;  
import java.util.Map;  
  
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.client.utils.URIBuilder;  
import org.apache.http.entity.ContentType;  
import org.apache.http.entity.StringEntity;  
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;  
/** 
 * httpClient工具类 
 * @author jianghui 
 * 百度搜索这个关键字,下载jar包: httpcomponents-client-4.5.3 
 */  
public class HttpClientUtil {  
    public static void main(String[] args) {  
        String doGet = doGet("http://www.baidu.com");  
        System.out.println(doGet);  
    }  
  
    public static String doGet(String url, Map<String, String> param) {  
  
        // 创建Httpclient对象  
        CloseableHttpClient httpclient = HttpClients.createDefault();  
  
        String resultString = "";  
        CloseableHttpResponse response = null;  
        try {  
            // 创建uri  
            URIBuilder builder = new URIBuilder(url);  
            if (param != null) {  
                for (String key : param.keySet()) {  
                    builder.addParameter(key, param.get(key));  
                }  
            }  
            URI uri = builder.build();  
  
            // 创建http GET请求  
            HttpGet httpGet = new HttpGet(uri);  
  
            // 执行请求  
            response = httpclient.execute(httpGet);  
            // 判断返回状态是否为200  
            if (response.getStatusLine().getStatusCode() == 200) {  
                resultString = EntityUtils.toString(response.getEntity(), "UTF-8");  
            }  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            try {  
                if (response != null) {  
                    response.close();  
                }  
                httpclient.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
        return resultString;  
    }  
  
    public static String doGet(String url) {  
        return doGet(url, null);  
    }  
  
    public static String doPost(String url, Map<String, String> param) {  
        // 创建Httpclient对象  
        CloseableHttpClient httpClient = HttpClients.createDefault();  
        CloseableHttpResponse response = null;  
        String resultString = "";  
        try {  
            // 创建Http Post请求  
            HttpPost httpPost = new HttpPost(url);  
            // 创建参数列表  
            if (param != null) {  
                List<NameValuePair> paramList = new ArrayList<>();  
                for (String key : param.keySet()) {  
                    paramList.add(new BasicNameValuePair(key, param.get(key)));  
                }  
                // 模拟表单  
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);  
                httpPost.setEntity(entity);  
            }  
            // 执行http请求  
            response = httpClient.execute(httpPost);  
            resultString = EntityUtils.toString(response.getEntity(), "utf-8");  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            try {  
                response.close();  
            } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            }  
        }  
  
        return resultString;  
    }  
  
    public static String doPost(String url) {  
        return doPost(url, null);  
    }  
      
    public static String doPostJson(String url, String json) {  
        // 创建Httpclient对象  
        CloseableHttpClient httpClient = HttpClients.createDefault();  
        CloseableHttpResponse response = null;  
        String resultString = "";  
        try {  
            // 创建Http Post请求  
            HttpPost httpPost = new HttpPost(url);  
            // 创建请求内容  
            StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);  
            httpPost.setEntity(entity);  
            // 执行http请求  
            response = httpClient.execute(httpPost);  
            resultString = EntityUtils.toString(response.getEntity(), "utf-8");  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            try {  
                response.close();  
            } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            }  
        }  
  
        return resultString;  
    }  
}