httpclient模拟post请求json封装表单数据

以下代码包括最基本的GET、POST、JSON参数的POST方式的请求。（相当于POSTMAN中使用raw编写的参数）

package com.chinecredit.eccis.utils;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.ParseException;
import org.apache.http.client.ClientProtocolException;
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.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;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.alibaba.fastjson.JSONObject;

/**
 * http访问方法实现
 * @author 王俊南 
 * @date: 2018-11-22
 */
public class HttpRequestUtils {
    private static Logger logger = LoggerFactory
            .getLogger(HttpRequestUtils.class); // 日志记录

    /**
     * GET提交
     * 
     * @return
     */
    public static String doGet(String url) {
        String strResult = "";
        // 1. 创建一个默认的client实例
        CloseableHttpClient client = HttpClients.createDefault();
        try {
            // 2. 创建一个httpget对象
            HttpGet httpGet = new HttpGet(url);
            System.out.println("executing GET request " + httpGet.getURI());

            // 3. 执行GET请求并获取响应对象
            CloseableHttpResponse resp = client.execute(httpGet);
            try {
                // 6. 打印响应长度和响应内容
                if (resp.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                    // 4. 获取响应体
                    HttpEntity entity = resp.getEntity();
                    System.out.println("Response content length = "
                            + entity.getContentLength());
                    System.out.println("------");
                    strResult = EntityUtils.toString(resp.getEntity());
                }
            } finally {
                //无论请求成功与否都要关闭resp
                resp.close();
            }
        } catch (ClientProtocolException e) {
            logger.error("get请求失败:", e);
            // e.printStackTrace();
        } catch (ParseException e) {
            logger.error("get请求解析出错:", e);
            // e.printStackTrace();
        } catch (IOException e) {
            logger.error("get请求IO出错:", e);
            // e.printStackTrace();
        } finally {
            // 8. 最终要关闭连接，释放资源
            try {
                client.close();
            } catch (Exception e) {
                logger.error("get请求完毕关闭连接出错:", e);
                // e.printStackTrace();
            }
        }
        return strResult;
    }

    /**
     * 普通POST提交
     * @param url
     * @param map
     * @return
     */
    public static String doPost(String url, Map<String, Object> map) {
        String strResult = "";
        // 1. 获取默认的client实例
        CloseableHttpClient client = HttpClients.createDefault();
        // 2. 创建httppost实例
        HttpPost httpPost = new HttpPost(url);
        // 3. 创建参数队列（键值对列表）
        List<NameValuePair> paramPairs = new ArrayList<>();
        Set<String> keySet = map.keySet();
        for (String key : keySet) {
            Object val = map.get(key);
            paramPairs.add(new BasicNameValuePair(key, val.toString()));
        }
        UrlEncodedFormEntity entity;
        try {
            // 4. 将参数设置到entity对象中
            entity = new UrlEncodedFormEntity(paramPairs, "UTF-8");
            // 5. 将entity对象设置到httppost对象中
            httpPost.setEntity(entity);
            // 6. 发送请求并回去响应
            CloseableHttpResponse resp = client.execute(httpPost);
            try {
                // 7. 获取响应entity
                HttpEntity respEntity = resp.getEntity();
                strResult = EntityUtils.toString(respEntity, "UTF-8");
            } finally {
                // 9. 关闭响应对象
                resp.close();
            }

        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 10. 关闭连接，释放资源
            try {
                client.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return strResult;
    }
    
    /**
     * json参数方式POST提交
     * @param url
     * @param params
     * @return
     */
    public static String doPost(String url, JSONObject params){
        String strResult = "";
        // 1. 获取默认的client实例
        CloseableHttpClient client = HttpClients.createDefault();
        // 2. 创建httppost实例
        HttpPost httpPost = new HttpPost(url);
        httpPost.addHeader("Content-Type", "application/json;charset=utf-8"); //添加请求头
        try {
            httpPost.setEntity(new StringEntity(params.toJSONString(),"utf-8"));
            CloseableHttpResponse resp = client.execute(httpPost);
            try {
                // 7. 获取响应entity
                HttpEntity respEntity = resp.getEntity();
                strResult = EntityUtils.toString(respEntity, "UTF-8");
            } finally {
                resp.close();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                client.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return strResult;
    }
}