java httpclient 后台post get请求

• 最近在做得工作和遇到的坑
  
  1. 阿里云OSS 图片上传服务
  2. 对接第三方网站的API 调试，使用httpclient请求对方的服务，对返回json进行解析，读取数据

划重点，

1. https请求要用jdk1.8 ，不要使用jdk1.7 ，会报socket refuse，，或者socket connection close错误 2.
2. 请求完毕后，一定要释放连接 response.close();
3. 关于跨域请求 ，服务器端可以在代码中硬编码，或者使用过滤器，或者在nginx web服务器中配置，或者在浏览器请求方解决

 this.getResponse().setHeader("Access-Control-Allow-Origin", "*");
      this.getResponse().setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
      this.getResponse().setHeader("Access-Control-Max-Age", "3600");
//      this.getResponse().setHeader("Access-Control-Allow-Headers", "x-requested-with");

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1. 引入lib包 httpclient-4.4.1.jar

2. 封装通用请求头

 public static String reqPack(String command) {
            Map<String, String> params = Collections.singletonMap("query", command);
            Map<String, String> headers = new HashMap<String, String>();
            headers.put("key", APPKEY);
            headers.put("altitoken", getToken());
            headers.put("Content-type", "application/x-www-form-urlencoded");
            headers.put("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");
            //传入请求地址，参数，请求头
            return DataCrawlingHelper.sendPost(ALTIZURE_API_URL, params, headers);
        }

1. 封装请求类

package com.momoda.client;

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.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;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

/**
 * A站数据抓取类
 */
public class DataCrawlingHelper {

    public static String sendPost(String requestUrl, Map<String, String> params, Map<String, String> headers) {
        String body = "";
        //创建httpclient对象
        CloseableHttpClient client = HttpClients.createDefault();
        //创建post方式请求对象
        HttpPost httpPost = new HttpPost(requestUrl);
        //装填参数
        List<NameValuePair> nvps = new ArrayList<NameValuePair>();
        if (params != null) {
            for (Entry<String, String> entry : params.entrySet()) {
                nvps.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
            }
        }
        try {
            //设置参数到请求对象中
            httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));

            //设置header信息
            headers.forEach((key, val) -> {
                httpPost.setHeader(key, val);
            });

            //执行请求操作，并拿到结果（同步阻塞）
            CloseableHttpResponse response = client.execute(httpPost);

            //获取结果实体
            HttpEntity entity = response.getEntity();
            if (entity != null) {
                //按指定编码转换结果实体为String类型
                body = EntityUtils.toString(entity, "utf-8");
            }
            EntityUtils.consume(entity);
            //释放链接
            response.close();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        return body;
    }
}

1. 操作返回数据

   • 一般网站的返回数据都是通用的JSON格式，所以我们需要对json进行操作,如果我们抓取的事第三方网站的数据，一般是没有对应的实体类的，所以我们可以利用fastjson-1.1.27.jar 这个lib包操作我们的返回数据，

  /**
     * 检查项目状态
     */
    public void checkProjectState() {
        String projectId = this.getPara("projectId");
        String projectInfoBack = reqPack(String.format(COMMAND_QUERY_PROJECT, projectId));

        JSONObject jsonObj2 = JSONObject.parseObject(projectInfoBack);
        //根据json的类型，使用对应的类型接受返回值
        JSONArray edges = jsonObj2.getJSONObject("data").getJSONObject("project").getJSONObject("tasks").getJSONArray("edges");
        String taskState = jsonObj2.getJSONObject("data").getJSONObject("project").getString("taskState"); //Unmodified  Failed  Done
        if ("Done".equals(taskState)) {
            renderJson(taskState);
        } else {
            renderJson(edges);
        }
    }

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• 利用自己封装的json解析类

  1. 抽象类 ,

package com.momoda.client.altizure;

import com.momoda.common.Const;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

public abstract class AltizureRestltParseSuper<T> {

    private T data = null;

    public AltizureRestltParseSuper(String json) {
        Class<T> entityClass = null;
        Type t = getClass().getGenericSuperclass();
        if (t instanceof ParameterizedType) {
            Type[] p = ((ParameterizedType) t).getActualTypeArguments();
            entityClass = (Class<T>) p[0];
        }
        this.data = Const.gson.fromJson(json, entityClass);
    }

    public T data() {
        return this.data;
    }
}

1. 继承类

public class AltizureRestltParse extends AltizureRestltParseSuper<Map> {


    public AltizureRestltParse(String json) {
        super(json);
    }


    /**
     * @Description :1. 选择最近的 bucket
     * @Author : xuyangyang
     * @Date :   14:26  2018/6/1/001
     */
    public String getGeoIPInfo() {

        Map data = new HashMap();

        data = (Map) data().get("data");
        Map getGeoIPInfo = (Map) data.get("getGeoIPInfo");
        System.out.println(getGeoIPInfo.toString());
        ArrayList nearestBuckets = (ArrayList) getGeoIPInfo.get("nearestBuckets");
        System.out.println(nearestBuckets);

        Map bucket = (Map) nearestBuckets.get(0);
        System.out.println(bucket);

        System.out.println((String) bucket.get("bucket"));


        return (String) bucket.get("bucket");
    }
}

1. 方法调用 ，new 继承类，传入json字符串，直接使用get（）方法，获取key值，但是注意要使用正确的类型转换

public String getGeoIPInfo() {

        Map<String, String> map = new HashMap<>();
        map.put("query", "query{getGeoIPInfo{nearestBuckets {\n" +
                "  bucket\n" +
                "  display\n" +
                "  cloud\n" +
                "  distance\n" +
                "}}}");
        String body = null;
        String bucket = null;
        try {
            body = HttpClientUtil.sendPost(map);


            AltizureRestltParse jsonParse = new AltizureRestltParse(body);

            bucket = jsonParse.getGeoIPInfo();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return bucket;
    }

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