Apache HttpClient发送POST请求

Apache的HttpClient是常用的HTTP请求工具组件，从业多年，该组件的版本已经更新多次，之前熟悉的代码已经不能使用了，一些类都还删除了。

一般在公司使用时候都会进行封装，这次是新项目，需要调用保险公司的文件服务器上传文件，也算是从零开始再了解一次。全部代码如下：

package com.henryge.life.pms.util;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
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.ContentType;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.multipart.MultipartFile;

import java.util.HashMap;
import java.util.Map;

public class InsuranceFileUtil {

    private final static Logger LOGGER = LoggerFactory.getLogger(InsuranceFileUtil.class);

    public static Map<String, Object> uppload(String url, MultipartFile file) throws Exception {
        CloseableHttpClient client = HttpClients.createDefault();
        Map<String, Object> resultMap = new HashMap<>();

        String fileName = file.getOriginalFilename();
        HttpPost httpPost = new HttpPost(url + "upload.do");
        MultipartEntityBuilder builder = MultipartEntityBuilder.create();
        builder.addBinaryBody(fileName, file.getInputStream(), ContentType.MULTIPART_FORM_DATA, fileName);
        builder.addTextBody("systemName", "test");
        builder.addTextBody("userName", "test");
        HttpEntity entity = builder.build();
        httpPost.setEntity(entity);

        HttpResponse response = client.execute(httpPost);
        HttpEntity responseEntity = response.getEntity();

        SAXBuilder sb = new SAXBuilder();
        Document doc = sb.build(responseEntity.getContent());
        Element root = doc.getRootElement();

        resultMap.put("fileId", root.getChild("attachment").getChildText("fileid"));
        resultMap.put("downloadUrl", url + "download.do?fileid=" + resultMap.get("fileId").toString());
        return resultMap;
    }

    public static Object[] download(String url) throws Exception {
        CloseableHttpResponse response = null;
        CloseableHttpClient client = null;
        try {
            client = HttpClients.createDefault();
            HttpGet httpGet = new HttpGet(url);
            response = client.execute(httpGet);
            HttpEntity entity = response.getEntity();
            if (entity == null) {
                return new Object[]{};
            } else {
                LOGGER.info("StatusCode is " + response.getStatusLine().getStatusCode());
                if (response.getStatusLine().getStatusCode() == 200) {
                    return new Object[]{entity.getContent()};
                } else {
                    return new Object[]{};
                }
            }
        } finally {

            if (response != null) {
                try {
                    response.close();
                } catch (Exception var28) {
                }
            }

            if (client != null) {
                try {
                    client.close();
                } catch (Exception var27) {
                }
            }

        }
    }

}

HttpClients.createDefault();初始化一个CloseableHttpClient，调用的是HttpClientBuilder.build()方法。使用MultipartEntityBuilder来组装请求参数，addBinaryBody和addTextBody均是填充请求参数，底层都是调用方法:
public MultipartEntityBuilder addPart(final FormBodyPart bodyPart) { if (bodyPart == null) { return this; } if (this.bodyParts == null) { this.bodyParts = new ArrayList<FormBodyPart>(); } this.bodyParts.add(bodyPart); return this; }