java后端发送请求并返回请求结果（纯干货分享）

在很多时候，例如调用别人的api的时候，不是通过前端调用，而是需要后端将接口调用的api和返回信息封装好后才返回给前端，这时需要通过后端去直接发送http请求，所以可以创建一个工具类来将post,get,put,delete请求直接封装好，通过调用工具类里的静态方法从而直接发送http请求。今天介绍的HttpUtils是具备发送更加简单，返回更加清楚，调用更加便捷的工具整合类，可以解决大部分后端发送Http请求问题。

引入依赖：

<dependency&gt;
	<groupId&gt;org.apache.commons</groupId>
	<artifactId>commons-lang3</artifactId>
	<version>3.3.2</version>
</dependency>

HttpUtils工具类：

package com.apoco.portalcommon.utils;


import org.apache.commons.lang3.StringUtils;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public class HttpUtils {

    /**
     * get
     *
     * @param host
     * @param path
     * @param method
     * @param headers
     * @param querys
     * @return
     * @throws Exception
     */
    public static HttpResponse doGet(String host, String path, String method,
                                     Map<String, String> headers,
                                     Map<String, String> querys)
            throws Exception {
        HttpClient httpClient = wrapClient(host);

        HttpGet request = new HttpGet(buildUrl(host, path, querys));
        for (Map.Entry<String, String> e : headers.entrySet()) {
            request.addHeader(e.getKey(), e.getValue());
        }

        return httpClient.execute(request);
    }

    /**
     * post form
     *
     * @param host
     * @param path
     * @param method
     * @param headers
     * @param querys
     * @param bodys
     * @return
     * @throws Exception
     */
    public static HttpResponse doPost(String host, String path, String method,
                                      Map<String, String> headers,
                                      Map<String, String> querys,
                                      Map<String, String> bodys)
            throws Exception {
        HttpClient httpClient = wrapClient(host);

        HttpPost request = new HttpPost(buildUrl(host, path, querys));
        for (Map.Entry<String, String> e : headers.entrySet()) {
            request.addHeader(e.getKey(), e.getValue());
        }

        if (bodys != null) {
            List<NameValuePair> nameValuePairList = new ArrayList<NameValuePair>();

            for (String key : bodys.keySet()) {
                nameValuePairList.add(new BasicNameValuePair(key, bodys.get(key)));
            }
            UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(nameValuePairList, "utf-8");
            formEntity.setContentType("application/x-www-form-urlencoded; charset=UTF-8");
            request.setEntity(formEntity);
        }

        return httpClient.execute(request);
    }

    /**
     * Post String
     *
     * @param host
     * @param path
     * @param method
     * @param headers
     * @param querys
     * @param body
     * @return
     * @throws Exception
     */
    public static HttpResponse doPost(String host, String path, String method,
                                      Map<String, String> headers,
                                      Map<String, String> querys,
                                      String body)
            throws Exception {
        HttpClient httpClient = wrapClient(host);

        HttpPost request = new HttpPost(buildUrl(host, path, querys));
        for (Map.Entry<String, String> e : headers.entrySet()) {
            request.addHeader(e.getKey(), e.getValue());
        }

        if (StringUtils.isNotBlank(body)) {
            request.setEntity(new StringEntity(body, "utf-8"));
        }

        return httpClient.execute(request);
    }

    /**
     * Post stream
     *
     * @param host
     * @param path
     * @param method
     * @param headers
     * @param querys
     * @param body
     * @return
     * @throws Exception
     */
    public static HttpResponse doPost(String host, String path, String method,
                                      Map<String, String> headers,
                                      Map<String, String> querys,
                                      byte[] body)
            throws Exception {
        HttpClient httpClient = wrapClient(host);

        HttpPost request = new HttpPost(buildUrl(host, path, querys));
        for (Map.Entry<String, String> e : headers.entrySet()) {
            request.addHeader(e.getKey(), e.getValue());
        }

        if (body != null) {
            request.setEntity(new ByteArrayEntity(body));
        }

        return httpClient.execute(request);
    }

    /**
     * Put String
     * @param host
     * @param path
     * @param method
     * @param headers
     * @param querys
     * @param body
     * @return
     * @throws Exception
     */
    public static HttpResponse doPut(String host, String path, String method,
                                     Map<String, String> headers,
                                     Map<String, String> querys,
                                     String body)
            throws Exception {
        HttpClient httpClient = wrapClient(host);

        HttpPut request = new HttpPut(buildUrl(host, path, querys));
        for (Map.Entry<String, String> e : headers.entrySet()) {
            request.addHeader(e.getKey(), e.getValue());
        }

        if (StringUtils.isNotBlank(body)) {
            request.setEntity(new StringEntity(body, "utf-8"));
        }

        return httpClient.execute(request);
    }

    /**
     * Put stream
     * @param host
     * @param path
     * @param method
     * @param headers
     * @param querys
     * @param body
     * @return
     * @throws Exception
     */
    public static HttpResponse doPut(String host, String path, String method,
                                     Map<String, String> headers,
                                     Map<String, String> querys,
                                     byte[] body)
            throws Exception {
        HttpClient httpClient = wrapClient(host);

        HttpPut request = new HttpPut(buildUrl(host, path, querys));
        for (Map.Entry<String, String> e : headers.entrySet()) {
            request.addHeader(e.getKey(), e.getValue());
        }

        if (body != null) {
            request.setEntity(new ByteArrayEntity(body));
        }

        return httpClient.execute(request);
    }

    /**
     * Delete
     *
     * @param host
     * @param path
     * @param method
     * @param headers
     * @param querys
     * @return
     * @throws Exception
     */
    public static HttpResponse doDelete(String host, String path, String method,
                                        Map<String, String> headers,
                                        Map<String, String> querys)
            throws Exception {
        HttpClient httpClient = wrapClient(host);

        HttpDelete request = new HttpDelete(buildUrl(host, path, querys));
        for (Map.Entry<String, String> e : headers.entrySet()) {
            request.addHeader(e.getKey(), e.getValue());
        }

        return httpClient.execute(request);
    }

    private static String buildUrl(String host, String path, Map<String, String> querys) throws UnsupportedEncodingException {
        StringBuilder sbUrl = new StringBuilder();
        sbUrl.append(host);
        if (!StringUtils.isBlank(path)) {
            sbUrl.append(path);
        }
        if (null != querys) {
            StringBuilder sbQuery = new StringBuilder();
            for (Map.Entry<String, String> query : querys.entrySet()) {
                if (0 < sbQuery.length()) {
                    sbQuery.append("&amp;");
                }
                if (StringUtils.isBlank(query.getKey()) &amp;& !StringUtils.isBlank(query.getValue())) {
                    sbQuery.append(query.getValue());
                }
                if (!StringUtils.isBlank(query.getKey())) {
                    sbQuery.append(query.getKey());
                    if (!StringUtils.isBlank(query.getValue())) {
                        sbQuery.append("=");
                        sbQuery.append(URLEncoder.encode(query.getValue(), "utf-8"));
                    }
                }
            }
            if (0 < sbQuery.length()) {
                sbUrl.append("?").append(sbQuery);
            }
        }

        return sbUrl.toString();
    }

    private static HttpClient wrapClient(String host) {
        HttpClient httpClient = new DefaultHttpClient();
        if (host.startsWith("https://")) {
            sslClient(httpClient);
        }

        return httpClient;
    }

    private static void sslClient(HttpClient httpClient) {
        try {
            SSLContext ctx = SSLContext.getInstance("TLS");
            X509TrustManager tm = new X509TrustManager() {
                public X509Certificate[] getAcceptedIssuers() {
                    return null;
                }
                public void checkClientTrusted(X509Certificate[] xcs, String str) {

                }
                public void checkServerTrusted(X509Certificate[] xcs, String str) {

                }
            };
            ctx.init(null, new TrustManager[] { tm }, null);
            SSLSocketFactory ssf = new SSLSocketFactory(ctx);
            ssf.setHostnameVerifier(SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
            ClientConnectionManager ccm = httpClient.getConnectionManager();
            SchemeRegistry registry = ccm.getSchemeRegistry();
            registry.register(new Scheme("https", 443, ssf));
        } catch (KeyManagementException ex) {
            throw new RuntimeException(ex);
        } catch (NoSuchAlgorithmException ex) {
            throw new RuntimeException(ex);
        }
    }
}

对请求结果处理：
例如：

	public static Result toJSONStatusCodeResult(HttpResponse httpResponse) throws IOException {
        //转换为json
        JSONObject jsonResponse = JSONObject.parseObject(EntityUtils.toString(httpResponse.getEntity()));
        //获取状态码
        int statusCode = httpResponse.getStatusLine().getStatusCode();
        if (statusCode == 200) { //返回2**代码即成功
            //查询成功，返回数据
            return Result.ok(jsonResponse);
        }
        //返回错误状态码及原因
        return Result.fail(jsonResponse, statusCode, httpResponse.getStatusLine().getReasonPhrase());
    }

调用：

		HttpResponse httpResponse = HttpUtils.doPut(URL, reqUrl, "PUT", headers, querys, body);
        //将响应通过StatusCodeUtil.toJSONStatusCodeResult()方法获取响应信息并判断和返回
        return StatusCodeUtil.toJSONStatusCodeResult(httpResponse);

个人学习，如有不足，请指正！！

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