Httpclient教程

<dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.5</version>
        </dependency>

package com.kaishengit.httclient;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

import java.io.IOException;
import java.io.InputStream;

/**
 * Created by wanggs on 2017/7/27.
 */
public class Httpclient {
    public static void main(String[] args) throws IOException {
        // 创建了一个可以发出请求的客户端
        CloseableHttpClient httpClient = HttpClients.createDefault();
        // 创建一个Get请求
        HttpGet httpGet = new HttpGet("http://www.pingwest.com/feed/");
//   HttpPost httpPost = new HttpPost("http://www.pingwest.com/feed/"); POST请求
        // 发出请求,并接受服务端相应
        HttpResponse response = httpClient.execute(httpGet);

        // 获取Http状态码
        int statusCode = response.getStatusLine().getStatusCode();

        if (statusCode == 200) {
            // html 也就是获取相应输入流
            InputStream inputStream = response.getEntity().getContent();

            String result = IOUtils.toString(inputStream, "UTF-8");
            inputStream.close();
            System.out.println(result);

        } else {
            System.out.println("服务器异常" + statusCode);
        }
        httpClient.close();
    }
}

工具类

package com.kaishengit.util;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class HttpUtil {

    public static String sendHttpGetRequestWithString(String url) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet(url);
        try {
            HttpResponse response = httpClient.execute(httpGet);

            InputStream inputStream = null;
            if (response.getStatusLine().getStatusCode() == 200) {
                inputStream = response.getEntity().getContent();

                String result =  IOUtils.toString(inputStream,"UTF-8");
                httpClient.close();
                return result;
            } else {
                throw new RuntimeException("请求" + url + "异常 : " + response.getStatusLine().getStatusCode());
            }
        } catch (IOException ex) {
            throw new RuntimeException("请求" + url + "异常",ex);
        }
    }


}

目前，要为另一个项目提供接口，接口是用HTTP URL实现的，最初的想法是另一个项目用jQuery post进行请求。
但是，很可能另一个项目是部署在别的机器上，那么就存在跨域问题，而jquery的post请求是不允许跨域的。
这时，就只能够用HttpClient包进行请求了，同时由于请求的URL是HTTPS的，为了避免需要证书，所以用一个类继承DefaultHttpClient类，忽略校验过程。

1.写一个SSLClient类，继承至HttpClient

package com.wanggs.httpclient;

import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;

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.impl.client.DefaultHttpClient;

/**
 * Created by wanggs on 2017/7/28.
 * 用于进行Https请求的HttpClient
 */
public class SSLClient extends DefaultHttpClient {
    public SSLClient() throws Exception {
        super();
        SSLContext ctx = SSLContext.getInstance("TLS");
        X509TrustManager tm = new X509TrustManager() {
            @Override
            public void checkClientTrusted(X509Certificate[] chain,
                                           String authType) throws CertificateException {
            }

            @Override
            public void checkServerTrusted(X509Certificate[] chain,
                                           String authType) throws CertificateException {
            }

            @Override
            public X509Certificate[] getAcceptedIssuers() {
                return null;
            }
        };
        ctx.init(null, new TrustManager[]{tm}, null);
        SSLSocketFactory ssf = new SSLSocketFactory(ctx, SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
        ClientConnectionManager ccm = this.getConnectionManager();
        SchemeRegistry sr = ccm.getSchemeRegistry();
        sr.register(new Scheme("https", 443, ssf));
    }
}


package com.wanggs.httpclient;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.http.HttpEntity;
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.HttpPost;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

/**
 * Created by wanggs on 2017/7/28.
 */
public class HttpClientUtil {
    public String doPost(String url,Map<String,String> map,String charset){
        HttpClient httpClient = null;
        HttpPost httpPost = null;
        String result = null;
        try{
            httpClient = new SSLClient();
            httpPost = new HttpPost(url);
            //设置参数
            List<NameValuePair> list = new ArrayList<NameValuePair>();
            Iterator iterator = map.entrySet().iterator();
            while(iterator.hasNext()){
                Entry<String,String> elem = (Entry<String, String>) iterator.next();
                list.add(new BasicNameValuePair(elem.getKey(),elem.getValue()));
            }
            if(list.size() > 0){
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list,charset);
                httpPost.setEntity(entity);
            }
            HttpResponse response = httpClient.execute(httpPost);
            if(response != null){
                HttpEntity resEntity = response.getEntity();
                if(resEntity != null){
                    result = EntityUtils.toString(resEntity,charset);
                }
            }
        }catch(Exception ex){
            ex.printStackTrace();
        }
        return result;
    }
}
测试
package com.wanggs.httpclient;

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

/**
 * Created by wanggs on 2017/7/28.
 */
public class TestMain {
    private String url = "http://www.pingwest.com/feed/";
    private String charset = "utf-8";
    private HttpClientUtil httpClientUtil = null;

    public TestMain(){
        httpClientUtil = new HttpClientUtil();
    }

    public void test(){
        String httpOrgCreateTest = url + "httpOrg/create";
        Map<String,String> createMap = new HashMap<String,String>();
        createMap.put("authuser","*****");
        createMap.put("authpass","*****");
        createMap.put("orgkey","****");
        createMap.put("orgname","****");
        String httpOrgCreateTestRtn = httpClientUtil.doPost(httpOrgCreateTest,createMap,charset);
        System.out.println("result:"+httpOrgCreateTestRtn);
    }

    public static void main(String[] args){
        TestMain main = new TestMain();
        main.test();
    }
}
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