apache HttpClient和HttpURLConnection发送get请求和post请求

本文主要介绍如题的两种方式下，如何发送http的get和post请求。

apache HttpClient

package com.xueyou.http;
import org.apache.http.HttpEntity;
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.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
public class HttpClient {
    public static final String GET_URL = "http://www.baidu.com";
    public static final String POST_URL = "http://www.baidu.com";
    public static void main(String[] args) throws Exception {
        getRequest();
        postRequest();
    }
    /**
     * post方式提交json代码
     *
     * @throws Exception
     */
    public static void getRequest() throws Exception {
        CloseableHttpClient httpclient = HttpClients.createDefault();
        try {
            // 创建httpget.
            HttpGet httpget = new HttpGet(GET_URL);
            System.out.println("executing request " + httpget.getURI());
            // 执行get请求.
            CloseableHttpResponse response = httpclient.execute(httpget);
            try {
                // 获取响应实体
                HttpEntity entity = response.getEntity();
                System.out.println("--------------------------------------");
                // 打印响应状态
                System.out.println(response.getStatusLine());
                if (entity != null) {
                    // 打印响应内容长度
                    System.out.println("Response content length: " + entity.getContentLength());
                    // 打印响应内容
                    System.out.println("Response content: " + EntityUtils.toString(entity));
                }
                System.out.println("------------------------------------");
            } finally {
                response.close();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (ParseException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭连接,释放资源
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    /**
     * 发送 post请求访问本地应用并根据传递参数不同返回不同结果
     */
    public static void postRequest() {
        // 创建默认的httpClient实例.
        CloseableHttpClient httpclient = HttpClients.createDefault();
        // 创建httppost
        HttpPost httppost = new HttpPost(POST_URL);
        // 创建参数队列
        List formparams = new ArrayList();
        formparams.add(new BasicNameValuePair("name", "xiaoming"));
        UrlEncodedFormEntity uefEntity;
        try {
            uefEntity = new UrlEncodedFormEntity(formparams, "UTF-8");
            httppost.setEntity(uefEntity);
            System.out.println("executing request " + httppost.getURI());
            CloseableHttpResponse response = httpclient.execute(httppost);
            try {
                HttpEntity entity = response.getEntity();
                if (entity != null) {
                    System.out.println("--------------------------------------");
                    System.out.println("Response content: " + EntityUtils.toString(entity, "UTF-8"));
                    System.out.println("--------------------------------------");
                }
            } finally {
                response.close();
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e1) {
            e1.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭连接,释放资源
            try {
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

HttpURLConnection方式

package com.xueyou.http;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
public class URLConnectionClient {
    private final static String HTTP_URL_GET = "http://www.baidu.com";
    private final static String HTTP_URL_POST =  "http://www.baidu.com";
    private static HashMap<String, String> mData = new HashMap<String, String>();
    public static void main(String[] args) throws Exception {
        mData.put("name", "HongBin");
        mData.put("sex", "male");
        System.out.println("GetResult:" + startGet(HTTP_URL_GET));
        System.out.println("PostResult:" + startPost(HTTP_URL_POST));
    }
    private static String startGet(String path) {
        BufferedReader in = null;
        StringBuilder result = new StringBuilder();
        try {
            //GET请求直接在链接后面拼上请求参数
            String mPath = path + "?";
            for (String key : mData.keySet()) {
                mPath += key + "=" + mData.get(key) + "&";
            }
            mPath = mPath.substring(0, mPath.length() - 1);
            URL url = new URL(mPath);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            //Get请求不需要DoOutPut
            conn.setDoOutput(false);
            conn.setDoInput(true);
            //设置连接超时时间和读取超时时间
            conn.setConnectTimeout(10000);
            conn.setReadTimeout(10000);
//            String routeCode = conn.getRequestProperty("routeCode");
            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            //连接服务器
            conn.connect();
            // 取得输入流，并使用Reader读取
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result.append(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        //关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result.toString();
    }
    private static String startPost(String path) {
        OutputStreamWriter out = null;
        BufferedReader in = null;
        StringBuilder result = new StringBuilder();
        try {
            URL url = new URL(path);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            // 发送POST请求必须设置为true
            conn.setDoOutput(true);
            conn.setDoInput(true);
            //设置连接超时时间和读取超时时间
            conn.setConnectTimeout(10000);
            conn.setReadTimeout(10000);
            conn.setRequestProperty("Content-Type", "x-www-form-urlencoded");
            out = new OutputStreamWriter(conn.getOutputStream());
            // POST的请求参数写在正文中
            for (String key : mData.keySet()) {
                out.write(key + "=" + mData.get(key) + "&");
            }
            out.flush();
            out.close();
            // 取得输入流，并使用Reader读取
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result.append(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        //关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result.toString();
    }
}