java中模拟http(https)请求的工具类

在java中，特别是java web中，我们经常需要碰到的一个场景是我们需要从服务端去发送http请求，获取到数据，而不是直接从浏览器输入请求网址获得相应。比如我们想访问微信接口，获取其返回信息。

在这里需要用到java的HttpURLConnection类，此类可以模拟http请求，获取到的响应以输入流的形式被程序所取到。现将相关方法整理为工具类。

package com.m_gecko.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.ConnectException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;

import org.apache.commons.io.IOUtils;

public class HttpUtil {
    /**
     * 模拟http的get请求，获取响应（输入流），然后把输入流转为
     *
     * @param url
     * @return
     */
    public static String httpGet(String url) {
        HttpURLConnection connection = null;
        InputStream response = null;
        try {
            connection = (HttpURLConnection) new URL(url).openConnection();
            connection.setConnectTimeout(10000);
            connection.setReadTimeout(10000);
            response = connection.getInputStream();
            if (response != null) {
                String nextLine = IOUtils.toString(response, "utf-8");
                return nextLine;
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (response != null)
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            if (connection != null) {
                connection.disconnect();
                connection = null;
            }
        }
        return null;
    }

    /**
     * 模拟http的post请求，类似上面
     *
     * @param url
     * @return
     */
    public static String httpPost(String url) {
        HttpURLConnection connection = null;
        InputStream response = null;
        try {
            connection = (HttpURLConnection) new URL(url).openConnection();
            connection.setConnectTimeout(30000);
            connection.setReadTimeout(30000);
            // 发送POST请求必须设置如下两行
            connection.setDoOutput(true);
            connection.setDoInput(true);
            response = connection.getInputStream();
            if (response != null) {
                String nextLine = IOUtils.toString(response, "utf-8");
                return nextLine;
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (response != null)
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            if (connection != null) {
                connection.disconnect();
                connection = null;
            }
        }
        return null;
    }

    /**
     * 向指定URL发送GET方法的请求
     *
     * @param url
     *            发送请求的URL
     * @param param
     *            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
     * @return URL 所代表远程资源的响应结果
     */
    public static String sendGet(String url, String param) {
        String result = "";
        BufferedReader in = null;
        try {
            String urlNameString = url + "?" + param;
            URL realUrl = new URL(urlNameString);
            // 打开和URL之间的连接
            HttpURLConnection connection = (HttpURLConnection) realUrl
                    .openConnection();
            // 设置通用的请求属性
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 建立实际的连接
            connection.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍历所有的响应头字段
            // for (String key : map.keySet()) {
            // System.out.println(key + "--->" + map.get(key));
            // }
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(
                    connection.getInputStream(), "utf-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 向指定 URL 发送POST方法的请求
     *
     * @param url
     *            发送请求的 URL
     * @param param
     *            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static String sendPost(String url, String param) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            HttpURLConnection conn = (HttpURLConnection) realUrl
                    .openConnection();
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            // out = new PrintWriter(conn.getOutputStream());
            // // 发送请求参数
            // out.print(param);
            // // flush输出流的缓冲
            // out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(
                    conn.getInputStream(), "utf-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 向指定 URL 发送POST方法的请求
     *
     * @param url
     *            发送请求的 URL
     * @param params
     *            请求的参数集合
     * @return 远程资源的响应结果
     */
    public static String sendPost(String url, Map<String, String> params) {
        OutputStreamWriter out = null;
        BufferedReader in = null;
        StringBuilder result = new StringBuilder();
        try {
            URL realUrl = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) realUrl
                    .openConnection();
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // POST方法
            conn.setRequestMethod("POST");
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            conn.setRequestProperty("Content-Type",
                    "application/x-www-form-urlencoded");
            conn.connect();
            // 获取URLConnection对象对应的输出流
            out = new OutputStreamWriter(conn.getOutputStream(), "UTF-8");
            // 发送请求参数
            if (params != null) {
                StringBuilder param = new StringBuilder();
                for (Map.Entry<String, String> entry : params.entrySet()) {
                    if (param.length() > 0) {
                        param.append("&");
                    }
                    param.append(entry.getKey());
                    param.append("=");
                    param.append(entry.getValue());
                    // System.out.println(entry.getKey()+":"+entry.getValue());
                }
                System.out.println("param:" + param.toString());
                out.write(param.toString());
            }
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(
                    conn.getInputStream(), "UTF-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result.append(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result.toString();
    }

    /**
     * url编码
     *
     * @param str
     * @param charset
     * @return
     * @throws UnsupportedEncodingException
     */
    public static String urlEncoder(String str, String charset)
            throws UnsupportedEncodingException {
        if (str == null) {
            str = "";
        }
        String result = URLEncoder.encode(str, charset);
        return result;
    }

    /**
     * 发送https请求
     *
     * @param requestUrl
     *            请求地址
     * @param requestMethod
     *            请求方式（GET、POST）
     * @param outputStr
     *            提交的数据
     * @return 返回微信服务器响应的信息
     */
    public static String httpsRequest(String requestUrl, String requestMethod,
            String outputStr) {
        try {
            // 创建SSLContext对象，并使用我们指定的信任管理器初始化
            TrustManager[] tm = { new MyX509TrustManager() };
            SSLContext sslContext = SSLContext.getInstance("SSL", "SunJSSE");
            sslContext.init(null, tm, new java.security.SecureRandom());
            // 从上述SSLContext对象中得到SSLSocketFactory对象
            SSLSocketFactory ssf = sslContext.getSocketFactory();
            URL url = new URL(requestUrl);
            HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
            conn.setSSLSocketFactory(ssf);
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setUseCaches(false);
            // 设置请求方式（GET/POST）
            conn.setRequestMethod(requestMethod);
            conn.setRequestProperty("content-type",
                    "application/x-www-form-urlencoded");
            // 当outputStr不为null时向输出流写数据
            if (null != outputStr) {
                OutputStream outputStream = conn.getOutputStream();
                // 注意编码格式
                outputStream.write(outputStr.getBytes("UTF-8"));
                outputStream.close();
            }
            // 从输入流读取返回内容
            InputStream inputStream = conn.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(
                    inputStream, "utf-8");
            BufferedReader bufferedReader = new BufferedReader(
                    inputStreamReader);
            String str = null;
            StringBuffer buffer = new StringBuffer();
            while ((str = bufferedReader.readLine()) != null) {
                buffer.append(str);
            }
            // 释放资源
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();
            inputStream = null;
            conn.disconnect();
            return buffer.toString();
        } catch (ConnectException ce) {
            ce.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

其中https请求所需要的信任管理器实现了X509TrustManager接口。

package com.m_gecko.util;

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

/**
 * 信任管理器
 * @author xdx
 */
public class MyX509TrustManager implements X509TrustManager {

    // 检查客户端证书
    public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
    }

    // 检查服务器端证书
    public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
    }

    // 返回受信任的X509证书数组
    public X509Certificate[] getAcceptedIssuers() {
        return null;
    }
}