java 常見幾種發送http請求案例

<span style="font-family: Arial, Helvetica, sans-serif;">import java.io.BufferedReader;</span>

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.Socket;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

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.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

/**
 * @Description:發送http請求幫助類
 * @author:liuyc
 * @time:2016年5月17日 下午3:25:32
 */
public class HttpClientHelper {
    /**
     * @Description:使用HttpURLConnection發送post請求
     * @author:liuyc
     * @time:2016年5月17日 下午3:26:07
     */
    public static String sendPost(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> e : params.entrySet()) {
                sbParams.append(e.getKey());
                sbParams.append("=");
                sbParams.append(e.getValue());
                sbParams.append("&");
            }
        }
        HttpURLConnection con = null;
        OutputStreamWriter osw = null;
        BufferedReader br = null;
        // 發送請求
        try {
            URL url = new URL(urlParam);
            con = (HttpURLConnection) url.openConnection();
            con.setRequestMethod("POST");
            con.setDoOutput(true);
            con.setDoInput(true);
            con.setUseCaches(false);
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            if (sbParams != null && sbParams.length() > 0) {
                osw = new OutputStreamWriter(con.getOutputStream(), charset);
                osw.write(sbParams.substring(0, sbParams.length() - 1));
                osw.flush();
            }
            // 讀取返回內容
            resultBuffer = new StringBuffer();
            int contentLength = Integer.parseInt(con.getHeaderField("Content-Length"));
            if (contentLength > 0) {
                br = new BufferedReader(new InputStreamReader(con.getInputStream(), charset));
                String temp;
                while ((temp = br.readLine()) != null) {
                    resultBuffer.append(temp);
                }
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (osw != null) {
                try {
                    osw.close();
                } catch (IOException e) {
                    osw = null;
                    throw new RuntimeException(e);
                } finally {
                    if (con != null) {
                        con.disconnect();
                        con = null;
                    }
                }
            }
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                } finally {
                    if (con != null) {
                        con.disconnect();
                        con = null;
                    }
                }
            }
        }

        return resultBuffer.toString();
    }

    /**
     * @Description:使用URLConnection發送post
     * @author:liuyc
     * @time:2016年5月17日 下午3:26:52
     */
    public static String sendPost2(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> e : params.entrySet()) {
                sbParams.append(e.getKey());
                sbParams.append("=");
                sbParams.append(e.getValue());
                sbParams.append("&");
            }
        }
        URLConnection con = null;
        OutputStreamWriter osw = null;
        BufferedReader br = null;
        try {
            URL realUrl = new URL(urlParam);
            // 打開和URL之間的連接
            con = realUrl.openConnection();
            // 設置通用的請求屬性
            con.setRequestProperty("accept", "*/*");
            con.setRequestProperty("connection", "Keep-Alive");
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            con.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 發送POST請求必須設置如下兩行
            con.setDoOutput(true);
            con.setDoInput(true);
            // 獲取URLConnection對象對應的輸出流
            osw = new OutputStreamWriter(con.getOutputStream(), charset);
            if (sbParams != null && sbParams.length() > 0) {
                // 發送請求參數
                osw.write(sbParams.substring(0, sbParams.length() - 1));
                // flush輸出流的緩衝
                osw.flush();
            }
            // 定義BufferedReader輸入流來讀取URL的響應
            resultBuffer = new StringBuffer();
            int contentLength = Integer.parseInt(con.getHeaderField("Content-Length"));
            if (contentLength > 0) {
                br = new BufferedReader(new InputStreamReader(con.getInputStream(), charset));
                String temp;
                while ((temp = br.readLine()) != null) {
                    resultBuffer.append(temp);
                }
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (osw != null) {
                try {
                    osw.close();
                } catch (IOException e) {
                    osw = null;
                    throw new RuntimeException(e);
                }
            }
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                }
            }
        }
        return resultBuffer.toString();
    }

    /**
     * @Description:發送get請求保存下載文件
     * @author:liuyc
     * @time:2016年5月17日 下午3:27:29
     */
    public static void sendGetAndSaveFile(String urlParam, Map<String, Object> params, String fileSavePath) {
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> entry : params.entrySet()) {
                sbParams.append(entry.getKey());
                sbParams.append("=");
                sbParams.append(entry.getValue());
                sbParams.append("&");
            }
        }
        HttpURLConnection con = null;
        BufferedReader br = null;
        FileOutputStream os = null;
        try {
            URL url = null;
            if (sbParams != null && sbParams.length() > 0) {
                url = new URL(urlParam + "?" + sbParams.substring(0, sbParams.length() - 1));
            } else {
                url = new URL(urlParam);
            }
            con = (HttpURLConnection) url.openConnection();
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            con.connect();
            InputStream is = con.getInputStream();
            os = new FileOutputStream(fileSavePath);
            byte buf[] = new byte[1024];
            int count = 0;
            while ((count = is.read(buf)) != -1) {
                os.write(buf, 0, count);
            }
            os.flush();
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (os != null) {
                try {
                    os.close();
                } catch (IOException e) {
                    os = null;
                    throw new RuntimeException(e);
                } finally {
                    if (con != null) {
                        con.disconnect();
                        con = null;
                    }
                }
            }
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                } finally {
                    if (con != null) {
                        con.disconnect();
                        con = null;
                    }
                }
            }
        }
    }

    /**
     * @Description:使用HttpURLConnection發送get請求
     * @author:liuyc
     * @time:2016年5月17日 下午3:27:29
     */
    public static String sendGet(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> entry : params.entrySet()) {
                sbParams.append(entry.getKey());
                sbParams.append("=");
                sbParams.append(entry.getValue());
                sbParams.append("&");
            }
        }
        HttpURLConnection con = null;
        BufferedReader br = null;
        try {
            URL url = null;
            if (sbParams != null && sbParams.length() > 0) {
                url = new URL(urlParam + "?" + sbParams.substring(0, sbParams.length() - 1));
            } else {
                url = new URL(urlParam);
            }
            con = (HttpURLConnection) url.openConnection();
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            con.connect();
            resultBuffer = new StringBuffer();
            br = new BufferedReader(new InputStreamReader(con.getInputStream(), charset));
            String temp;
            while ((temp = br.readLine()) != null) {
                resultBuffer.append(temp);
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                } finally {
                    if (con != null) {
                        con.disconnect();
                        con = null;
                    }
                }
            }
        }
        return resultBuffer.toString();
    }

    /**
     * @Description:使用URLConnection發送get請求
     * @author:liuyc
     * @time:2016年5月17日 下午3:27:58
     */
    public static String sendGet2(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> entry : params.entrySet()) {
                sbParams.append(entry.getKey());
                sbParams.append("=");
                sbParams.append(entry.getValue());
                sbParams.append("&");
            }
        }
        BufferedReader br = null;
        try {
            URL url = null;
            if (sbParams != null && sbParams.length() > 0) {
                url = new URL(urlParam + "?" + sbParams.substring(0, sbParams.length() - 1));
            } else {
                url = new URL(urlParam);
            }
            URLConnection con = url.openConnection();
            // 設置請求屬性
            con.setRequestProperty("accept", "*/*");
            con.setRequestProperty("connection", "Keep-Alive");
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            con.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 建立連接
            con.connect();
            resultBuffer = new StringBuffer();
            br = new BufferedReader(new InputStreamReader(con.getInputStream(), charset));
            String temp;
            while ((temp = br.readLine()) != null) {
                resultBuffer.append(temp);
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                }
            }
        }
        return resultBuffer.toString();
    }

    /**
     * @Description:使用HttpClient發送post請求
     * @author:liuyc
     * @time:2016年5月17日 下午3:28:23
     */
    public static String httpClientPost(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        HttpClient client = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(urlParam);
        // 構建請求參數
        List<NameValuePair> list = new ArrayList<NameValuePair>();
        Iterator<Entry<String, Object>> iterator = params.entrySet().iterator();
        while (iterator.hasNext()) {
            Entry<String, Object> elem = iterator.next();
            list.add(new BasicNameValuePair(elem.getKey(), String.valueOf(elem.getValue())));
        }
        BufferedReader br = null;
        try {
            if (list.size() > 0) {
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, charset);
                httpPost.setEntity(entity);
            }
            HttpResponse response = client.execute(httpPost);
            // 讀取服務器響應數據
            resultBuffer = new StringBuffer();
            br = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
            String temp;
            while ((temp = br.readLine()) != null) {
                resultBuffer.append(temp);
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                }
            }
        }
        return resultBuffer.toString();
    }

    /**
     * @Description:使用HttpClient發送get請求
     * @author:liuyc
     * @time:2016年5月17日 下午3:28:56
     */
    public static String httpClientGet(String urlParam, Map<String, Object> params, String charset) {
        StringBuffer resultBuffer = null;
        HttpClient client = new DefaultHttpClient();
        BufferedReader br = null;
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> entry : params.entrySet()) {
                sbParams.append(entry.getKey());
                sbParams.append("=");
                try {
                    sbParams.append(URLEncoder.encode(String.valueOf(entry.getValue()), charset));
                } catch (UnsupportedEncodingException e) {
                    throw new RuntimeException(e);
                }
                sbParams.append("&");
            }
        }
        if (sbParams != null && sbParams.length() > 0) {
            urlParam = urlParam + "?" + sbParams.substring(0, sbParams.length() - 1);
        }
        HttpGet httpGet = new HttpGet(urlParam);
        try {
            HttpResponse response = client.execute(httpGet);
            // 讀取服務器響應數據
            br = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
            String temp;
            resultBuffer = new StringBuffer();
            while ((temp = br.readLine()) != null) {
                resultBuffer.append(temp);
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    br = null;
                    throw new RuntimeException(e);
                }
            }
        }
        return resultBuffer.toString();
    }

    /**
     * @Description:使用socket發送post請求
     * @author:liuyc
     * @time:2016年5月18日 上午9:26:22
     */
    public static String sendSocketPost(String urlParam, Map<String, Object> params, String charset) {
        String result = "";
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> entry : params.entrySet()) {
                sbParams.append(entry.getKey());
                sbParams.append("=");
                sbParams.append(entry.getValue());
                sbParams.append("&");
            }
        }
        Socket socket = null;
        OutputStreamWriter osw = null;
        InputStream is = null;
        try {
            URL url = new URL(urlParam);
            String host = url.getHost();
            int port = url.getPort();
            if (-1 == port) {
                port = 80;
            }
            String path = url.getPath();
            socket = new Socket(host, port);
            StringBuffer sb = new StringBuffer();
            sb.append("POST " + path + " HTTP/1.1\r\n");
            sb.append("Host: " + host + "\r\n");
            sb.append("Connection: Keep-Alive\r\n");
            sb.append("Content-Type: application/x-www-form-urlencoded; charset=utf-8 \r\n");
            sb.append("Content-Length: ").append(sb.toString().getBytes().length).append("\r\n");
            // 這裏一個回車換行，表示消息頭寫完，不然服務器會繼續等待
            sb.append("\r\n");
            if (sbParams != null && sbParams.length() > 0) {
                sb.append(sbParams.substring(0, sbParams.length() - 1));
            }
            osw = new OutputStreamWriter(socket.getOutputStream());
            osw.write(sb.toString());
            osw.flush();
            is = socket.getInputStream();
            String line = null;
            // 服務器響應體數據長度
            int contentLength = 0;
            // 讀取http響應頭部信息
            do {
                line = readLine(is, 0, charset);
                if (line.startsWith("Content-Length")) {
                    // 拿到響應體內容長度
                    contentLength = Integer.parseInt(line.split(":")[1].trim());
                }
                // 如果遇到了一個單獨的回車換行，則表示請求頭結束
            } while (!line.equals("\r\n"));
            // 讀取出響應體數據（就是你要的數據）
            result = readLine(is, contentLength, charset);
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (osw != null) {
                try {
                    osw.close();
                } catch (IOException e) {
                    osw = null;
                    throw new RuntimeException(e);
                } finally {
                    if (socket != null) {
                        try {
                            socket.close();
                        } catch (IOException e) {
                            socket = null;
                            throw new RuntimeException(e);
                        }
                    }
                }
            }
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    is = null;
                    throw new RuntimeException(e);
                } finally {
                    if (socket != null) {
                        try {
                            socket.close();
                        } catch (IOException e) {
                            socket = null;
                            throw new RuntimeException(e);
                        }
                    }
                }
            }
        }
        return result;
    }

    /**
     * @Description:使用socket發送get請求
     * @author:liuyc
     * @time:2016年5月18日 上午9:27:18
     */
    public static String sendSocketGet(String urlParam, Map<String, Object> params, String charset) {
        String result = "";
        // 構建請求參數
        StringBuffer sbParams = new StringBuffer();
        if (params != null && params.size() > 0) {
            for (Entry<String, Object> entry : params.entrySet()) {
                sbParams.append(entry.getKey());
                sbParams.append("=");
                sbParams.append(entry.getValue());
                sbParams.append("&");
            }
        }
        Socket socket = null;
        OutputStreamWriter osw = null;
        InputStream is = null;
        try {
            URL url = new URL(urlParam);
            String host = url.getHost();
            int port = url.getPort();
            if (-1 == port) {
                port = 80;
            }
            String path = url.getPath();
            socket = new Socket(host, port);
            StringBuffer sb = new StringBuffer();
            sb.append("GET " + path + " HTTP/1.1\r\n");
            sb.append("Host: " + host + "\r\n");
            sb.append("Connection: Keep-Alive\r\n");
            sb.append("Content-Type: application/x-www-form-urlencoded; charset=utf-8 \r\n");
            sb.append("Content-Length: ").append(sb.toString().getBytes().length).append("\r\n");
            // 這裏一個回車換行，表示消息頭寫完，不然服務器會繼續等待
            sb.append("\r\n");
            if (sbParams != null && sbParams.length() > 0) {
                sb.append(sbParams.substring(0, sbParams.length() - 1));
            }
            osw = new OutputStreamWriter(socket.getOutputStream());
            osw.write(sb.toString());
            osw.flush();
            is = socket.getInputStream();
            String line = null;
            // 服務器響應體數據長度
            int contentLength = 0;
            // 讀取http響應頭部信息
            do {
                line = readLine(is, 0, charset);
                if (line.startsWith("Content-Length")) {
                    // 拿到響應體內容長度
                    contentLength = Integer.parseInt(line.split(":")[1].trim());
                }
                // 如果遇到了一個單獨的回車換行，則表示請求頭結束
            } while (!line.equals("\r\n"));
            // 讀取出響應體數據（就是你要的數據）
            result = readLine(is, contentLength, charset);
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            if (osw != null) {
                try {
                    osw.close();
                } catch (IOException e) {
                    osw = null;
                    throw new RuntimeException(e);
                } finally {
                    if (socket != null) {
                        try {
                            socket.close();
                        } catch (IOException e) {
                            socket = null;
                            throw new RuntimeException(e);
                        }
                    }
                }
            }
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    is = null;
                    throw new RuntimeException(e);
                } finally {
                    if (socket != null) {
                        try {
                            socket.close();
                        } catch (IOException e) {
                            socket = null;
                            throw new RuntimeException(e);
                        }
                    }
                }
            }
        }
        return result;
    }

    /**
     * @Description:讀取一行數據，contentLe內容長度爲0時，讀取響應頭信息，不爲0時讀正文
     * @time:2016年5月17日 下午6:11:07
     */
    private static String readLine(InputStream is, int contentLength, String charset) throws IOException {
        List<Byte> lineByte = new ArrayList<Byte>();
        byte tempByte;
        int cumsum = 0;
        if (contentLength != 0) {
            do {
                tempByte = (byte) is.read();
                lineByte.add(Byte.valueOf(tempByte));
                cumsum++;
            } while (cumsum < contentLength);// cumsum等於contentLength表示已讀完
        } else {
            do {
                tempByte = (byte) is.read();
                lineByte.add(Byte.valueOf(tempByte));
            } while (tempByte != 10);// 換行符的ascii碼值爲10
        }

        byte[] resutlBytes = new byte[lineByte.size()];
        for (int i = 0; i < lineByte.size(); i++) {
            resutlBytes[i] = (lineByte.get(i)).byteValue();
        }
        return new String(resutlBytes, charset);
    }

}

以上4種分別可發送get和post請求的方法，

第1種：HttpURLConnection、

第2種：URLConnection、

第3種：HttpClient、

第4種：Socket，

朋友們要注意的是，使用第3種HttpClient時需要依賴於三個jar包，分別是：apache-httpcomponents-httpclient.jar、commons-logging-1.0.4.jar、httpcore-4.1.1.jar。