HttpURLConnection 发送http请求帮助类

java 利用HttpURLConnection 发送http请求

提供GET / POST /上传文件/下载文件 功能

import java.io.*;
import java.net.*;
import java.util.Iterator;
import java.util.Map;

import net.sf.jmimemagic.Magic;
import net.sf.jmimemagic.MagicMatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Author:   Administrator
 */
public class HttpHelper {

    private final static Logger logger = LoggerFactory.getLogger(HttpHelper.class);

    /**
     * 发送get请求
     *
     * @param urlPath
     * @return
     */
    public static String get(String urlPath) {

        String res = "";
        HttpURLConnection conn = null;
        try {
            URL url = new URL(urlPath);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setConnectTimeout(5000);
            urlConnection.setReadTimeout(5000);
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();
            int code = urlConnection.getResponseCode();

            if (code == 200) {
                InputStream inputStream = urlConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                String line;
                StringBuffer buffer = new StringBuffer();
                while ((line = bufferedReader.readLine()) != null) {
                    buffer.append(line);

                }
                res = buffer.toString();

            }

        } catch (Exception e) {
            logger.error("发送get请求出错");
            e.printStackTrace();
        } finally {
            if (conn != null) {
                conn.disconnect();
                conn = null;
            }
        }

        return res;
    }

    /**
     * 发送post请求
     *
     * @param urlPath  http://host:port/test.jsp
     * @param postData name=abc&age=10
     * @throws Exception
     */
    public static String post(String urlPath, String postData) {

        HttpURLConnection conn = null;
        String res = "";

        try {
            //建立连接
            URL url = new URL(urlPath);

            conn = (HttpURLConnection) url.openConnection();
            //设置参数
            conn.setDoOutput(true);     //需要输出
            conn.setDoInput(true);      //需要输入
            conn.setUseCaches(false);   //不允许缓存
            conn.setRequestMethod("POST");      //设置POST方式连接

            //设置请求属性
            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            conn.setRequestProperty("Connection", "Keep-Alive");// 维持长连接
            conn.setRequestProperty("Charset", "UTF-8");

            //连接,也可以不用明文connect，使用下面的httpConn.getOutputStream()会自动connect
            conn.connect();

            //建立输入流，向指向的URL传入参数
            DataOutputStream dos = new DataOutputStream(conn.getOutputStream());
            dos.write(postData.getBytes("utf-8"));
            dos.flush();
            dos.close();

            //获得响应状态
            int resultCode = conn.getResponseCode();
            if (HttpURLConnection.HTTP_OK == resultCode) {
                StringBuffer sb = new StringBuffer();
                String readLine = new String();
                BufferedReader responseReader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
                while ((readLine = responseReader.readLine()) != null) {
                    sb.append(readLine).append("\n");
                }
                responseReader.close();
                res = sb.toString();
            }
        } catch (Exception e) {
            logger.error("发送POST请求出错。" + urlPath);
            e.printStackTrace();
        } finally {
            if (conn != null) {
                conn.disconnect();
                conn = null;
            }
        }

        return res;
    }

    /**
     * 发送post 数据为json
     *
     * @param urlPath
     * @param Json
     * @return
     * @throws Exception
     */
    public static String postJson(String urlPath, String Json) {

        HttpURLConnection conn = null;
        String res = "";

        try {
            //建立连接
            URL url = new URL(urlPath);
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setUseCaches(false);
            conn.setRequestProperty("Connection", "Keep-Alive");
            conn.setRequestProperty("Charset", "UTF-8");
            // 设置文件类型:
            conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
            // 设置接收类型否则返回415错误
            //conn.setRequestProperty("accept","*/*")此处为暴力方法设置接受所有类型，以此来防范返回415;
            conn.setRequestProperty("accept", "application/json");
            // 往服务器里面发送数据

            byte[] writebytes = Json.getBytes();
            // 设置文件长度
            conn.setRequestProperty("Content-Length", String.valueOf(writebytes.length));
            OutputStream outwritestream = conn.getOutputStream();
            outwritestream.write(Json.getBytes("utf-8"));
            outwritestream.flush();
            outwritestream.close();

            if (conn.getResponseCode() == 200) {
                StringBuffer sb = new StringBuffer();
                String readLine = new String();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
                while ((readLine = bufferedReader.readLine()) != null) {
                    sb.append(readLine).append("\n");
                }
                bufferedReader.close();
                res = sb.toString();
            }
        } catch (Exception e) {
            logger.error("发送POST请求出错。" + urlPath);
            e.printStackTrace();
        } finally {
            if (conn != null) {
                conn.disconnect();
                conn = null;
            }
        }

        return res;
    }

    /**
     * formupload方式提交数据
     *
     * @param urlPath
     * @param textMap 表单字段
     * @param fileMap 文件列表
     * @return
     */
    public static String formUpload(String urlPath, Map<String, String> textMap, Map<String, String> fileMap) {
        String res = "";
        HttpURLConnection conn = null;
        String BOUNDARY = "----lwm12345boundary"; //boundary就是request头和上传文件内容的分隔符
        try {
            URL url = new URL(urlPath);
            conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(5000);
            conn.setReadTimeout(30000);
            conn.setDoOutput(true);
            conn.setDoInput(true);
            conn.setUseCaches(false);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Connection", "Keep-Alive");
            conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");
            conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);

            OutputStream out = new DataOutputStream(conn.getOutputStream());
            // text
            if (textMap != null) {
                StringBuffer strBuf = new StringBuffer();
                Iterator<Map.Entry<String, String>> iter = textMap.entrySet().iterator();
                while (iter.hasNext()) {
                    Map.Entry<String, String> entry = iter.next();
                    String inputName = (String) entry.getKey();
                    String inputValue = (String) entry.getValue();
                    if (inputValue == null) {
                        continue;
                    }
                    strBuf.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
                    strBuf.append("Content-Disposition: form-data; name=\"" + inputName + "\"\r\n\r\n");
                    strBuf.append(inputValue);
                }
                out.write(strBuf.toString().getBytes("utf-8"));
            }

            // file
            if (fileMap != null) {
                Iterator<Map.Entry<String, String>> iter = fileMap.entrySet().iterator();
                while (iter.hasNext()) {
                    Map.Entry<String, String> entry = iter.next();
                    String inputName = (String) entry.getKey();
                    String inputValue = (String) entry.getValue();
                    if (inputValue == null) {
                        continue;
                    }
                    File file = new File(inputValue);
                    String filename = file.getName();
                    MagicMatch match = Magic.getMagicMatch(file, false, true);
                    String contentType = match.getMimeType();

                    StringBuffer strBuf = new StringBuffer();
                    strBuf.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
                    strBuf.append("Content-Disposition: form-data; name=\"" + inputName + "\"; filename=\"" + filename + "\"\r\n");
                    strBuf.append("Content-Type:" + contentType + "\r\n\r\n");

                    out.write(strBuf.toString().getBytes("utf-8"));

                    DataInputStream in = new DataInputStream(new FileInputStream(file));
                    int bytes = 0;
                    byte[] bufferOut = new byte[1024];
                    while ((bytes = in.read(bufferOut)) != -1) {
                        out.write(bufferOut, 0, bytes);
                    }
                    in.close();
                }
            }

            byte[] endData = ("\r\n--" + BOUNDARY + "--\r\n").getBytes();
            out.write(endData);
            out.flush();
            out.close();

            // 读取返回数据
            StringBuffer strBuf = new StringBuffer();
            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                strBuf.append(line).append("\n");
            }
            res = strBuf.toString();
            reader.close();
            reader = null;
        } catch (Exception e) {
            logger.error("发送POST请求出错。" + urlPath);
            e.printStackTrace();
        } finally {
            if (conn != null) {
                conn.disconnect();
                conn = null;
            }
        }
        return res;
    }

    /**
     * 发送下载文件请求
     *
     * @param urlPath
     * @param downloadDir
     * @return
     */
    public static File downloadFile(String urlPath, String downloadDir) {
        File file = null;
        try {
            // 统一资源
            URL url = new URL(urlPath);
            // 连接类的父类，抽象类
            URLConnection urlConnection = url.openConnection();
            // http的连接类
            HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
            // 设定请求的方法，默认是GET
            httpURLConnection.setRequestMethod("POST");
            // 设置字符编码
            httpURLConnection.setRequestProperty("Charset", "UTF-8");
            // 打开到此 URL 引用的资源的通信链接（如果尚未建立这样的连接）。
            httpURLConnection.connect();

            // 文件大小
            int fileLength = httpURLConnection.getContentLength();

            // 文件名
            String filePathUrl = httpURLConnection.getURL().getFile();
            String fileFullName = filePathUrl.substring(filePathUrl.lastIndexOf(File.separatorChar) + 1);

            System.out.println("file length---->" + fileLength);

            URLConnection con = url.openConnection();

            BufferedInputStream bin = new BufferedInputStream(httpURLConnection.getInputStream());

            String path = downloadDir + File.separatorChar + fileFullName;
            file = new File(path);
            if (!file.getParentFile().exists()) {
                file.getParentFile().mkdirs();
            }
            OutputStream out = new FileOutputStream(file);
            int size = 0;
            int len = 0;
            byte[] buf = new byte[1024];
            while ((size = bin.read(buf)) != -1) {
                len += size;
                out.write(buf, 0, size);
                // 打印下载百分比
                // System.out.println("下载了-------> " + len * 100 / fileLength +
                // "%\n");
            }
            bin.close();
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return file;
        }

    }
}