使用HttpURLConnection发送GE,POST请求

package com.conn.http;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import javax.activation.MimetypesFileTypeMap;
 
public class HttpUtil {
    
    /**
     * 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
            URLConnection connection = 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()));
            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
            URLConnection conn = 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()));
            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;
    }
    
    /**
     * @param url 访问地址
     *  @param param 需要传输参数参数；对象可以通过json转换成String
     * @param header header 参数；可以通过下面工具类将string类型转换成map
     * @return 返回网页返回的数据
     */
    public static String sendPost(String url, String param, Map<String, String> header) throws UnsupportedEncodingException, IOException {
            OutputStreamWriter out;
            BufferedReader in = null;
            String result = "";
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection();
            //设置超时时间
            conn.setConnectTimeout(5000);
            conn.setReadTimeout(15000);
            // 设置通用的请求属性
            if (header!=null) {
                for (Entry<String, String> entry : header.entrySet()) {
                    conn.setRequestProperty(entry.getKey(), entry.getValue());
                }
            }
            conn.setRequestMethod("POST");
            conn.addRequestProperty("Content-Type", "application/json");
            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 OutputStreamWriter( conn.getOutputStream(),"UTF-8");// utf-8编码
            // 发送请求参数
            out.write(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(), "utf8"));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
            if(out!=null){
                out.close();
            }
            if(in!=null){
                in.close();
            }
            return result;
        }

    
    

    /**
     * 上传图片
     * @param urlStr
     * @param textMap
     * @param fileMap
     * @param contentType 没有传入文件类型默认采用application/octet-stream
     * contentType非空采用filename匹配默认的图片类型
     * @return 返回response数据
     */
    @SuppressWarnings("rawtypes")
    public static String formUpload(String urlStr, Map<String, String> textMap,
            Map<String, String> fileMap,String contentType) {
        String res = "";
        HttpURLConnection conn = null;
        // boundary就是request头和上传文件内容的分隔符
        String BOUNDARY = "---------------------------1234567890110"; 
        try {
            URL url = new URL(urlStr);
            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 iter = textMap.entrySet().iterator();
                while (iter.hasNext()) {
                    Map.Entry entry = (Map.Entry) iter.next();
                    String inputName = (String) entry.getKey();
                    String inputValue = (String) entry.getValue();
                    if (inputValue == null) {
                        continue;
                    }
                    strBuf.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());
            }
            // file
            if (fileMap != null) {
                Iterator iter = fileMap.entrySet().iterator();
                while (iter.hasNext()) {
                    Map.Entry entry = (Map.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();
                    
                    if (contentType == null || "".equals(contentType)) {
                        contentType = "application/octet-stream";
                    }
                    StringBuffer strBuf = new StringBuffer();
                    strBuf.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());
                    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) {
            System.out.println("发送POST请求出错。" + urlStr);
            e.printStackTrace();
        } finally {
            if (conn != null) {
                conn.disconnect();
                conn = null;
            }
        }
        return res;
    }
    public static void main(String[] args) throws Throwable, IOException {
    
        String req = "{\"principal\":\"\",\"password\":\"1\",\"principalType\":\"UserID\",\"hostName\":\"\",\"appName\":\"\",\"rememberMe\":false}";
        
        String result = sendPost("http://xxx/logon?_=1630813394270", req, null);
        
        System.out.println(result);
        
        
        
        
    }
}