HttpURLConnection实现HttpClient工具类（get/post请求，文件上传）

一时失言乱红尘 2022-06-04 00:08 225阅读 0赞

本博客简单介绍一下HttpURLConnection实现的POST和GET请求以及文件上传，还有文件上传的服务器代码实现。

import java.io.BufferedReader;
    import java.io.DataOutputStream;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.OutputStream;
    import java.net.HttpURLConnection;
    import java.net.URL;
    import java.net.URLEncoder;
    import java.util.HashMap;
    import java.util.Map;
    
    import org.apache.http.client.HttpResponseException;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    public class HttpClient {
    	protected final static Logger logger = LoggerFactory.getLogger(HttpClient.class);
    
    	/**
    	  * Description:文件上传，以及可以传递参数，支持文件批量上传
    	  * 
    	  * @param actionUrl 请求地址
    	  * @param params  参数
    	  * @param files  多个文件
    	  * @return
    	  * @throws Exception
    	 */
    	public static Map<String, Object> post(String actionUrl, Map<String, String> params, Map<String, File> files)
    			throws Exception {
    		Map<String, Object> map = new HashMap<String, Object>();
    		logger.info("post file  url:" + actionUrl + "  params:" + params);
    		String BOUNDARY = java.util.UUID.randomUUID().toString();
    		String PREFIX = "--", LINEND = "\r\n";
    		String MULTIPART_FROM_DATA = "multipart/form-data";
    		String CHARSET = "UTF-8";
    
    		URL uri = new URL(actionUrl);
    		HttpURLConnection conn = (HttpURLConnection) uri.openConnection();
    		conn.setReadTimeout(10 * 1000); // cache max time
    		conn.setConnectTimeout(5*1000);
    		conn.setDoInput(true);// allow input
    		conn.setDoOutput(true);// allow output
    		conn.setUseCaches(false); // cache is disable
    		conn.setRequestMethod("POST");
    		conn.setRequestProperty("connection", "keep-alive");
    		conn.setRequestProperty("Charsert", "UTF-8");
    		conn.setRequestProperty("Content-Type", MULTIPART_FROM_DATA + ";boundary=" + BOUNDARY);
    		// construct params for Text
    		StringBuilder sb = new StringBuilder();
    		for (Map.Entry<String, String> entry : params.entrySet()) {
    			sb.append(PREFIX);
    			sb.append(BOUNDARY);
    			sb.append(LINEND);
    			sb.append("Content-Disposition: form-data; name=\"" + entry.getKey() + "\"" + LINEND);
    			sb.append("Content-Type: text/plain; charset=" + CHARSET + LINEND);
    			sb.append("Content-Transfer-Encoding: 8bit" + LINEND);
    			sb.append(LINEND);
    			sb.append(entry.getValue());
    			sb.append(LINEND);
    		}
    
    		DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());
    		outStream.write(sb.toString().getBytes("utf-8"));
    		// send data
    		if (files != null) {
    			for (Map.Entry<String, File> file : files.entrySet()) {
    				StringBuilder sb1 = new StringBuilder();
    				sb1.append(PREFIX);
    				sb1.append(BOUNDARY);
    				sb1.append(LINEND);
    				sb1.append("Content-Disposition: form-data; name=\"" + file.getKey() + "\"; filename=\""
    						+ file.getValue() + "\"" + LINEND);
    				sb1.append("Content-Type: application/octet-stream; charset=" + CHARSET + LINEND);
    				sb1.append(LINEND);
    				outStream.write(sb1.toString().getBytes());
    
    				InputStream is = new FileInputStream(file.getValue());
    				try {
    					byte[] buffer = new byte[(int) file.getValue().length()];
    					int len = 0;
    					while ((len = is.read(buffer)) != -1) {
    						outStream.write(buffer, 0, len);
    					}
    				} catch (Exception e) {
    					throw e;
    				} finally {
    					is.close();
    					outStream.write(LINEND.getBytes());
    				}
    
    			}
    		}
    
    		// the finsh flag
    		byte[] end_data = (PREFIX + BOUNDARY + PREFIX + LINEND).getBytes();
    		outStream.write(end_data);
    		outStream.flush();
    
    		// get response
    		int res = conn.getResponseCode();
    		map.put("status", res);
    		InputStream in = null;
    		String result = null;
    		switch (res) {
    		case 200:
    			in = conn.getInputStream();
    			int ch;
    			StringBuilder sb2 = new StringBuilder();
    			while ((ch = in.read()) != -1) {
    				sb2.append((char) ch);
    			}
    			result = sb2.toString();
    			map.put("returnString", result);
    			break;
    		case 403:
    			throw new HttpResponseException(res, "request forbided");
    		case 404:
    			throw new HttpResponseException(res, "not fonud such address");
    		default:
    			throw new Exception("undefine error:" + res);
    		}
    		conn.disconnect();
    		return map;
    	}
    
    	public static String post(String actionUrl, Map<String, String> params) throws Exception {
    		String contentType = "application/x-www-form-urlencoded";
    		URL uri = new URL(actionUrl);
    		HttpURLConnection conn = (HttpURLConnection) uri.openConnection();
    		conn.setReadTimeout(5 * 1000); // Cache max time
    		conn.setConnectTimeout(5*1000);
    		conn.setDoInput(true);// allow input
    		conn.setDoOutput(true);// Allow output
    		conn.setUseCaches(false); // cache is disable
    		conn.setRequestMethod("POST");
    		conn.setRequestProperty("connection", "keep-alive");
    		conn.setRequestProperty("Charsert", "UTF-8");
    		conn.setRequestProperty("Content-Type", contentType);
    		StringBuilder sb = new StringBuilder();
    
    		for (Map.Entry<String, String> entry : params.entrySet()) {
    			if (sb.length() > 0) {
    				sb.append("&");
    			}
    			sb.append(entry.getKey());
    			sb.append("=");
    			sb.append(URLEncoder.encode(entry.getValue()));
    		}
    		OutputStream output = conn.getOutputStream();
    		output.write(sb.toString().getBytes());
    		output.flush();
    
    		int res = conn.getResponseCode();
    		InputStream in = null;
    		String result = null;
    		switch (res) {
    			case 200:
    				in = conn.getInputStream();
    				String line;
    				StringBuilder sb2 = new StringBuilder();
    				BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in,"UTF-8")); 
    				while ((line = bufferedReader.readLine()) != null) {  
    					sb2.append(line);  
    	            }  
    				result = sb2.toString();
    				break;
    			case 403:
    				throw new HttpResponseException(res, "request forbided");
    			case 404:
    				throw new HttpResponseException(res, "not fonud such address");
    			default:
    				throw new Exception("undefine error:" + res);
    		}
    		return result;
    	}
    
    	public static String get(String actionUrl, Map<String, String> params) throws Exception {
    		String contentType = "application/x-www-form-urlencoded";
    
    		StringBuilder sb = new StringBuilder();
    		for (Map.Entry<String, String> entry : params.entrySet()) {
    			if (sb.length() > 0) {
    				sb.append("&");
    			}
    			sb.append(entry.getKey());
    			sb.append("=");
    			sb.append(URLEncoder.encode(entry.getValue()));
    		}
    		if (actionUrl.endsWith("?")) {
    			actionUrl += sb.toString();
    		} else {
    			actionUrl += "?" + sb.toString();
    		}
    		URL uri = new URL(actionUrl);
    		HttpURLConnection conn = (HttpURLConnection) uri.openConnection();
    		conn.setReadTimeout(5 * 1000); // Cache max time
    		conn.setDoInput(true);// allow input
    		conn.setDoOutput(true);// Allow output
    		conn.setUseCaches(false); // cache is disable
    		conn.setRequestMethod("GET");
    		conn.setRequestProperty("connection", "keep-alive");
    		conn.setRequestProperty("Charsert", "UTF-8");
    		conn.setRequestProperty("Content-Type", contentType);
    
    		int res = conn.getResponseCode();
    		// Log.i("le_assistant","actionUrl:" +actionUrl+"  ResponseCode:"+res);
    		InputStream in = null;
    		String result = null;
    		switch (res) {
    		case 200:
    			in = conn.getInputStream();
    			String line;
    			StringBuilder sb2 = new StringBuilder();
    			BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in,"UTF-8")); 
    			while ((line = bufferedReader.readLine()) != null) {  
    				sb2.append(line);  
                }
    			result = sb2.toString();
    			break;
    		case 403:
    			throw new HttpResponseException(res, "request forbided");
    		case 404:
    			throw new HttpResponseException(res, "not fonud such address");
    		default:
    			throw new Exception("undefine error:" + res);
    		}
    		return result;
    	}
    	
    	public static void main(String[] args) {
    		String url = "http://localhost:8990/file/Upload";
    		Map<String,String> params = new HashMap<String, String>();
    		Map<String, File> files = new HashMap<String, File>();
    		File file = new File("d:\\a.png");
    		files.put("file", file);
        	
    		try {
    			System.out.println(post(url, params,files));
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    	
    	
    }

文件上传的服务器代码实现(Java)：

@RestController
    @RequestMapping("/file")
    public class FileUploadController {
    
        /**
         * 图片上传
         * @param file
         * @return
         */
        @RequestMapping("/upload")
        @ResponseBody
        public Object fileUpload(@RequestParam(value = "file", required = false) MultipartFile file){
            JSONObject object = new JSONObject();
            try {
                if(file!=null){
                    //保存文件
                    String fileName = file.getOriginalFilename();
                    String fileExt = getExtention(fileName);
                    byte[] fileByte = file.getBytes();
                    //文件处理
                    
                }
            } catch (IOException e) {
            	e.printStackTrace();
            }
            return object;
        }
    
    }