java后台訪问url连接——HttpClients

java后台訪问url，并传递数据——通过httpclient方式

须要的包，包可能多几个额外的，假设无用或者冲突删除就可以。httpclient是使用的是4.4.1的版本号：http://download.csdn.net/detail/myfmyfmyfmyf/8894191

1、无參数传递，以微信开发为例，后台訪问url连接获得所有的人员列表

	/**
	 * 获取所有人员列表
	 * @return
	 */
    public  JSONObject getAllEmployee(){
    	//获取微信号
    	String token=getTokenFromWx();
    	 String dep_root=ROOT_DEP;//跟部门树
		 try {
			 CloseableHttpClient httpclient = HttpClients.createDefault();
			 HttpPost httpPost= new HttpPost("https://qyapi.weixin.qq.com/cgi-bin/user/list?

access_token="+token+"&department_id="+dep_root+"&fetch_child="+FETCH_CHILD+"&status="+STATE);
			 // Create a custom response handler
			 ResponseHandler<JSONObject> responseHandler = new ResponseHandler<JSONObject>() {
				//成功调用连接后。对返回数据进行的操作
                public JSONObject handleResponse(
                        final HttpResponse response) throws ClientProtocolException, IOException {
                    int status = response.getStatusLine().getStatusCode();
                    if (status >= 200 && status < 300) {
                    	//获得调用成功后  返回的数据
                        HttpEntity entity = response.getEntity();
                        if(null!=entity){
                        	String result= EntityUtils.toString(entity);
                            //依据字符串生成JSON对象
                   		 	JSONObject resultObj = JSONObject.fromObject(result);
                   		 	return resultObj;
                        }else{
                        	return null;
                        }
                    } else {
                        throw new ClientProtocolException("Unexpected response status: " + status);
                    }
                }

            };
          //返回的json对象
            JSONObject responseBody = httpclient.execute(httpPost, responseHandler);
            //System.out.println(responseBody);
            return responseBody;
		 }catch (Exception e) {
			e.printStackTrace();
			return null;
		}
    }

2、有參数传递，以微信开发为例，后台訪问url主动发送消息（json数据），httpClient通过设置StringEntity对象传递

/**
  	 * 主动发送消息
  	 * @param mess
  	 * @return
  	 */
  	public  boolean sendReqMsg(ReqBaseMessage mess){
  		//消息json格式
  		String jsonContext=mess.toJsonStr();
  		//System.out.println(jsonContext);
  		//获得token
  		String token=getTokenFromWx();
		 boolean flag=false;
		 try {
			 CloseableHttpClient httpclient = HttpClients.createDefault();
			 HttpPost httpPost= new HttpPost("https://qyapi.weixin.qq.com/cgi-bin/message/send?

access_token="+token);
			 //发送json格式的数据
			 StringEntity myEntity = new StringEntity(jsonContext,
					   ContentType.create("text/plain", "UTF-8"));
			 //设置须要传递的数据
			 httpPost.setEntity(myEntity);
			 // Create a custom response handler
            ResponseHandler<JSONObject> responseHandler = new ResponseHandler<JSONObject>() {
            	//对訪问结果进行处理
                public JSONObject handleResponse(
                        final HttpResponse response) throws ClientProtocolException, IOException {
                    int status = response.getStatusLine().getStatusCode();
                    if (status >= 200 && status < 300) {
                        HttpEntity entity = response.getEntity();
                        if(null!=entity){
                        	String result= EntityUtils.toString(entity);
                            //依据字符串生成JSON对象
                   		 	JSONObject resultObj = JSONObject.fromObject(result);
                   		 	return resultObj;
                        }else{
                        	return null;
                        }
                    } else {
                        throw new ClientProtocolException("Unexpected response status: " + status);
                    }
                }

            };
          //返回的json对象
            JSONObject responseBody = httpclient.execute(httpPost, responseHandler);
            System.out.println(responseBody);
            int result= (Integer) responseBody.get("errcode");
            if(0==result){
            	flag=true;
            }else{
            	flag=false;
            }
			httpclient.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		 return flag;
	}

3、传递图片、文件等媒体信息，还是以微信开发为例

/**
     * 文件上传到微信server
     * @param fileType 文件类型 媒体文件类型，分别有图片（image）、语音（voice）、视频（video），普通文件(file)
     * @param filePath 文件路径
     * @return JSONObject
     * @throws Exception
     */
    public  JSONObject send(String fileType, String filePath) throws Exception {
        String result = null;
        File file = new File(filePath);
        if (!file.exists() || !file.isFile()) {
            throw new IOException("文件不存在");
        }
        String token=getTokenFromWx();
        /**
        * 第一部分
        */
        URL urlObj = new URL("https://qyapi.weixin.qq.com/cgi-bin/media/upload?access_token="+ token
        		+ "&type="+fileType+""); 

        HttpURLConnection con = (HttpURLConnection) urlObj.openConnection();
        con.setRequestMethod("POST"); // 以Post方式提交表单。默认get方式
        con.setDoInput(true);
        con.setDoOutput(true);
        con.setUseCaches(false); // post方式不能使用缓存
        // 设置请求头信息
        con.setRequestProperty("Connection", "Keep-Alive");
        con.setRequestProperty("Charset", "UTF-8");
        // 设置边界
        String BOUNDARY = "----------" + System.currentTimeMillis();
        con.setRequestProperty("Content-Type", "multipart/form-data; boundary="+ BOUNDARY);
        // 请求正文信息
        // 第一部分：
        StringBuilder sb = new StringBuilder();
        sb.append("--"); // 必须多两道线
        sb.append(BOUNDARY);
        sb.append("\r\n");
        sb.append("Content-Disposition: form-data;name=\"media\";filename=\""+ file.getName() + "\"\r\n");
        sb.append("Content-Type:application/octet-stream\r\n\r\n");
        byte[] head = sb.toString().getBytes("utf-8");
        // 获得输出流
        OutputStream out = new DataOutputStream(con.getOutputStream());
        // 输出表头
        out.write(head);
        // 文件正文部分
        // 把文件已流文件的方式 推入到url中
        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();
        // 结尾部分
        byte[] foot = ("\r\n--" + BOUNDARY + "--\r\n").getBytes("utf-8");// 定义最后数据分隔线
        out.write(foot);
        out.flush();
        out.close();
        StringBuffer buffer = new StringBuffer();
        BufferedReader reader = null;
        try {
        // 定义BufferedReader输入流来读取URL的响应
        reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String line = null;
        while ((line = reader.readLine()) != null) {
        //System.out.println(line);
        buffer.append(line);
        }
        if(result==null){
        result = buffer.toString();
        }
        } catch (IOException e) {
        System.out.println("发送POST请求出现异常！

" + e);
        e.printStackTrace();
        throw new IOException("数据读取异常");
        } finally {
        if(reader!=null){
        reader.close();
        }
        }
        JSONObject jsonObj =JSONObject.fromObject(result);
        return jsonObj;
    }