java - Python/Flask 服务器端 - Java/HttpURLConnection 客户端 - REST 实现

Question

我目前正在从补充该服务的桌面应用程序中为我的 Web 应用程序实现一个 REST 接口(interface)。我们使用 Python 和 Flask 来实现 REST 服务器。

我们有这样一种情况，Java 客户端将请求一个 POST，而 python 服务器端将处理该 post，直到它需要连接到 MySQL 数据库。

这是 python/flask 代码:

@app.route("/update_project/<project_data>", methods=['GET','POST'])
def updateWPProject(project_data):
    """project_data = user+++++pw+++++pj_jsondoc.
    This will update an existing project data or insert a non-existant project data item."""
    usrpw = project_data.split("+++++")
    dblogin = wplogin(usr=usrpw[0], pw=usrpw[1])
    if dblogin[0] == 'SUCCESS':
        db_name = dblogin[1][0].strip()
        db_user = dblogin[1][1].strip()
        db_pw = dblogin[1][2].strip()
        if flask.request.method == 'POST':
            fname = flask.request.form['fName']
            if fname:
                pj = Project()
                try:
                    pj = json.loads(fname)
                except TypeError:
                    sys.stdout.write("JSON conversion error...%s" % sys.exc_info()[0])
                except AttributeError:
                    sys.stdout.write("JSON conversion error...%s" % sys.exc_info()[0])

                updateProject(db_name,db_user,db_pw,pj)
                #return redirect(url_for('/'))
    else:
        return 'Login failure.'
    pass

在到达“updateProject(db_name,db_user,db_pw,pj)”行之前，一切正常。然后它将转到该函数，并在“cursor=conn.cursor()”处返回 500，但没有完成该函数。

    def updateProject(dbname, dbuser, dbpw, pj):
        """Updates or inserts a project record is not exists. PJ passed as an argument is a Project object."""

        try:
            conn = getConnection(dbuser, dbpw, dbname)
            cursor = conn.cursor()
        except:
            sys.stdout.write("MySQL connection error...%s" % sys.exc_info()[0])

        sql_stmt = """INSERT INTO projects( projNo, projName, worksteplabel, workstep1label, workstep2label, workstep3label, resultlabel, result1label, result2label, result3label, projectowner, dbname, dblogin, dbpw, role, preference1, preference2, preference3 )
VALUES (
'projNo', 'projName', 'wslabel', 'wslabel', 'wslabel', 'wslabel', 'rlabel', 'rlabel', 'rlabel', 'rlabel', 'pjowner', 'dbname', 'dblogin', 'dbpw', 'role', 'pref1', 'pref2', 'pref3'
) ON DUPLICATE
KEY UPDATE projName = 'projName',
worksteplabel = 'wslabel',
workstep1label = 'wslabel',
workstep2label = 'wslabel',
workstep3label = 'wslabel',
resultlabel = 'rlabel',
result1label = 'rlabel',
result2label = 'rlabel',
result3label = 'rlabel',
projectowner = 'pjowner',
dbname = 'dbname',
dblogin = 'dblogin',
dbpw = 'dbpw',
role = 'role',
preference1 = 'pref1',
preference2 = 'pref2',
preference3 = 'pref3' )

        try:
            cursor.execute(sql_stmt)
            return 'SUCCESS'
        except MySQLdb.Error:
            sys.stdout.write("MySQLdb error...%s" % sys.exc_info()[0])
            return 'FAILURE'

在 Java 客户端，我使用以下代码从客户端发送 POST 请求和数据。

public void DB_NewProjectREST(ProjectData proj, WPUser usr) {
        // public static String excutePost(String targetURL, String urlParameters)
        //URL url;
        HttpURLConnection connection = null;  

        ///First, all the GSON/JSon stuff up front
        Gson gson = new Gson();
        //convert java object to JSON format
        String json = gson.toJson(proj);
      //Then credentials and send string
        String send_string = usr.getUserEmail()+"+++++"+usr.getUserHash();

        try {
          //Create connection
          URL url = new URL("http://127.0.0.1:5000/update_project/"+send_string);
          String urlParameters = "fName=" + URLEncoder.encode(json, "UTF-8");

          connection = (HttpURLConnection)url.openConnection();
          connection.setRequestMethod("POST");
          connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

          connection.setRequestProperty("Content-Length", "" + Integer.toString(urlParameters.getBytes().length));
          connection.setRequestProperty("Content-Language", "en-US");  

          connection.setUseCaches(false);
          connection.setDoInput(true);
          connection.setDoOutput(true);

          //Send request
          DataOutputStream wr = new DataOutputStream (connection.getOutputStream ());
          wr.writeBytes (urlParameters);
          wr.flush ();
          wr.close ();

          //Get Response    
          InputStream is = connection.getInputStream();
          BufferedReader rd = new BufferedReader(new InputStreamReader(is));
          String line;
          StringBuffer response = new StringBuffer(); 
          while((line = rd.readLine()) != null) {
            response.append(line);
            response.append('\r');
          }
          rd.close();
        } catch (Exception e) {
            e.printStackTrace();
            //return null;
        }finally {
            if(connection != null) {
                connection.disconnect(); 
            }
        }
    }

似乎我必须将某种响应(针对输入流)发送回客户端，这就是我的 python 代码突然返回的地方。(？)数据从 java 客户端获取到 python/flask 代码，所以有什么方法可以快速返回“确定”并继续处理数据库更新。或者，python updateProject 函数中的游标连接调用是否以某种方式干扰了 http 连接？

感谢任何帮助。

Answer 1

这是在 python 服务器端运行的代码，但不确定它是否是“正确”的方式....

@app.route("/update_project/<project_data>", methods=['GET','POST'])
def updateWPProject(project_data):
    """project_data = user+++++pw+++++pj_jsondoc.
    This will update an existing project data or insert a non-existant project data item."""
    usrpw = project_data.split("+++++")
    dblogin = wplogin(usr=usrpw[0], pw=usrpw[1])
    if dblogin[0] == 'SUCCESS':
        db_name = dblogin[1][0].strip()
        db_user = dblogin[1][1].strip()
        db_pw = dblogin[1][2].strip()
        if flask.request.method == 'POST':
            fname = flask.request.form['fName']
            if fname:
                pj = Project()
                try:
                    pj = json.loads(fname)
                    try:
                        #threading.Thread(target=updateProject, args=(db_name,db_user,db_pw,pj)).start()
                        return Response(updateProject(db_name,db_user,db_pw,pj), direct_passthrough=True)

                    except Exception, errtxt:
                        sys.stdout.write(errtxt)
                    #threading.thread.start_new_thread(updateProject,(db_name,db_user,db_pw,pj))
                except TypeError:
                    sys.stdout.write("JSON conversion error...%s" % sys.exc_info()[0])
                except AttributeError:
                    sys.stdout.write("JSON conversion error...%s" % sys.exc_info()[0])
    else:
        return 'Login failure.'
    pass

最值得注意的是，'return Response(......' 解决了这个挑战。我认为。