我正在尝试登录.它的工作，但是如果没有互联网连接，我的应用程序会破坏

Question

这是我所做的登录活动，如果互联网连接正常可用，其中有一个问题问题

我使用JSON

public class LoginActivity extends Activity implements OnClickListener{
private EditText etUser,etPassword;
private ImageView bLogin,bCancel,bRegister;
private Spinner spPermission;
private static String[] PERMISSIONS = {"Admin","Donor","Accepter"};
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login_layout);
    etUser = (EditText)findViewById(R.id.etUserName);
    etPassword = (EditText)findViewById(R.id.etPassword);
    etUser.setText("");
    etPassword.setText("");
    spPermission = (Spinner)findViewById(R.id.spPermission);
    ArrayAdapter<String> permAdapter  = new ArrayAdapter<String>(LoginActivity.this,android.R.layout.simple_spinner_item,PERMISSIONS);
    permAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spPermission.setAdapter(permAdapter);
    bLogin = (ImageView)findViewById(R.id.imLogin);
    bCancel= (ImageView)findViewById(R.id.imCancel);
    bRegister = (ImageView)findViewById(R.id.imRegister);
    bLogin.setOnClickListener(this);
    bCancel.setOnClickListener(this);
    bRegister.setOnClickListener(this);
}
@Override
public void onClick(View view) {
    switch(view.getId())
    {
    case R.id.imLogin:
        String uName = etUser.getText().toString();
        String password = etPassword.getText().toString();
        String type  = spPermission.getSelectedItem().toString();
        String message = "POST";
        LoginTask task = new LoginTask(this);
        task.execute(message,uName,password,type);
        break;
    case R.id.imCancel:
        finish();
        break;
    case R.id.imRegister:
        startActivity(new Intent(getApplicationContext(), Registration.class));
        break;
    default:
        break;
    }
}
public class LoginTask extends AsyncTask<String, Void, String>{
    private Context context;
    private JSONParser jsonParser = new JSONParser();
    private JSONObject json;
    private String login_url = //"http://192.168.1.3/login.php";
            "http://10.0.2.2/login.php";
    private String s;
    private String USER_TYPE;
    public LoginTask(Context c)
    {
        context  = c;
    }
    @Override
    protected String doInBackground(String... params) 
    {
        String message = params[0];
        if(message.equals("POST"))
        {
             List<NameValuePair> list = new ArrayList<NameValuePair>();
             final String uName = params[1];
             final String uPass = params[2];
             final String uType = params[3];
             USER_TYPE = uType;
             list.add(new BasicNameValuePair("username", uName));
             list.add(new BasicNameValuePair("password",uPass));
             list.add(new BasicNameValuePair("type", uType));
             json = jsonParser.makeHttpRequest(login_url, params[0], list);
        }
        try 
        {
            s = json.getString("message");
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return s;
    }
    @Override
    protected void onPostExecute(String result)
    {
        try {
            int success = json.getInt("success");
            if(success==1)
            {
                Toast.makeText(context, result, Toast.LENGTH_LONG).show();
                Intent i = new Intent(context.getApplicationContext(),MainView.class);
                i.putExtra("type", USER_TYPE);
                context.startActivity(i);
            }
            else
                //Toast.makeText(context, result, Toast.LENGTH_LONG).show();
                Toast.makeText(context, "Sorry No connection", Toast.LENGTH_LONG).show();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
}

Answer 1

更改youur doInBackground(）方法为：

@Override
protected String doInBackground(String... params) {
    String message = params[0];
    if (message.equals("POST")) {
        try {
            List<NameValuePair> list = new ArrayList<NameValuePair>();
            final String uName = params[1];
            final String uPass = params[2];
            final String uType = params[3];
            USER_TYPE = uType;
            list.add(new BasicNameValuePair("username", uName));
            list.add(new BasicNameValuePair("password", uPass));
            list.add(new BasicNameValuePair("type", uType));
            json = jsonParser.makeHttpRequest(login_url, params[0], list);
        }
        s = json.getString("message");
    }catch(Exception ex){
        ex.printStackTrace();
    }catch(JSONException e){
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return s;
}
}

Answer 2

在调用asyntask查看您的Internet连接如下

之前

将其放在某些常数类

中

 public static boolean isConnectingToInternet(){
    ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivity != null)
    {
        NetworkInfo[] info = connectivity.getAllNetworkInfo();
        if (info != null)
            for (int i = 0; i < info.length; i++)
                if (info[i].getState() == NetworkInfo.State.CONNECTED)
                {
                    return true;
                }
    }
    return false;
}

且调用Asyntask检查连接以下

 if(Constants.isConnectingToInternet()) {LoginTask task = new LoginTask(this);
    task.execute(message,uName,password,type);}

它肯定会起作用。

Answer 3

您的班级就像

 public class LoginActivity extends Activity implements OnClickListener{
    private EditText etUser,etPassword;
    private ImageView bLogin,bCancel,bRegister;
    private Spinner spPermission;
    private static String[] PERMISSIONS = {"Admin","Donor","Accepter"};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login_layout);
    Constants.context=this;
        etUser = (EditText)findViewById(R.id.etUserName);
        etPassword = (EditText)findViewById(R.id.etPassword);
        etUser.setText("");
        etPassword.setText("");
        spPermission = (Spinner)findViewById(R.id.spPermission);
        ArrayAdapter<String> permAdapter  = new ArrayAdapter<String>(LoginActivity.this,android.R.layout.simple_spinner_item,PERMISSIONS);
        permAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spPermission.setAdapter(permAdapter);
        bLogin = (ImageView)findViewById(R.id.imLogin);
        bCancel= (ImageView)findViewById(R.id.imCancel);
        bRegister = (ImageView)findViewById(R.id.imRegister);
        bLogin.setOnClickListener(this);
        bCancel.setOnClickListener(this);
        bRegister.setOnClickListener(this);
    }
    @Override
    public void onClick(View view) {
        switch(view.getId())
        {
        case R.id.imLogin:
            String uName = etUser.getText().toString();
            String password = etPassword.getText().toString();
            String type  = spPermission.getSelectedItem().toString();
            String message = "POST";
     if(Constants.isConnectingToInternet()) {LoginTask task = new LoginTask(this);
task.execute(message,uName,password,type);}

            break;
        case R.id.imCancel:
            finish();
            break;
        case R.id.imRegister:
            startActivity(new Intent(getApplicationContext(), Registration.class));
            break;
        default:
            break;
        }
    }
    public class LoginTask extends AsyncTask<String, Void, String>{
        private Context context;
        private JSONParser jsonParser = new JSONParser();
        private JSONObject json;
        private String login_url = //"http://192.168.1.3/login.php";
                "http://10.0.2.2/login.php";
        private String s;
        private String USER_TYPE;
        public LoginTask(Context c)
        {
            context  = c;
        }
        @Override
        protected String doInBackground(String... params) 
        {
            String message = params[0];
            if(message.equals("POST"))
            {
                 List<NameValuePair> list = new ArrayList<NameValuePair>();
                 final String uName = params[1];
                 final String uPass = params[2];
                 final String uType = params[3];
                 USER_TYPE = uType;
                 list.add(new BasicNameValuePair("username", uName));
                 list.add(new BasicNameValuePair("password",uPass));
                 list.add(new BasicNameValuePair("type", uType));
                 json = jsonParser.makeHttpRequest(login_url, params[0], list);
            }
            try 
            {
                s = json.getString("message");
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return s;
        }
        @Override
        protected void onPostExecute(String result)
        {
            try {
                int success = json.getInt("success");
                if(success==1)
                {
                    Toast.makeText(context, result, Toast.LENGTH_LONG).show();
                    Intent i = new Intent(context.getApplicationContext(),MainView.class);
                    i.putExtra("type", USER_TYPE);
                    context.startActivity(i);
                }
                else
                    //Toast.makeText(context, result, Toast.LENGTH_LONG).show();
                    Toast.makeText(context, "Sorry No connection", Toast.LENGTH_LONG).show();
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
    }

，您的常数课程为

public class Constants {
    public static final Context context=null;
    public static boolean isConnectingToInternet(){
        ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connectivity != null)
        {
            NetworkInfo[] info = connectivity.getAllNetworkInfo();
            if (info != null)
                for (int i = 0; i < info.length; i++)
                    if (info[i].getState() == NetworkInfo.State.CONNECTED)
                    {
                        return true;
                    }
        }
        return false;
    }
}