使用Android从服务器获取数据并加载新屏幕

Question

我正在使用以下代码从服务器获取数据，如果来自服务器的值为，GEEK则它将加载至下一个类，但不会加载新视图。你能说出什么问题吗？

    公共无效onCreate（捆绑保存的InstanceState）{
        super.onCreate（savedInstanceState）;
        setContentView（R.layout.main）;

        登录=（按钮）findViewById（R.id.login）;
        用户名=（EditText）findViewById（R.id.username）;
        密码=（EditText）findViewById（R.id.password）;

        login.setOnClickListener（new OnClickListener（）{

            @Override
            public void onClick（View v）{
字符串Re;
                字符串mUsername = username.getText（）。toString（）;
                字符串mPassword = password.getText（）。toString（）;

                Re = tryLogin（mUsername，mPassword）;

                if（Re ==“ GEEK”）
                {
                    意图i = new Intent（）;
                    i.setClassName（v.getContext（），“ com.httplogin.MainScreen”）;
                    startActivity（i）;

                }
            }
        }）;
    }

    受保护的String tryLogin（String mUsername，String mPassword）
    {           
        HttpURLConnection连接；
       OutputStreamWriter request = null;

            URL url = null;   
            字符串响应= null;         
            字符串参数=“ username =” + mUsername +“＆password =” + mPassword;   

            尝试
            {
                url =新的URL（“ http：//serverspace/script.php”）;
                连接=（HttpURLConnection）url.openConnection（）;
                connection.setDoOutput（true）;
                connection.setRequestProperty（“ Content-Type”，“ application / x-www-form-urlencoded”）;
                connection.setRequestMethod（“ POST”）;    

                request = new OutputStreamWriter（connection.getOutputStream（））;
                request.write（参数）;
                request.flush（）;
                request.close（）;            
                字符串行=“”;               
                InputStreamReader isr =新的InputStreamReader（connection.getInputStream（））;
                BufferedReader reader =新的BufferedReader（isr）;
                StringBuilder sb = new StringBuilder（）;
                while（（line = reader.readLine（））！= null）
                {
                    sb.append（line +“ \ n”）;
                }
                //登录过程后服务器的响应将存储在响应变量中。                
                响应= sb.toString（）;

                isr.close（）;
                reader.close（）;


            }
            catch（IOException e）
            {
                Toast.makeText（this，e.toString（），0）.show（）;
            }
            返回响应；
    }
}

Answer 1

请参阅此代码。..............，使用修整功能，因为它消除了字符串中的空格。

public class HttpLogin extends Activity {
    /** Called when the activity is first created. */
    private Button login;
    private EditText username, password;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        login = (Button) findViewById(R.id.login);
        username = (EditText) findViewById(R.id.username);
        password = (EditText) findViewById(R.id.password);

        login.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
             String Re;
                String   mUsername = username.getText().toString();
                String  mPassword = password.getText().toString();

                Re=tryLogin(mUsername, mPassword);
                Log.d(" Check ","Here");
                Log.d("Re",Re);
                String temp_check=Re.trim();
                if(temp_check.equals("GEEK"))
                {
                    Intent i = new Intent();
                    i.setClassName(v.getContext(),"com.httplogin.MainScreen");
                    startActivity(i);

                }
                else
                {
                 //Toast.makeText(HttpLogin.this,"MAX Returned",0).show();
                 displayAlert(Re);
//                  Intent i = new Intent();
//                     i.setClassName(v.getContext(),"com.san.MainScreen");
//                     startActivity(i);
                }
            }
        });
    }

    protected String tryLogin(String mUsername, String mPassword)
    {           
      Log.d(" TryLoginCheck ","Here");
        HttpURLConnection connection;
       OutputStreamWriter request = null;

            URL url = null;   
            String response = null;   
            String temp=null;
            String parameters = "username="+mUsername+"&password="+mPassword;   
            System.out.println("UserName"+mUsername+"\n"+"password"+mPassword);
            Log.d("Parameters",parameters);
            try
            {

                url = new URL("http://serverspace/script.php");
                connection = (HttpURLConnection) url.openConnection();
                connection.setDoOutput(true);
                connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
                connection.setRequestMethod("POST");    

                request = new OutputStreamWriter(connection.getOutputStream());
                request.write(parameters);
                request.flush();
                request.close();            
                String line = "";               
                InputStreamReader isr = new InputStreamReader(connection.getInputStream());
                BufferedReader reader = new BufferedReader(isr);
                StringBuilder sb = new StringBuilder();
                while ((line = reader.readLine()) != null)
                {

                    sb.append(line + "\n");
                }
                temp=sb.toString();
                Log.d("Temp",temp);
                // Response from server after login process will be stored in response variable.                
                response = sb.toString();
                Log.d("Response",response);
               Log.d("Sb Value",sb.toString());
                isr.close();
                reader.close();


            }
            catch(IOException e)
            {
                Toast.makeText(this,e.toString(),0).show();
            }
           // Log.d("Response",response);
            return response;
    }
    public  void displayAlert(String Re)
    {
     new AlertDialog.Builder(this).setMessage(Re)
        .setTitle("Returned Value")  
        .setCancelable(true)  
        .setNeutralButton(android.R.string.ok, new DialogInterface.OnClickListener() {  
           public void onClick(DialogInterface dialog, int whichButton){
            finish();
           }  
           })  
        .show(); 
    }
}