Android实现简洁的APP登录界面

<?xml version="1.0" encoding="utf-8"?><RelativeLayout          xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:background="#2197db"  > <ImageView    android:id="@+id/loginbutton"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_centerHorizontal="true"    android:layout_marginTop="40dp"    android:src="@drawable/login_pic"/>  <LinearLayout    android:id="@+id/input"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_below="@+id/loginbutton"    android:layout_marginLeft="28dp"    android:layout_marginRight="28dp"    android:background="#fff"    android:orientation="vertical"><LinearLayout    android:layout_width="fill_parent"    android:layout_height="44dp"    android:background="#fff"    android:gravity="center_vertical"    android:orientation="horizontal" > <EditText      android:id="@+id/userId"      android:layout_width="wrap_content"      android:layout_height="fill_parent"      android:layout_weight="1"      android:background="@null"      android:imeOptions="actionDone"      android:textSize="16sp"      android:ems="10"      android:hint="请输入用户名"      >  </EditText><Button      android:id="@+id/button_bar"      android:layout_width="20dp"      android:layout_height="20dp"      android:layout_marginRight="8dp"      android:layout_marginLeft="1dp"      android:background="@drawable/login_input_arrow"      /> </LinearLayout> <View      android:layout_width="fill_parent"      android:layout_height="1.0px"      android:layout_marginLeft="1.0px"      android:layout_marginRight="1.0px"      android:background="#ffc0c3c4" /><EditText      android:id="@+id/pass"      android:layout_width="fill_parent"      android:layout_height="44.0dip"      android:background="#00ffffff"      android:gravity="center_vertical"      android:inputType="textPassword"      android:maxLength="16"      android:maxLines="1"      android:textColor="#ff1d1d1d"      android:textColorHint="#ff666666"      android:textSize="16.0sp"      android:hint="请输入密码"      />  </LinearLayout> <Button   android:id="@+id/loginBtn"   android:layout_width="fill_parent"   android:layout_height="wrap_content"   android:layout_below="@+id/input"   android:layout_marginTop="10dp"   android:background="#3aadfd"   android:text="登  录"   android:textColor="#ffffff"   android:textSize="18dp"    android:layout_centerHorizontal="true"    android:layout_marginLeft="28dp"    android:layout_marginRight="28dp"/>  <TextView    android:text=""    android:layout_width="wrap_content"    android:layout_below="@+id/loginBtn"    android:layout_height="wrap_content"    android:layout_centerHorizontal="true"    android:id="@+id/promptText"    android:textColor="#ff0000"    android:layout_marginTop="10dp"    android:textSize="18sp"/></RelativeLayout>

public class LoginActivity extends Activity implements View.OnClickListener{    private static final String TAG = "login";      Button loginBtn = null;      EditText useridEt = null;      EditText passEt = null;      TextView promptText = null;     @Override    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_login);    loginBtn = (Button) findViewById(R.id.loginBtn);    loginBtn.setOnClickListener(this);    useridEt = (EditText) findViewById(R.id.userId);     passEt = (EditText) findViewById(R.id.pass);    promptText = (TextView) findViewById(R.id.promptText);    OkHttpClient okHttpClient = new OkHttpClient.Builder()        .connectTimeout(10000L, TimeUnit.MILLISECONDS)        .readTimeout(10000L, TimeUnit.MILLISECONDS)        .build();    OkHttpUtils.initClient(okHttpClient);  @Override  public void onClick(View v) {    String userid = useridEt.getText().toString().trim();    String pass = passEt.getText().toString().trim();    if(userid.equals("")){      promptText.setText(R.string.userIdError);      return ;    }    if(pass.equals("")){      promptText.setText(R.string.passError);      return ;    } WebConstant.digest = ("Basic " + new String(Base64.encode((userid + ':' + pass).getBytes(), Base64.DEFAULT))).replace("/n", "");      String url = WebConstant.REQUESTPATH+"/users/" + userid+"?getAll=true";      OkHttpUtils.get()          .url(url).addHeader("Authorization", WebConstant.digest).addHeader("Accept-Language","zh-CN")          .build().execute(new Callback()          {            @Override            public String parseNetworkResponse(Response response, int id) throws Exception {              String string = response.body().string();              JSONObject jsonObj = new JSONObject(string);              if(jsonObj.get("userName")!=null){                WebConstant.userId = (String)jsonObj.get("userId");                WebConstant.userName = (String)jsonObj.get("userName");                return (String) jsonObj.get("userName");              }              return null;            }            @Override            public void onError(Call call, Exception e, int id) {              WebConstant.digest = null;              promptText.setText(R.string.loginError);              Log.i(TAG,e.getMessage());              e.printStackTrace();            }            @Override            public void onResponse(Object response, int id) {              promptText.setText(R.string.loginSuccess+" "+response);              Intent intent = new Intent();              LoginActivity.this.setResult(WebConstant.RESULT_OK, intent);              LoginActivity.this.finish();            }          });  }}