详解Android Studio实现用户登陆界面demo（xml实现）

<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingLeft="55px"
android:paddingRight="50px"
tools:context=".MainActivity" 
<TextView
android:id="@+id/message"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/activity_horizontal_margin"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginTop="@dimen/activity_vertical_margin"
android:text="Hello Word！"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" / 
<View
android:layout_width="match_parent"
android:layout_height="2px"
android:layout_marginTop="16px"
android:background="#000000" / 
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="28dp"
android:layout_gravity="center_horizontal"
android:layout_marginTop="20px"
android:text="登陆界面" / 
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
<EditText
android:id="@+id/et1"
android:layout_width="280dp"
android:layout_height="wrap_content"
android:layout_marginTop="30dp"
android:paddingLeft="10dp"
android:hint="请输入账号"
android:inputType="text"/ 
<ImageView
android:id="@+id/bt1"
android:layout_width="25dp"
android:layout_height="25dp"
android:layout_marginTop="37dp"
android:src="@drawable/delete" / 
</LinearLayout 
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingLeft="8px" 
<EditText
android:id="@+id/et2"
android:layout_width="280dp"
android:layout_height="wrap_content"
android:layout_marginTop="26dp"
android:hint="请输入密码"
android:inputType="textPassword" / 
<ImageView
android:id="@+id/bt2"
android:layout_width="25dp"
android:layout_height="25dp"
android:layout_marginTop="33dp"
android:src="@drawable/delete" / 
</LinearLayout 
<Button
android:id="@+id/btn_login"
android:layout_width="match_parent"
android:layout_height="48dp"
android:background="@color/bbutton_danger_disabled_edge"
android:layout_marginTop="30dp"
android:text="登 陆"
android:textSize="30dp"
android:textColor="@color/bbutton_danger"/ 
<Button
android:id="@+id/bbt1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="15dp"
android:layout_gravity="right"
android:layout_marginTop="20px"
android:background="@color/bbutton_danger"
android:text="Adapter" / 
</LinearLayout  

/**
* 用于实现点击叉叉时 , 清空输入框的内容
*/
class EditTextUtils {
public static void clearButtonListener(final EditText et, final View view) {
// 取得et中的文字
String etInputString = et.getText().toString();
// 根据et中是否有文字进行X可见或不可见的判断
if (TextUtils.isEmpty(etInputString)) {
view.setVisibility(View.INVISIBLE);
} else {
view.setVisibility(View.VISIBLE);
}
//点击X时使et中的内容为空
view.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
et.setText("");
et.requestFocusFromTouch();
}
});
//对et的输入状态进行监听
et.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void afterTextChanged(Editable s) {
if (s.length() == 0) {
view.setVisibility(View.INVISIBLE);
} else {
view.setVisibility(View.VISIBLE);
}
}
});
}
}

private TextView mTextMessage;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EditText et1 = (EditText) findViewById(R.id.et1);
EditText et2 = (EditText) findViewById(R.id.et2);
View bt = findViewById(R.id.bt1);
View iv = findViewById(R.id.bt2);
EditTextUtils.clearButtonListener(et1, bt);
EditTextUtils.clearButtonListener(et2, iv);
Button btn1 = (Button) findViewById(R.id.bbt1);
btn1.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
//Intent是一种运行时绑定（run-time binding）机制，它能在程序运行过程中连接两个不同的组件，在存放资源代码的文件夹下下，
Intent i = new Intent(MainActivity.this , Main2ActivityAdapterDemo.class);
//启动
startActivity(i);
}
});
mTextMessage = (TextView) findViewById(R.id.message);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}

<resources 
<!-- Default screen margins, per the Android Design guidelines. -- 
<dimen name="activity_horizontal_margin" 16dp</dimen 
<dimen name="activity_vertical_margin" 16dp</dimen 
<dimen name="text_size_16" 22dp</dimen 
<dimen name="space_8" 8</dimen 
<dimen name="space_16" 16</dimen 
<dimen name="fab_margin" 16dp</dimen 
</resources 

<?xml version="1.0" encoding="utf-8"? 
<resources 
<color name="colorPrimary" #008577</color 
<color name="colorPrimaryDark" #00574B</color 
<color name="colorAccent" #D81B60</color 
<color name="main_gray" #CCCCCC</color 
<color name="main_black" #000000</color 
<color name="bbutton_danger_disabled_edge" #00CC33</color 
<color name="bbutton_danger" #FFFFFF</color 
</resources