登录界面

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_height="match_parent"
    android:layout_width="match_parent">

    <TextView
        android:id="@+id/edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="用户登录界面"
        android:textAlignment="center"
        android:textSize="24sp" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="用户名"
        android:textAlignment="center"
        android:textSize="24sp" />

    <EditText
        android:id="@+id/username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入您的用户名"/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="密码"
        android:textAlignment="center"
        android:textSize="24sp" />

    <EditText
        android:id="@+id/password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入您的密码"/>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_height="match_parent"
    android:layout_width="match_parent">

    <Button
        android:id="@+id/login"
        android:layout_height="60dp"
        android:layout_width="wrap_content"
        android:text="登录"
        android:layout_gravity="center"
        android:textAlignment="center"
        android:textSize="18sp" />

</LinearLayout>

</LinearLayout>

　　

package com.example.dl;

import android.os.Bundle;
import android.app.Activity;
import android.text.method.KeyListener;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public abstract class MainActivity extends Activity implements KeyListener {
	    Button button;
	    EditText username;
	    EditText password;

	    @Override
	    protected void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
	        setContentView(R.layout.activity_main);

	        button = (Button)findViewById(R.id.action_settings);
	        username = (EditText)findViewById(R.id.action_settings);
	        password = (EditText)findViewById(R.id.action_settings);
	        button.setKeyListener(this);
	    }

	    public void onClick(View v) {
	        String username1 = username.getText().toString();
	        String password1 = password.getText().toString();
	        String ok = "登录成功";
	        String fail = "登录失败";
	        if (username1.equals("lhk") && password1.equals("123456")) {
	            Toast.makeText(MainActivity.this,ok,Toast.LENGTH_SHORT).show();
	        }else {
	            Toast.makeText(MainActivity.this,fail,Toast.LENGTH_SHORT).show();
	        }
	    }

	protected void onCreate1(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}