05_登陆案例基本逻辑实现

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package com.itheima.logindemo;

import android.os.Bundle;
import android.app.Activity;
import android.content.DialogInterface;
import android.text.TextUtils;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    private EditText et_pwd;
    private CheckBox cb_isSave;
    private Button btn_login;
    private EditText et_username;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //加载界面
        setContentView(R.layout.activity_main);
        et_username = (EditText) findViewById(R.id.et_username);
        
        et_pwd = (EditText) findViewById(R.id.et_password);
        cb_isSave = (CheckBox) findViewById(R.id.cb_isSave);
        btn_login = (Button) findViewById(R.id.btn_login);
        
        //设置点击事件
        btn_login.setOnClickListener(new MyListener());
    }
private class MyListener implements OnClickListener{

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        //当按钮被点击就会走这个方法
        //①获取用户输入
        String pwd = et_pwd.getText().toString().trim();
        String username = et_username.getText().toString().trim();
        //②判断输入是否为空
        if(TextUtils.isEmpty(username)||TextUtils.isEmpty(pwd)){
            //2.1如果为空Toast提示用户 不能为空
            Toast.makeText(MainActivity.this, "用户名密码不能为空", Toast.LENGTH_SHORT).show();//上下文是MainActivity
        }else{
            //2.2如果不为空 判断是否保存密码
            //③通过checkbox的状态 判断是否保存
            boolean checked = cb_isSave.isChecked();
            if(checked){
                //勾选上了 保存用户名密码
                Log.d("MainActivity", "保存用户名:"+username+"密码:"+pwd);
            }
            //④执行登录的业务逻辑
            Log.d("MainActivity", "开始登录....");
        }


    }
    
}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <EditText android:id="@+id/et_username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="请输入用户名"/>
     <EditText 
         android:id="@+id/et_password"
         android:layout_below="@id/et_username"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:inputType="textPassword"
         android:hint="请输入密码"/>
     <CheckBox
         android:id="@+id/cb_isSave"
         android:layout_below="@id/et_password"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="勾选保存信息"/>
     <Button
         android:id="@+id/btn_login"
         android:layout_below="@id/cb_isSave"
         android:layout_alignParentRight="true"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="登陆"
         />
</RelativeLayout>