Android 消息对话框的应用

一种是发出提示信息的普通对话框，另一种是用用户登录对话框

设计用户布局

<?xml version="1.0" encoding="utf-8" ?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:gravity="center">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button1"
        android:text="打开普通对话框"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button2"
        android:text="打开输入对话框"/>
</LinearLayout>

设计登录对话框的界面布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center_vertical"
    android:orientation="vertical">
     <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/text1"
    android:text="@string/txt1"
/>
    <EditText
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:id="@+id/edt1"/>
    <TextView
     android:id="@+id/text2"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:text="@string/txt2"/>
    <EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/edt2"/>
</LinearLayout>

Strings.xml

<resources>
    <string name="app_name">ex3_5</string>
    <string name="txt1">用户名</string>
    <string name="txt2">密码</string>
</resources>

设计控制文件

package com.example.ex3_5;

import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    Button but1,but2;
    TextView txt2;
    LinearLayout login;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        but1=(Button)findViewById(R.id.button1);
        but2=(Button)findViewById(R.id.button2);
        but1.setOnClickListener(new mclick());
        but2.setOnClickListener(new mclick());
    }
    class mclick implements View.OnClickListener {
        AlertDialog.Builder dialog=new AlertDialog.Builder(MainActivity.this);//新建消息对话框dialog

        @Override
        public void onClick(View view){
            if(view==but1){
                dialog.setTitle("警告");//设置对话框的标题
                dialog.setIcon(R.drawable.con2);//设置对话框的图标
                dialog.setMessage("本项操作可能会导致信息泄露！");//设置对话框显示的内容
                dialog.setPositiveButton("确定",new okClick());//设置对话框的“确定”按钮
                dialog.create();//创建对象框
                dialog.show();//显示对象框
            }
          if(view==but2) {

           login = (LinearLayout) getLayoutInflater().inflate(R.layout.login, null);
              //从另外的布局中关联组件
            dialog.setTitle("用户登录").setMessage("请输入用户名和密码").setView(login);
            dialog.setPositiveButton("确定", new loginClick());//setPositiveButton 确定用户的输入
            dialog.setNegativeButton("退出", new exitClick());//setNegativeButton取消用户的输入
            dialog.setIcon(R.drawable.icon1);
            dialog.create();
            dialog.show();
            }
        }
    }
    class okClick  implements DialogInterface.OnClickListener{
        @Override
        public void onClick(DialogInterface dialog,int which){
            dialog.cancel();//取消对话框
        }
    }
    class loginClick implements DialogInterface.OnClickListener{
        public void onClick(DialogInterface dialog,int which){
            txt2=(EditText)login.findViewById(R.id.edt2);//关联布局文件中的组件
            if(txt2.getText().toString().equals("admin")){
                Toast.makeText(getApplicationContext(),"登录成功", Toast.LENGTH_SHORT).show();
            }//取输入编辑框中的值与密码匹配
            else
                Toast.makeText(getApplicationContext(),"密码错误",Toast.LENGTH_SHORT).show();
            dialog.dismiss();//关闭对话框
        }
    }
    class exitClick implements DialogInterface.OnClickListener{
        @Override
        public void onClick(DialogInterface dialog,int which){
            MainActivity.this.finish();//退出MainActivity程序
        }
    }
}