AlertDialog自定义

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="用户名"/>

<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>

</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="密码"/>

<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>

</LinearLayout>

</LinearLayout>

package com.pingyijinren.helloworld.activity;

import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;

import com.pingyijinren.helloworld.R;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private AlertDialog alertDialog;
private Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button=(Button)findViewById(R.id.button);
button.setOnClickListener(this);
}

@Override
public void onClick(View v) {
AlertDialog.Builder builder=new AlertDialog.Builder(this);
builder.setIcon(R.mipmap.ic_launcher);
builder.setTitle("用户登录");
builder.setView(R.layout.alert_dialog_layout);
builder.setPositiveButton("退出", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
finish();
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {

}
});
alertDialog=builder.create();
alertDialog.show();
}
}