一、常用到的属性：

android:hint：文本提示信息

android:maxLength：控制EditText字符数

android:inputType：限制输入的类型

 

二、文本监听事件

获取到的EditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                Log.d("before", "输入之前字符串为：" + s.toString() + ",从下标为：[" + start + "]开始操作，操作的数量为：" + after);
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                Log.d("on", "输入后的字符串为： " + s.toString() + " ，从下标为： [ " + start + " ]开始操作，操作的数量为： " + count);
            }

            @Override
            public void afterTextChanged(Editable s) {
                Log.d("after", "输入结束后的字符串为 ：" + s.toString() + "\n--------------------------------------------");
            }
        });

 

三、问题解决：

 在app目录下的build.gradle文件里面添加两行代码：

aaptOptions.cruncherEnabled =false
aaptOptions.useNewCruncher =false

 

 

四、练习

（1）布局文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="15dp">

    <EditText
        android:id="@+id/txt01"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@drawable/bg_txt"
        android:hint="请输入用户名"
        android:paddingLeft="10dp"
        android:maxLines="1"
        android:maxLength="30"
        android:singleLine="true"
        android:textColor="#ed1941"/>

    <EditText
        android:singleLine="true"
        android:id="@+id/txt02"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_below="@+id/txt01"
        android:textColor="#ed1941"
        android:inputType="textPassword"
        android:background="@drawable/bg_txt"
        android:hint="请输入密码"
        android:paddingLeft="10dp"
        android:maxLines="1"
        android:layout_marginTop="10dp"/>

    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_below="@+id/txt02"
        android:layout_height="50dp"
        android:layout_marginTop="10dp"
        android:text="登录"
        android:textSize="20sp"
        android:background="@drawable/bg_btn"
        android:textColor="#ffffff"/>
</RelativeLayout>

（2）Activity文件：

package com.example.lqh.firstproctect;

import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    private EditText mTxt01;
    private EditText mTxt02;
    private Button mBtn;

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

        mTxt01 = (EditText) findViewById(R.id.txt01);
        mTxt02 = (EditText) findViewById(R.id.txt02);
        Drawable drawable = getResources().getDrawable(R.drawable.user);
        drawable.setBounds(0, 0, 50, 50);
        mTxt01.setCompoundDrawables(drawable, null, null, null);
        drawable = getResources().getDrawable(R.drawable.pass);
        drawable.setBounds(0, 0, 50, 50);
        mTxt02.setCompoundDrawables(drawable, null, null, null);

        mBtn = (Button) findViewById(R.id.btn);
        mBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "登录成功！", Toast.LENGTH_SHORT).show();
            }
        });

        mTxt01.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                Log.d("before", "输入之前字符串为：" + s.toString() + ",从下标为：[" + start + "]开始操作，操作的数量为：" + after);
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                Log.d("on", "输入后的字符串为： " + s.toString() + " ，从下标为： [ " + start + " ]开始操作，操作的数量为： " + count);
            }

            @Override
            public void afterTextChanged(Editable s) {
                Log.d("after", "输入结束后的字符串为 ：" + s.toString() + "\n--------------------------------------------");
            }
        });
    }
}

（3）新建drawable-xxhdpi文件夹，图片放里面：

 

（4）样式文件：

 bg_btn.xml:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="false">
        <shape>
            <solid android:color="#007d65" />
            <corners android:radius="15dp" />
        </shape>
    </item>
    <item android:state_pressed="true">
        <shape>
            <solid android:color="#225a1f" />
            <corners android:radius="15dp" />

        </shape>
    </item>
</selector>

bg_txt.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <stroke
        android:width="2dp"
        android:color="#007d65"/>
    <corners
        android:radius="10dp"/>
</shape>

 

（5）效果图：