35.Android之带删除按钮EditText学习

今天实现Android里自定义带删除功能的EditText，效果如下：

当输入内容时，EditText变为带有一个删除功能按钮的编辑框，如图：

实现代码很简单，直接上代码,

布局文件xml:

 <?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:background="#000000"
     android:orientation="vertical" >

     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:background="@drawable/back"
         android:layout_marginBottom="5dp"
         android:layout_marginLeft="5dp"
         android:layout_marginRight="5dp"
         android:layout_marginTop="5dp" >

         <ImageView
             android:id="@+id/search_img"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:paddingTop="7dp"
             android:src="@drawable/search" />

         <EditText
             android:id="@+id/clearText"
             android:layout_width="fill_parent"
             android:layout_height="wrap_content"
             android:layout_weight="1"
             android:background="@null"
             android:hint="搜索"
             android:imeOptions="actionDone"
             android:singleLine="true" >
         </EditText>

         <Button
             android:id="@+id/clear_btn"
             android:layout_width="40dp"
             android:layout_height="40dp"
             android:background="@drawable/clear" />
     </LinearLayout>

 </LinearLayout>

activity代码：

 package com.example.cleartextdemo;

 import android.app.Activity;
 import android.os.Bundle;
 import android.text.Editable;
 import android.text.TextWatcher;
 import android.view.View;
 import android.widget.Button;
 import android.widget.EditText;

 public class MainActivity extends Activity {

     private EditText clearEditText;
     private Button clearbtn;

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

         clearEditText = (EditText) findViewById(R.id.clearText);
         clearbtn = (Button) findViewById(R.id.clear_btn);
         clearbtn.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 clearEditText.setText("");
             }
         });

         clearEditText.addTextChangedListener(mTextWatcher);

     }

     TextWatcher mTextWatcher = new TextWatcher() {

         @Override
         public void beforeTextChanged(CharSequence s, int start, int count,
                 int after) {
             // TODO Auto-generated method stub

         }

         @Override
         public void onTextChanged(CharSequence s, int start, int before,
                 int count) {
             // TODO Auto-generated method stub

         }

         @Override
         public void afterTextChanged(Editable s) {
             if (clearEditText.getText().toString() != null
                     && !clearEditText.getText().toString().equals("")) {
                 clearbtn.setVisibility(View.VISIBLE);
             } else {
                 clearbtn.setVisibility(View.INVISIBLE);
             }

         }

     };

 }

运行后输入信息如图：

按下删除控件变为：