Android自定义密码样式 黑点转换成特殊字符

<?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"  >  <EditText    android:id="@+id/et"    android:layout_width="match_parent"    android:layout_height="50dp"    android:layout_marginTop="25dp"    android:hint="请输入数据"    />  <LinearLayout    android:layout_width="match_parent"    android:layout_height="50dp"    android:orientation="horizontal">    <Button      android:id="@+id/password"      android:layout_width="0dp"      android:layout_height="match_parent"      android:layout_weight="1"      android:text="密文"/>    <Button      android:id="@+id/show_text"      android:layout_width="0dp"      android:layout_height="match_parent"      android:layout_marginLeft="20dp"      android:layout_weight="1"      android:text="明文"/>  </LinearLayout>  <Button    android:id="@+id/clean"    android:layout_width="match_parent"    android:layout_height="50dp"    android:text="清除"/></LinearLayout>

package com.chen;import android.app.Activity;import android.os.Bundle;import android.text.method.HideReturnsTransformationMethod;import android.text.method.PasswordTransformationMethod;import android.view.View;import android.widget.Button;import android.widget.EditText;public class MainActivity extends Activity {  Button psd;  Button show_text;  EditText et;  Button clean;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    //将输入框中的内容变为密码格式    psd = (Button) findViewById(R.id.password);    //将密码变为明文    show_text = (Button) findViewById(R.id.show_text);    //清空输入框    clean = (Button) findViewById(R.id.clean);    et = (EditText) findViewById(R.id.et);    show_text.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View v) {        //获取编辑框中的数据内容        String context = et.getText().toString();        //将密码变为明文，这里不用setInputType        et.setTransformationMethod(HideReturnsTransformationMethod.getInstance());        //设置光标位置在数据最后        et.setSelection(context.length());      }    });    psd.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View v) {        //获取编辑框中的数据内容        String context = et.getText().toString();        //将数据变为指定样式的密码        et.setTransformationMethod(new AsteriskPasswordTransformationMethod());        //设置光标位置在数据最后        et.setSelection(context.length());      }    });    clean.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View v) {        et.setText("");      }    });  }  private class AsteriskPasswordTransformationMethod extends PasswordTransformationMethod {    @Override    public CharSequence getTransformation(CharSequence source, View view) {      return new PasswordCharSequence(source);    }    private class PasswordCharSequence implements CharSequence {      private CharSequence mSource;      public PasswordCharSequence(CharSequence source) {        mSource = source; // Store char sequence      }      public char charAt(int index) {        /*        当在编辑框中输入1的时候，会连续打印0...        当在编辑框中继续输入2的时候，会连续01...        不影响功能使用，但是出现原因不知，待解决         */        System.out.println("-----" + index + "-----");        //这里返回的char，就是密码的样式，注意，是char类型的        return '$'; // This is the important part      }      public int length() {        return mSource.length(); // Return default      }      public CharSequence subSequence(int start, int end) {        return mSource.subSequence(start, end); // Return default      }    }  }}