我正在尝试用asterisk (*)符号代替点EditText中inputType textPassword作为setTransformationMethod()。我遇到了要求使用PasswordTransformationMethod并实施{{1}}的帖子。但是我需要实现该类的哪种方法以及如何显示星号？还有其他办法吗？
由于
答案 0 :(得分：9)
我认为你应该通过the documentation。创建PasswordTransformationMethod类，在getTransformation()方法中，只返回一串*个字符，其长度与密码字段的内容相同。
我做了一些摆弄，并提出了一个匿名课程，这个课程对我来说是一个充满* s的字段。我把它转换成了一个可用的类：
public class MyPasswordTransformationMethod 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) {
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
}
}
};
// Call the above class using this:
text.setTransformationMethod(new MyPasswordTransformationMethod());
答案 1 :(得分：0)
使用可从＆＃39; \ u2022＆＃39;更改DOT值的自定义类到＆＃39; \ u002A＆＃39;
import android.graphics.Rect;
import android.os.Handler;
import android.os.SystemClock;
import android.text.Editable;
import android.text.GetChars;
import android.text.NoCopySpan;
import android.text.Spannable;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.TextWatcher;
import android.text.method.TransformationMethod;
import android.text.style.UpdateLayout;
import android.view.View;
import java.lang.ref.WeakReference;
public class PasswordTransformationMethod
implements TransformationMethod, TextWatcher {
/* package */ static final Object ACTIVE = new NoCopySpan.Concrete();
/* package */ static final Object CAPPED = new NoCopySpan.Concrete();
/* package */ static final int SHOW_PASSWORD = 8;
public CharSequence getTransformation(CharSequence source, View view) {
if (source instanceof Spannable) {
Spannable sp = (Spannable) source;
/*
* Remove any references to other views that may still be
* attached. This will happen when you flip the screen
* while a password field is showing; there will still
* be references to the old EditText in the text.
*/
ViewReference[] vr = sp.getSpans(0, sp.length(),
ViewReference.class);
for (int i = 0; i < vr.length; i++) {
sp.removeSpan(vr[i]);
}
removeVisibleSpans(sp);
sp.setSpan(new ViewReference(view), 0, 0,
Spannable.SPAN_POINT_POINT);
}
return new PasswordCharSequence(source);
}
public static android.text.method.PasswordTransformationMethod getInstance() {
if (sInstance != null)
return sInstance;
sInstance = new android.text.method.PasswordTransformationMethod();
return sInstance;
}
public void beforeTextChanged(CharSequence s, int start,
int count, int after) {
// This callback isn't used.
}
public void onTextChanged(CharSequence s, int start,
int before, int count) {
if (s instanceof Spannable) {
Spannable sp = (Spannable) s;
ViewReference[] vr = sp.getSpans(0, s.length(),
ViewReference.class);
if (vr.length == 0) {
return;
}
/*
* There should generally only be one ViewReference in the text,
* but make sure to look through all of them if necessary in case
* something strange is going on. (We might still end up with
* multiple ViewReferences if someone moves text from one password
* field to another.)
*/
View v = null;
for (int i = 0; v == null && i < vr.length; i++) {
v = vr[i].get();
}
if (v == null) {
return;
}
/* int pref = TextKeyListener.getInstance().getPrefs(v.getContext());
if ((pref & SHOW_PASSWORD) != 0) {
if (count > 0) {
removeVisibleSpans(sp);
if (count == 1) {
sp.setSpan(new Visible(sp, this), start, start + count,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}*/
}
}
public void afterTextChanged(Editable s) {
// This callback isn't used.
}
public void onFocusChanged(View view, CharSequence sourceText,
boolean focused, int direction,
Rect previouslyFocusedRect) {
if (!focused) {
if (sourceText instanceof Spannable) {
Spannable sp = (Spannable) sourceText;
removeVisibleSpans(sp);
}
}
}
private static void removeVisibleSpans(Spannable sp) {
Visible[] old = sp.getSpans(0, sp.length(), Visible.class);
for (int i = 0; i < old.length; i++) {
sp.removeSpan(old[i]);
}
}
private static class PasswordCharSequence
implements CharSequence, GetChars {
public PasswordCharSequence(CharSequence source) {
mSource = source;
}
public int length() {
return mSource.length();
}
public char charAt(int i) {
if (mSource instanceof Spanned) {
Spanned sp = (Spanned) mSource;
int st = sp.getSpanStart(ACTIVE);
int en = sp.getSpanEnd(ACTIVE);
if (i >= st && i < en) {
return mSource.charAt(i);
}
Visible[] visible = sp.getSpans(0, sp.length(), Visible.class);
for (int a = 0; a < visible.length; a++) {
if (sp.getSpanStart(visible[a].mTransformer) >= 0) {
st = sp.getSpanStart(visible[a]);
en = sp.getSpanEnd(visible[a]);
if (i >= st && i < en) {
return mSource.charAt(i);
}
}
}
}
return DOT;
}
public CharSequence subSequence(int start, int end) {
char[] buf = new char[end - start];
getChars(start, end, buf, 0);
return new String(buf);
}
public String toString() {
return subSequence(0, length()).toString();
}
public void getChars(int start, int end, char[] dest, int off) {
TextUtils.getChars(mSource, start, end, dest, off);
int st = -1, en = -1;
int nvisible = 0;
int[] starts = null, ends = null;
if (mSource instanceof Spanned) {
Spanned sp = (Spanned) mSource;
st = sp.getSpanStart(ACTIVE);
en = sp.getSpanEnd(ACTIVE);
Visible[] visible = sp.getSpans(0, sp.length(), Visible.class);
nvisible = visible.length;
starts = new int[nvisible];
ends = new int[nvisible];
for (int i = 0; i < nvisible; i++) {
if (sp.getSpanStart(visible[i].mTransformer) >= 0) {
starts[i] = sp.getSpanStart(visible[i]);
ends[i] = sp.getSpanEnd(visible[i]);
}
}
}
for (int i = start; i < end; i++) {
if (!(i >= st && i < en)) {
boolean visible = false;
for (int a = 0; a < nvisible; a++) {
if (i >= starts[a] && i < ends[a]) {
visible = true;
break;
}
}
if (!visible) {
dest[i - start + off] = DOT;
}
}
}
}
private CharSequence mSource;
}
private static class Visible
extends Handler
implements UpdateLayout, Runnable {
public Visible(Spannable sp, android.text.method.PasswordTransformationMethod ptm) {
mText = sp;
mTransformer = ptm;
postAtTime(this, SystemClock.uptimeMillis() + 1500);
}
public void run() {
mText.removeSpan(this);
}
private Spannable mText;
private android.text.method.PasswordTransformationMethod mTransformer;
}
/**
* Used to stash a reference back to the View in the Editable so we
* can use it to check the settings.
*/
private static class ViewReference extends WeakReference<View>
implements NoCopySpan {
public ViewReference(View v) {
super(v);
}
}
private static android.text.method.PasswordTransformationMethod sInstance;
private static char DOT = '\u002A';
}