/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.text;
/**
* InputFilters can be attached to {@link Editable}s to constrain the
* changes that can be made to them.
*/
/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.text;
/**
* InputFilters can be attached to {@link Editable}s to constrain the
* changes that can be made to them.
*/
//InputFilter接口，需要重寫filter方法
public interface InputFilter
{
/**
* This method is called when the buffer is going to replace the
* range <code>dstart … dend</code> of <code>dest</code>
* with the new text from the range <code>start … end</code>
* of <code>source</code>. Return the CharSequence that you would
* like to have placed there instead, including an empty string
* if appropriate, or <code>null</code> to accept the original
* replacement. Be careful to not to reject 0-length replacements,
* as this is what happens when you delete text. Also beware that
* you should not attempt to make any changes to <code>dest</code>
* from this method; you may only examine it for context.
*
* Note: If <var>source</var> is an instance of {@link Spanned} or
* {@link Spannable}, the span objects in the <var>source</var> should be
* copied into the filtered result (i.e. the non-null return value).
* {@link TextUtils#copySpansFrom} can be used for convenience.
*/
/**
* @param source 輸入的文字
* @param start 輸入-0，刪除-0
* @param end 輸入-source文字的長度，刪除-0
* @param dest 原先顯示的內容
* @param dstart 輸入-原光標位置，刪除-光標刪除結束位置
* @param dend 輸入-原光標位置，刪除-光標刪除開始位置
* @return
*/
//主要重寫這個方法
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart, int dend);
/**
* This filter will capitalize all the lower case letters that are added
* through edits.
*/
//接口內的靜態內部類，，，輸入小寫轉換成大寫
public static class AllCaps implements InputFilter {
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart, int dend) {
for (int i = start; i < end; i++) {
if (Character.isLowerCase(source.charAt(i))) {
char[] v = new char[end - start];
TextUtils.getChars(source, start, end, v, 0);
String s = new String(v).toUpperCase();
if (source instanceof Spanned) {
SpannableString sp = new SpannableString(s);
TextUtils.copySpansFrom((Spanned) source,
start, end, null, sp, 0);
return sp;
} else {
return s;
}
}
}
return null; // keep original
}
}
/**
* This filter will constrain edits not to make the length of the text
* greater than the specified length.
*/
// 長度過濾器，限制輸入的長度
public static class LengthFilter implements InputFilter {
private final int mMax;
public LengthFilter(int max) {
mMax = max;
}
public CharSequence filter(CharSequence source, int start, int end, Spanned dest,
int dstart, int dend) {
int keep = mMax - (dest.length() - (dend - dstart));
if (keep <= 0) {
return "";
} else if (keep >= end - start) {
return null; // keep original
} else {
keep += start;
if (Character.isHighSurrogate(source.charAt(keep - 1))) {
--keep;
if (keep == start) {
return "";
}
}
return source.subSequence(start, keep);
}
}
/**
* @return the maximum length enforced by this input filter
*/
public int getMax() {
return mMax;
}
}
}
詳細使用參考:https://www.jianshu.com/p/b24dddaf64ab
