Android带有undo,redo功能的EditText

package zwp.mycalendar.widget;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.AttributeSet;
import android.widget.EditText;

/**
* 自定义EditText
* @author 周文鹏
* @date 2015-6-23
*/
public class ZPEditText extends EditText {
private List<EditHistory> undoHistories; // 撤销文字
private List<EditHistory> redoHistories; // 重做文字
private boolean activate = false; // 是否激活redo
private boolean clear = true; // 是否清空redo
private OnTextChangeListener listener; // 文字改变监听器

public ZPEditText(Context context) {
this(context, null);
}

public ZPEditText(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}

public ZPEditText(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}

/**
* 初始化
*/
private void init() {
undoHistories = new ArrayList<EditHistory>();
redoHistories = new ArrayList<EditHistory>();
addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (listener != null) {
listener.onTextChange(ZPEditText.this, s);
}
}

@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
if (activate) {
redoHistories.add(new EditHistory(s.toString(), start, count, after));
activate = false;
} else {
undoHistories.add(new EditHistory(s.toString(), start, count, after));
if (clear) {
redoHistories.clear();
}
clear = true;
}
}

@Override
public void afterTextChanged(Editable s) {
}
});
}

/**
* 撤销
*/
public void undo() {
if (canUndo()) {
activate = true;
Editable editable = getEditableText();
EditHistory history = undoHistories.remove(undoHistories.size() - 1);
if (history.count > 0) {
editable.append(history.text.subSequence(history.start, history.start + history.count));
}
if (history.after > 0) {
editable.delete(history.start, history.start + history.after);
}
}
}

/**
* 重做
*/
public void redo() {
if (canRedo()) {
clear = false;
Editable editable = getEditableText();
EditHistory history = redoHistories.remove(redoHistories.size() - 1);
if (history.count > 0) {
editable.append(history.text.subSequence(history.start, history.start + history.count));
}
if (history.after > 0) {
editable.delete(history.start, history.start + history.after);
}
}
}

/**
* 是否可以撤销
*/
public boolean canUndo() {
if (undoHistories.size() > 0) {
return true;
}
return false;
}

/**
* 是否可以重做
*/
public boolean canRedo() {
if (redoHistories.size() > 0) {
return true;
}
return false;
}

/**
* 获取文字改变监听器
* @return
*/
public OnTextChangeListener getOnTextChangeListener() {
return listener;
}

/**
* 设置文字改变监听器
* @param listener
*/
public void setOnTextChangeListener(OnTextChangeListener listener) {
this.listener = listener;
}

/**
* 存储Edit操作
* @author 周文鹏
* @date 2015-6-24
*/
private class EditHistory {
public CharSequence text;
public int start;
public int count;
public int after;

public EditHistory(CharSequence text, int start, int count, int after) {
this.text = text;
this.start = start;
this.count = count;
this.after = after;
}

@Override
public String toString() {
return "EditHistory [text=" + text + ", start=" + start
+ ", count=" + count + ", after=" + after + "]";
}
}

/**
* 文字改变监听器
* @author 周文鹏
* @date 2015-6-24
*/
public interface OnTextChangeListener {
void onTextChange(ZPEditText editText, CharSequence text);
}
}