EditText限制输入字数，并且禁止输入表情符号

场景：在EditText输入表情符号，但发送到服务器之后，变成了问好，因为服务器无法识别。

解决方案：ContainsEmojiEditText,通过输入字符的长度，判断是否为表情符号。

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

public class ContainsEmojiEditText extends EditText {
    //输入表情前的光标位置
    private int cursorPos;
    //输入表情前EditText中的文本
    private String inputAfterText;
    //是否重置了EditText的内容
    private boolean resetText;

    private Context mContext;

    public ContainsEmojiEditText(Context context) {
        super(context);
        this.mContext = context;
        initEditText();
    }

    public ContainsEmojiEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.mContext = context;
        initEditText();
    }

    public ContainsEmojiEditText(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.mContext = context;
        initEditText();
    }

    // 初始化edittext 控件
    private void initEditText() {
        addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int before, int count) {
                if (!resetText) {
                    cursorPos = getSelectionEnd();
                    // 这里用s.toString()而不直接用s是因为如果用s，
                    // 那么，inputAfterText和s在内存中指向的是同一个地址，s改变了，
                    // inputAfterText也就改变了，那么表情过滤就失败了
                    inputAfterText= s.toString();
                }

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                if (!resetText) {
                    if (count >= 2) {//表情符号的字符长度最小为2
                        CharSequence input = s.subSequence(cursorPos, cursorPos + count);
                        if (containsEmoji(input.toString())) {
                            resetText = true;
                            Toast.makeText(mContext, "不支持输入Emoji表情符号", Toast.LENGTH_SHORT).show();
                            //是表情符号就将文本还原为输入表情符号之前的内容
                            setText(inputAfterText);
                            CharSequence text = getText();
                            if (text instanceof Spannable) {
                                Spannable spanText = (Spannable) text;
                                Selection.setSelection(spanText, text.length());
                            }
                        }
                    }
                } else {
                    resetText = false;
                }
            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        });
    }


    /**
     * 检测是否有emoji表情
     *
     * @param source
     * @return
     */
    public static boolean containsEmoji(String source) {
        int len = source.length();
        for (int i = 0; i < len; i++) {
            char codePoint = source.charAt(i);
            if (!isEmojiCharacter(codePoint)) { //如果不能匹配,则该字符是Emoji表情
                return true;
            }
        }
        return false;
    }

    /**
     * 判断是否是Emoji
     *
     * @param codePoint 比较的单个字符
     * @return
     */
    private static boolean isEmojiCharacter(char codePoint) {
        return (codePoint == 0x0) || (codePoint == 0x9) || (codePoint == 0xA) ||
                (codePoint == 0xD) || ((codePoint >= 0x20) && (codePoint <= 0xD7FF)) ||
                ((codePoint >= 0xE000) && (codePoint <= 0xFFFD)) || ((codePoint >= 0x10000)
                && (codePoint <= 0x10FFFF));
    }

}

在布局文件中定义：

<com.ak.qmyd.view.ContainsEmojiEditText
                android:id="@+id/et_content_edit"
                android:layout_width="match_parent"
                android:layout_height="50dp"
                android:background="@drawable/editext_jianjie_border"
                android:drawableLeft="@drawable/edit_big"
                android:drawablePadding="10dp"
                android:gravity="top"
                android:hint="说点什么"
                android:imeOptions="actionSend"
                android:inputType="text"
                android:padding="10dp"
                android:singleLine="true" />

在Activity中实现输入监听，用于判断输入长度.

et_content_note_edit.addTextChangedListener(new TextWatcher() {
			private int cou = 0;
			int selectionEnd = 0;

			@Override
			public void onTextChanged(CharSequence s, int start, int before,
					int count) {
				cou = before + count;
				String editable = et_content_note_edit.getText().toString();
				String str = StringUtil.stringFilter(editable); // 过滤特殊字符
				if (!editable.equals(str)) {
					et_content_note_edit.setText(str);
				}
				et_content_note_edit.setSelection(et_content_note_edit.length());
				cou = et_content_note_edit.length();
			}

			@Override
			public void beforeTextChanged(CharSequence s, int start, int count,
					int after) {
			}

			@Override
			public void afterTextChanged(Editable s) {
				if (cou > mMaxLenth) {
					selectionEnd = et_content_note_edit.getSelectionEnd();
					s.delete(mMaxLenth, selectionEnd);
					ToastManager.show(DongTaiDetailActivity.this,
							"评论内容不能超过200个字符");
				}
			}
		});

ok，这样就可以实时监听输入的长度，也可以限制表情符号的输入了。