package com.example.panchengjia.limittext;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;

/**
 * Created by panhouye on 2017/5/7 0007.
 */

public class LimitInputTextWatcher implements TextWatcher {
  /**
   * et
   */
  private EditText et = null;
  /**
   * 筛选条件
   */
  private String regex;
  /**
   * 默认的筛选条件(正则:不能输入中文和空格)
   * \u4E00-\u9FA5匹配中文\u0020匹配空格
   */
  private String DEFAULT_REGEX = "[\u4E00-\u9FA5\u0020]";

  /**
   * 构造方法
   *
   * @param et
   */
  public LimitInputTextWatcher(EditText et) {
    this.et = et;
    this.regex = DEFAULT_REGEX;
  }

  /**
   * 构造方法
   *
   * @param et  et
   * @param regex 筛选条件
   */
  public LimitInputTextWatcher(EditText et, String regex) {
    this.et = et;
    this.regex = regex;
  }

  @Override
  public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

  }

  @Override
  public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

  }

  @Override
  public void afterTextChanged(Editable editable) {
    String str = editable.toString();
    String inputStr = clearLimitStr(regex, str);
    et.removeTextChangedListener(this);
    // et.setText方法可能会引起键盘变化,所以用editable.replace来显示内容
    editable.replace(0, editable.length(), inputStr.trim());
    et.addTextChangedListener(this);

  }
  /**
   * 清除不符合条件的内容
   *
   * @param regex
   * @return
   */
  private String clearLimitStr(String regex, String str) {
    return str.replaceAll(regex, "");
  }
}

package com.example.panchengjia.limittext;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    EditText et = (EditText) findViewById(R.id.et);
    //使用LimitInputTextWatcher中默认的输入规则
    et.addTextChangedListener(new LimitInputTextWatcher(et));
    EditText ett = (EditText) findViewById(R.id.ett);
    //设置只能输入中文
    ett.addTextChangedListener(new LimitInputTextWatcher(ett,"[^\u4E00-\u9FA5]"));
  }
}