EditText输入事件截获与监听

本节介绍一下EditText中进行文字截获和事件监听。   预期目标：如下图，输入框中每输入一个字符，下面的TextView可以迅速的显示出来输入框中的内容    1.第一种实现方法：使用setOnKeyListener(),不过这种方式只能监听硬键盘事件 Java代码 edittext.setOnKeyListener(new View.OnKeyListener() {                       @Override          public boolean onKey(View v, int keyCode, KeyEvent event) {               textview.setText(edittext.getText());               return false;           }       });   [java] view plain copy print ? edittext.setOnKeyListener(new View.OnKeyListener() {                      @Override          public boolean onKey(View v, int keyCode, KeyEvent event) {              textview.setText(edittext.getText());              return false;          }      });   edittext.setOnKeyListener(new View.OnKeyListener() { @Override public boolean onKey(View v, int keyCode, KeyEvent event) { textview.setText(edittext.getText()); return false; } }); 2.使用TextWatcher类，这种方式是可以监听软键盘和硬键盘的，我们只需要实现onTextChanged方法即可，另外TextWatcher还提供了beforeTextChanged和afterTextChanged方法，用于更加详细的输入监听处理 Java代码 edittext.addTextChangedListener(new TextWatcher() {                        @Override              public void onTextChanged(CharSequence s, int start, int before, int count) {                   textview.setText(edittext.getText());               }                              @Override              public void beforeTextChanged(CharSequence s, int start, int count,                       int after) {                               }                              @Override              public void afterTextChanged(Editable s) {                                             }           });   [java] view plain copy print ? edittext.addTextChangedListener(new TextWatcher() {                       @Override              public void onTextChanged(CharSequence s, int start, int before, int count) {                  textview.setText(edittext.getText());              }                            @Override              public void beforeTextChanged(CharSequence s, int start, int count,                      int after) {                              }                            @Override              public void afterTextChanged(Editable s) {                                            }          });   edittext.addTextChangedListener(new TextWatcher() { @Override public void onTextChanged(CharSequence s, int start, int before, int count) { textview.setText(edittext.getText()); } @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { } @Override public void afterTextChanged(Editable s) { } }); 3、 代码片段：实现当输入到最大值时则不允许再输入了，另外，由于EditText并没有提供给我们EditText的禁止输入功能，以下方法也实现了此功能。 Java代码 private void setEditable(EditText mEdit, int maxLength, boolean value) {           if (value) {               mEdit.setFilters(new InputFilter[] { new MyEditFilter(maxLength) });               mEdit.setCursorVisible(true);               mEdit.setFocusableInTouchMode(true);               mEdit.requestFocus();           } else {               mEdit.setFilters(new InputFilter[] { new InputFilter() {                   @Override                  public CharSequence filter(CharSequence source, int start,                           int end, Spanned dest, int dstart, int dend) {                       return source.length() < 1 ? dest.subSequence(dstart, dend)                               : "";                   }               } });               mEdit.setCursorVisible(false);               mEdit.setFocusableInTouchMode(false);               mEdit.clearFocus();           }       }   [java] view plain copy print ? private void setEditable(EditText mEdit, int maxLength, boolean value) {          if (value) {              mEdit.setFilters(new InputFilter[] { new MyEditFilter(maxLength) });              mEdit.setCursorVisible(true);              mEdit.setFocusableInTouchMode(true);              mEdit.requestFocus();          } else {              mEdit.setFilters(new InputFilter[] { new InputFilter() {                  @Override                  public CharSequence filter(CharSequence source, int start,                          int end, Spanned dest, int dstart, int dend) {                      return source.length() < 1 ? dest.subSequence(dstart, dend)                              : "";                  }              } });              mEdit.setCursorVisible(false);              mEdit.setFocusableInTouchMode(false);              mEdit.clearFocus();          }      }   private void setEditable(EditText mEdit, int maxLength, boolean value) { if (value) { mEdit.setFilters(new InputFilter[] { new MyEditFilter(maxLength) }); mEdit.setCursorVisible(true); mEdit.setFocusableInTouchMode(true); mEdit.requestFocus(); } else { mEdit.setFilters(new InputFilter[] { new InputFilter() { @Override public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) { return source.length() < 1 ? dest.subSequence(dstart, dend) : ""; } } }); mEdit.setCursorVisible(false); mEdit.setFocusableInTouchMode(false); mEdit.clearFocus(); } }