Android：自定义输入法（输入密码时防止第三方窃取）

对于Android用户而言，一般都会使用第三方的输入法。可是，在输入密码时（尤其是支付相关的密码），使用第三方输入法有极大的安全隐患。目前很多网银类的APP和支付宝等软件在用户输入密码时，都会弹出自定义的输入法而不是直接使用系统输入法。

本文介绍的就是如何实现一个简单的自定义输入法。当然，也可以自己写一个Dialog加上几十个按钮让用户输入，只不过这样显得不够专业。

（一）首先上效果图：

1.前面两个输入框使用了自定义的输入法：

2.第三个输入框没有进行任何设置，因此将使用默认的输入法：

（二）代码简介：

1.主页面布局，由3个输入框加上一个android.inputmethodservice.KeyboardView组成。android.inputmethodservice.KeyboardView是一个系统自带的继承自View的组件，但是它不在android.view这个包下面，因此这里需要写上完整的包名。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <!--前两个EditText均使用自定义的输入法-->    <EditText        android:id="@+id/input_password"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_margin="8dp"        android:hint="one password"        android:layout_alignParentTop="true"        android:inputType="textPassword" />    <EditText        android:id="@+id/input_password2"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_below="@+id/input_password"        android:layout_margin="8dp"        android:hint="another password"        android:inputType="textPassword" />    <!--这个EditText使用默认的输入法-->    <EditText        android:id="@+id/input_normal_text"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_below="@+id/input_password2"        android:layout_margin="8dp"        android:hint="normal text" />    <android.inputmethodservice.KeyboardView        android:id="@+id/keyboardview"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_alignParentBottom="true"        android:layout_centerHorizontal="true"        android:focusable="true"        android:focusableInTouchMode="true"        android:visibility="gone" /></RelativeLayout>

2.KeyboardView是一个显示输入法的容器控件，使用时需要设置具体的输入法面板内容。

（1）首先在res下新建xml目录，然后创建文件keys_layout.xml，即输入法面板的内容。每个row表示一行，Keyboad的属性keyWidth和keyHeight表示每个按键的大小，25%p表示占父组件的25%. Key的属性codes表示该按键的编号（点击时系统回调方法中会返回这个值，用以区分不同的按键），keyLabel表示按键上面显示的文字。还有很多其它的属性，不再陈述。

<?xml version="1.0" encoding="utf-8"?><Keyboard xmlns:android="http://schemas.android.com/apk/res/android"    android:keyWidth="25%p"    android:keyHeight="10%p">    <Row>        <Key            android:codes="55"            android:keyLabel="7"            android:keyEdgeFlags="left" />        <Key            android:codes="56"            android:keyLabel="8" />        <Key            android:codes="57"            android:keyLabel="9" />       <!--删除按键长按时连续响应-->    <Key      android:codes="60001"      android:keyLabel="DEL"      android:isRepeatable="true" />    </Row>    <Row>        <Key            android:codes="52"            android:keyLabel="4"            android:keyEdgeFlags="left" />        <Key            android:codes="53"            android:keyLabel="5" />        <Key            android:codes="54"            android:keyLabel="6" />        <Key            android:codes="48"            android:keyLabel="0" />    </Row>    <Row>        <Key            android:codes="49"            android:keyLabel="1"            android:keyEdgeFlags="left" />        <Key            android:codes="50"            android:keyLabel="2" />        <Key            android:codes="51"            android:keyLabel="3" />        <Key            android:codes="60002"            android:keyLabel="Cancel" />    </Row></Keyboard>

（2）为了使用方便，新建一个类：KeyboardBuilder.java，用于初始化自定义输入法和绑定EditText，代码如下：

public class KeyboardBuilder {    private static final String TAG = "KeyboardBuilder";    private Activity mActivity;    private KeyboardView mKeyboardView;    public KeyboardBuilder(Activity ac, KeyboardView keyboardView, int keyBoardXmlResId) {        mActivity = ac;        mKeyboardView = keyboardView;        Keyboard mKeyboard = new Keyboard(mActivity, keyBoardXmlResId);        // Attach the keyboard to the view        mKeyboardView.setKeyboard(mKeyboard);        // Do not show the preview balloons        mKeyboardView.setPreviewEnabled(false);        KeyboardView.OnKeyboardActionListener keyboardListener = new KeyboardView.OnKeyboardActionListener() {            @Override            public void onKey(int primaryCode, int[] keyCodes) {                // Get the EditText and its Editable                View focusCurrent = mActivity.getWindow().getCurrentFocus();                if (focusCurrent == null || !(focusCurrent instanceof EditText)) {                    return;                }                EditText edittext = (EditText) focusCurrent;                Editable editable = edittext.getText();                int start = edittext.getSelectionStart();                // Handle key                if (primaryCode == Constant.CodeCancel) {                    hideCustomKeyboard();                } else if (primaryCode == Constant.CodeDelete) {                    if (editable != null && start > 0) {                        editable.delete(start - 1, start);                    }                } else {                    // Insert character                    editable.insert(start, Character.toString((char) primaryCode));                }            }            @Override            public void onPress(int arg0) {            }            @Override            public void onRelease(int primaryCode) {            }            @Override            public void onText(CharSequence text) {            }            @Override            public void swipeDown() {            }            @Override            public void swipeLeft() {            }            @Override            public void swipeRight() {            }            @Override            public void swipeUp() {            }        };        mKeyboardView.setOnKeyboardActionListener(keyboardListener);    }    //绑定一个EditText    public void registerEditText(EditText editText) {        // Make the custom keyboard appear        editText.setOnFocusChangeListener(new View.OnFocusChangeListener() {            @Override            public void onFocusChange(View v, boolean hasFocus) {                if (hasFocus) {                    showCustomKeyboard(v);                } else {                    hideCustomKeyboard();                }            }        });        editText.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                Log.d(TAG, "onClick");                showCustomKeyboard(v);            }        });        editText.setOnTouchListener(new View.OnTouchListener() {            @Override            public boolean onTouch(View v, MotionEvent event) {                Log.d(TAG, "onTouch");                EditText edittext = (EditText) v;                int inType = edittext.getInputType();       // Backup the input type                edittext.setInputType(InputType.TYPE_NULL); // Disable standard keyboard                edittext.onTouchEvent(event);               // Call native handler                edittext.setInputType(inType);              // Restore input type                edittext.setSelection(edittext.getText().length());                return true;            }        });    }    public void hideCustomKeyboard() {        mKeyboardView.setVisibility(View.GONE);        mKeyboardView.setEnabled(false);    }    public void showCustomKeyboard(View v) {        mKeyboardView.setVisibility(View.VISIBLE);        mKeyboardView.setEnabled(true);        if (v != null) {            ((InputMethodManager) mActivity.getSystemService(Activity.INPUT_METHOD_SERVICE)).hideSoftInputFromWindow(v.getWindowToken(), 0);        }    }    public boolean isCustomKeyboardVisible() {        return mKeyboardView.getVisibility() == View.VISIBLE;    }

3.最后是主Activity的代码，这里就很简单了。

/** * 自定义安全输入法 */public class MainActivity extends ActionBarActivity {    private KeyboardBuilder builder;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);        KeyboardView keyboardView = (KeyboardView) findViewById(R.id.keyboardview);        builder = new KeyboardBuilder(this, keyboardView, R.xml.keys_layout);        EditText editText = (EditText) findViewById(R.id.input_password);        builder.registerEditText(editText);        EditText editText2 = (EditText) findViewById(R.id.input_password2);        builder.registerEditText(editText2);    }    @Override    public void onBackPressed() {        if (builder != null && builder.isCustomKeyboardVisible()) {            builder.hideCustomKeyboard();        } else {            this.finish();        }    }}

参考文档：http://www.fampennings.nl/maarten/android/09keyboard/index.htm

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