基于Android DataBinding的BindingAdapter实现密码字符*的回显

基于Android DataBinding的BindingAdapter实现密码字符*的回显

作为BindingAdapter使用的简单小练习，记下。本例实现一个简单功能：当在EditText里面输入一个任意字符时候，在下方的TextView实时回显*号。

写一个User数据模型：

package zhangphil.test;

import android.databinding.BaseObservable;
import android.databinding.ObservableField;

/**
 * Created by Phil on 2017/8/17.
 */

public class User extends BaseObservable {
    public final ObservableField<String> content = new ObservableField<>();
}

写一个activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>
        <import type="zhangphil.test.Util" />

        <variable
            name="user"
            type="zhangphil.test.User" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:text="@={user.content}" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:password="@{user.content}" />
    </LinearLayout>
</layout>

MainActivity.java：

package zhangphil.test;

import android.databinding.DataBindingUtil;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import zhangphil.test.databinding.ActivityMainBinding;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);

        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

        User user = new User();
        binding.setUser(user);
    }
}

任意写一个Util.java：

package zhangphil.test;

import android.databinding.BindingAdapter;
import android.util.Log;
import android.widget.TextView;

/**
 * Created by Phil on 2017/8/18.
 */

public class Util {
    @BindingAdapter(value = {"password"})
    public static void setTxt(TextView view, CharSequence text) {
        if (text == null) {
            Log.d("BindingAdapter setText", "为空");
            return;
        }

        String s = "";
        for (int i = 0; i < text.length(); i++) {
            s = s + "*";
        }

        view.setText(s);
    }
}

app:password

代码运行结果：