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

淩亂°似流年 2024-02-18 14:31 26阅读 0赞

**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);
        }
    }

注意这里面的定义和特性。BindingAdapter的注解符会将在xml定义的：

app:password

与Util.java中定义的setText方法绑定，而setTxt由password触发。然后显示密码符号\*。

代码运行结果：

![Center][]

[Center]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/4982c548371a4bd6b89cbf740e6e3e63.png