由其他现有视图组成的自定义小部件

Question

我想创建一个具有以下布局的小部件：

<LinearLayout orientation="horizontal">
<CheckBox />
<EditText />
<SeekBar />
</LinearLayout>

当搜索栏被移动时，它应该选中复选框并使用当前搜索栏值更新编辑框。

我在应用程序中一遍又一遍地使用类似的东西，并且厌倦了重新实现相同的东西。

将所有这些封装到自己的类中以供重用的最佳方法是什么？

---

public class SeekChoice extends LinearLayout {



    public SeekChoice(Context context) {
        super(context);
        LayoutInflater inflater = (LayoutInflater) context.getSystemService( Context.LAYOUT_INFLATER_SERVICE );
        LinearLayout ll = (LinearLayout) inflater.inflate(R.id.widget_item, null);
        this.addView(ll);
    }
}


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal" 
    android:id="@+id/widget_item"
    >


    <CheckBox
        android:id="@+id/checkBox_item_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Item Name" />



    <EditText
        android:id="@+id/editText_item_count"
        android:layout_width="82dp"
        android:layout_height="wrap_content"
        android:enabled="false"
        android:ems="10" >

    </EditText>


    <SeekBar
        android:id="@+id/seekBar_item_count"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1" />

</LinearLayout>

然后在我的布局中输入：

<com.example.lobsternav.widget.SeekChoice
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>    

例外情况如下：

09-09 20:23:08.759: E/AndroidRuntime(21888): FATAL EXCEPTION: main
09-09 20:23:08.759: E/AndroidRuntime(21888): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.lobsternav/com.example.lobsternav.MarkActivity}: android.view.InflateException: Binary XML file line #344: Error inflating class com.example.lobsternav.widget.SeekChoice
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.ActivityThread.access$600(ActivityThread.java:130)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.os.Handler.dispatchMessage(Handler.java:99)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.os.Looper.loop(Looper.java:137)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.ActivityThread.main(ActivityThread.java:4745)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at java.lang.reflect.Method.invokeNative(Native Method)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at java.lang.reflect.Method.invoke(Method.java:511)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at dalvik.system.NativeStart.main(Native Method)
09-09 20:23:08.759: E/AndroidRuntime(21888): Caused by: android.view.InflateException: Binary XML file line #344: Error inflating class com.example.lobsternav.widget.SeekChoice
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.createView(LayoutInflater.java:596)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:687)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:749)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:749)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:256)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.Activity.setContentView(Activity.java:1867)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at com.example.lobsternav.MarkActivity.onCreate(MarkActivity.java:85)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.Activity.performCreate(Activity.java:5008)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
09-09 20:23:08.759: E/AndroidRuntime(21888):    ... 11 more
09-09 20:23:08.759: E/AndroidRuntime(21888): Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
09-09 20:23:08.759: E/AndroidRuntime(21888):    at java.lang.Class.getConstructorOrMethod(Class.java:460)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at java.lang.Class.getConstructor(Class.java:431)
09-09 20:23:08.759: E/AndroidRuntime(21888):    at android.view.LayoutInflater.createView(LayoutInflater.java:561)
09-09 20:23:08.759: E/AndroidRuntime(21888):    ... 24 more

---

疯狂...如果我没有定义以下构造函数，它会引发异常：

public SeekChoice(Context context, AttributeSet attrs) {
    super(context, attrs);


}

我猜LinearLayout的所有构造函数都需要定义，需要调用超级构造函数？

Answer 1

终于有这个工作了。

我的 Java 代码：

package com.example.lobsternav.widget;

import java.util.ArrayList;
import java.util.List;

import com.example.lobsternav.R;

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.SeekBar;
import android.widget.RelativeLayout.LayoutParams;
import android.widget.SeekBar.OnSeekBarChangeListener;

public  class SeekChoice extends LinearLayout implements OnSeekBarChangeListener, OnCheckedChangeListener{

    CheckBox checkbox = null;
    EditText editBox =null;
    SeekBar seekbar = null;

    boolean isChecked = false;
    int curValue = 0;
    List <String> mappings = new ArrayList<String>();
    int startRange = 0;
    int endRange = 50;
    int defaultValue = 0;

    private void init(Context context)
    {
        this.setOrientation(LinearLayout.HORIZONTAL);
        LayoutInflater inflater = (LayoutInflater) context.getSystemService( Context.LAYOUT_INFLATER_SERVICE );

        LinearLayout layout = (LinearLayout)inflater.inflate(R.layout.item_widget, null);
        layout.setOrientation(LinearLayout.HORIZONTAL);
        layout.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.WRAP_CONTENT));


        checkbox = (CheckBox)layout.findViewById(R.id.checkBox_item_name);
        checkbox.setOnCheckedChangeListener(this);
        //this.addView(checkbox);

        editBox = (EditText)layout.findViewById(R.id.editText_item_count);
        editBox.setEnabled(false);
        editBox.setText(getMappedValue(defaultValue));

        int ems = (new Integer(endRange)).toString().length()+1;
        editBox.setEms(ems);
        //this.addView(editBox);

        seekbar = (SeekBar)layout.findViewById(R.id.seekBar_item_count);
        seekbar.setMax(endRange);
        seekbar.setProgress(defaultValue);
        //seekbar.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.WRAP_CONTENT));
        seekbar.setOnSeekBarChangeListener(this);
        //this.addView(seekbar);    
        this.addView(layout);

    }


    public void readAttributes(Context context, AttributeSet attrs)
    {
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.SeekChoice);
        this.startRange = a.getInteger(R.styleable.SeekChoice_startRange, 0);
        this.endRange = a.getInteger(R.styleable.SeekChoice_endRange, 100);
        this.defaultValue = a.getInteger(R.styleable.SeekChoice_defaultValue, 0);
        this.isChecked = a.getBoolean(R.styleable.SeekChoice_isChecked, false);
        a.recycle();
    }

    public SeekChoice(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        readAttributes( context,  attrs);
        init(context);

    }

    public SeekChoice(Context context, AttributeSet attrs) {
        super(context, attrs);
        readAttributes( context,  attrs);
        init(context);

    }
    public SeekChoice(Context context) {
        super(context);
        init(context);
    }

    public SeekChoice(Context context,int startRange, int endRange, int defaultValue) {
        super(context);
        init(context);
    }
    @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) 
    {
        this.editBox.setText("" + getMappedValue(progress));

        if (progress > 0)
        {
            this.checkbox.setChecked(true);
            isChecked = true;
        }

    }


    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }


    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }




    public int getStartRange() {
        return startRange;
    }


    public void setStartRange(int startRange) {
        this.startRange = startRange;
    }


    public int getEndRange() {
        return endRange;
    }


    public void setEndRange(int endRange) {
        this.endRange = endRange;
    }


    public int getDefaultValue() {
        return defaultValue;
    }


    public void setDefaultValue(int defaultValue) {
        this.defaultValue = defaultValue;
    }


    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) 
    {

        this.isChecked = isChecked;

        if (isChecked == false)
        {
            this.seekbar.setProgress(0);
        }

        this.editBox.setText("" + getMappedValue(0));
    }



    public String getMappedValue(int current)
    {
        if (current < this.getMappings().size())
        {
            return this.getMappings().get(current);
        }



        return "" + current;


    }

    public List<String> getMappings() {
        return mappings;
    }


    public void setMappings(List<String> mappings) {
        this.mappings = mappings;
    }

    public void addMappings(String mapping) {
        this.mappings.add(mapping);
    }
    public boolean isChecked() {
        return isChecked;
    }


    public String getCurrentValue()
    {
        return this.editBox.getText().toString();
    }
    public void setChecked(boolean isChecked) {
        this.isChecked = isChecked;
    }


}

我在构造函数中膨胀的布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" 
    android:id="@layout/item_widget">

   <CheckBox
        android:id="@+id/checkBox_item_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Item Name" />



    <EditText
        android:id="@+id/editText_item_count"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:enabled="false"
        android:ems="10" >

    </EditText>


    <SeekBar
        android:id="@+id/seekBar_item_count"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1" />
</LinearLayout>

/res/values/attr.xml（用于将自定义属性传递给小部件）：

<?xml version="1.0" encoding="utf-8"?>
<resources>
       <declare-styleable name="SeekChoice">
            <attr name="startRange" format="integer"/>
            <attr name="endRange" format="integer"/>
            <attr name="defaultValue" format="integer"/>                
            <attr name="isChecked" format="boolean"/>       




       </declare-styleable>

</resources> 

我在其中包含小部件的布局文件：

    <RelativeLayout android:layout_width="fill_parent"
        android:layout_height="match_parent" 
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:custom="http://schemas.android.com/apk/res/com.example.lobsternav">
.....
.....

<com.example.lobsternav.widget.SeekChoice
android:layout_width="match_parent"
android:layout_height="wrap_content"
custom:defaultValue="10"
/>

.....
.....

</RelativeLayout>

浪费了我的时间，所以我分享给大家：

1)。确保添加要覆盖的类的所有构造函数

2)。命名空间（在我的示例中为“xmlns:custom="http://schemas.android.com/apk/res/com.example.lobsternav"）必须是您的 R 所在的包名称，而不是小部件驻留。

3)。在 attr.xml 文件中，标签 declare-styleable 不会在 eclipse xml 编辑器中自动完成，因此它看起来不像是一个有效的标签 - 但它是。我读了另外 2 篇文章说要使用它，但是 android eclipse 插件没有将它显示为资源下的有效标签，所以我几乎没有尝试使用该标签。

Answer 2

选项 #1：不要将其打包到自定义小部件中，而是打包到片段中。

选项#2：创建LinearLayout 的子类，将其方向设置为水平并将布局文件膨胀到自身中，其中包含您上面的内容，并用merge 标记替换LinearLayout（或将其子类直接添加到Java 代码，如果您喜欢并且不需要布局级别的可定制性）。然后LinearLayout 可以连接其子级中的事件侦听器等等。