自定义Preference时遇到的问题

在自定义Preference时需要使用一个完全不同的布局,在使用的过程中遇到一个问题,就是数据刷新不了.找到很长时间,现在总结一下原因,以便后续犯了类似的错误.

 

 上面图中的红色部分就是我想要的效果的未完成的样子,本意是想传递4个float 类型的数字后,可以把手机存储的使用情况显示出来.

但是发现数据也已经传递成功了,对应的textview 打印的值也是期望的xxGB ,但是实际显示的确实错误的.

下面贴上主要的源码:

DoovInternalStorageItemPreference.java 是自定义的Preference

public class DoovInternalStorageItemPreference extends Preference {
	private final String TAG = DoovInternalStorageItemPreference.class.getSimpleName();
	private TextView mTotalSpace ;
	private TextView mOthersSpace ;
	private TextView mUsedSpace ;
	private TextView mAvaliableSpace ;
	
	private float total;
    private float others;
    private float used;
    private float avaliable;
	
	public DoovInternalStorageItemPreference(Context context,
			AttributeSet attrs, int defStyleAttr) {
		this(context, attrs, defStyleAttr,0);
	}
	public DoovInternalStorageItemPreference(Context context, AttributeSet attrs) {
		this(context, attrs,0);
	}
	public DoovInternalStorageItemPreference(Context context) {
		this(context,null);
	}
	
	public DoovInternalStorageItemPreference(Context context,
			AttributeSet attrs, int defStyleAttr, int defStyleRes) {
		super(context, attrs, defStyleAttr, defStyleRes);
		setLayoutResource(R.layout.doov_preference_internal_stroge);
		Log.d(TAG,"DoovInternalStorageItemPreference mTotalSpace=" + mTotalSpace);
	}
	@Override
    protected View onCreateView(ViewGroup parent) {
		View view = super.onCreateView(parent);
		Log.d(TAG,"onCreateView=" + mTotalSpace);
    	return view;
    }
    
    @Override
    protected void onBindView(View view) {
    	super.onBindView(view);
    	mTotalSpace = (TextView)view.findViewById(R.id.total_storage);
    	mOthersSpace = (TextView)view.findViewById(R.id.others_storage);
    	mUsedSpace = (TextView)view.findViewById(R.id.used_storage);
    	mAvaliableSpace = (TextView)view.findViewById(R.id.available_storage);
    	Log.d(TAG,"onBindView=" + mTotalSpace);
    }
    
    public void setData(float total,float other,float used,float avaliable){
    	this.total = (float)(Math.round(total*100))/100;//保留2个小数点
    	this.others = (float)(Math.round(other*100))/100;//保留2个小数点
    	this.used = (float)(Math.round(used*100))/100;//保留2个小数点
    	this.avaliable = (float)(Math.round(avaliable*100))/100;//保留2个小数点
    	Log.d(TAG,"total=" + mTotalSpace.getText().toString() + 
    			"others=" + others + "other=" + other);
    	//error
    	mTotalSpace.setText(getContext().getString(R.string.memoryusage_item_total_space, this.total));
    	mOthersSpace.setText(getContext().getString(R.string.memoryusage_item_available_space, this.others)); 
    	mUsedSpace.setText(getContext().getString(R.string.memoryusage_item_used_space, this.used));
    	mAvaliableSpace.setText(getContext().getString(R.string.memoryusage_item_other_space, this.avaliable));
    	notifyChanged(); 
    	
    	/*
    	//ok 
    	mTotalSpace.setText(getContext().getString(R.string.memoryusage_item_total_space, total));
    	mOthersSpace.setText(getContext().getString(R.string.memoryusage_item_available_space, other)); 
    	mUsedSpace.setText(getContext().getString(R.string.memoryusage_item_used_space, used));
    	mAvaliableSpace.setText(getContext().getString(R.string.memoryusage_item_other_space, avaliable));*/
    }
}

光键就是上面的这个自定义的Preference.它的setData 中有2种写法,一种是带notifyChange(),另外一种不是.第一种是错误的.第2种是错误的.

原因就是调用notifyChange() 之后会导致DoovInternalStorageItemPreference 的onCreateView() 和onBindView()重新执行.也就相当于layout被重新加载了.所以手机显示的值就是配置的xml 里面的默认的字符.

去掉notifyChange() 就恢复正常了.

其实这样还是有其他问题.继续看调用setData() 的地方

public class DoovPreferenceActivity extends PreferenceActivity {
	
	private DoovInternalStorageItemPreference mpreference ;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		
		addPreferencesFromResource(R.xml.test_preferencescreen);
		mpreference = new DoovInternalStorageItemPreference(this.getApplicationContext());
		//mpreference.setData(7, 8, 9, 10);
		getPreferenceScreen().addPreference(mpreference);
	}
	
	@Override
	protected void onResume() {
		super.onResume();
		
		new Handler().postDelayed(new Runnable() {
			@Override
			public void run() {
				mpreference.setData(17, 18, 19, 20);
			}
		}, 200);
		
		
		//mpreference.setData(17, 18, 19, 20);
	}
}

在onResume 里面有2个调用setData() 的方法的地方.在上面代码的前提下,第2个是会报错的.但是第一种方法有不常用,怎么办?

所以正确的写法是应该在setData() 里面只记录下相关float 类型的值,将TextView 相关的数据更新操作放在Preference 的onBindView() 里面去.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:settings="http://schemas.android.com/apk/res/com.android.settings"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <TextView
        android:id="@+id/total_storage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
	    android:layout_marginLeft="16dip"
        android:layout_marginTop="10dip"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:text="@string/memoryusage_item_total_space"
        android:textColor="#999999"
        android:textSize="14sp" />
    
    <TextView
        android:id="@+id/others_storage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:layout_alignParentTop="true"
        android:layout_toRightOf="@id/total_storage"
        android:layout_alignLeft="@+id/available_storage"
        android:text="@string/memoryusage_item_other_space"
        android:textColor="#999999"
        android:textSize="14sp" />
    
    <TextView
        android:id="@+id/available_storage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="32dip"
        android:layout_marginTop="10dip"
        android:layout_marginBottom="10dip"
        android:layout_toRightOf="@+id/used_storage"
        android:layout_below="@+id/others_storage"
        android:text="@string/memoryusage_item_available_space"
        android:textColor="#999999"
        android:textSize="14sp" />
    <TextView
        android:id="@+id/used_storage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
	    android:layout_marginLeft="16dip"
        android:layout_marginTop="10dip"
        android:layout_marginBottom="10dip"
        android:layout_alignParentLeft="true"
        android:layout_below="@id/total_storage"
        android:text="@string/memoryusage_item_used_space"
        android:textColor="#999999"
        android:textSize="14sp" />
</RelativeLayout>