小視頻系統源碼Android ListView的回彈效果

使用動態佈局實現該方法，重寫ListView中的scroll方法可以實現該ListView的回彈效果：

1、重寫ListView中的方法：

package com.isoftstone.pop;
import android.annotation.SuppressLint;
import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.widget.ListView;

@SuppressLint("NewApi")
public class BounceListView extends ListView {
private static final int MAX_Y_OVERSCROLL_DISTANCE = 200;
private Context mContext;
private int mMaxYOverscrollDistance;



public BounceListView(Context context) {
super(context);
mContext = context;
initBounceListView();
}

public BounceListView(Context context, AttributeSet attrs) {
super(context, attrs);
mContext = context;
initBounceListView();
}

public BounceListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mContext = context;
initBounceListView();
}

private void initBounceListView() {
// get the density of the screen and do some maths with it on the max
// overscroll distance
// variable so that you get similar behaviors no matter what the screen
// size

final DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
final float density = metrics.density;
mMaxYOverscrollDistance = (int) (density * MAX_Y_OVERSCROLL_DISTANCE);
}


@Override
protected boolean overScrollBy(int deltaX, int deltaY, int scrollX,
int scrollY, int scrollRangeX, int scrollRangeY,
int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) {
// This is where the magic happens, we have replaced the incoming
// maxOverScrollY with our own custom variable mMaxYOverscrollDistance;
return super.overScrollBy(deltaX, deltaY, scrollX, scrollY,
scrollRangeX, scrollRangeY, maxOverScrollX,
mMaxYOverscrollDistance, isTouchEvent);
}


}

2、MainActivity文件中的內容：

package com.isoftstone.pop;
import android.support.v7.app.ActionBarActivity;
import android.view.ViewGroup.LayoutParams;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.os.Bundle;

public class MainActivity extends ActionBarActivity {
private BounceListView bl;



@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

LinearLayout linearLayout = new LinearLayout(this);    
        linearLayout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));       
        setContentView(linearLayout);

bl = new BounceListView(this);

String[] data = new String[30];    
        for (int i = 0; i < data.length; i++) {    
            data[i] = "回彈效果 " + i;    
        }  


ArrayAdapter<String> aa = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, data);

bl.setAdapter(aa);

linearLayout.addView(bl);    

}
}