写一个linearayout，并且使得它的宽度适应屏幕宽度

宽度自适应：

      container = (LinearLayout) rootView.findViewById(R.id.update_float_container);
        LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) container.getLayoutParams();
        params.width = context.getResources().getDisplayMetrics().widthPixels;
        container.setLayoutParams(params);

完整代码

public class UpdateFloatView extends LinearLayout {
    private Context context;
    private LinearLayout container;
    private TextView closeView;
    private TextView confirmView;
    private TextView promptView;

    public UpdateFloatView(Context context) {
        super(context);
        this.context = context;
        init();
    }

    private void init() {
        View rootView = inflate(getContext(), R.layout.update_apk_float_view, this);

        container = (LinearLayout) rootView.findViewById(R.id.update_float_container);
        LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) container.getLayoutParams();
        params.width = context.getResources().getDisplayMetrics().widthPixels;
        container.setLayoutParams(params);

        closeView = (TextView) rootView.findViewById(R.id.update_float_close);
        promptView = (TextView) rootView.findViewById(R.id.update_float_prompt);
        confirmView = (TextView) rootView.findViewById(R.id.update_float_confirm);
        confirmView.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                if(onConfirmClickListener != null)
                {
                    onConfirmClickListener.onConfirmClick();
                }
            }
        });
        closeView.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                UpdateApkDialog.dismissTeleport();
            }
        });
    }


    public void setMessageText(String messageText) {
        if(TMTextUtil.isEmpty(messageText) == false)
        {
            promptView.setText(messageText);
        }
    }

    interface OnConfirmClickLisntener
    {
        public void onConfirmClick();
    }
    private OnConfirmClickLisntener onConfirmClickListener;

    public void setConfirmAction(String confirmText, OnConfirmClickLisntener onConfirmClickListener)
    {
        confirmView.setText(confirmText);
        this.onConfirmClickListener = onConfirmClickListener;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/update_float_container"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    android:padding="2dp"
    android:background="@drawable/update_apk_container_background">


    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:orientation="horizontal"
        android:gravity="center_vertical"
        android:background="@drawable/update_apk_float_background">

    <com.tmall.wireless.mui.TMIconFontTextView
        android:id="@+id/update_float_close"
        android:text="&#xe6ba;"
        android:gravity="center"
        android:textSize="14dp"
        android:paddingLeft="6dp"
        android:paddingRight="8dp"
        android:textColor="#999999"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"/>

    <TextView
        android:id="@+id/update_float_prompt"
        android:layout_width="270dp"
        android:layout_height="wrap_content"
        android:textSize="14dp"
        android:text="@string/update_apk_prompt"
        android:textColor="#051b28"
        android:gravity="left" />

    <TextView
        android:id="@+id/update_float_confirm"
        android:layout_width="50dp"
        android:layout_height="24dp"
        android:textColor="#CD2626"
        android:textSize="14dp"
        android:text="@string/update_apk_confirm"
        android:background="@drawable/update_apk_confirm_background"
        android:gravity="center"
        android:textAlignment="center"
        android:layout_marginRight="5dp"
        android:layout_marginLeft="5dp"/>

    </LinearLayout>

</LinearLayout>