android 自定义导航控件

    在编写android应用程序的过程中，经常会使用到导航控件。如果每一个activity都需要用到导航控件，可以将这个导航控件独立出来，方便程序开发。

   写一个导航的代码类：

  

public class NavigationBar extends RelativeLayout implements OnClickListener {

    public static final int NAVIGATION_BUTTON_LEFT = 0;
    public static final int NAVIGATION_BUTTON_RIGHT = 1;

    private Context mContext;
    private NavigationBarListener mListener;

    public NavigationBar(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    public NavigationBar(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

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

    private void init(Context context) {
        mContext = context;

        RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(-1, -2);
        this.setLayoutParams(lp);
        this.setBackgroundResource(R.drawable.navigation_bar_bg);
    }

    public void setLeftBarButton(String title) {
        setButton(title, NAVIGATION_BUTTON_LEFT);
    }

    public void setRightBarButton(String title) {
        setButton(title, NAVIGATION_BUTTON_RIGHT);
    }

    private void setButton(String title, int which) {
        // remove the old button (if there is one)
        Button oldButton = (Button) this.findViewWithTag(new Integer(which));
        if (oldButton != null)
            this.removeView(oldButton);

        Button newButton = new Button(mContext);
        newButton.setTag(new Integer(which)); // used to determine which button is pressed and to remove old buttons

        // set OnClickListener
        newButton.setOnClickListener(this);

        // set LayoutParams
        RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(-2, -2);
        if (which == NAVIGATION_BUTTON_LEFT)
            lp.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
        else if (which == NAVIGATION_BUTTON_RIGHT)
            lp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
        else
            throw new IllegalArgumentException("Parameter 'which' must be 0 or 1");
        lp.addRule(RelativeLayout.CENTER_VERTICAL);
        lp.setMargins(10, 0, 10, 0);
        newButton.setLayoutParams(lp);

        // set button text
        newButton.setText(title);
        newButton.setTextSize(12);
        newButton.setTextColor(Color.WHITE);

        // set button drawable
        newButton.setBackgroundResource(R.drawable.navigation_bar_btn);

        // add button
        this.addView(newButton);
    }

    public void setBarTitle(String title) {
        // remove old title (if exists)
        TextView oldTitle = (TextView) this.findViewWithTag("title");
        if (oldTitle != null)
            this.removeView(oldTitle);

        TextView newTitle = new TextView(mContext);
        newTitle.setTag("title");

        // set LayoutParams
        RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(-2, -2);
        lp.addRule(RelativeLayout.CENTER_IN_PARENT);
        lp.setMargins(0, 30, 0, 30);
        newTitle.setLayoutParams(lp);

        // set text
        newTitle.setText(title);
        newTitle.setTextSize(22);
        newTitle.setTextColor(Color.WHITE);

        // add title to NavigationBar
        this.addView(newTitle);
    }

    public void setNavigationBarListener(NavigationBarListener listener) {
        mListener = listener;
    }

    @Override
    public void onClick(View v) {
        int which = ((Integer) v.getTag()).intValue();
        if (mListener != null) {
            mListener.OnNavigationButtonClick(which);
        }
    }

    /**
     * Listener for NavigationBar.
     */
    public interface NavigationBarListener {

        /**
         * Called when the user presses either of the buttons on the NavigationBar.
         *
         * @param which - indicates which button was pressed, ie: NavigationBar.NAVIGATION_BUTTON_LEFT
         */
        public void OnNavigationButtonClick(int which);
    }
}

 背景样式定义navigation_bar_bg.xml：

  

 导航按钮样式定义navigation_bar_btn.xml

 那么在activity怎么使用呢？

activity调用代码如下：

  

	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.change_device);
		NavigationBar nb = (NavigationBar)findViewById(R.id.detailNavBar);
        nb.setLeftBarButton(getString(R.string.cancel));
        nb.setRightBarButton(getString(R.string.save));
        nb.setBarTitle(getString(R.string.details));
        NavigationBar.NavigationBarListener nbl = new NavigationBar.NavigationBarListener() {
            @Override
            public void OnNavigationButtonClick(int which) {
                if (which == NavigationBar.NAVIGATION_BUTTON_LEFT) {
                    finish();
                } else {
                	
                }
            }
        };
        nb.setNavigationBarListener(nbl);
}

 在layout里面定义我们的导航控件

  

 现在看看效果图：

那么在你以后想使用这个控件的时候，就可以直接调用了。