Android 侧边触摸式导航栏

先上动态效果图

利用一个自定义View ，和其中的dispatchTouchEvent 拦截触摸事件实现

SideBar.java

package xyz.slideviewgettext;import android.content.Context;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.Typeface;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import java.util.List;/** * Created by xyz on 2017/2/5. */public class SideBar extends View {    PRivate List<String> letterList;    private Paint paint;    public SideBar(Context context,List<String> list){        this(context,(AttributeSet) null);        this.letterList=list;    }    public  SideBar(Context context, AttributeSet attributeSet){        this(context,attributeSet,0);    }    public  SideBar(Context context,AttributeSet attributeSet,int defStyle){        super(context,attributeSet,defStyle);        init();    }    private void init(){        setBackgroundColor(0x000000);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        int height=getHeight();//获取view的高度        int width=getWidth();//获取view的宽度        int singleHeight=height/letterList.size();//获取每一个字母所占的高度        int textHight= getFontAboveBaseLineHeight(35);        paint=new Paint();        for(int i=0;i<letterList.size();i++){            paint.setColor(0xff606060);            paint.setTypeface(Typeface.DEFAULT_BOLD);            paint.setAntiAlias(true);            paint.setTextSize(35);            //文字x轴坐标            float xPos=width/2-paint.measureText(letterList.get(i))/2;            //文字y轴坐标//            float yPos=(singleHeight*(i)) + (2*singleHeight/3);            float yPos=(singleHeight*i)+((singleHeight+textHight)/2);            canvas.drawText(letterList.get(i),xPos,yPos,paint);            paint.reset();//重置画笔        }    }    @Override    public boolean dispatchTouchEvent(MotionEvent event) {        int action=event.getAction();        final float x=event.getX();        final float y=event.getY();        // 点击y坐标所占总高度的比例*b数组的长度就等于点击b中的个数.        final int index=(int)((y/getHeight())*letterList.size());        if(x<0||x>getWidth()||y<0||y>getHeight()) {            action = MotionEvent.ACTION_UP;        }            switch (action) {                case MotionEvent.ACTION_UP:                    setBackgroundColor(0x000000);                    if (onTouchBarListener != null) {                        onTouchBarListener.onTouch(null, -1, false);                    }                    invalidate();                    break;                default:                    setBackgroundColor(0xffffffff);                    if (onTouchBarListener != null) {                        onTouchBarListener.onTouch(letterList.get(index), index, true);                    }                        invalidate();                        break;            }        return true;//要实现触摸式的动态效果，必须返回true，使得事件能够被拦截    }    //获得字体baseLine以上的高度    //若需要了解关于单行文本高度分析详情请看 http://blog.csdn.net/uyy203/article/details/54926753    public int getFontAboveBaseLineHeight(float fontSize)    {        Paint paint = new Paint();        paint.setTextSize(fontSize);        Paint.FontMetrics fm = paint.getFontMetrics();        return (int)(Math.ceil(- fm.ascent));    }    //外部设置列表数据方法，重绘view    public void setLetterList(List<String> list){        this.letterList=list;        invalidate();    }    //外部调用接口，以便让外部获得当前触摸到的字母    private OnTouchBarListener onTouchBarListener;    public interface OnTouchBarListener{        void onTouch(String letter,int pos,boolean state);    }    public void setOnTouchBarLisstener(OnTouchBarListener l){        this.onTouchBarListener=l;    }}
MainActivity.java
package xyz.slideviewgettext;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.view.Window;import android.widget.Button;import android.widget.RelativeLayout;import android.widget.TextView;import java.util.ArrayList;import java.util.Arrays;import java.util.List;public class MainActivity extends Activity {    public List<String> letterList;    public static String[] INDEX_STRING = {            "A", "B", "C", "D", "E", "F", "G", "H", "I",            "J", "K", "L", "M", "N", "O", "P",            "Q", "R", "S", "T", "U", "V",            "W", "X", "Y", "Z",            "#"    };    public static String[] Afterstring = {            "1", "2", "3", "4", "5", "6", "7", "8", "9",            "@"    };    private RelativeLayout rlayout;    private static int WC= ViewGroup.LayoutParams.WRAP_CONTENT;    private static int MP=ViewGroup.LayoutParams.MATCH_PARENT;    private SideBar sideBar;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        requestWindowFeature(Window.FEATURE_NO_TITLE);//        setContentView(R.layout.activity_main);        letterList=new ArrayList<String>();        letterList= Arrays.asList(INDEX_STRING);        //整体布局        rlayout=new RelativeLayout(getBaseContext());        RelativeLayout.LayoutParams rp=new RelativeLayout.LayoutParams(MP,MP);        setContentView(rlayout,rp);        //屏幕中间显示的文本，会将当前触摸到的字母显示出来        final TextView text=new TextView(getBaseContext());        rp=new RelativeLayout.LayoutParams(WC,WC);        rp.addRule(RelativeLayout.CENTER_IN_PARENT);        text.setTextSize(100);        text.setTextColor(0xff606060);        rlayout.addView(text,rp);        //包裹侧边导航栏view的布局        final RelativeLayout sideLayout=new RelativeLayout(getBaseContext());        rp=new RelativeLayout.LayoutParams(80,letterList.size()*60);        rp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);        rp.addRule(RelativeLayout.CENTER_VERTICAL);        rlayout.addView(sideLayout,rp);        //包裹侧边导航栏view        sideBar=new SideBar(getBaseContext(),letterList);        rp=new RelativeLayout.LayoutParams(WC,WC);        sideLayout.addView(sideBar,rp);        sideBar.setOnTouchBarLisstener(new SideBar.OnTouchBarListener() {            @Override            public void onTouch(String letter, int pos,boolean state) {                if(state)                    text.setText(letter);                else                    text.setText("");            }        });        //改变list内容 重绘view        Button button =new Button(getBaseContext());        rp=new RelativeLayout.LayoutParams(WC,WC);        button.setText("点我");        rlayout.addView(button,rp);        button.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                letterList= Arrays.asList(Afterstring);                sideBar.setLetterList(letterList);            }        });    }}
若需要了解关于单行文本高度分析详情请看 http://blog.csdn.net/uyy203/article/details/54926753