ListView上滑和下滑,显示和隐藏Toolbar的实现方法

android:theme="@style/Theme.AppCompat.Light.NoActionBar">

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.listview_unit4_1.MainActivity"> <ListView  android:id="@+id/list_view"  android:layout_width="match_parent"  android:layout_height="match_parent"/> <android.support.v7.widget.Toolbar  android:id="@+id/toolbar"  android:layout_width="match_parent"  android:layout_height="?attr/actionBarSize"  android:background="@color/colorPrimary"/></RelativeLayout>

package com.example.listview_unit4_1;import android.animation.ObjectAnimator;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.Toolbar;import android.util.Log;import android.view.MotionEvent;import android.view.View;import android.view.ViewConfiguration;import android.widget.ArrayAdapter;import android.widget.ListView;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity { private ListView listView; private List<String> listViewData;//数据源 private ArrayAdapter<String> adapter; private Toolbar toolbar; private int mTouchSlop;//系统认为的最小滑动距离 private float mFirstY;//用户首次触摸的Y坐标 private float mLastY;//用户滑动结束时Y坐标 private ObjectAnimator mAnimator;//将控件与动画联系起来的类（可以使指定的控件，实现指定的动画效果） private boolean mShow;//toolbar是否显示 @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  toolbar = (Toolbar) findViewById(R.id.toolbar);  setSupportActionBar(toolbar);  //初始化数据源  initData();  listView = (ListView) findViewById(R.id.list_view);  //为ListView增加一个HeadView(避免第一个Item被toolbar遮挡)  //abc_action_bar_default_height_material属性获取系统actionBar的高度  View headView = new View(this);  headView.setLayoutParams(new ListView.LayoutParams(ListView.LayoutParams.MATCH_PARENT,    (int)getResources().getDimension(R.dimen.abc_action_bar_default_height_material)));  listView.addHeaderView(headView);  //获取系统定义的最低滑动距离  mTouchSlop = ViewConfiguration.get(this).getScaledTouchSlop();  adapter = new ArrayAdapter<String>(this, R.layout.support_simple_spinner_dropdown_item, listViewData);  listView.setAdapter(adapter);  //为ListView设置触摸事件监听  listView.setOnTouchListener(new View.OnTouchListener() {   @Override   public boolean onTouch(View v, MotionEvent event) {    switch (event.getAction()){     case MotionEvent.ACTION_DOWN:      mFirstY = event.getY();//getY获取的是相对于View的坐标，getRawY获取的是相对于屏幕的坐标      break;     case MotionEvent.ACTION_MOVE:      mLastY = event.getY();      if(mLastY - mFirstY > mTouchSlop){//手指向下滑动，显示toolbar       if(!mShow){        Log.i("tag", "mLastY_手指下滑="+mLastY);        toolbarAnim(0);//显示        mShow = !mShow;       }      }else if(mFirstY - mLastY > mTouchSlop){//手指向上滑动，隐藏toolbar       if(mShow){        Log.i("tag", "mLastY_手指上滑="+mLastY);        toolbarAnim(1);//隐藏        mShow = !mShow;       }      }      break;     default:break;    }    return false;//一般返回false，提交给上级   }  }); } public void toolbarAnim(int flag){  if(mAnimator != null && mAnimator.isRunning()){   mAnimator.cancel();  }  if(flag == 0){   Log.i("tag", "手指下滑,》》》》》》》显示");   mAnimator = ObjectAnimator.ofFloat(toolbar, "translationY", toolbar.getTranslationY(), 0);  }else if(flag == 1){   Log.i("tag", "手指上滑，》》》》》》》隐藏");   mAnimator = ObjectAnimator.ofFloat(toolbar, "translationY", toolbar.getTranslationY(),     -toolbar.getHeight());  }  mAnimator.start();//开始动画 } /**  * 初始化ListView的数据源  */ public void initData(){  listViewData = new ArrayList<>();  String s;  for(int i = 0; i < 20; i ++){   s = ""+i;   listViewData.add(s);  } }}

//第一个参数用于指定这个动画要操作的是哪个控件//第二个参数用于指定这个动画要操作这个控件的哪个属性//第三个参数是可变长参数,指这个属性值是从多少变到多少mAnimator = ObjectAnimator.ofFloat(toolbar, "translationY", toolbar.getTranslationY(), 0);mAnimator = ObjectAnimator.ofFloat(toolbar, "translationY", toolbar.getTranslationY(),     -toolbar.getHeight());