Android0924（事件传递、手势操作）

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事件传递

事件传递的机制图：
这里写图片描述
利用事件传递机制简单的做一个下拉刷新的，

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">    <android.support.v4.widget.SwipeRefreshLayout        android:id="@+id/swiperefreshlayout"        android:layout_height="match_parent"        android:layout_width="match_parent"        >        <ListView            android:id="@+id/listview"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:background="#fff"></ListView>    </android.support.v4.widget.SwipeRefreshLayout></RelativeLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {    private ListView mListView;    private SwipeRefreshLayout mRefreshLayout;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mListView= (ListView) findViewById(R.id.listview);        mRefreshLayout= (SwipeRefreshLayout) findViewById(R.id.swiperefreshlayout);        ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,new String[]{"a","b","c","d","e","f","g","b","c","d","e","f","g","b","c","d","e","f","g"});        mListView.setAdapter(adapter);        mRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {            @Override            public void onRefresh() {                mRefreshLayout.setRefreshing(false);            }        });    }}

注意：需要导入android.support.v4.jar包
这里写图片描述
还可以自已定义一个View来实现刷新内容
首先自定义一个View，MyTouch.java

public class MyTouch extends FrameLayout{    private ListView content;    public MyTouch(Context context) {        super(context);    }    public MyTouch(Context context, AttributeSet attrs) {        super(context, attrs);        LayoutInflater inflater= (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);        View update=inflater.inflate(R.layout.activity_update,null);        addView(update);        content= (ListView) inflater.inflate(R.layout.activity_listview,null);        addView(content);        ArrayAdapter<String> adapter=new ArrayAdapter<String>(context,android.R.layout.simple_list_item_1,                new String[]{"a","b","c","d","e","f","g","b","c","d","e","f","g","b","c","d","e","f","g"});        content.setAdapter(adapter);    }    public MyTouch(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    }    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        if (content.getFirstVisiblePosition()==0){            View firstView=content.getChildAt(content.getFirstVisiblePosition());            if (firstView.getY()>=0){                return true;            }        }        return super.onInterceptTouchEvent(ev);    }    @Override    public boolean dispatchTouchEvent(MotionEvent ev) {        return super.dispatchTouchEvent(ev);    }    float oldY=0;    float y=0;    int offset=0;    @Override    public boolean onTouchEvent(MotionEvent event) {        switch(event.getAction()){            case MotionEvent.ACTION_DOWN:                oldY=event.getY();                break;            case MotionEvent.ACTION_MOVE:                y=event.getY();                float distance=y-oldY;                content.setTranslationY(content.getTranslationY()+distance);                oldY=y;                invalidate();                break;            case MotionEvent.ACTION_UP:                ObjectAnimator.ofFloat(content,"translationY",content.getTranslationY(),0).setDuration(300).start();                break;        }        return true;    }}

activity_main.xml

<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="horizontal"    tools:context=".MainActivity"><com.example.administrator.mytouch.MyTouch    android:layout_width="match_parent"    android:layout_height="match_parent"></com.example.administrator.mytouch.MyTouch></LinearLayout>

activity_listview.xml

<?xml version="1.0" encoding="utf-8"?><ListView xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="#fff"></ListView>

activity_update.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center"        android:text="下拉刷新"/></LinearLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }}

这里写图片描述

手势操作

Android 为手势检测提供了一个GestureDetector类，GestrueDetector实例代表了一个手势检测器，创建GestureDetector时需要传入一个GestureDetector.OnGestrureListener实例，GestureDetector.OnGestrueListener就是一个监听器，负责对用户的手势行为提供响应。

GestrueDetector.OnGestureListener里包含的事件处理抽象方法如下。

boolean onDown(MotionEvent e)：当触碰事件按下时触发该方法。

boolean onFling(MotionEvent e1，MotionEvent e2，float velocitX,floatvelocity):当用户在触屏上拖过是触发该方法。其中velocityX，velocityY代表拖过动作在横向，纵向上的速度。

void onLongPress(MotionEvent e):当用户在屏幕上长按时触发该方法。

boolean onScroll(MotionEvent e1,MotionEvent e2,float distance,float distance):当用户在屏幕上滚动式触发该方法。

void onShowPress(MotionEvent e):当用户在触摸屏上按下，而且还未移动和松开时触发该方法。

boolean onSingleTapUp(MotionEvent e):用户在触摸屏上的轻击事件将会触发该方法。
（注意：这里也可以传入GestureDetector.SimpleOnGestureListener()监听器，只对我们需要的方法进行重写。）

先写一个双击事件，自定义一个Button，MyButton.java

public class MyButton extends Button{    private GestureDetector mGesture;    interface OnDoubleTouchClick{        public void onDoubleTouchClick(View v);    }    private OnDoubleTouchClick onDoubleTouchClickListener;    public void setOnDoubleTouchClickListener(OnDoubleTouchClick onDoubleTouchClickListener) {        this.onDoubleTouchClickListener = onDoubleTouchClickListener;    }    public MyButton(Context context) {        super(context);    }    public MyButton(Context context, AttributeSet attrs) {        super(context, attrs);        mGesture=new GestureDetector(context,new GestureDetector.SimpleOnGestureListener(){            @Override            public boolean onDoubleTap(MotionEvent e) {                if (onDoubleTouchClickListener!=null){                    onDoubleTouchClickListener.onDoubleTouchClick(MyButton.this);                }                return true;            }             });    }    public MyButton(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        mGesture.onTouchEvent(event);        return super.onTouchEvent(event);    }}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">   <com.example.administrator.mygesture.MyButton       android:id="@+id/button"       android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:text="手势按钮"/></RelativeLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {    private MyButton button;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        button= (MyButton) findViewById(R.id.button);        button.setOnDoubleTouchClickListener(new MyButton.OnDoubleTouchClick() {            @Override            public void onDoubleTouchClick(View v) {                Toast.makeText(MainActivity.this, "点击了两次", Toast.LENGTH_SHORT).show();            }        });    }}

这里写图片描述

滑动事件，只需要在监听事件里添加onFiling（）方法即可，里面注明要监听事件的距离时长

public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {                if (Math.abs(e2.getX()-e1.getX())>50){                    ObjectAnimator.ofFloat(MyButton.this,"translationX",getTranslationX(),getTranslationX()+e2.getX()-e1.getX()).setDuration(500).start();                    return true;                }                else if(Math.abs(e2.getY()-e1.getY())>50){                    ObjectAnimator.ofFloat(MyButton.this,"translationY",getTranslationY(),getTranslationY()+e2.getY()-e1.getY()).setDuration(500).start();                }                return super.onFling(e1, e2, velocityX, velocityY);            }

这里写图片描述
拖动事件，只需在监听事件里添加onScroll()方法，

 @Override            public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {                setTranslationX(getTranslationX()+e2.getX()-e1.getX());                setTranslationY(getTranslationY()+e2.getY()-e1.getY());                return true;            }

这里写图片描述

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