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Android挪动应用开发中常见的经验技巧总结

热度:292   发布时间:2016-04-25 08:22:45.0
Android移动应用开发中常见的经验技巧总结

1. 对话保持的解决方案。

要求:
1、app中使用webview访问具体网站的内容,但是app与服务器的沟通是使用HttpUrlConnection来完成。
2、webview访问时不需要再次登陆,继承app的登陆状态。

对话未保持的现象:、
这里写图片描述

 1、 虽然app已经登录服务器,但是在webview中还是提示需要登录。2、app下一次对服务器的请求也会失败,提示session过期。

解决方案:
1、获取到HttpUrlConnection中服务器返回的session id。
2、本地保存session id,每次对服务器的请求,手动添加。
3、将此session id设置到持有webview的activity中的CookieManager里。

关键代码:

网络处理类  NetHelper/**     * 发送登陆请求,并将SESSIONID保存起来     * @param urlPath 登陆请求的地址     * @return 返回的内容     * */public static String login(String urlPath)  {        ......省略号......        try {            URL url = new URL(urlPath);            HttpURLConnection conn = (HttpURLConnection) url.openConnection();            //设置请求方式            conn.setRequestMethod("GET");            conn.setConnectTimeout(5000);//            conn.setReadTimeout(5000);            int responseCode = conn.getResponseCode();            if (responseCode == HttpURLConnection.HTTP_OK) {                InputStream is = conn.getInputStream();                cookList = conn.getHeaderFields().get("Set-Cookie");                if ((sessionId == null) && (cookList != null)) {                    for (String value : cookList) {                        if ((value != null) && (value.toUpperCase().indexOf(";") > 0)) {                            sessionId = value.split(";")[0];                        }                    }                }            ......省略号......}        }catch (Exception e){            e.printStackTrace();}......省略号......    }/**     * 发送一条请求,将内容以字符串返回     * @param urlPath 请求的地址     * @return 返回的内容     * */public static String request(String urlPath) {        ......省略号......        try {            URL url = new URL(urlPath);            HttpURLConnection conn = (HttpURLConnection) url.openConnection();            if(sessionId !=null ){                conn.setRequestProperty("Cookie",sessionId);            }            conn.setRequestMethod("GET");            conn.setConnectTimeout(5000);//          conn.setReadTimeout(5000);        ......省略号......        } catch (Exception e) {            e.printStackTrace();}        ......省略号......    }持有webview的Activity  MainActivityprivate CookieManager cookieManager;cookieManager = CookieManager.getInstance();cookieManager.setAcceptCookie(true);clearSession();private void clearSession() {    if (NetHelper.cookList != null) {    cookieManager.removeSessionCookie();    }}//在第一次请求的时候,设置一次session即可private void setSession(String url) {    if (NetHelper.cookList != null) {        String values = NetHelper.cookList.toString();        cookieManager.setCookie(url, values); //设置cookie        CookieSyncManager.getInstance().sync(); //同步    }}

2. 自定义控件的实现方案

自定义控件的实现方式(详细内容可以参考压缩包中的<自定义控件.pdf>):
1、继承方式
当简单控件不满足需求时,通过继承重写简单控件,实现对控件的定制。
2、组合方式
当单个控件不满足需求时,可以采用多个控件的组合,实现对控件的定制。
3、控件自绘方式
通过继承自view,重写onDraw方法实现。

项目中的具体应用:
1、登录邮箱的自动补全功能实现(纯代码实现布局)。
2、弹窗滚轮的实现(代码加布局文件)
3、TabButton的实现(两种实现方式)

A、 登录邮箱的自动补全功能实现:
效果:
这里写图片描述
实现原理:
1、继承重写简单控件AutoCompleteTextView
2、编写自定义数据适配器和布局文件,并实现文字变化监听器
3、通过组合方式,实现右侧的删除图标。并根据焦点和文字的变化,动态显示右侧删除图标。

1、通过继承自简单控件AutoCompleteTextView实现帐号自动补全
关键代码:

   public class AutoComplete extends AutoCompleteTextView {    private static final String[] emailSuffix = {        "@qq.com", "@163.com", "@126.com", "@gmail.com", "@sina.com", "@hotmail.com",        "@yahoo.cn", "@sohu.com", "@foxmail.com", "@139.com", "@yeah.net", "@vip.qq.com",        "@vip.sina.com"};    ......省略号......    //构造函数原型要正确,留给系统调用    public AutoComplete(Context context) {        super(context);        mContext = context;    }    public AutoComplete(Context context, AttributeSet attrs) {        super(context, attrs);        mContext = context;    }    public void init(ImageView imageView) {        mImageView = imageView;        final MyAdatper adapter = new MyAdatper(mContext);        setAdapter(adapter);        addTextChangedListener(new TextWatcher() {            @Override            public void afterTextChanged(Editable s) {                if (isTextWatch) {                    String input = s.toString();                    ......省略号......                    adapter.clearList(); //注意要清空数据,根据输入的变化,自动生成数据                    if (input.length() > 0) {                        for (int i = 0; i < emailSuffix.length; ++i) {                            adapter.addListData(input + emailSuffix[i]);                        }                    }                    adapter.notifyDataSetChanged();                    showDropDown();//该行代码会造成崩溃                }            }        });        //当输入一个字符的时候就开始检测        setThreshold(1);    }    private class ViewHolder {        TextView tv_Text;    }    class MyAdatper extends BaseAdapter implements Filterable {        private List<String> mList;        private Context mContext;        private MyFilter mFilter;        ......省略号......        public void clearList() {            mList.clear();        }        public void addListData(String strData) {            mList.add(strData);        }        @Override        public View getView(int position, View convertView, ViewGroup parent) {            View view;            ViewHolder viewHolder;            if (convertView == null) {                view = LayoutInflater.from(mContext).inflate(R.layout.activity_autocomplete_item, null);                viewHolder = new ViewHolder();                viewHolder.tv_Text = (TextView) view.findViewById(R.id.tv_autocomplete);                view.setTag(viewHolder);            } else {                view = convertView;                viewHolder = (ViewHolder) view.getTag();            }            viewHolder.tv_Text.setText(mList.get(position));            return view;        }        ......省略号......    }activity_autocomplete_item 下拉列表布局文件<?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:background="@color/White"    android:layout_height="wrap_content">    <TextView        android:id="@+id/tv_autocomplete"        android:padding="15dp"        android:textSize="20sp"        android:singleLine="true"        android:textColor="@color/Black"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout> 

上面自动补全的效果图:
这里写图片描述
2、通过组合方式实现帐号自动补全复杂控件
关键代码:

public class AdvancedAutoCompleteTextView extends RelativeLayout {    private Context mContext;    private AutoComplete mAutoComplete; //上面的自定义控件    private ImageView mImageView;       //右侧的图标控件    ......省略号......    @Override    protected void onFinishInflate() {        super.onFinishInflate();        initViews();    }    //代码方式,初始化布局    private void initViews() {        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);        params.addRule(RelativeLayout.ALIGN_PARENT_LEFT);        params.addRule(RelativeLayout.CENTER_VERTICAL);        mAutoComplete = new AutoComplete(mContext);        mAutoComplete.setLayoutParams(params);        mAutoComplete.setPadding(0, 0, 40, 0);        mAutoComplete.setSingleLine(true);        mAutoComplete.setInputType(InputType.TYPE_TEXT_VARIATION_EMAIL_ADDRESS);        mAutoComplete.setFitsSystemWindows(true);        mAutoComplete.setEms(10);        mAutoComplete.setHint("URS账号");        mAutoComplete.setImeOptions(EditorInfo.IME_ACTION_NEXT                                | EditorInfo.IME_FLAG_NO_EXTRACT_UI | EditorInfo.IME_FLAG_NO_FULLSCREEN);        mAutoComplete.setDropDownHorizontalOffset(0);        mAutoComplete.setDropDownVerticalOffset(2);        mAutoComplete.setBackgroundResource(R.drawable.edit_text_background);        RelativeLayout.LayoutParams p = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, LayoutParams.FILL_PARENT);        p.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);        p.addRule(RelativeLayout.CENTER_VERTICAL);        p.rightMargin = 10;        mImageView = new ImageView(mContext);        mImageView.setLayoutParams(p);        mImageView.setScaleType(ImageView.ScaleType.FIT_CENTER);        mImageView.setImageResource(R.drawable.unselect);        mImageView.setClickable(true);        mImageView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                setText("");            }        });        this.addView(mAutoComplete);        this.addView(mImageView);        //监听获取焦点事件,目的:输入帐号时,右侧图标的显示        mAutoComplete.setOnFocusChangeListener(new OnFocusChangeListener() {            @Override            public void onFocusChange(View v, boolean hasFocus) {                if (hasFocus && !mAutoComplete.getText().toString().isEmpty()) {                    mAutoComplete.setShow(false); //如果获取首次获取焦点,此时文本不为空,则显示,并禁止文本改变监听里的设置                    mImageView.setImageResource(R.drawable.item_delete);                } else if (hasFocus) {                    mAutoComplete.setShow(true);//如果获取首次获取焦点,此时文本为空,则不改变,并开启文本改变监听里的设置                } else {                    mAutoComplete.setShow(false);                    mImageView.setImageResource(R.drawable.unselect);                }            }        });                 //对AutoComplete自定义控件初始化,一定要放到最后.否则,会由于AutoComplete初始化未完成,就弹窗,而崩溃        mAutoComplete.init(mImageView);     }}

B、弹窗滚轮的实现
效果:
这里写图片描述
实现原理:
1、继承重写简单控件ScrollView,实现滚动效果,并添加回调接口,用于获取选择的内容。
2、为自定义控件添加内容,其中每一项为一个TextView,用于内容显示。
3、通过自绘添加上下两条直线,实现选中状态。
4、最后利用popup弹窗,加载整个视图,显示弹窗滚动效果。

1、通过继承ScrollView实现滚动,并向布局添加具体项
关键代码:

public class WheelView extends ScrollView {    //选择后的回调接口    public interface OnWheelViewListener {        void onSelected(int selectedIndex, String item);    }    ......省略号......    //初始化,并创建布局    private void init(Context context) {        this.context = context;        this.setVerticalScrollBarEnabled(false);        views = new LinearLayout(context);  //为自定义控件创建线性布局        views.setOrientation(LinearLayout.VERTICAL);        this.addView(views);        //异步任务,根据滚动的位置自动调整待显示的数据,该异步任务会在滚动事件触发式执行        scrollerTask = new Runnable() {            public void run() {                if (itemHeight == 0) {                    return;                }                int newY = getScrollY();                if (initialY - newY == 0) { // stopped                    final int remainder = initialY % itemHeight;                    final int divided = initialY / itemHeight;                    if (remainder == 0) {                        selectedIndex = divided + offset;                        onSeletedCallBack();                    } else {                        if (remainder > itemHeight / 2) {                            WheelView.this.post(new Runnable() {                                @Override                                public void run() {                                    WheelView.this.smoothScrollTo(0, initialY - remainder + itemHeight);                                    selectedIndex = divided + offset + 1;                                    onSeletedCallBack();                                }                            });                        } else {                            WheelView.this.post(new Runnable() {                                @Override                                public void run() {                                    WheelView.this.smoothScrollTo(0, initialY - remainder);                                    selectedIndex = divided + offset;                                    onSeletedCallBack();                                }                            });                        }                    }                } else {                    initialY = getScrollY();                    WheelView.this.postDelayed(scrollerTask, newCheck);                }            }        };    }    //往布局添加数据    private void initData() {        displayItemCount = offset * 2 + 1;        //添加新view之前,必须移除旧的,否则不正确        views.removeAllViews();        for (String item : items) {            views.addView(createView(item));        }        refreshItemView(0);    }    private TextView createView(String item) {        TextView tv = new TextView(context);        tv.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));        tv.setSingleLine(true);        tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, 20);        tv.setText(item);        tv.setGravity(Gravity.CENTER);        int padding = dip2px(15);        tv.setPadding(padding, padding, padding, padding);        if (0 == itemHeight) {            itemHeight = getViewMeasuredHeight(tv);            views.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, itemHeight * displayItemCount));            LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) this.getLayoutParams();            this.setLayoutParams(new LinearLayout.LayoutParams(lp.width, itemHeight * displayItemCount));        }        return tv;    }    ......省略号......    @Override   //上下直线的自绘    public void setBackgroundDrawable(Drawable background) {        if (viewWidth == 0) {            viewWidth = ((Activity) context).getWindowManager().getDefaultDisplay().getWidth();        }        if (null == paint) {            paint = new Paint();            paint.setColor(Color.parseColor("#83cde6"));            paint.setStrokeWidth(dip2px(1f));        }        background = new Drawable() {            @Override            public void draw(Canvas canvas) {                canvas.drawLine(viewWidth * 1 / 6, obtainSelectedAreaBorder()[0], viewWidth * 5 / 6, obtainSelectedAreaBorder()[0], paint);                canvas.drawLine(viewWidth * 1 / 6, obtainSelectedAreaBorder()[1], viewWidth * 5 / 6, obtainSelectedAreaBorder()[1], paint);            }        };        super.setBackgroundDrawable(background);    }}

2、动态加载布局,并利用PopupWindow弹窗显示。
关键代码:

rivate void addView(int num){    ......省略号......    wheel_layout_view = LayoutInflater.from(this).inflate(R.layout.wheel_view, null);    ......省略号...... }

布局文件 wheel_view 效果图
这里写图片描述

private void popupWindows(List<String> list){    if (wheel_layout_view != null){        mPopupWindow = null;        mPopupWindow = new PopupWindow(wheel_layout_view);        mPopupWindow.setWidth(ViewGroup.LayoutParams.MATCH_PARENT);        mPopupWindow.setHeight(ViewGroup.LayoutParams.WRAP_CONTENT);        //点击外部,自动消失        mPopupWindow.setFocusable(true);        mPopupWindow.setOutsideTouchable(true);        ......省略号......        mPopupWindow.showAtLocation(ll_weidu_condition, Gravity.BOTTOM, 0, 0);    }}

C、TabButton的实现
效果:
这里写图片描述
1、利用.9.png图标实现(简单、美观)

属性定义attrs.xml:

<?xml version="1.0" encoding="utf-8"?><resources>    <!-- 自定义的button控件,用于日期的选择-->    <declare-styleable name="TabButton">        <attr name="normal_bg_res" format="reference" />        <attr name="selected_bg_res" format="reference" />    </declare-styleable></resources>

布局文件:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:custom="http://schemas.android.com/apk/res-auto"   //声明自定义属性空间    ......省略号......    android:orientation="vertical">    ......省略号......        <xxxxxxxxxxx.customui.TabButton            style="@style/commonButton"            android:layout_width="0dp"            android:layout_margin="0dp"            android:layout_weight="1"            android:layout_height="40dp"            android:text="昨天"            android:textSize="22sp"            android:gravity="center"            android:background="@drawable/btn_left"            android:textColor="@color/blue"            custom:normal_bg_res="@drawable/btn_left"            custom:selected_bg_res="@drawable/btn_left_selected"            android:id="@+id/bt_yesterday" />    ......省略号......</LinearLayout>

关键代码:

public class TabButton extends Button {    private int normal_bg_res;    private int selected_bg_res;    public TabButton(Context context) {        super(context);    }    public TabButton(Context context, AttributeSet attrs) {        super(context, attrs);        TypedArray typeArray = context.obtainStyledAttributes(attrs, R.styleable.TabButton);        normal_bg_res = typeArray.getResourceId(R.styleable.TabButton_normal_bg_res, 0);        selected_bg_res = typeArray.getResourceId(R.styleable.TabButton_selected_bg_res, 0);        typeArray.recycle();    }    public void setSelected(boolean selected) {        if (selected) {            setBackgroundResource(selected_bg_res);            setTextColor(Color.WHITE);        } else {            setBackgroundResource(normal_bg_res);            setTextColor(getResources().getColor(R.color.blue));        }    }}

2、利用布局文件实现(复杂、灵活)。
更多样式,可以参数官方的SDK(android-sdk-windows\platforms\android-1.5\data\res\)

布局样式button_style:

<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="true">        <shape android:shape="rectangle">            <solid android:color="#0d76e1" />        </shape>    </item>    <item android:state_focused="true">        <shape android:shape="rectangle">            <solid android:color="@color/Grey" />        </shape>    </item>    <item>        <shape android:shape="rectangle">            <solid android:color="@color/Grey" />        </shape>    </item></selector>

样式应用:

<Button android:id="@+id/tab_button"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:background="@drawable/button_style">

3. 蒙板效果的实现

1、不保留标题栏蒙板的实现
效果:
这里写图片描述

原理:
1、弹窗时,设置背景窗体的透明度
2、取消弹窗时,恢复背景窗体的透明度

关键代码:

private void popupWindows(List<String> list){    //产生背景变暗效果    WindowManager.LayoutParams lp=getWindow().getAttributes();    lp.alpha = 0.4f;    getWindow().setAttributes(lp);        ......省略号......    mPopupWindow.setOnDismissListener(new PopupWindow.OnDismissListener() {            @Override            public void onDismiss() {                WindowManager.LayoutParams lp = getWindow().getAttributes();                lp.alpha = 1f;                getWindow().setAttributes(lp);            }        });      ......省略号......}

2、保留标题栏蒙板的实现
效果:
这里写图片描述
原理:
1、根据需求,设置蒙板布局大小。
2、弹窗时,显示蒙板布局
2、取消弹窗时,隐藏蒙板布局

关键代码:
1、蒙板布局实现:

<!-- popup蒙板 --><LinearLayout    android:id="@+id/ll_popup_hide"    android:layout_width="match_parent"    android:background="@color/hide_bg"    android:orientation="vertical"    android:layout_height="match_parent"></LinearLayout><color name="hide_bg">#88323232</color>

2、代码处理

ll_popup_hide.setVisibility(View.VISIBLE); //显示蒙板
ll_popup_hide.setVisibility(View.INVISIBLE); //隐藏蒙板

4. Activity的回收与操作超时的处理

1、Activity的回收
针对多个activity退出的处理

关键代码:
1、新建活动管理类:

public class ActivityCollector {    private static List<Activity> activityList = new ArrayList<Activity>();    public static void addActivity(Activity activity){        activityList.add(activity);    }    public static void removeActivity(Activity activity){        activityList.remove(activity);    }    public static void finishAllButLast(){        Activity activity = activityList.get(activityList.size()-1);        removeActivity(activity);        for (Activity activityItem: activityList){            if (!activityItem.isFinishing()){                activityItem.finish();            }        }        activityList.clear();        activityList.add(activity);    }    public static void finishAll(){        for (Activity activity: activityList){            if (!activity.isFinishing()){                activity.finish();            }        }        activityList.clear();    }}

2、创建基类BaseActivity,并使所有的activity继承自该基类 。在创建时,添加到活动管理器,销毁时,从活动管理器中移除。

public class BaseActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        ActivityCollector.addActivity(this);    }    @Override    protected void onDestroy() {        super.onDestroy();        ActivityCollector.removeActivity(this);    }}

如果需要销毁所有activity,只需调用finishAll()即可

2、操作超时处理

原理:
1、在activity的stop函数中,根据app进程IMPORTANCE_FOREGROUND判断app在前台或后台
2、在activity的onResume函数中,做超时检查。

关键代码:

abstract public class TimeOutCheckActivity extends BaseActivity {    private boolean isLeave = false;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        pref = getSharedPreferences(Constant.CONFIG_NAME, Context.MODE_PRIVATE);    }    /**     * 回调函数,方便测试     * @return    */    abstract protected String getTag();    ......省略号......    /***     * 当用户使程序恢复为前台显示时执行onResume()方法,在其中判断是否超时.     */    @Override    protected void onResume() {//        Log.i("Back",getTag() + ",onResume,是否在前台:" + isOnForeground());        super.onResume();        if (isLeave) {            isLeave = false;            timeOutCheck();        }    }    @Override     protected void onStop() {        super.onStop();        if (!isOnForeground()){            if (!isLeave && isOpenALP()) {                isLeave = true;                saveStartTime();            }        }    }    public void timeOutCheck() {        long endtime = System.currentTimeMillis();        if (endtime - getStartTime() >= Constant.TIMEOUT_ALP * 1000) {            Util.toast(this, "超时了,请重新验证");            String alp = pref.getString(Constant.ALP, null);            if (alp == null || alp == "") {            } else {                Intent intent = new Intent(this, UnlockGesturePasswordActivity.class);                intent.putExtra("pattern", alp);                intent.putExtra("login",false); //手势验证,不进行登录验证                intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);                // 打开新的Activity                startActivityForResult(intent, Constant.REQ_COMPARE_PATTERN_TIMEOUT_CHECK);            }        }    }    public void saveStartTime() {        pref.edit().putLong(Constant.START_TIME, System.currentTimeMillis()).commit();    }    public long getStartTime() {        long startTime = 0;        try {            startTime = pref.getLong(Constant.START_TIME, 0);        }catch (Exception e){            startTime = 0;        }        return startTime;    }    /**     * 程序是否在前端运行,通过枚举运行的app实现。防止重复超时检测多次,保证只有一个activity进入超时检测     *当用户按home键时,程序进入后端运行,此时会返回false,其他情况引起activity的stop函数的调用,会返回true     * @return    */    public boolean isOnForeground() {        ActivityManager activityManager = (ActivityManager) getApplicationContext().getSystemService(Context.ACTIVITY_SERVICE);        String packageName = getApplicationContext().getPackageName();        List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();        if (appProcesses == null)            return false;        for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {            if (appProcess.processName.equals(packageName)                    && appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {                 return true;            }        }        return false;    }}

补充说明:
可以根据importance的不同来判断前台或后台,RunningAppProcessInfo 里面的常量IMTANCE就是上面所说的前台后台,其实IMOPORTANCE是表示这个app进程的重要性,因为系统回收时候,会根据IMOPORTANCE来回收进程的。具体可以去看文档。
public static final int IMPORTANCE_BACKGROUND = 400//后台
public static final int IMPORTANCE_EMPTY = 500//空进程
public static final int IMPORTANCE_FOREGROUND = 100//在屏幕最前端、可获取到焦点 可理解为Activity生命周期的OnResume();
public static final int IMPORTANCE_SERVICE = 300//在服务中
public static final int IMPORTANCE_VISIBLE = 200//在屏幕前端、获取不到焦点可理解为Activity生命周期的OnStart();

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1楼lxf1683昨天 16:29
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