[android] 实现返回键操作思路详解手机开发

    /** 
     * 返回键处理 
     */ 
    @Override 
    public boolean onKeyDown(int keyCode, KeyEvent event) { 
        if(keyCode==KeyEvent.KEYCODE_BACK){ 
            boolean result=MiddleManager.getInstance().goBack(); 
            if(!result){ 
                Toast.makeText(MainActivity.this, "是否退出应用", 1).show(); 
            } 
            return false; 
        } 
        return super.onKeyDown(keyCode, event); 
    }

    //操作历史栈 
    private LinkedList<String> HISTORY=new LinkedList<String>(); 
    /** 
     * 处理返回键 
     * @return  
     */ 
    public boolean goBack() { 
        //如果为空会抛异常 
        if(HISTORY.size()>0){ 
            if(HISTORY.size()==1){ 
                return false; 
            } 
             
            HISTORY.removeFirst(); 
            if(HISTORY.size()>0){ 
                String key=HISTORY.getFirst(); 
                BaseView targetView=VIEWCACHE.get(key); 
                mainContainer.removeAllViews(); 
                View child=targetView.getView(); 
                mainContainer.addView(child); 
                child.startAnimation(AnimationUtils.loadAnimation(mainContainer.getContext(), R.anim.left_to_right)); 
                currentView=targetView; 
                return true; 
            } 
        } 
        return false; 
    }

    /** 
     * 加载界面 
     */ 
    public void loadView(Class<? extends BaseView> baseViewClass) { 
        BaseView baseView=null; 
        //判断是否存在 
        String key=baseViewClass.getSimpleName(); 
        if(VIEWCACHE.containsKey(key)){ 
            baseView=VIEWCACHE.get(key); 
        }else{ 
            try { 
                Constructor<? extends BaseView> constructor; 
                constructor = baseViewClass.getConstructor(Context.class); 
                baseView=constructor.newInstance(mainContainer.getContext()); 
            } catch (Exception e) { 
                e.printStackTrace(); 
            } 
            VIEWCACHE.put(key, baseView); 
        } 
        mainContainer.removeAllViews(); 
        View child=baseView.getView(); 
        mainContainer.addView(child); 
        child.startAnimation(AnimationUtils.loadAnimation(mainContainer.getContext(), R.anim.left_to_right)); 
        currentView=baseView; 
        //放入栈 
        HISTORY.addFirst(key); 
    }