StatusBarCompat使用心得

StatusBarCompat是网络大神封装
专门从代码角度来实现状态栏的操作。并且完成了4.4~5.0和5.0+的适配，先上源码:

import android.app.Activity;
import android.content.Context;
import android.graphics.Color;
import android.os.Build;
import android.support.v4.view.ViewCompat;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.FrameLayout;
public class StatusBarCompat {

    private static final int COLOR_TRANSLUCENT = Color.parseColor("#00000000");

    public static final int DEFAULT_COLOR_ALPHA = 112;

    /**
     * set statusBarColor
     * @param statusColor color
     * @param alpha 0 - 255
     */
    public static void setStatusBarColor(Activity activity, int statusColor, int alpha) {
        setStatusBarColor(activity, calculateStatusBarColor(statusColor, alpha));
    }
    public static void setStatusBarColor(Activity activity, int statusColor) {
        Window window = activity.getWindow();
        ViewGroup mContentView = (ViewGroup) activity.findViewById(Window.ID_ANDROID_CONTENT);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            //First translucent status bar.
            window.addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                //After LOLLIPOP not translucent status bar
                window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
                //Then call setStatusBarColor.
                window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
                window.setStatusBarColor(statusColor);
                //set child View not fill the system window
                View mChildView = mContentView.getChildAt(0);
                if (mChildView != null) {
                    ViewCompat.setFitsSystemWindows(mChildView, true);
                }
            } else {
                ViewGroup mDecorView = (ViewGroup) window.getDecorView();
                if (mDecorView.getTag() != null && mDecorView.getTag() instanceof Boolean && (Boolean)mDecorView.getTag()) {
                    //if has add fake status bar view
                    View mStatusBarView = mDecorView.getChildAt(0);
                    if (mStatusBarView != null) {
                        mStatusBarView.setBackgroundColor(statusColor);
                    }
                } else {
                    int statusBarHeight = getStatusBarHeight(activity);
                    //add margin
                    View mContentChild = mContentView.getChildAt(0);
                    if (mContentChild != null) {
                        ViewCompat.setFitsSystemWindows(mContentChild, false);
                        FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) mContentChild.getLayoutParams();
                        lp.topMargin += statusBarHeight;
                        mContentChild.setLayoutParams(lp);
                    }
                    //add fake status bar view
                    View mStatusBarView = new View(activity);
                    FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, statusBarHeight);
                    layoutParams.gravity = Gravity.TOP;
                    mStatusBarView.setLayoutParams(layoutParams);
                    mStatusBarView.setBackgroundColor(statusColor);
                    mDecorView.addView(mStatusBarView, 0);
                    mDecorView.setTag(true);
                }
            }
        }
    }

    public static void translucentStatusBar(Activity activity) {
        translucentStatusBar(activity, false);
    }

    /**
     * change to full screen mode
     * @param hideStatusBarBackground hide status bar alpha Background when SDK > 21, true if hide it
     */
    public static void translucentStatusBar(Activity activity, boolean hideStatusBarBackground) {
        Window window = activity.getWindow();
        ViewGroup mContentView = (ViewGroup) activity.findViewById(Window.ID_ANDROID_CONTENT);

        //set child View not fill the system window
        View mChildView = mContentView.getChildAt(0);
        if (mChildView != null) {
            ViewCompat.setFitsSystemWindows(mChildView, false);
        }

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            int statusBarHeight = getStatusBarHeight(activity);

            //First translucent status bar.
            window.addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                //After LOLLIPOP just set LayoutParams.
                window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
                if (hideStatusBarBackground) {
                    window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
                    window.setStatusBarColor(COLOR_TRANSLUCENT);
                } else {
                    window.setStatusBarColor(calculateStatusBarColor(COLOR_TRANSLUCENT, DEFAULT_COLOR_ALPHA));
                }
                //must call requestApplyInsets, otherwise it will have space in screen bottom
                if (mChildView != null) {
                    ViewCompat.requestApplyInsets(mChildView);
                }
            } else {
                ViewGroup mDecorView = (ViewGroup) window.getDecorView();
                if (mDecorView.getTag() != null && mDecorView.getTag() instanceof Boolean && (Boolean)mDecorView.getTag()) {
                    mChildView = mDecorView.getChildAt(0);
                    //remove fake status bar view.
                    mContentView.removeView(mChildView);
                    mChildView = mContentView.getChildAt(0);
                    if (mChildView != null) {
                        FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) mChildView.getLayoutParams();
                        //cancel the margin top
                        if (lp != null && lp.topMargin >= statusBarHeight) {
                            lp.topMargin -= statusBarHeight;
                            mChildView.setLayoutParams(lp);
                        }
                    }
                    mDecorView.setTag(false);
                }
            }
        }
    }

    //Get status bar height
    public static int getStatusBarHeight(Context context) {
        int result = 0;
        int resId = context.getResources().getIdentifier("status_bar_height", "dimen", "android");
        if (resId > 0) {
            result = context.getResources().getDimensionPixelOffset(resId);
        }
        return result;
    }

    //Get alpha color
    private static int calculateStatusBarColor(int color, int alpha) {
        float a = 1 - alpha / 255f;
        int red = color >> 16 & 0xff;
        int green = color >> 8 & 0xff;
        int blue = color & 0xff;
        red = (int) (red * a + 0.5);
        green = (int) (green * a + 0.5);
        blue = (int) (blue * a + 0.5);
        return 0xff << 24 | red << 16 | green << 8 | blue;
    }
}

概念定义说明:
1.状态栏的两种模式及词汇定义

着色模式:就是自由指定状态栏的颜色
沉浸模式:又称透明状态，就是content_view充斥StatusBar区域
content_view:
其实就是我们在layout中定义的最外层View，注意:他是activity.findViewById(Window.ID_ANDROID_CONTENT).getChileAt(0)的值
fitsSystemWindows属性:
本质就是改变View的paddingTop，true时设置paddingTop为StatusBar高度(原来的paddingTop属性无效)，false时不改变原来的paddingTop值。

2.着色模式思路

5.0+:利用setStatusBarColor()方法指定颜色，让content_view下具有fitsSystemWindows=”true”属性
4.4~5.0:让content_view具有fitsSystemWindows=”false”属性，然后增加StatusBar的高度给content_view的marginTop，之后手工在DecorView上添加一个指定颜色，指定高度为StatusBar高度的假View来填充StatusBar区域
3.沉浸模式思路
5.0+:让content_view具有fitsSystemWindows=”false”属性，利用setStatusBarColor()将状态栏颜色设置为透明色
4.4~5.0:让content_view具有fitsSystemWindows=”false”属性即可，如果之前设置过着色模式，需要移除添加的假View，减少content_view的marginTop(减少StatusBar个高度)。

使用
1.着色模式:建议在setContentView后(可以防止childView为空导致的无效问题)调用setStatusBarColor()即可
2.沉浸模式:建议在setContentView后(可以防止childView为空导致的无效问题)调用translucentStatusBar()，这里要特别注意，这个会让content_view与StatusBar重叠，如果你有信息不想重叠，需要在layout的中指定你不相重叠的那个View的fitsSystemWindows的值为true。（实践中很容指定最外层的布局这个属性，发现没有与最上面的title颜色一致，是因为你指定的最外层实际改变的是最外层的padding，沉浸的自然是你最外层的背景，如果想让title颜色沉浸又不想被覆盖需要在title的View上指定fitsSystemWindows的值为true）