雙親委托

某個(gè)類加載時(shí)，首先委托給parent加載，依次遞歸，如果parent可以拿到對(duì)象則返回，否則由子類獲取

優(yōu)點(diǎn)

1. 避免重復(fù)加載
2. 安全考慮，防止核心API被修改

    protected Class<?> loadClass(String name, boolean resolve)
        throws ClassNotFoundException
    {
            // First, check if the class has already been loaded
            Class<?> c = findLoadedClass(name);
            if (c == null) {
                try {
                    if (parent != null) {
                        c = parent.loadClass(name, false);
                    } else {
                        c = findBootstrapClassOrNull(name);
                    }
                } catch (ClassNotFoundException e) {
                    // ClassNotFoundException thrown if class not found
                    // from the non-null parent class loader
                }

                if (c == null) {
                    // If still not found, then invoke findClass in order
                    // to find the class.
                    c = findClass(name);
                }
            }
            return c;
    }

熱修復(fù)

類加載是有先后順序，
首先獲取到當(dāng)前應(yīng)用PathClassLoader，通過反射獲取到DexPathList的pathList；修改pathList中的dexElements，

1. 把補(bǔ)丁包patch.dex轉(zhuǎn)化為Element[] patch
2. 獲取到dexElement對(duì)象屬性

3. patch+Dexelement合并，并反射賦值給dexElements

   
   
   image.png

image.png

AndFix

反射 類加載

image.png

參考：https://www.bilibili.com/video/BV1tS4y1r7qe/?spm_id_from=333.880.my_history.page.click&vd_source=5e4ad34e631c98068c626ad8a062e008