android 插件化atlas,Atlas插件化踩坑

最近在使用Altas插件化框架，遇到了一些问题，记录下

bundle传值报class not found

我们给bundle传了一个继承Serializable的对象，但是在4.x的系统里，报了class not found的异常

at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:53)

at java.lang.ClassLoader.loadClass(ClassLoader.java:501)

at java.lang.ClassLoader.loadClass(ClassLoader.java:461)

at java.lang.Class.classForName(Native Method)

at java.lang.Class.forName(Class.java:217)

at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:2304)

at java.io.ObjectInputStream.readNewClassDesc(ObjectInputStream.java:1663)

at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:683)

at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:1806)

at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:787)

at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2006)

at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1963)

at android.os.Parcel.readSerializable(Parcel.java:2142)

at android.os.Parcel.readValue(Parcel.java:2016)

at android.os.Parcel.readMapInternal(Parcel.java:2226)

at android.os.Bundle.unparcel(Bundle.java:223)

at android.os.Bundle.getString(Bundle.java:1055)

at android.content.Intent.getStringExtra(Intent.java:4488)

显然不是bundle的classloader，但是altas怎么控制解析时classloader的查找呢。根据研究altas源码发现，在查找bundle前，已经给intent设置了classloader

//InstrumentationHook.java

@Override

public void callActivityOnCreate(Activity activity, Bundle icicle) {

if(activity.getIntent()!=null){

activity.getIntent().setExtrasClassLoader(RuntimeVariables.delegateClassLoader);

}

}

但是这个代码居然没用，于是我们进一步分析，发现了关键问题。

因为ObjectInputStream的查找类的时候，是通过vmstack来查找最近的classloader的，这是不靠谱的。

protected Class> resolveClass(ObjectStreamClass desc)

throws IOException, ClassNotFoundException

{

String name = desc.getName();

try {

return Class.forName(name, false, latestUserDefinedLoader());

} catch (ClassNotFoundException ex) {

Class> cl = primClasses.get(name);

if (cl != null) {

return cl;

} else {

throw ex;

}

}

}

就是这里导致了bug，但是为啥5.0以上没问题呢。通过研究源码发现，5.0的代码，重写了resolveClass这个方法

// 19

2196 public final Serializable readSerializable() {

2197 String name = readString();

2198 if (name == null) {

2199 // For some reason we were unable to read the name of the Serializable (either there

2200 // is nothing left in the Parcel to read, or the next value wasn't a String), so

2201 // return null, which indicates that the name wasn't found in the parcel.

2202 return null;

2203 }

2204

2205 byte[] serializedData = createByteArray();

2206 ByteArrayInputStream bais = new ByteArrayInputStream(serializedData);

2207 try {

2208 ObjectInputStream ois = new ObjectInputStream(bais);

2209 return (Serializable) ois.readObject();

2210 } catch (IOException ioe) {

2211 throw new RuntimeException("Parcelable encountered " +

2212 "IOException reading a Serializable object (name = " + name +

2213 ")", ioe);

2214 } catch (ClassNotFoundException cnfe) {

2215 throw new RuntimeException("Parcelable encountered" +

2216 "ClassNotFoundException reading a Serializable object (name = "

2217 + name + ")", cnfe);

2218 }

2219 }

// 25

private final Serializable readSerializable(final ClassLoader loader) {

String name = readString();

if (name == null) {

// For some reason we were unable to read the name of the Serializable (either there

// is nothing left in the Parcel to read, or the next value wasn't a String), so

// return null, which indicates that the name wasn't found in the parcel.

return null;

}

byte[] serializedData = createByteArray();

ByteArrayInputStream bais = new ByteArrayInputStream(serializedData);

try {

ObjectInputStream ois = new ObjectInputStream(bais) {

@Override

protected Class> resolveClass(ObjectStreamClass osClass)

throws IOException, ClassNotFoundException {

// try the custom classloader if provided

if (loader != null) {

Class> c = Class.forName(osClass.getName(), false, loader);

if (c != null) {

return c;

}

}1

return super.resolveClass(osClass);

}

};

return (Serializable) ois.readObject();

} catch (IOException ioe) {

throw new RuntimeException("Parcelable encountered " +

"IOException reading a Serializable object (name = " + name +

")", ioe);

} catch (ClassNotFoundException cnfe) {

throw new RuntimeException("Parcelable encountered " +

"ClassNotFoundException reading a Serializable object (name = "

+ name + ")", cnfe);

}

}