Android插件化初探之apk加载和反射调用函数

分类：Android, Java 阅读 (1,326)

12月 022019

转载请注明原文地址：http://bcoder.com/java/android-plugin-develop-start-load-apk-and-invoke-method-by-reflecting

一、整体试验步骤

1.建立子apk，新建一个android应用项目，叫firstplugin

2.在java根目录下新建一个类，叫LoginImpl

3.在LoginImpl.java中实现一个静态方法, login()，此方法只输出一个Log

package com.zht.car.firstplugin;

import android.util.Log;
import android.widget.Toast;

public class LoginImpl {
    public static void login(){
        Log.i("LoginImpl", "login");
    }
}

package com.zht.car.firstplugin;

import android.util.Log;

import android.widget.Toast;

public class LoginImpl {

public static void login(){

Log.i("LoginImpl", "login");

}

4.编译生成apk，push到手机的/sdcard目录，此处生成的文件名为firstplugin-debug.apk

5.开始建宿主apk，新建另外一个Android应用项目PlugInHostApp

6.在MainActivity的onCreate中增加如下代码：

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        String dexOutputDir = getApplicationInfo().dataDir;

        String apkpath = "/sdcard/firstplugin-debug.apk";
        DexClassLoader loader = new DexClassLoader(apkpath, dexOutputDir,
                null,getClass().getClassLoader());
        try {
            Class&lt;?&gt; aClass = loader.loadClass("com.zht.car.firstplugin.LoginImpl");
            Object aClassInstance = aClass.newInstance();
            Method method = aClass.getMethod("login");
            method.invoke(null, null);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

String dexOutputDir = getApplicationInfo().dataDir;

String apkpath = "/sdcard/firstplugin-debug.apk";

DexClassLoader loader = new DexClassLoader(apkpath, dexOutputDir,

null,getClass().getClassLoader());

try {

Class<?> aClass = loader.loadClass("com.zht.car.firstplugin.LoginImpl");

Object aClassInstance = aClass.newInstance();

Method method = aClass.getMethod("login");

method.invoke(null, null);

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (InstantiationException e) {

e.printStackTrace();

} catch (NoSuchMethodException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

}

7.编译运行，看log中是否输出了login这个字符串

二、遇到的问题和解决方法

1.java.lang.ClassNotFoundException: Didn’t find class “com.zht.car.firstplugin.LoginImpl” on path错误

解决方法：

查看是否有访问外部存储目录的权限（笔者遇到的就是这个问题，程序不会在new DexClassLoader时报无权限访问或者找不到文件的错误，而会在loadClass时报找不到类的错误）
关闭Android Studio的Instant run选项，在菜单Settings->Build, Execution, Deployment中（笔者是在Ubuntu中使用Android Studio，没找到此选项）

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