android实现插件化

新建项目

新建一个项目，然后在项目中添加一个项目和一个module

 主项目中添加HookManager

import static android.os.Environment.DIRECTORY_DOWNLOADS;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.IntentFilter;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.res.AssetManager;
import android.content.res.Resources;
import android.os.Environment;
import android.widget.Toast;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.List;

import dalvik.system.DexClassLoader;

/**
 * Created by Dou on 2019/7/27.
 */
public class HookManager {
    private static final HookManager ourInstance = new HookManager();
    private Resources resources;
    private DexClassLoader loader;
    public PackageInfo packageInfo;

    public static HookManager getInstance() {
        return ourInstance;
    }

    private HookManager() {
    }


    //用来加载插件
    public void loadPlugin(Activity activity) {
        // 假如这里是从网络获取的插件 我们直接从sd卡获取 然后读取到我们的cache目录
        String pluginName = "plug-debug.apk";
        File filesDir = activity.getDir("plugin", activity.MODE_PRIVATE);
        String filePath = new File(filesDir, pluginName).getAbsolutePath();
        File file = new File(filePath);
        if (file.exists()) {
            file.delete();
        }
        File plug = new File(Environment.getExternalStoragePublicDirectory(DIRECTORY_DOWNLOADS) + "/" + pluginName);

        FileInputStream is = null;
        FileOutputStream os = null;
        //读取的目录
        try {
            is = new FileInputStream(plug);
            //要输入的目录
            os = new FileOutputStream(filePath);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        try {
            int len = 0;
            byte[] buffer = new byte[1024];
            while ((len = is.read(buffer)) != -1) {
                os.write(buffer, 0, len);
            }
            File f = new File(filePath);
            if (f.exists()) {
                Toast.makeText(activity, "加载完成", Toast.LENGTH_LONG).show();
            }
            loadPathToPlugin(activity);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            try {
                os.close();
                is.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }


    }

    private void loadPathToPlugin(Activity activity) {
        File filesDir = activity.getDir("plugin", activity.MODE_PRIVATE);
        String name = "plug-debug.apk";
        String path = new File(filesDir, name).getAbsolutePath();

        //然后我们开始加载我们的apk 使用DexClassLoader
        File dexOutDir = activity.getDir("dex", activity.MODE_PRIVATE);
        loader = new DexClassLoader(path, dexOutDir.getAbsolutePath(), null, activity.getClassLoader());

        //通过PackAgemanager 来获取插件的第一个activity是哪一个
        PackageManager packageManager = activity.getPackageManager();
        packageInfo = packageManager.getPackageArchiveInfo(path, PackageManager.GET_ACTIVITIES);


        //然后开始加载我们的资源 肯定要使用Resource 但是它是AssetManager创建出来的 就是AssertManager 有一个addAssertPath 这个方法 但是私有的 所有使用反射
        Class<?> assetManagerClass = AssetManager.class;
        try {
            AssetManager assertManagerObj = (AssetManager) assetManagerClass.newInstance();
            Method addAssetPathMethod = assetManagerClass.getMethod("addAssetPath", String.class);
            addAssetPathMethod.setAccessible(true);
            addAssetPathMethod.invoke(assertManagerObj, path);
            //在创建一个Resource
            resources = new Resources(assertManagerObj, activity.getResources().getDisplayMetrics(), activity.getResources().getConfiguration());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }



    public ClassLoader getClassLoader() {
        return loader;
    }

    public Resources getResource() {
        return resources;
    }
}

主项目中添加ProxyActivity

import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.res.Resources;
import android.os.Bundle;
import android.widget.Toast;


import androidx.appcompat.app.AppCompatActivity;

import com.example.baseinterface.ProxyActivityInterface;

import java.lang.reflect.Constructor;

/**
 * 类说明 一个占位的activity
 */
public class ProxyActivity extends AppCompatActivity {

    private ProxyActivityInterface pluginObj;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //在这里拿到了真实跳转的activity 拿出来 再去启动真实的activity

        String className = getIntent().getStringExtra("ClassName");

        //通过反射在去启动一个真实的activity 拿到Class对象
        try {
            Class<?> plugClass = getClassLoader().loadClass(className);
            Constructor<?> pluginConstructor = plugClass.getConstructor(new Class[]{});
            //因为插件的activity实现了我们的标准
            pluginObj = (ProxyActivityInterface) pluginConstructor.newInstance(new Object[]{});
            pluginObj.attach(this);//注入上下文
            pluginObj.onCreate(new Bundle());
        } catch (Exception e) {
            if (e.getClass().getSimpleName().endsWith("ClassCastException")) {
                finish();
                Toast.makeText(this, "不是插件类", Toast.LENGTH_LONG).show();
                return;
            }
            e.printStackTrace();
        }
    }

    @Override
    public void startActivity(Intent intent) {
        String className1 = intent.getStringExtra("ClassName");
        Intent intent1 = new Intent(this, ProxyActivity.class);
        intent1.putExtra("ClassName", className1);
        super.startActivity(intent1);
    }

    @Override
    public ClassLoader getClassLoader() {
        return HookManager.getInstance().getClassLoader();
    }

    @Override
    public Resources getResources() {
        return HookManager.getInstance().getResource();
    }

    @Override
    protected void onStart() {
        super.onStart();
        pluginObj.onStart();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        pluginObj.onDestroy();
    }

    @Override
    protected void onPause() {
        super.onPause();
        pluginObj.onPause();
    }
}

MainActivity中的两个方法，加载插件和跳转操作

    private void loadPlugin() {
        HookManager.getInstance().loadPlugin(this);

    }

    /**
     * 跳转插件
     */
    private void startProxy() {
        //
        Intent intent = new Intent(this, ProxyActivity.class);
        intent.putExtra("ClassName", HookManager.getInstance().packageInfo.activities[0].name);
        //intent.putExtra("ClassName", "MainActivity");

        startActivity(intent);
    }

权限和activity声明添加到manifest

<activity android:name=".ProxyActivity" />

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission
        android:name="android.permission.WRITE_EXTERNAL_STORAGE"
        android:maxSdkVersion="28" />
    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
        tools:ignore="ScopedStorage" />

module中添加interface

public interface ProxyActivityInterface {

    //生命周期的activity

    public void attach(Activity proxyActivity);

    public void onCreate(Bundle savedInstanceState);

    public void onStart();

    public void onPause();

    public void onDestroy();

}

插件项目中添加BaseActivity

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.ApplicationInfo;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

import androidx.annotation.NonNull;

import com.example.baseinterface.ProxyActivityInterface;


/**
 * Created by Dou on 2019/7/27.
 * <p>
 * 和上下文有关的方法都要重写
 */
public class BaseActivity extends Activity implements ProxyActivityInterface {
    public Activity that;

    @Override
    public void attach(Activity proxyActivity) {
        that = proxyActivity;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
    }

    @Override
    public void onStart() {

    }

    @Override
    public void onPause() {

    }

    @Override
    public void onDestroy() {

    }

    @Override
    public void setContentView(View view) {
        if (that != null) {
            Log.e("---","taht=null");
            that.setContentView(view);
        } else {
            super.setContentView(view);
        }
    }

    @Override
    public void setContentView(int layoutResID) {
        that.setContentView(layoutResID);
    }

    @Override
    public View findViewById(int id) {
        return that.findViewById(id);
    }

    @Override
    public Intent getIntent() {
        if (that != null) {
            return that.getIntent();
        }
        return super.getIntent();
    }

    @Override
    public ClassLoader getClassLoader() {
        return that.getClassLoader();
    }

    @NonNull
    @Override
    public LayoutInflater getLayoutInflater() {
        return that.getLayoutInflater();
    }

    @Override
    public ApplicationInfo getApplicationInfo() {
        return that.getApplicationInfo();
    }

    @Override
    public Window getWindow() {
        return that.getWindow();
    }


    @Override
    public WindowManager getWindowManager() {
        return that.getWindowManager();
    }

    @Override
    public void startActivity(Intent intent) {
        Intent m = new Intent();
        m.putExtra("ClassName", intent.getComponent().getClassName());
        that.startActivity(m);
    }

    @Override
    public Intent registerReceiver(BroadcastReceiver receiver, IntentFilter filter) {
        return that.registerReceiver(receiver, filter);
    }

    @Override
    public void sendBroadcast(Intent intent) {
        that.sendBroadcast(intent);
    }



    @Override
    public void onSaveInstanceState(Bundle outState) {

    }
}

插件中的编程和正常的一样，只是要继承BaseActivity

 如果遇到打开插件后页面空白就把build删除后重新编译即可

Attempt to read from field 'java.lang.String android.content.pm.ActivityInfo.parentActivityName' on a null object reference

如果加载就闪退是因为你没开权限