--《摘自android插件化开发指南》
1.有些项目，整个app只有一个Activity，切换页面全靠Fragment，盛行过一时，但有点极端
2.Activity切换fragment页面
第一步：FragmentLoaderActivity作为Fragment的承载容器
<activity android:name=".FragmentLoaderActivity">
<intent-filter>
<action android:name="jianqiang.com.hostapp.VIEW" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
public class BaseHostActivity extends Activity {
private AssetManager mAssetManager;
private Resources mResources;
private Theme mTheme;
protected String mDexPath;
protected ClassLoader dexClassLoader;
protected void loadClassLoader() {
File dexOutputDir = this.getDir("dex", Context.MODE_PRIVATE);
final String dexOutputPath = dexOutputDir.getAbsolutePath();
dexClassLoader = new DexClassLoader(mDexPath,
dexOutputPath, null, getClassLoader());
}
protected void loadResources() {
try {
AssetManager assetManager = AssetManager.class.newInstance();
Method addAssetPath = assetManager.getClass().getMethod("addAssetPath", String.class);
addAssetPath.invoke(assetManager, mDexPath);
mAssetManager = assetManager;
} catch (Exception e) {
e.printStackTrace();
}
Resources superRes = super.getResources();
mResources = new Resources(mAssetManager, superRes.getDisplayMetrics(),
superRes.getConfiguration());
mTheme = mResources.newTheme();
mTheme.setTo(super.getTheme());
}
@Override
public AssetManager getAssets() {
return mAssetManager == null ? super.getAssets() : mAssetManager;
}
@Override
public Resources getResources() {
return mResources == null ? super.getResources() : mResources;
}
@Override
public Theme getTheme() {
return mTheme == null ? super.getTheme() : mTheme;
}
}
public class FragmentLoaderActivity extends BaseHostActivity {
private String mClass;
@Override
protected void onCreate(Bundle savedInstanceState) {
mDexPath = getIntent().getStringExtra(AppConstants.EXTRA_DEX_PATH);
mClass = getIntent().getStringExtra(AppConstants.EXTRA_CLASS);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fragment_loader);
loadClassLoader();
loadResources();
try {
//反射出插件的Fragment对象
Class<?> localClass = dexClassLoader.loadClass(mClass);
Constructor<?> localConstructor = localClass.getConstructor(new Class[] {});
Object instance = localConstructor.newInstance(new Object[] {});
Fragment f = (Fragment) instance;
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.container, f);
ft.commit();
} catch (Exception e) {
Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();
}
}
}
第二步：
MainActivity跳转到FragmentLoaderActivity，传两个参数（dexPath和fragment的名称），FragmentLoaderActivity根据参数加载对应的Fragment
Intent intent = new Intent(AppConstants.ACTION);
intent.putExtra(AppConstants.EXTRA_DEX_PATH, mPluginItems.get(position).pluginPath);
intent.putExtra(AppConstants.EXTRA_CLASS, mPluginItems.get(position).packageInfo.packageName + ".Fragment1");
startActivity(intent);
3.插件内部的Fragment跳转
public class BaseFragment extends Fragment {
private int containerId;
public int getContainerId() {
return containerId;
}
public void setContainerId(int containerId) {
this.containerId = containerId;
}
}
public class Fragment2 extends BaseFragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment2, container, false);
if (getArguments() != null) {
String username = getArguments().getString("username");
TextView tv = (TextView)view.findViewById(R.id.label);
tv.setText(username);
}
view.findViewById(R.id.btnReturn).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
//从栈中将当前fragment推出
getFragmentManager().popBackStack();
}
});
return view;
}
}
public class Fragment1 extends BaseFragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment1, container, false);
view.findViewById(R.id.load_fragment2_btn).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Fragment2 fragment2 = new Fragment2();
Bundle args = new Bundle();
args.putString("username", "baobao");
fragment2.setArguments(args);
getFragmentManager()
.beginTransaction()
.addToBackStack(null) //将当前fragment加入到返回栈中
.replace(Fragment1.this.getContainerId(), fragment2).commit();
}
});
return view;
}
}
其实就是利用FragmentManager动态切换Fragment技术来实现
4.插件Fragment跳转插件外部的Fragment（包括宿主中的，另一个插件中的）
第一步：把宿主和插件的资源都合并到一起，这样就能想用哪个资源就用哪个资源
public class PluginManager {
public final static List<PluginItem> plugins = new ArrayList<PluginItem>();
//正在使用的Resources
public static volatile Resources mNowResources;
//原始的application中的BaseContext，不能是其他的，否则会内存泄漏
public static volatile Context mBaseContext;
//ContextImpl中的LoadedAPK对象mPackageInfo
private static Object mPackageInfo = null;
public static void init(Application application) {
//初始化一些成员变量和加载已安装的插件
mPackageInfo = RefInvoke.getFieldObject(application.getBaseContext(), "mPackageInfo");
mBaseContext = application.getBaseContext();
mNowResources = mBaseContext.getResources();
try {
AssetManager assetManager = application.getAssets();
String[] paths = assetManager.list("");
ArrayList<String> pluginPaths = new ArrayList<String>();
for(String path : paths) {
if(path.endsWith(".apk")) {
String apkName = path;
PluginItem item = generatePluginItem(apkName);
plugins.add(item);
Utils.extractAssets(mBaseContext, apkName);
pluginPaths.add(item.pluginPath);
}
}
reloadInstalledPluginResources(pluginPaths);
} catch (Exception e) {
e.printStackTrace();
}
}
private static PluginItem generatePluginItem(String apkName) {
File file = mBaseContext.getFileStreamPath(apkName);
PluginItem item = new PluginItem();
item.pluginPath = file.getAbsolutePath();
item.packageInfo = DLUtils.getPackageInfo(mBaseContext, item.pluginPath);
return item;
}
private static void reloadInstalledPluginResources(ArrayList<String> pluginPaths) {
try {
AssetManager assetManager = AssetManager.class.newInstance();
Method addAssetPath = AssetManager.class.getMethod("addAssetPath", String.class);
addAssetPath.invoke(assetManager, mBaseContext.getPackageResourcePath());
for(String pluginPath: pluginPaths) {
addAssetPath.invoke(assetManager, pluginPath);
}
Resources newResources = new Resources(assetManager,
mBaseContext.getResources().getDisplayMetrics(),
mBaseContext.getResources().getConfiguration());
RefInvoke.setFieldObject(mBaseContext, "mResources", newResources);
//这是最主要的需要替换的，如果不支持插件运行时更新，只留这一个就可以了
RefInvoke.setFieldObject(mPackageInfo, "mResources", newResources);
//清除一下之前的resource的数据，释放一些内存
//因为这个resource有可能还被系统持有着，内存都没被释放
//clearResoucesDrawableCache(mNowResources);
mNowResources = newResources;
//需要清理mtheme对象，否则通过inflate方式加载资源会报错
//如果是activity动态加载插件，则需要把activity的mTheme对象也设置为null
RefInvoke.setFieldObject(mBaseContext, "mTheme", null);
} catch (Throwable e) {
e.printStackTrace();
}
}
}
第二步：把所有的插件的ClassLoader都放进一个集合MyClassLoaders，在FragmentLoaderActivity中，使用MyClassLoaders来加载相应插件的Fragment
public class MyClassLoaders {
public static final HashMap<String, DexClassLoader> classLoaders = new HashMap<String, DexClassLoader>();
}
public class FragmentLoaderActivity extends Activity {
private DexClassLoader classLoader;
@Override
protected void onCreate(Bundle savedInstanceState) {
//String pluginName = getIntent().getStringExtra(AppConstants.EXTRA_PLUGIN_NAME);
String mClass = getIntent().getStringExtra(AppConstants.EXTRA_CLASS);
String mDexPath = getIntent().getStringExtra(AppConstants.EXTRA_DEX_PATH);
classLoader = MyClassLoaders.classLoaders.get(mDexPath);
super.onCreate(savedInstanceState);
FrameLayout rootView = new FrameLayout(this);
rootView.setLayoutParams(new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT));
rootView.setId(android.R.id.primary);
setContentView(rootView);
BaseFragment fragment = null;
try {
if(classLoader == null) {
fragment = (BaseFragment) getClassLoader().loadClass(mClass).newInstance();
} else {
fragment = (BaseFragment) classLoader.loadClass(mClass).newInstance();
}
fragment.setContainerId(android.R.id.primary);
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(android.R.id.primary, fragment);
ft.commit();
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public Resources getResources() {
return PluginManager.mNowResources;
}
}
fragment插件化的好处避开了Activity必须要面对AMS的尴尬
