Android动态加载之插件开发

动态加载可以用来进行插件开发，这些插件大概都是为了在一个主程序中实现比较通用的功能，使主程序具有可扩展性。实现原理是实现一套插件接口，把插件实现编成apk或dex，在运行时用DexClassLoader动态加载进来。
预备知识：Android中的动态加载机制

插件演示

这里用了三个项目：

PInterface：插件接口项目（只是接口的定义）
PImplement：插件项目（实现插件接口，定义具体的功能）
HostProject：宿主项目（需要引用插件接口项目，然后动态加载插件项目）

项目介绍

下面看一下项目源代码：
1.PInterface项目

IBean.java

package com.pluginsdk.interfaces;

public abstract interface IBean{
  public abstract String getName();
  public abstract void setName(String paramString);
}

IDynamic.java

package com.pluginsdk.interfaces;

import android.content.Context;

public abstract interface IDynamic{
  public abstract void methodWithCallBack(YKCallBack paramYKCallBack);
  public abstract void showPluginWindow(Context paramContext);
  public abstract void startPluginActivity(Context context,Class<?> cls);
  public abstract String getStringForResId(Context context);
}

没有太多可说的，后面的代码可以下载项目之后自己看。

2.PImplement项目

Dynamic.java

package com.pluginsdk.pimplement;

import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;

import com.pluginsdk.R;
import com.pluginsdk.bean.Bean;
import com.pluginsdk.interfaces.IDynamic;
import com.pluginsdk.interfaces.YKCallBack;

public class Dynamic implements IDynamic{

    public void methodWithCallBack(YKCallBack callback) {
        Bean bean = new Bean();
        bean.setName("PLUGIN_SDK_USER");
        callback.callback(bean);
    }
    
    public void showPluginWindow(Context context) {
         AlertDialog.Builder builder = new Builder(context);
          builder.setMessage("对话框");
          builder.setTitle(R.string.hello_world);
          builder.setNegativeButton("取消", new Dialog.OnClickListener() {
               @Override
               public void onClick(DialogInterface dialog, int which) {
                   dialog.dismiss();
               }
              });
          Dialog dialog = builder.create();//.show();
          dialog.show();
    }
    
    public void startPluginActivity(Context context, Class<?> cls){
        /*
         * 这里要注意几点:
         * 1、如果单纯的写一个MainActivity的话，在主项目中也有一个MainActivity，开启的Activity还是主项目中的MainActivity
         * 2、如果这里将MainActivity写成全名的话，还是有问题，会报找不到这个Activity的错误
         */
        Intent intent = new Intent(context, cls);
        context.startActivity(intent);
    }
    
    public String getStringForResId(Context context){
        return context.getResources().getString(R.string.hello_world);
    }

}

Bean.java

package com.pluginsdk.bean;


public class Bean implements com.pluginsdk.interfaces.IBean{
    private String name = "这是来自于插件项目中设置的初始化的名字";

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

3.宿主项目HostProject

MainActivity.java

package com.plugindemo;
import java.io.File;
import java.lang.reflect.Method;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.res.AssetManager;
import android.content.res.Resources;
import android.content.res.Resources.Theme;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

import com.pluginsdk.interfaces.IBean;
import com.pluginsdk.interfaces.IDynamic;
import com.pluginsdk.interfaces.YKCallBack;

import dalvik.system.DexClassLoader;

public class MainActivity extends Activity {
    private AssetManager mAssetManager;//资源管理器
    private Resources mResources;//资源
    private Theme mTheme;//主题
    private String apkFileName = "Pimplement.apk";
    private String dexpath = null;//apk文件地址
    private File fileRelease = null; //释放目录
    private DexClassLoader classLoader = null;
    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        dexpath = getApplicationContext().getFilesDir().getAbsolutePath() + File.separator + apkFileName;
        fileRelease = getDir("dex", 0);
        
        /*初始化classloader
         * dexpath dex文件地址
         * fileRelease 文件释放地址 
         * 父classLoader
         */
        classLoader = new DexClassLoader(dexpath, fileRelease.getAbsolutePath(), null, getClassLoader());
        
        Button btn_1 = (Button)findViewById(R.id.btn_1);
        Button btn_2 = (Button)findViewById(R.id.btn_2);
        Button btn_3 = (Button)findViewById(R.id.btn_3);
        Button btn_4 = (Button)findViewById(R.id.btn_4);
        Button btn_5 = (Button)findViewById(R.id.btn_5);
        Button btn_6 = (Button)findViewById(R.id.btn_6);
        
        btn_1.setOnClickListener(new View.OnClickListener() {//普通调用  反射的方式
            @Override
            public void onClick(View v) {
                Class mLoadClassBean;
                try {
                    mLoadClassBean = classLoader.loadClass("com.pluginsdk.bean.Bean");
                    Object beanObject = mLoadClassBean.newInstance();
                    Log.d("DEMO", "ClassLoader:" + mLoadClassBean.getClassLoader());
                    Log.d("DEMO", "ClassLoader:" + mLoadClassBean.getClassLoader().getParent());
                    Method getNameMethod = mLoadClassBean.getMethod("getName");
                    getNameMethod.setAccessible(true);
                    String name = (String) getNameMethod.invoke(beanObject);
                    Toast.makeText(MainActivity.this, name, Toast.LENGTH_SHORT).show();
                } catch (Exception e) {
                    Log.e("DEMO", "msg:"+e.getMessage());
                } 
            }
        });
        btn_2.setOnClickListener(new View.OnClickListener() {//带参数调用
            @Override
            public void onClick(View arg0) {
                Class mLoadClassBean;
                try {
                    mLoadClassBean = classLoader.loadClass("com.pluginsdk.bean.Bean");
                    Object beanObject = mLoadClassBean.newInstance();
                    //接口形式调用
                    Log.d("DEMO", beanObject.getClass().getClassLoader()+"");
                    Log.d("DEMO",IBean.class.getClassLoader()+"");
                    Log.d("DEMO",ClassLoader.getSystemClassLoader()+"");
                    IBean bean = (IBean)beanObject;
                    bean.setName("宿主程序设置的新名字");
                    Toast.makeText(MainActivity.this, bean.getName(), Toast.LENGTH_SHORT).show();
                }catch (Exception e) {
                    Log.e("DEMO", "msg:"+e.getMessage());
                }
               
            }
        });
        btn_3.setOnClickListener(new View.OnClickListener() {//带回调函数的调用
            @Override
            public void onClick(View arg0) {
                Class mLoadClassDynamic;
                try {
                    mLoadClassDynamic = classLoader.loadClass("com.pluginsdk.pimplement.Dynamic");
                     Object dynamicObject = mLoadClassDynamic.newInstance();
                      //接口形式调用
                    IDynamic dynamic = (IDynamic)dynamicObject;
                    //回调函数调用
                    YKCallBack callback = new YKCallBack() {//回调接口的定义
                        public void callback(IBean arg0) {
                            Toast.makeText(MainActivity.this, arg0.getName(), Toast.LENGTH_SHORT).show();
                        };
                    };
                    dynamic.methodWithCallBack(callback);
                } catch (Exception e) {
                    Log.e("DEMO", "msg:"+e.getMessage());
                }
               
            }
        });
        btn_4.setOnClickListener(new View.OnClickListener() {//带资源文件的调用
            @Override
            public void onClick(View arg0) {
                loadResources();
                Class mLoadClassDynamic;
                try {
                    mLoadClassDynamic = classLoader.loadClass("com.pluginsdk.pimplement.Dynamic");
                    Object dynamicObject = mLoadClassDynamic.newInstance();
                    //接口形式调用
                    IDynamic dynamic = (IDynamic)dynamicObject;
                    dynamic.showPluginWindow(MainActivity.this);
                } catch (Exception e) {
                    Log.e("DEMO", "msg:"+e.getMessage());
                }
            }
        });
        btn_5.setOnClickListener(new View.OnClickListener() {//带资源文件的调用
            @Override
            public void onClick(View arg0) {
                loadResources();
                Class mLoadClassDynamic;
                try {
                    mLoadClassDynamic = classLoader.loadClass("com.pluginsdk.pimplement.Dynamic");
                    Object dynamicObject = mLoadClassDynamic.newInstance();
                    //接口形式调用
                    IDynamic dynamic = (IDynamic)dynamicObject;
                    dynamic.startPluginActivity(MainActivity.this,
                            classLoader.loadClass("com.plugindemo.MainActivity"));
                } catch (Exception e) {
                    Log.e("DEMO", "msg:"+e.getMessage());
                }
            }
        });
        btn_6.setOnClickListener(new View.OnClickListener() {//带资源文件的调用
            @Override
            public void onClick(View arg0) {
                loadResources();
                Class mLoadClassDynamic;
                try {
                    mLoadClassDynamic = classLoader.loadClass("com.pluginsdk.pimplement.Dynamic");
                    Object dynamicObject = mLoadClassDynamic.newInstance();
                    //接口形式调用
                    IDynamic dynamic = (IDynamic)dynamicObject;
                    String content = dynamic.getStringForResId(MainActivity.this);
                    Toast.makeText(getApplicationContext(), content+"", Toast.LENGTH_LONG).show();
                } catch (Exception e) {
                    Log.e("DEMO", "msg:"+e.getMessage());
                }
            }
        });
        
    }

     protected void loadResources() {
            try {
                AssetManager assetManager = AssetManager.class.newInstance();
                Method addAssetPath = assetManager.getClass().getMethod("addAssetPath", String.class);
                addAssetPath.invoke(assetManager, dexpath);
                mAssetManager = assetManager;
            } catch (Exception e) {
                e.printStackTrace();
            }
            Resources superRes = super.getResources();
            superRes.getDisplayMetrics();
            superRes.getConfiguration();
            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;
    }
}

项目引用关系

1.将接口项目PInterface设置成一个Library，

并导出项目为一个jar。

2.插件项目PImplement引用接口项目的jar
注意是lib文件夹，而不是libs，在Android中的动态加载机制
中说过这样做的原因：插件项目打包不能集成接口jar，宿主项目打包一定要集成接口jar。

3.HostProject项目引用PInterface这个Library

项目引用完成后，我们编译PImplement项目，生成PImplement.apk放到/data/data/com.plugindemo/files，因为代码中是从这个目录进行加载的，这个目录是可以修改的。运行HostProject

运行成功，这个对话框其实是在插件中定义的。
项目下载
reference
http://blog.csdn.net/jiangwei0910410003/article/details/41384667