將Android打包成jar包供人使用，可利用java的反射技術，獲取相應的id.方便使用者替換自己所需要的。

1.新建Android專案：ActivityLibrary，這就是需要我們打包成jar包的專案：

2.MResource這個類的作用，就是利用J2SE反射技術獲取相應的ID資源。Android SDK也提供了獲取Id資源的方法：getResources().getIdentifier("main_activity", "layout", getPackageName());

看下MResource的程式碼：

package com.example.activitylibrary;

import android.content.Context;

/** 
 * 根據資源的名字獲取其ID值 
 * @author howlaa
 */ 
public class MResource {
	
	//根據名稱獲取ID
    public static int getIdByName(Context context, String className, String name) {  
        String packageName = context.getPackageName();  
        Class r = null;  
        int id = 0;  
        try{  
            r = Class.forName(packageName + ".R");  
            Class[] classes = r.getClasses();  
            Class desireClass = null;  
            for (int i = 0; i < classes.length; ++i) {  
                if (classes[i].getName().split("\\$")[1].equals(className)) {  
                    desireClass = classes[i];  
                    break;  
                }  
            }  
         if (desireClass != null)  
         id = desireClass.getField(name).getInt(desireClass);  
        } catch (ClassNotFoundException e) {  
            e.printStackTrace();  
        } catch (IllegalArgumentException e) {  
            e.printStackTrace();  
        } catch (SecurityException e) {  
            e.printStackTrace();  
        } catch (IllegalAccessException e) {  
            e.printStackTrace();  
        } catch (NoSuchFieldException e) {  
            e.printStackTrace();  
        }  
        return id;  
    }
    
    //獲取ID陣列
    public static int[] getIdsByName(Context context, String className, String name) {  
        String packageName = context.getPackageName();  
        Class r = null;  
        int[] ids = null;  
        try {  
          r = Class.forName(packageName + ".R");  
      
          Class[] classes = r.getClasses();  
          Class desireClass = null;  
      
          for (int i = 0; i < classes.length; ++i) {  
            if (classes[i].getName().split("\\$")[1].equals(className)) {  
              desireClass = classes[i];  
              break;  
            }  
          }  
      
          if ((desireClass != null) && (desireClass.getField(name).get(desireClass) != null) && (desireClass.getField(name).get(desireClass).getClass().isArray()))  
            ids = (int[])desireClass.getField(name).get(desireClass);  
        }  
        catch (ClassNotFoundException e) {  
          e.printStackTrace();  
        } catch (IllegalArgumentException e) {  
          e.printStackTrace();  
        } catch (SecurityException e) {  
          e.printStackTrace();  
        } catch (IllegalAccessException e) {  
          e.printStackTrace();  
        } catch (NoSuchFieldException e) {  
          e.printStackTrace();  
        }  
      
        return ids;  
      } 
}
 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/button1" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="28dp"
        android:src="@drawable/ic_launcher" />

</RelativeLayout>
 

package com.example.activitylibrary;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.app.Activity;

public class MainActivity extends Activity {
	
	String msg = "hello bitch";  
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(MResource.getIdByName(getApplication(), "layout", "activity_main"));
		
		TextView mTextView = (TextView) findViewById(MResource.getIdByName(getApplication(), "id", "textView1")); 
		mTextView.setText(msg);  
		
		Button mButton = (Button) findViewById(MResource.getIdByName(getApplication(), "id", "button1"));  
        
        mButton.setText(msg);  
        mButton.setOnClickListener(new OnClickListener() {  
              
            @Override  
            public void onClick(View v) {  
                Toast.makeText(getApplication(), msg, Toast.LENGTH_SHORT).show();  
            }  
        });  
	}

}
 

只需要SRC裡面的程式碼就可以了。其他的去掉

6.新建一個專案APP2，使用剛才的jar包。把剛才匯出的jar包拷貝到libs下面,把原來的資原始檔拷貝過去。或者自己新建一個layout的資原始檔，id要和之前的對應。

7.假如我們想使用上個專案中的mainactivity介面：我們可以在此有個跳轉的程式碼：

public void btnClick(View view){
		Intent intent = new Intent();  
        intent.setClassName(getApplication(), "com.example.activitylibrary.MainActivity");  
        startActivity(intent);  
	}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.app2"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.app2.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name="com.example.activitylibrary.MainActivity"></activity>
    </application>

</manifest>