如果对Android的ClassLoader加载机制不熟悉，猛戳Android插件化开发动态加载基础之ClassLoader工作机制 http://blog.csdn.net/u011068702/article/details/53248960
PathClassLoader：只能加载已经安装搭配Android系统中的apk文件
package com.example.testclassloader;
public interface ShowString {
public String sayChenyu();
}
package com.example.testclassloader;
import android.util.Log;
public class ShowStringClass implements ShowString{
public static final String TAG = "ShowStringClass";
@Override
public String sayChenyu() {
String chenyu = "chenyu";
Log.i(TAG, chenyu);
return chenyu;
}
}
dx --dex --output=showStringClass_impl.jar showStringClass.jar然后再把showStringClass_impl.jar文件放到手机目录里面去用这个命令
adb push showStringClass_impl.jar /sdcard/具体操作图片如下
package com.example.testclassloader;
import java.io.File;
import android.content.Context;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.widget.TextView;
import dalvik.system.DexClassLoader;
public class MainActivity extends ActionBarActivity {
public static final String TAG = "MainActivityClassLoader";
public static final String SHOWSTRINGCLASS = "showStringClass_impl.jar";
public static final String SHOWSTRINGCLASS_PATH= "com.example.testclassloader.ShowStringClass";
public static final String DEX = "dex";
public ShowStringClass mShowStringClass = null;
public TextView mTv = null;
public int i = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTv = (TextView)findViewById(R.id.hello);
DexClassLoader(this);
}
/**
* 使用DexClassLoader方式加载类
*/
public void DexClassLoader(Context context) {
// dex压缩文件的路径（可以是apk,jar,zip格式）
String dexPath = Environment.getExternalStorageDirectory().toString() + File.separator + SHOWSTRINGCLASS;
// dex解压释放后的目录
String dexOutputDirs = Environment.getExternalStorageDirectory().toString();
//指定dexoutputpath为APP自己的缓存目录
File dexOutputDir = context.getDir(DEX, 0);
// 定义DexClassLoader
// 第一个参数：是dex压缩文件的路径
// 第二个参数：是dex解压缩后存放的目录
// 第三个参数：是C/C++依赖的本地库文件目录,可以为null
// 第四个参数：是上一级的类加载器
//DexClassLoader dexClassLoader = new DexClassLoader(dexPath,dexOutputDirs,null,getClassLoader());
DexClassLoader dexClassLoader = new DexClassLoader(dexPath,dexOutputDir.getAbsolutePath(),null,getClassLoader());
Class libProvierClazz = null;
// 使用DexClassLoader加载类
try {
libProvierClazz = dexClassLoader.loadClass(SHOWSTRINGCLASS_PATH);
// 创建dynamic实例
mShowStringClass = (ShowStringClass) libProvierClazz.newInstance();
if (mShowStringClass != null) {
final String chenyu = mShowStringClass.sayChenyu();
if (chenyu != null) {
mTv.post(new Runnable() {
@Override
public void run() {
mTv.setText(chenyu);
}
});
}
} else {
Log.d(TAG, "mShowStringClass is null");
}
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 打印系统的classLoader
*/
public void showClassLoader() {
ClassLoader classLoader = getClassLoader();
if (classLoader != null){
Log.i(TAG, "[onCreate] classLoader " + i + " : " + classLoader.toString());
while (classLoader.getParent()!=null){
classLoader = classLoader.getParent();
Log.i(TAG,"[onCreate] classLoader " + i + " : " + classLoader.toString());
i++;
}
}
}
}
DexClassLoader dexClassLoader = new DexClassLoader(dexPath,dexOutputDirs,null,getClassLoader());会报下面的错误
//指定dexoutputpath为APP自己的缓存目录
File dexOutputDir = context.getDir(DEX, 0);Android插件化开发之DexClassLoader动态加载dex、jar小Demo
原文：http://blog.csdn.net/u011068702/article/details/53263442