android - 如何为 android.os.systemproperties 设置反射？

Question

所以我试图让这个应用程序从反射中调用 android.os.SystemProperties 但它有点痛苦，所以如果有人能提供帮助，我们将不胜感激。

所以这是让我失望的代码部分:

        String str1 = SystemPropertiesProxy.get("ro.url.changelog");
        String str2 = SystemPropertiesProxy.get("ro.build.incremental");
        String str4 = String.format("?version=%s", str2);
        Object[] arrayOfObject1 = new Object[2];
        arrayOfObject1[0] = str1;
        arrayOfObject1[1] = str4;
        String str5 = String.format("%s%s", arrayOfObject1);
        ...
        myWebView.loadUrl(str5);

上面的代码给我错误:“String str1 = SystemPropertiesProxy.get(”ro.url.变更日志”)”这是我试图设置为访问 android.os.SystemProperties 的反射代码:

package com.package.name;

import java.io.File;  
import java.lang.reflect.Method;
import android.content.Context;
import dalvik.system.DexFile;


public class SystemPropertiesProxy
{

/**
 * This class cannot be instantiated
 */
private SystemPropertiesProxy(){

}

/**
 * Get the value for the given key.
 * @return an empty string if the key isn't found
 * @throws IllegalArgumentException if the key exceeds 32 characters
 */
public static String get(Context context, String key) throws IllegalArgumentException {

    String ret= "";

    try{

      ClassLoader cl = context.getClassLoader(); 
      @SuppressWarnings("rawtypes")
      Class SystemProperties = cl.loadClass("android.os.SystemProperties");

      //Parameters Types
      @SuppressWarnings("rawtypes")
      Class[] paramTypes= new Class[1];
      paramTypes[0]= String.class;

      Method get = SystemProperties.getMethod("get", paramTypes);

      //Parameters
      Object[] params= new Object[1];
      params[0]= new String(key);

      ret= (String) get.invoke(SystemProperties, params);

    }catch( IllegalArgumentException iAE ){
        throw iAE;
    }catch( Exception e ){
        ret= "";
        //TODO
    }

    return ret;

}

/**
 * Get the value for the given key.
 * @return if the key isn't found, return def if it isn't null, or an empty string otherwise
 * @throws IllegalArgumentException if the key exceeds 32 characters
 */
public static String get(Context context, String key, String def) throws IllegalArgumentException {

    String ret= def;

    try{

      ClassLoader cl = context.getClassLoader(); 
      @SuppressWarnings("rawtypes")
      Class SystemProperties = cl.loadClass("android.os.SystemProperties");

      //Parameters Types
      @SuppressWarnings("rawtypes")
      Class[] paramTypes= new Class[2];
      paramTypes[0]= String.class;
      paramTypes[1]= String.class;          

      Method get = SystemProperties.getMethod("get", paramTypes);

      //Parameters
      Object[] params= new Object[2];
      params[0]= new String(key);
      params[1]= new String(def);

      ret= (String) get.invoke(SystemProperties, params);

    }catch( IllegalArgumentException iAE ){
        throw iAE;
    }catch( Exception e ){
        ret= def;
        //TODO
    }

    return ret;

}

/**
 * Get the value for the given key, and return as an integer.
 * @param key the key to lookup
 * @param def a default value to return
 * @return the key parsed as an integer, or def if the key isn't found or
 *         cannot be parsed
 * @throws IllegalArgumentException if the key exceeds 32 characters
 */
public static Integer getInt(Context context, String key, int def) throws IllegalArgumentException {

    Integer ret= def;

    try{

      ClassLoader cl = context.getClassLoader(); 
      @SuppressWarnings("rawtypes")
      Class SystemProperties = cl.loadClass("android.os.SystemProperties");

      //Parameters Types
      @SuppressWarnings("rawtypes")
      Class[] paramTypes= new Class[2];
      paramTypes[0]= String.class;
      paramTypes[1]= int.class;  

      Method getInt = SystemProperties.getMethod("getInt", paramTypes);

      //Parameters
      Object[] params= new Object[2];
      params[0]= new String(key);
      params[1]= new Integer(def);

      ret= (Integer) getInt.invoke(SystemProperties, params);

    }catch( IllegalArgumentException iAE ){
        throw iAE;
    }catch( Exception e ){
        ret= def;
        //TODO
    }

    return ret;

}

/**
 * Get the value for the given key, and return as a long.
 * @param key the key to lookup
 * @param def a default value to return
 * @return the key parsed as a long, or def if the key isn't found or
 *         cannot be parsed
 * @throws IllegalArgumentException if the key exceeds 32 characters
 */
public static Long getLong(Context context, String key, long def) throws IllegalArgumentException {

    Long ret= def;

    try{

      ClassLoader cl = context.getClassLoader();
      @SuppressWarnings("rawtypes")
      Class SystemProperties= cl.loadClass("android.os.SystemProperties");

      //Parameters Types
      @SuppressWarnings("rawtypes")
      Class[] paramTypes= new Class[2];
      paramTypes[0]= String.class;
      paramTypes[1]= long.class;  

      Method getLong = SystemProperties.getMethod("getLong", paramTypes);

      //Parameters
      Object[] params= new Object[2];
      params[0]= new String(key);
      params[1]= new Long(def);

      ret= (Long) getLong.invoke(SystemProperties, params);

    }catch( IllegalArgumentException iAE ){
        throw iAE;
    }catch( Exception e ){
        ret= def;
        //TODO
    }

    return ret;

}

/**
 * Get the value for the given key, returned as a boolean.
 * Values 'n', 'no', '0', 'false' or 'off' are considered false.
 * Values 'y', 'yes', '1', 'true' or 'on' are considered true.
 * (case insensitive).
 * If the key does not exist, or has any other value, then the default
 * result is returned.
 * @param key the key to lookup
 * @param def a default value to return
 * @return the key parsed as a boolean, or def if the key isn't found or is
 *         not able to be parsed as a boolean.
 * @throws IllegalArgumentException if the key exceeds 32 characters
 */
public static Boolean getBoolean(Context context, String key, boolean def) throws IllegalArgumentException {

    Boolean ret= def;

    try{

      ClassLoader cl = context.getClassLoader(); 
      @SuppressWarnings("rawtypes")
      Class SystemProperties = cl.loadClass("android.os.SystemProperties");

      //Parameters Types
      @SuppressWarnings("rawtypes")
      Class[] paramTypes= new Class[2];
      paramTypes[0]= String.class;
      paramTypes[1]= boolean.class;  

      Method getBoolean = SystemProperties.getMethod("getBoolean", paramTypes);

      //Parameters         
      Object[] params= new Object[2];
      params[0]= new String(key);
      params[1]= new Boolean(def);

      ret= (Boolean) getBoolean.invoke(SystemProperties, params);

    }catch( IllegalArgumentException iAE ){
        throw iAE;
    }catch( Exception e ){
        ret= def;
        //TODO
    }

    return ret;

}

/**
 * Set the value for the given key.
 * @throws IllegalArgumentException if the key exceeds 32 characters
 * @throws IllegalArgumentException if the value exceeds 92 characters
 */
public static void set(Context context, String key, String val) throws IllegalArgumentException {

    try{

      @SuppressWarnings("unused")
      DexFile df = new DexFile(new File("/system/app/Settings.apk"));
      @SuppressWarnings("unused")
      ClassLoader cl = context.getClassLoader(); 
      @SuppressWarnings("rawtypes")
      Class SystemProperties = Class.forName("android.os.SystemProperties");

      //Parameters Types
      @SuppressWarnings("rawtypes")
      Class[] paramTypes= new Class[2];
      paramTypes[0]= String.class;
      paramTypes[1]= String.class;  

      Method set = SystemProperties.getMethod("set", paramTypes);

      //Parameters         
      Object[] params= new Object[2];
      params[0]= new String(key);
      params[1]= new String(val);

      set.invoke(SystemProperties, params);

    }
    catch( IllegalArgumentException iAE ){
        throw iAE;
    }
    catch( Exception e ){
        //TODO
    }

}
}

再次感谢任何帮助。谢谢。

Answer 1

你没写，这是编译错误

没有方法

public static String get(String key){}

在 SystemPropertiesProxy 中。使用

public static String get(Context context, String key):


SystemPropertiesProxy.get(context, "ro.url.changelog");

无论如何......使用私有(private)API不是一个好主意