android - 在android应用程序上以编程方式获取cpu信息

Question

我在网上找到这段代码:

package com.exercise.AndroidCPUinfo;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;

import android.app.Activity;
import android.os.Build;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity {

    /** 
     * Called when the activity is first created. 
     */
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);

         TextView CPUinfo = (TextView) findViewById(R.id.CPUinfo);
         CPUinfo.setText(getInfo());

     }

    private String getInfo() {
        StringBuffer sb = new StringBuffer();
        sb.append("abi: ").append(Build.CPU_ABI).append("\n");
        if (new File("/proc/cpuinfo").exists()) {
            try {
                BufferedReader br = new BufferedReader(
                    new FileReader(new File("/proc/cpuinfo")));
                String aLine;
                while ((aLine = br.readLine()) != null) {
                    sb.append(aLine + "\n");
                }
                if (br != null) {
                    br.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            } 
        }
        return sb.toString();
    }
}

这是 MainActivity.java

package eu.lucazanini.swipeviews;

import android.app.ActionBar;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.support.v4.app.NotificationCompat;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends FragmentActivity {

CollectionPagerAdapter mCollectionPagerAdapter;
    ViewPager mViewPager;
    TextView textOut;
 // Notification code

private static final int SIMPLE_NOTIFICATION_ID = 1;

 NotificationManager mNotificationManager;
 // fine
 @Override
public void onCreate(Bundle savedInstanceState) {        
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Readcpuinfo 
 TextView CPUinfo = (TextView) findViewById(R.id.CPUinfo);
 CPUinfo.setText(getInfo());
//fine readcpuinfo

// Notification code
mNotificationManager = (NotificationManager) `getSystemService(Context.NOTIFICATION_SERVICE);`

View btnradio_hindi = findViewById(R.id.radio_hindi);
// fine
mCollectionPagerAdapter = new CollectionPagerAdapter(
    getSupportFragmentManager());

// Set up action bar.
final ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);

// Set up the ViewPager, attaching the adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mCollectionPagerAdapter);
}
 private String getInfo() {
        StringBuffer sb = new StringBuffer();
        sb.append("abi: ").append(Build.CPU_ABI).append("\n");
        if (new File("/proc/cpuinfo").exists()) {
            try {
                BufferedReader br = new BufferedReader(new FileReader(new `File("/proc/cpuinfo")));`
                String aLine;
                while ((aLine = br.readLine()) != null) {
                    sb.append(aLine + "\n");
                }
                if (br != null) {
                    br.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            } 
        }
        return sb.toString();
    }

/// Inizio creazione funzioni

public Boolean execCommands(String... command) {
    try {
        Runtime rt = Runtime.getRuntime();
        Process process = rt.exec("su");
        DataOutputStream os = new DataOutputStream(process.getOutputStream());

        for(int i = 0; i < command.length; i++) {
            os.writeBytes(command[i] + "\n");
            os.flush();
        }
        os.writeBytes("exit\n");
        os.flush();
        process.waitFor();
    } catch (IOException e) {
        return false;
    } catch (InterruptedException e) {
        return false;
    }
    return true; 
}

/**
 * A {@link android.support.v4.app.FragmentStatePagerAdapter} that returns a
 * fragment representing an object in the collection.
 */
public class CollectionPagerAdapter extends FragmentStatePagerAdapter {

final int NUM_ITEMS = 3; // number of tabs

public CollectionPagerAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public Fragment getItem(int i) {
    Fragment fragment = new TabFragment();
    Bundle args = new Bundle();
    args.putInt(TabFragment.ARG_OBJECT, i);
    fragment.setArguments(args);
    return fragment;
}

@Override
public int getCount() {
    return NUM_ITEMS;
}

@Override
public CharSequence getPageTitle(int position) {

    String tabLabel = null;
    switch (position) {
    case 0:
    tabLabel = getString(R.string.label1);
    break;
    case 1:
    tabLabel = getString(R.string.label2);
    break;
    case 2:
    tabLabel = getString(R.string.label3);
    break;
    }

    return tabLabel;
}
}

/**
 * A dummy fragment representing a section of the app, but that simply
 * displays dummy text.
 */
public static class TabFragment extends Fragment {

public static final String ARG_OBJECT = "object";

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {

    Bundle args = getArguments();
    int position = args.getInt(ARG_OBJECT);

    int tabLayout = 0;
    switch (position) {
    case 0:
    tabLayout = R.layout.tab1;
    break;
    case 1:
    tabLayout = R.layout.tab2;
    break;
    case 2:
    tabLayout = R.layout.tab3;
    break;
    }

    View rootView = inflater.inflate(tabLayout, container, false);

    return rootView;
}
}
public void onRadioButtonClicked(View view) {

    ((RadioButton) view).isChecked();

    // Check which radio button was clicked
   // switch(view.getId()) {
   // case R.id.radio_hindi:
    //    if (checked)

    switch (view.getId())
    {
    case R.id.radio_hindi:
        String[] commands = {
                "echo 3 > /proc/sys/vm/drop_caches",
                "cat /proc/meminfo | awk 'NR == 2'"

        };
        sendSimpleNotification();
        Toast.makeText(this, "Hai liberato memoria! Hai: " + `Runtime.getRuntime().freeMemory() + "", Toast.LENGTH_LONG).show();`
        execCommands(commands);

        String commandText = "echo 'foo' >> /sdcard/foo.txt\necho 'bar' >> `/sdcard/foo.txt";`

        execCommands(commandText.split("\n"));
    break;

    case R.id.radio_english:
        String[] commands1 = {"echo ondemand > `/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor",`
                "/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor",
                "/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor", 
                "/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor"};
        execCommands(commands1);
        sendSimpleNotificationOndemand();
        Toast.makeText(this, "Hai selezionato il governor Ondemand", `Toast.LENGTH_LONG).show();`
    break;
    case R.id.interactive_btn:
        String[] commands2 = {"echo interactive > `/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor",`
                "/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor",
                "/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor", 
                "/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor"};
        execCommands(commands2);
        sendSimpleNotificationInteractive();
        Toast.makeText(this, "Hai selezionato il governor: Interactive", `Toast.LENGTH_LONG).show();`
    break;
    case R.id.conservative_btn:
        String[] commands3 = {"echo conservative > `/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor",`
                "/sys/devices/system/cpu/cpu1/cpufreq/scaling_governor",
                "/sys/devices/system/cpu/cpu2/cpufreq/scaling_governor", 
                "/sys/devices/system/cpu/cpu3/cpufreq/scaling_governor"};
        execCommands(commands3);
        sendSimpleNotificationConservative();
        Toast.makeText(this, "Hai selezionato il governor: Conservative", `Toast.LENGTH_LONG).show();`
    break;
    } 
}
protected void cancelSimpleNotification() {
    mNotificationManager.cancel(SIMPLE_NOTIFICATION_ID);
}
private void sendSimpleNotification() {

    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                    MainActivity.this);

    // Titolo e testo della notifica
    notificationBuilder.setContentTitle("Boost RAM");
    notificationBuilder.setContentText("Memoria libera: "+ `Runtime.getRuntime().freeMemory() + "bytes");`

    // Testo che compare nella barra di stato non appena compare la notifica
    notificationBuilder.setTicker("Memoria liberata con successo");

    // Data e ora della notifica
    notificationBuilder.setWhen(System.currentTimeMillis());

    // Icona della notifica
    notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

    // Creiamo il pending intent che verrà lanciato quando la notifica
    // viene premuta
    Intent notificationIntent = new Intent(this, MainActivity.class);
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                    notificationIntent, 0);

    notificationBuilder.setContentIntent(contentIntent);

    // Impostiamo il suono, le luci e la vibrazione di default
    notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                    | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

    mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                    notificationBuilder.build());
}
// Notification per il governor ondemand
private void sendSimpleNotificationOndemand() {

NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                MainActivity.this);

// Titolo e testo della notifica
notificationBuilder.setContentTitle("Governor Changed");
notificationBuilder.setContentText("Hai selezionato il governor Ondemand");

// Testo che compare nella barra di stato non appena compare la notifica
notificationBuilder.setTicker("Governor Ondemand settato");

// Data e ora della notifica
notificationBuilder.setWhen(System.currentTimeMillis());

// Icona della notifica
notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

// Creiamo il pending intent che verrà lanciato quando la notifica
// viene premuta
Intent notificationIntent = new Intent(this, MainActivity.class);
PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                notificationIntent, 0);

notificationBuilder.setContentIntent(contentIntent);

// Impostiamo il suono, le luci e la vibrazione di default
notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                notificationBuilder.build());
}

//Notification per il governor interactive
private void sendSimpleNotificationInteractive() {

 NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                 MainActivity.this);

 // Titolo e testo della notifica
 notificationBuilder.setContentTitle("Governor Changed");
 notificationBuilder.setContentText("Hai selezionato il governor Interactive");

 // Testo che compare nella barra di stato non appena compare la notifica
 notificationBuilder.setTicker("Governor Interactive settato");

 // Data e ora della notifica
 notificationBuilder.setWhen(System.currentTimeMillis());

 // Icona della notifica
 notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

 // Creiamo il pending intent che verrà lanciato quando la notifica
 // viene premuta
 Intent notificationIntent = new Intent(this, MainActivity.class);
 PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                 notificationIntent, 0);

 notificationBuilder.setContentIntent(contentIntent);

 // Impostiamo il suono, le luci e la vibrazione di default
 notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                 | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

 mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                 notificationBuilder.build());
}

//Notification per il governor conservative
private void sendSimpleNotificationConservative() {

 NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(
                 MainActivity.this);

 // Titolo e testo della notifica
 notificationBuilder.setContentTitle("Governor Changed");
 notificationBuilder.setContentText("Hai selezionato il governor Conservative");

 // Testo che compare nella barra di stato non appena compare la notifica
 notificationBuilder.setTicker("Governor Conservative settato");

 // Data e ora della notifica
 notificationBuilder.setWhen(System.currentTimeMillis());

 // Icona della notifica
 notificationBuilder.setSmallIcon(R.drawable.ic_launcher);

 // Creiamo il pending intent che verrà lanciato quando la notifica
 // viene premuta
 Intent notificationIntent = new Intent(this, MainActivity.class);
 PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                 notificationIntent, 0);

 notificationBuilder.setContentIntent(contentIntent);

 // Impostiamo il suono, le luci e la vibrazione di default
 notificationBuilder.setDefaults(Notification.DEFAULT_SOUND
                 | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);

 mNotificationManager.notify(SIMPLE_NOTIFICATION_ID,
                 notificationBuilder.build());
}
}

我有一个带有 3 个 tab.xml(tab1.xml、tab2.xml 和 tab3.xml)的 swipeview 在 tab1 中有 cpu 信息的 id。

<?xml version="1.0" encoding="utf-8"?>
<RadioGroup xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView5"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_marginTop="10dp"
    android:text="CHANGE GOVERNOR"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textColor="#FF8000"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:text="Change the CPU Governor: "
    android:textColor="#00AEEF"
    tools:ignore="HardcodedText" />

<RadioButton
    android:id="@+id/radio_english"
    android:layout_width="201dp"
    android:layout_height="55dp"
    android:onClick="onRadioButtonClicked"
    android:text="OnDemand"
    tools:ignore="HardcodedText" />

<RadioButton
    android:id="@+id/interactive_btn"
    android:layout_width="200dp"
    android:layout_height="55dp"
    android:onClick="onRadioButtonClicked"
    android:text="Interactive"
    tools:ignore="HardcodedText" />

<RadioButton
    android:id="@+id/conservative_btn"
    android:layout_width="200dp"
    android:layout_height="55dp"
    android:layout_gravity="fill"
    android:onClick="onRadioButtonClicked"
    android:text="Conservative"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/AndroidCPUInfo"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Android CPU Info.:"
    tools:ignore="HardcodedText" />

<TextView
    android:id="@+id/CPUinfo"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    tools:ignore="SelectableText" />

</RadioGroup>

如果我尝试在新应用程序中运行这段代码，它会很顺利并显示 cpu 信息。当我将代码放入我的应用程序时，它在启动时崩溃了!日志很干净，没有错误。没什么.. 太奇怪了。我用的是swipeview..有问题吗？

Answer 1

行:

05-23 20:58:37.803: E/AndroidRuntime(30025): at `eu.lucazanini.swipeviews.MainActivity.onCreate(MainActivity.java:49)`

表明 java.lang.NullPointerException 发生在您的 onCreate 方法中。查看您发布的代码，我的猜测是 findViewById(R.id.CPUinfo) 返回 null。我建议您添加 Log.d(...) 以打印出 CPUinfo 是否为空。