admin/mkdocs

Fork 0

Files

renjianbo 580cd5adb0 鏇存柊鏂囨。

2026-01-16 14:54:07 +08:00

28 KiB

Raw Blame History

系统API

系统API是Android平台提供的系统级服务接口，用于访问系统功能、管理权限、获取系统信息等。本文档介绍Android系统API的使用方法。

系统服务API

1. ActivityManager

ActivityManager用于管理Activity和任务栈。

获取ActivityManager

// 获取ActivityManager实例
ActivityManager activityManager = (ActivityManager) 
    getSystemService(Context.ACTIVITY_SERVICE);

常用方法

// 获取运行中的应用列表
List<ActivityManager.RunningAppProcessInfo> runningApps = 
    activityManager.getRunningAppProcesses();

// 获取内存信息
ActivityManager.MemoryInfo memoryInfo = new ActivityManager.MemoryInfo();
activityManager.getMemoryInfo(memoryInfo);
long totalMemory = memoryInfo.totalMem;
long availableMemory = memoryInfo.availMem;
boolean lowMemory = memoryInfo.lowMemory;

// 获取任务栈信息
List<ActivityManager.RunningTaskInfo> runningTasks = 
    activityManager.getRunningTasks(10);

// 获取应用任务信息
List<ActivityManager.AppTask> appTasks = 
    activityManager.getAppTasks();

使用示例

class SystemInfoActivity : AppCompatActivity() {
    private lateinit var activityManager: ActivityManager
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_system_info)
        
        activityManager = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
        
        // 获取内存信息
        val memoryInfo = ActivityManager.MemoryInfo()
        activityManager.getMemoryInfo(memoryInfo)
        
        val totalMemoryMB = memoryInfo.totalMem / (1024 * 1024)
        val availableMemoryMB = memoryInfo.availMem / (1024 * 1024)
        
        Log.d("Memory", "总内存: ${totalMemoryMB}MB")
        Log.d("Memory", "可用内存: ${availableMemoryMB}MB")
        Log.d("Memory", "低内存: ${memoryInfo.lowMemory}")
    }
}

2. WindowManager

WindowManager用于管理窗口和显示。

获取WindowManager

WindowManager windowManager = (WindowManager) 
    getSystemService(Context.WINDOW_SERVICE);

常用方法

// 获取默认显示信息
Display display = windowManager.getDefaultDisplay();
DisplayMetrics metrics = new DisplayMetrics();
display.getMetrics(metrics);

int width = metrics.widthPixels;
int height = metrics.heightPixels;
float density = metrics.density;
int densityDpi = metrics.densityDpi;

// 添加窗口
WindowManager.LayoutParams params = new WindowManager.LayoutParams(
    WindowManager.LayoutParams.WRAP_CONTENT,
    WindowManager.LayoutParams.WRAP_CONTENT,
    WindowManager.LayoutParams.TYPE_APPLICATION,
    WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
    PixelFormat.TRANSLUCENT
);
windowManager.addView(view, params);

// 移除窗口
windowManager.removeView(view);

使用示例

class WindowManagerActivity : AppCompatActivity() {
    private lateinit var windowManager: WindowManager
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_window_manager)
        
        windowManager = getSystemService(Context.WINDOW_SERVICE) as WindowManager
        
        // 获取屏幕信息
        val display = windowManager.defaultDisplay
        val metrics = DisplayMetrics()
        display.getMetrics(metrics)
        
        Log.d("Display", "屏幕宽度: ${metrics.widthPixels}px")
        Log.d("Display", "屏幕高度: ${metrics.heightPixels}px")
        Log.d("Display", "屏幕密度: ${metrics.density}")
        Log.d("Display", "DPI: ${metrics.densityDpi}")
    }
}

3. NotificationManager

NotificationManager用于管理通知。

获取NotificationManager

NotificationManager notificationManager = (NotificationManager) 
    getSystemService(Context.NOTIFICATION_SERVICE);

创建通知渠道（Android 8.0+）

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    String channelId = "my_channel_id";
    String channelName = "My Channel";
    int importance = NotificationManager.IMPORTANCE_DEFAULT;
    
    NotificationChannel channel = new NotificationChannel(
        channelId, channelName, importance
    );
    channel.setDescription("Channel description");
    
    notificationManager.createNotificationChannel(channel);
}

发送通知

// 创建通知
NotificationCompat.Builder builder = new NotificationCompat.Builder(
    context, "my_channel_id"
)
    .setSmallIcon(R.drawable.ic_notification)
    .setContentTitle("通知标题")
    .setContentText("通知内容")
    .setPriority(NotificationCompat.PRIORITY_DEFAULT)
    .setAutoCancel(true);

// 发送通知
int notificationId = 1;
notificationManager.notify(notificationId, builder.build());

// 取消通知
notificationManager.cancel(notificationId);

使用示例

class NotificationActivity : AppCompatActivity() {
    private lateinit var notificationManager: NotificationManager
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_notification)
        
        notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) 
            as NotificationManager
        
        // 创建通知渠道（Android 8.0+）
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val channel = NotificationChannel(
                "my_channel_id",
                "My Channel",
                NotificationManager.IMPORTANCE_DEFAULT
            ).apply {
                description = "Channel description"
            }
            notificationManager.createNotificationChannel(channel)
        }
        
        // 发送通知
        button.setOnClickListener {
            showNotification()
        }
    }
    
    private fun showNotification() {
        val builder = NotificationCompat.Builder(this, "my_channel_id")
            .setSmallIcon(R.drawable.ic_notification)
            .setContentTitle("通知标题")
            .setContentText("通知内容")
            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
            .setAutoCancel(true)
        
        notificationManager.notify(1, builder.build())
    }
}

4. LocationManager

LocationManager用于管理位置服务。

获取LocationManager

LocationManager locationManager = (LocationManager) 
    getSystemService(Context.LOCATION_SERVICE);

检查位置服务是否可用

boolean isGpsEnabled = locationManager.isProviderEnabled(
    LocationManager.GPS_PROVIDER
);
boolean isNetworkEnabled = locationManager.isProviderEnabled(
    LocationManager.NETWORK_PROVIDER
);

请求位置更新

// 检查权限
if (ContextCompat.checkSelfPermission(this, 
        Manifest.permission.ACCESS_FINE_LOCATION) 
    != PackageManager.PERMISSION_GRANTED) {
    // 请求权限
    return;
}

// 请求位置更新
LocationListener locationListener = new LocationListener() {
    @Override
    public void onLocationChanged(Location location) {
        double latitude = location.getLatitude();
        double longitude = location.getLongitude();
        float accuracy = location.getAccuracy();
    }
    
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {}
    
    @Override
    public void onProviderEnabled(String provider) {}
    
    @Override
    public void onProviderDisabled(String provider) {}
};

locationManager.requestLocationUpdates(
    LocationManager.GPS_PROVIDER,
    1000, // 最小时间间隔（毫秒）
    10,   // 最小距离（米）
    locationListener
);

// 停止位置更新
locationManager.removeUpdates(locationListener);

使用示例

class LocationActivity : AppCompatActivity() {
    private lateinit var locationManager: LocationManager
    private lateinit var locationListener: LocationListener
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_location)
        
        locationManager = getSystemService(Context.LOCATION_SERVICE) 
            as LocationManager
        
        locationListener = object : LocationListener {
            override fun onLocationChanged(location: Location) {
                val latitude = location.latitude
                val longitude = location.longitude
                val accuracy = location.accuracy
                
                Log.d("Location", "纬度: $latitude, 经度: $longitude, 精度: $accuracy")
            }
            
            override fun onStatusChanged(provider: String?, status: Int, extras: Bundle?) {}
            override fun onProviderEnabled(provider: String) {}
            override fun onProviderDisabled(provider: String) {}
        }
        
        // 检查权限
        if (ContextCompat.checkSelfPermission(this, 
                Manifest.permission.ACCESS_FINE_LOCATION) 
            == PackageManager.PERMISSION_GRANTED) {
            startLocationUpdates()
        } else {
            // 请求权限
            ActivityCompat.requestPermissions(
                this,
                arrayOf(Manifest.permission.ACCESS_FINE_LOCATION),
                REQUEST_LOCATION_PERMISSION
            )
        }
    }
    
    private fun startLocationUpdates() {
        locationManager.requestLocationUpdates(
            LocationManager.GPS_PROVIDER,
            1000L,
            10f,
            locationListener
        )
    }
    
    override fun onDestroy() {
        super.onDestroy()
        locationManager.removeUpdates(locationListener)
    }
    
    companion object {
        private const val REQUEST_LOCATION_PERMISSION = 100
    }
}

5. TelephonyManager

TelephonyManager用于访问电话相关信息。

获取TelephonyManager

TelephonyManager telephonyManager = (TelephonyManager) 
    getSystemService(Context.TELEPHONY_SERVICE);

常用方法

// 获取设备ID（需要READ_PHONE_STATE权限）
String deviceId = telephonyManager.getDeviceId();

// 获取SIM卡信息
String simSerialNumber = telephonyManager.getSimSerialNumber();
String simOperatorName = telephonyManager.getSimOperatorName();
String networkOperatorName = telephonyManager.getNetworkOperatorName();

// 获取网络类型
int networkType = telephonyManager.getNetworkType();
// NETWORK_TYPE_LTE, NETWORK_TYPE_UMTS, etc.

// 检查电话功能
boolean isPhone = telephonyManager.getPhoneType() != 
    TelephonyManager.PHONE_TYPE_NONE;

使用示例

class TelephonyActivity : AppCompatActivity() {
    private lateinit var telephonyManager: TelephonyManager
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_telephony)
        
        telephonyManager = getSystemService(Context.TELEPHONY_SERVICE) 
            as TelephonyManager
        
        // 检查权限
        if (ContextCompat.checkSelfPermission(this, 
                Manifest.permission.READ_PHONE_STATE) 
            == PackageManager.PERMISSION_GRANTED) {
            getTelephonyInfo()
        }
    }
    
    private fun getTelephonyInfo() {
        val deviceId = telephonyManager.deviceId
        val simOperatorName = telephonyManager.simOperatorName
        val networkOperatorName = telephonyManager.networkOperatorName
        val networkType = telephonyManager.networkType
        
        Log.d("Telephony", "设备ID: $deviceId")
        Log.d("Telephony", "SIM运营商: $simOperatorName")
        Log.d("Telephony", "网络运营商: $networkOperatorName")
        Log.d("Telephony", "网络类型: $networkType")
    }
}

6. PowerManager

PowerManager用于管理电源和唤醒锁。

获取PowerManager

PowerManager powerManager = (PowerManager) 
    getSystemService(Context.POWER_SERVICE);

唤醒锁

// 获取唤醒锁
PowerManager.WakeLock wakeLock = powerManager.newWakeLock(
    PowerManager.PARTIAL_WAKE_LOCK,
    "MyApp::MyWakeLock"
);

// 获取唤醒锁
wakeLock.acquire();

// 释放唤醒锁
wakeLock.release();

// 检查是否持有唤醒锁
boolean isHeld = wakeLock.isHeld();

使用示例

class PowerManagerActivity : AppCompatActivity() {
    private lateinit var powerManager: PowerManager
    private var wakeLock: PowerManager.WakeLock? = null
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_power_manager)
        
        powerManager = getSystemService(Context.POWER_SERVICE) as PowerManager
        
        // 创建唤醒锁
        wakeLock = powerManager.newWakeLock(
            PowerManager.PARTIAL_WAKE_LOCK,
            "MyApp::MyWakeLock"
        )
    }
    
    private fun acquireWakeLock() {
        wakeLock?.acquire(10 * 60 * 1000L) // 10分钟超时
    }
    
    private fun releaseWakeLock() {
        wakeLock?.let {
            if (it.isHeld) {
                it.release()
            }
        }
    }
    
    override fun onDestroy() {
        super.onDestroy()
        releaseWakeLock()
    }
}

系统权限API

1. 权限检查

检查权限

// 检查单个权限
int result = ContextCompat.checkSelfPermission(
    context,
    Manifest.permission.CAMERA
);

boolean hasPermission = result == PackageManager.PERMISSION_GRANTED;

// 检查多个权限
String[] permissions = {
    Manifest.permission.CAMERA,
    Manifest.permission.READ_EXTERNAL_STORAGE
};

int[] results = new int[permissions.length];
for (int i = 0; i < permissions.length; i++) {
    results[i] = ContextCompat.checkSelfPermission(
        context,
        permissions[i]
    );
}

使用示例

class PermissionActivity : AppCompatActivity() {
    private fun checkPermission(permission: String): Boolean {
        return ContextCompat.checkSelfPermission(
            this,
            permission
        ) == PackageManager.PERMISSION_GRANTED
    }
    
    private fun checkPermissions(permissions: Array<String>): Boolean {
        return permissions.all { checkPermission(it) }
    }
}

2. 权限申请

请求权限

// 请求单个权限
ActivityCompat.requestPermissions(
    activity,
    new String[]{Manifest.permission.CAMERA},
    REQUEST_CODE_CAMERA
);

// 请求多个权限
ActivityCompat.requestPermissions(
    activity,
    new String[]{
        Manifest.permission.CAMERA,
        Manifest.permission.READ_EXTERNAL_STORAGE
    },
    REQUEST_CODE_PERMISSIONS
);

// 处理权限结果
@Override
public void onRequestPermissionsResult(
    int requestCode,
    @NonNull String[] permissions,
    @NonNull int[] grantResults
) {
    if (requestCode == REQUEST_CODE_CAMERA) {
        if (grantResults.length > 0 && 
            grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            // 权限已授予
        } else {
            // 权限被拒绝
        }
    }
}

使用示例

class PermissionActivity : AppCompatActivity() {
    companion object {
        private const val REQUEST_CODE_CAMERA = 100
        private const val REQUEST_CODE_PERMISSIONS = 101
    }
    
    private fun requestPermission(permission: String, requestCode: Int) {
        ActivityCompat.requestPermissions(
            this,
            arrayOf(permission),
            requestCode
        )
    }
    
    private fun requestPermissions(permissions: Array<String>, requestCode: Int) {
        ActivityCompat.requestPermissions(
            this,
            permissions,
            requestCode
        )
    }
    
    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        
        when (requestCode) {
            REQUEST_CODE_CAMERA -> {
                if (grantResults.isNotEmpty() && 
                    grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // 权限已授予
                    openCamera()
                } else {
                    // 权限被拒绝
                    showPermissionDeniedMessage()
                }
            }
        }
    }
}

3. 权限说明

显示权限说明

// 检查是否需要显示权限说明
if (ActivityCompat.shouldShowRequestPermissionRationale(
        activity,
        Manifest.permission.CAMERA)) {
    // 显示说明对话框
    showPermissionRationale();
} else {
    // 直接请求权限
    ActivityCompat.requestPermissions(
        activity,
        new String[]{Manifest.permission.CAMERA},
        REQUEST_CODE_CAMERA
    );
}

使用示例

class PermissionActivity : AppCompatActivity() {
    private fun requestPermissionWithRationale(permission: String, requestCode: Int) {
        if (ActivityCompat.shouldShowRequestPermissionRationale(this, permission)) {
            // 显示说明对话框
            MaterialAlertDialogBuilder(this)
                .setTitle("需要权限")
                .setMessage("此功能需要相机权限才能使用")
                .setPositiveButton("确定") { _, _ ->
                    ActivityCompat.requestPermissions(
                        this,
                        arrayOf(permission),
                        requestCode
                    )
                }
                .setNegativeButton("取消", null)
                .show()
        } else {
            // 直接请求权限
            ActivityCompat.requestPermissions(
                this,
                arrayOf(permission),
                requestCode
            )
        }
    }
}

系统功能API

1. 文件系统API

访问外部存储

// 检查外部存储是否可用
boolean isExternalStorageAvailable = Environment.getExternalStorageState()
    .equals(Environment.MEDIA_MOUNTED);

// 获取外部存储目录
File externalStorageDir = Environment.getExternalStorageDirectory();
File downloadsDir = Environment.getExternalStoragePublicDirectory(
    Environment.DIRECTORY_DOWNLOADS
);

// 获取应用专用外部存储目录
File appExternalDir = getExternalFilesDir(null);
File appPicturesDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);

使用示例

class FileSystemActivity : AppCompatActivity() {
    private fun getExternalStorageInfo() {
        // 检查外部存储状态
        val state = Environment.getExternalStorageState()
        val isAvailable = state == Environment.MEDIA_MOUNTED
        
        if (isAvailable) {
            // 获取外部存储目录
            val externalStorageDir = Environment.getExternalStorageDirectory()
            val downloadsDir = Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_DOWNLOADS
            )
            
            // 获取应用专用目录
            val appExternalDir = getExternalFilesDir(null)
            val appPicturesDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES)
            
            Log.d("Storage", "外部存储: ${externalStorageDir.absolutePath}")
            Log.d("Storage", "下载目录: ${downloadsDir.absolutePath}")
            Log.d("Storage", "应用外部目录: ${appExternalDir?.absolutePath}")
        }
    }
}

2. 网络API

检查网络连接

ConnectivityManager connectivityManager = (ConnectivityManager) 
    getSystemService(Context.CONNECTIVITY_SERVICE);

// 检查网络连接
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
boolean isConnected = networkInfo != null && networkInfo.isConnected();

// 获取网络类型
int networkType = networkInfo.getType();
// ConnectivityManager.TYPE_WIFI
// ConnectivityManager.TYPE_MOBILE

使用示例

class NetworkActivity : AppCompatActivity() {
    private lateinit var connectivityManager: ConnectivityManager
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_network)
        
        connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) 
            as ConnectivityManager
        
        checkNetworkConnection()
    }
    
    private fun checkNetworkConnection() {
        val networkInfo = connectivityManager.activeNetworkInfo
        val isConnected = networkInfo != null && networkInfo.isConnected
        
        if (isConnected) {
            val networkType = networkInfo.type
            when (networkType) {
                ConnectivityManager.TYPE_WIFI -> {
                    Log.d("Network", "WiFi连接")
                }
                ConnectivityManager.TYPE_MOBILE -> {
                    Log.d("Network", "移动网络连接")
                }
            }
        } else {
            Log.d("Network", "无网络连接")
        }
    }
}

3. 传感器API

使用传感器

SensorManager sensorManager = (SensorManager) 
    getSystemService(Context.SENSOR_SERVICE);

// 获取传感器
Sensor accelerometer = sensorManager.getDefaultSensor(
    Sensor.TYPE_ACCELEROMETER
);

// 注册传感器监听器
SensorEventListener listener = new SensorEventListener() {
    @Override
    public void onSensorChanged(SensorEvent event) {
        float x = event.values[0];
        float y = event.values[1];
        float z = event.values[2];
    }
    
    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {}
};

sensorManager.registerListener(
    listener,
    accelerometer,
    SensorManager.SENSOR_DELAY_NORMAL
);

// 取消注册
sensorManager.unregisterListener(listener);

使用示例

class SensorActivity : AppCompatActivity() {
    private lateinit var sensorManager: SensorManager
    private var accelerometer: Sensor? = null
    private val sensorListener = object : SensorEventListener {
        override fun onSensorChanged(event: SensorEvent) {
            val x = event.values[0]
            val y = event.values[1]
            val z = event.values[2]
            
            Log.d("Sensor", "X: $x, Y: $y, Z: $z")
        }
        
        override fun onAccuracyChanged(sensor: Sensor?, accuracy: Int) {}
    }
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_sensor)
        
        sensorManager = getSystemService(Context.SENSOR_SERVICE) as SensorManager
        accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER)
    }
    
    override fun onResume() {
        super.onResume()
        accelerometer?.let {
            sensorManager.registerListener(
                sensorListener,
                it,
                SensorManager.SENSOR_DELAY_NORMAL
            )
        }
    }
    
    override fun onPause() {
        super.onPause()
        sensorManager.unregisterListener(sensorListener)
    }
}

系统版本API

1. 获取系统版本信息

系统版本

// 获取Android版本号
int sdkVersion = Build.VERSION.SDK_INT;
String sdkVersionName = Build.VERSION.RELEASE; // "13", "12", etc.

// 获取设备信息
String manufacturer = Build.MANUFACTURER; // "Samsung", "Google", etc.
String model = Build.MODEL; // "Pixel 6", "Galaxy S21", etc.
String brand = Build.BRAND; // "google", "samsung", etc.
String device = Build.DEVICE; // "oriole", "o1q", etc.
String product = Build.PRODUCT; // "oriole", "o1q", etc.

使用示例

class SystemVersionActivity : AppCompatActivity() {
    private fun getSystemVersionInfo() {
        // Android版本
        val sdkVersion = Build.VERSION.SDK_INT
        val sdkVersionName = Build.VERSION.RELEASE
        
        // 设备信息
        val manufacturer = Build.MANUFACTURER
        val model = Build.MODEL
        val brand = Build.BRAND
        val device = Build.DEVICE
        val product = Build.PRODUCT
        
        Log.d("System", "SDK版本: $sdkVersion")
        Log.d("System", "Android版本: $sdkVersionName")
        Log.d("System", "制造商: $manufacturer")
        Log.d("System", "型号: $model")
        Log.d("System", "品牌: $brand")
        Log.d("System", "设备: $device")
        Log.d("System", "产品: $product")
    }
}

2. 版本检查

检查Android版本

// 检查Android版本
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    // Android 8.0及以上
}

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
    // Android 9.0及以上
}

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
    // Android 10及以上
}

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
    // Android 11及以上
}

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
    // Android 12及以上
}

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
    // Android 13及以上
}

使用示例

class VersionCheckActivity : AppCompatActivity() {
    private fun checkAndroidVersion() {
        when {
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU -> {
                // Android 13+
                Log.d("Version", "Android 13或更高版本")
            }
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
                // Android 12+
                Log.d("Version", "Android 12或更高版本")
            }
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.R -> {
                // Android 11+
                Log.d("Version", "Android 11或更高版本")
            }
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q -> {
                // Android 10+
                Log.d("Version", "Android 10或更高版本")
            }
            else -> {
                Log.d("Version", "Android 10以下版本")
            }
        }
    }
    
    private fun useNewFeature() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            // 使用Android 8.0+的新特性
            useNotificationChannel()
        } else {
            // 使用旧版本API
            useOldNotification()
        }
    }
}

3. 应用版本信息

获取应用版本

try {
    PackageInfo packageInfo = getPackageManager().getPackageInfo(
        getPackageName(),
        0
    );
    
    String versionName = packageInfo.versionName; // "1.0.0"
    int versionCode = packageInfo.versionCode; // 1
    String packageName = packageInfo.packageName; // "com.example.app"
    
} catch (PackageManager.NameNotFoundException e) {
    e.printStackTrace();
}

使用示例

class AppVersionActivity : AppCompatActivity() {
    private fun getAppVersionInfo() {
        try {
            val packageInfo = packageManager.getPackageInfo(
                packageName,
                0
            )
            
            val versionName = packageInfo.versionName
            val versionCode = packageInfo.longVersionCode // API 28+
            val packageName = packageInfo.packageName
            
            Log.d("App", "版本名称: $versionName")
            Log.d("App", "版本代码: $versionCode")
            Log.d("App", "包名: $packageName")
            
        } catch (e: PackageManager.NameNotFoundException) {
            e.printStackTrace()
        }
    }
}

总结

系统API提供了访问Android系统功能和信息的能力：

系统服务API：ActivityManager、WindowManager、NotificationManager等
系统权限API：权限检查、申请和处理
系统功能API：文件系统、网络、传感器等
系统版本API：获取系统和应用版本信息

使用系统API时需要注意：

申请必要的权限
检查系统版本兼容性
正确处理生命周期
及时释放资源

通过合理使用系统API，可以构建功能强大的Android应用。

28 KiB Raw Blame History Unescape Escape

系统API

目录

系统服务API

1. ActivityManager

获取ActivityManager

常用方法

使用示例

2. WindowManager

获取WindowManager

常用方法

使用示例

3. NotificationManager

获取NotificationManager

创建通知渠道（Android 8.0+）

发送通知

使用示例

4. LocationManager

获取LocationManager

检查位置服务是否可用

请求位置更新

使用示例

5. TelephonyManager

获取TelephonyManager

常用方法

使用示例

6. PowerManager

获取PowerManager

唤醒锁

使用示例

系统权限API

1. 权限检查

检查权限

使用示例

2. 权限申请

请求权限

使用示例

3. 权限说明

显示权限说明

使用示例

系统功能API

1. 文件系统API

访问外部存储

使用示例

2. 网络API

检查网络连接

使用示例

3. 传感器API

使用传感器

使用示例

系统版本API

1. 获取系统版本信息

系统版本

使用示例

2. 版本检查

检查Android版本

使用示例

3. 应用版本信息

获取应用版本

使用示例

总结

28 KiB

Raw Blame History