Android应用开发（22）获取Property系统属性

news2024/10/6 6:03:31

Android应用开发学习笔记——目录索引

开发过程中我们经常需要获取Property系统属性，比如model、device、product 等等，通常debug的时候可以使用如下命令获取。

adb shell getprop <property name>
adb shell setprop <property name> <property value>

但是一个android 应用程序中需要获取系统的属性，该怎么获取呢？

通常有就如下几种方法：

使用android.os.Build提供的API，所有应用皆可使用，但是能获取的property非常有限
使用android.os.SystemProperties提供的API，但仅系统app可用
使用反射机制获取property，所有第三方app都可以使用

一、使用android.os.Build提供的API

frameworks/base/core/java/android/os/Build.java

public class Build {
    private static final String TAG = "Build";

    /** Value used for when a build property is unknown. */
    public static final String UNKNOWN = "unknown";

    /** Either a changelist number, or a label like "M4-rc20". */
    public static final String ID = getString("ro.build.id");

    /** A build ID string meant for displaying to the user */
    public static final String DISPLAY = getString("ro.build.display.id");

    /** The name of the overall product. */
    public static final String PRODUCT = getString("ro.product.name");

    /** The name of the industrial design. */
    public static final String DEVICE = getString("ro.product.device");

    /** The name of the underlying board, like "goldfish". */
    public static final String BOARD = getString("ro.product.board");

    /** The manufacturer of the product/hardware. */
    public static final String MANUFACTURER = getString("ro.product.manufacturer");

    /** The consumer-visible brand with which the product/hardware will be associated, if any. */
    public static final String BRAND = getString("ro.product.brand");

    /** The end-user-visible name for the end product. */
    public static final String MODEL = getString("ro.product.model");

    /** The manufacturer of the device's primary system-on-chip. */
    @NonNull
    public static final String SOC_MANUFACTURER = SocProperties.soc_manufacturer().orElse(UNKNOWN);

    /** The model name of the device's primary system-on-chip. */
    @NonNull
    public static final String SOC_MODEL = SocProperties.soc_model().orElse(UNKNOWN);

    /** The system bootloader version number. */
    public static final String BOOTLOADER = getString("ro.bootloader");
...
    /** Various version strings. */
    public static class VERSION {
        /**
         * The internal value used by the underlying source control to
         * represent this build.  E.g., a perforce changelist number
         * or a git hash.
         */
        public static final String INCREMENTAL = getString("ro.build.version.incremental");

        /**
         * The user-visible version string.  E.g., "1.0" or "3.4b5" or "bananas".
         *
         * This field is an opaque string. Do not assume that its value
         * has any particular structure or that values of RELEASE from
         * different releases can be somehow ordered.
         */
        public static final String RELEASE = getString("ro.build.version.release");
...
        public static final String SDK = getString("ro.build.version.sdk");
        public static final int SDK_INT = SystemProperties.getInt(
                "ro.build.version.sdk", 0);
...
    }

    @UnsupportedAppUsage
    private static String getString(String property) {
        return SystemProperties.get(property, UNKNOWN);
    }

    private static String[] getStringList(String property, String separator) {
        String value = SystemProperties.get(property);
        if (value.isEmpty()) {
            return new String[0];
        } else {
            return value.split(separator);
        }
    }

    @UnsupportedAppUsage
    private static long getLong(String property) {
        try {
            return Long.parseLong(SystemProperties.get(property));
        } catch (NumberFormatException e) {
            return -1;
        }
    }

API在应用程序中使用非常简单：

// 1. import
import android.os.Build;

// 2. 直接使用
Log.d(TAG, "Build.PRODUCT: " + Build.PRODUCT);
Log.d(TAG, "Build.MODEL: " + Build.MODEL);
Log.d(TAG, "Build.SOC_MODEL: " + Build.SOC_MODEL);
Log.d(TAG, "Build.MANUFACTURER: " + Build.MANUFACTURER);

// Android 4.4W (KitKat Wear)系统及以上
if (Build.VERSION.SDK_INT >= 20) {
    do something
} else {
    do something
}

如我使用xiaomi 13 Ultra，打印如下：

D/lzl-test: Build.PRODUCT: ishtar
D/lzl-test: Build.MODEL: 2304FPN6DC
D/lzl-test: Build.SOC_MODEL: SM8550
D/lzl-test: Build.MANUFACTURER: Xiaomi

二、使用android.os.SystemProperties提供的API

frameworks/base/core/java/android/os/SystemProperties.java

public class SystemProperties {
    private static final String TAG = "SystemProperties";

    @NonNull
    @SystemApi
    public static String get(@NonNull String key, @Nullable String def) {
        if (TRACK_KEY_ACCESS) onKeyAccess(key);
        return native_get(key, def);
    }

    @SystemApi
    public static int getInt(@NonNull String key, int def) {
        if (TRACK_KEY_ACCESS) onKeyAccess(key);
        return native_get_int(key, def);
    }

    @SystemApi
    public static boolean getBoolean(@NonNull String key, boolean def) {
        if (TRACK_KEY_ACCESS) onKeyAccess(key);
        return native_get_boolean(key, def);
    }
...

使用非常简单，但API只有系统应用才有权限，第三方应用请使用第三种方法。

三、使用反射机制获取property

    public static String getProperty(String key, String defaultValue) {
        String value = defaultValue;
        try {
            Class<?> c = Class.forName("android.os.SystemProperties");
            Method get = c.getMethod("get", String.class, String.class);
            value = (String) (get.invoke(c, key, "unknown"));
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return value;
        }
    }

    public static int setProperty(String key, String value) {
        try {
            Class<?> c = Class.forName("android.os.SystemProperties");
            Method set = c.getMethod("set", String.class, String.class);
            set.invoke(c, key, value);
            return 0;
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        }
    }