[Android] Property를 이용한 Log Level 조절로 Log 출력하기.

Property를 이용한 Log Level 조절로 Log 출력하기.

- 형식
#setprop log.tag.<log_tag> <level>


- 예제
public class SQLiteQueryBuilder
{
    private static final String TAG = "SQLiteQueryBuilder";

        if (Log.isLoggable(TAG, Log.DEBUG)) {
            Log.d(TAG, "Performing query: " + sql);
        }
}

위와 같은 경우, Log.isLoggable 을 확인해 보면,
log.tag."TAG" 값이 DEBUG 이상이면 동작한다.
ex) adb shell setprop log.tag.SQLiteQueryBuilder DEBUG


Framework Log.javapublic final class Log {
    /**
     * Priority constant for the println method; use Log.v.
     */
    public static final int VERBOSE = 2;
    /**
     * Priority constant for the println method; use Log.d.
     */
    public static final int DEBUG = 3;
    /**
     * Priority constant for the println method; use Log.i.
     */
    public static final int INFO = 4;
    /**
     * Priority constant for the println method; use Log.w.
     */
    public static final int WARN = 5;
    /**
     * Priority constant for the println method; use Log.e.
     */
    public static final int ERROR = 6;
    /**
     * Priority constant for the println method.
     */
    public static final int ASSERT = 7;
}

Native android_util_log.cppstruct levels_t {
    jint verbose;
    jint debug;
    jint info;
    jint warn;
    jint error;
    jint assert;
};

static levels_t levels;
static int toLevel(const char* value)
{
    switch (value[0]) {
        case 'V': return levels.verbose;
        case 'D': return levels.debug;
        case 'I': return levels.info;
        case 'W': return levels.warn;
        case 'E': return levels.error;
        case 'A': return levels.assert;
        case 'S': return -1; // SUPPRESS
    }
    return levels.info;
}

int register_android_util_Log(JNIEnv* env)
{
    jclass clazz = env->FindClass("android/util/Log");
    if (clazz == NULL) {
        LOGE("Can't find android/util/Log");
        return -1;
    }
 
    levels.verbose = env->GetStaticIntField(clazz, env->GetStaticFieldID(clazz, "VERBOSE", "I"));
    levels.debug = env->GetStaticIntField(clazz, env->GetStaticFieldID(clazz, "DEBUG", "I"));
    levels.info = env->GetStaticIntField(clazz, env->GetStaticFieldID(clazz, "INFO", "I"));
    levels.warn = env->GetStaticIntField(clazz, env->GetStaticFieldID(clazz, "WARN", "I"));
    levels.error = env->GetStaticIntField(clazz, env->GetStaticFieldID(clazz, "ERROR", "I"));
    levels.assert = env->GetStaticIntField(clazz, env->GetStaticFieldID(clazz, "ASSERT", "I"));
             
    return AndroidRuntime::registerNativeMethods(env, "android/util/Log", gMethods, NELEM(gMethods));
}