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      1 /*
      2  * Copyright (C) 2006 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.os;
     18 
     19 
     20 /**
     21  * Gives access to the system properties store.  The system properties
     22  * store contains a list of string key-value pairs.
     23  *
     24  * {@hide}
     25  */
     26 public class SystemProperties
     27 {
     28     public static final int PROP_NAME_MAX = 31;
     29     public static final int PROP_VALUE_MAX = 91;
     30 
     31     private static native String native_get(String key);
     32     private static native String native_get(String key, String def);
     33     private static native int native_get_int(String key, int def);
     34     private static native long native_get_long(String key, long def);
     35     private static native boolean native_get_boolean(String key, boolean def);
     36     private static native void native_set(String key, String def);
     37 
     38     /**
     39      * Get the value for the given key.
     40      * @return an empty string if the key isn't found
     41      * @throws IllegalArgumentException if the key exceeds 32 characters
     42      */
     43     public static String get(String key) {
     44         if (key.length() > PROP_NAME_MAX) {
     45             throw new IllegalArgumentException("key.length > " + PROP_NAME_MAX);
     46         }
     47         return native_get(key);
     48     }
     49 
     50     /**
     51      * Get the value for the given key.
     52      * @return if the key isn't found, return def if it isn't null, or an empty string otherwise
     53      * @throws IllegalArgumentException if the key exceeds 32 characters
     54      */
     55     public static String get(String key, String def) {
     56         if (key.length() > PROP_NAME_MAX) {
     57             throw new IllegalArgumentException("key.length > " + PROP_NAME_MAX);
     58         }
     59         return native_get(key, def);
     60     }
     61 
     62     /**
     63      * Get the value for the given key, and return as an integer.
     64      * @param key the key to lookup
     65      * @param def a default value to return
     66      * @return the key parsed as an integer, or def if the key isn't found or
     67      *         cannot be parsed
     68      * @throws IllegalArgumentException if the key exceeds 32 characters
     69      */
     70     public static int getInt(String key, int def) {
     71         if (key.length() > PROP_NAME_MAX) {
     72             throw new IllegalArgumentException("key.length > " + PROP_NAME_MAX);
     73         }
     74         return native_get_int(key, def);
     75     }
     76 
     77     /**
     78      * Get the value for the given key, and return as a long.
     79      * @param key the key to lookup
     80      * @param def a default value to return
     81      * @return the key parsed as a long, or def if the key isn't found or
     82      *         cannot be parsed
     83      * @throws IllegalArgumentException if the key exceeds 32 characters
     84      */
     85     public static long getLong(String key, long def) {
     86         if (key.length() > PROP_NAME_MAX) {
     87             throw new IllegalArgumentException("key.length > " + PROP_NAME_MAX);
     88         }
     89         return native_get_long(key, def);
     90     }
     91 
     92     /**
     93      * Get the value for the given key, returned as a boolean.
     94      * Values 'n', 'no', '0', 'false' or 'off' are considered false.
     95      * Values 'y', 'yes', '1', 'true' or 'on' are considered true.
     96      * (case sensitive).
     97      * If the key does not exist, or has any other value, then the default
     98      * result is returned.
     99      * @param key the key to lookup
    100      * @param def a default value to return
    101      * @return the key parsed as a boolean, or def if the key isn't found or is
    102      *         not able to be parsed as a boolean.
    103      * @throws IllegalArgumentException if the key exceeds 32 characters
    104      */
    105     public static boolean getBoolean(String key, boolean def) {
    106         if (key.length() > PROP_NAME_MAX) {
    107             throw new IllegalArgumentException("key.length > " + PROP_NAME_MAX);
    108         }
    109         return native_get_boolean(key, def);
    110     }
    111 
    112     /**
    113      * Set the value for the given key.
    114      * @throws IllegalArgumentException if the key exceeds 32 characters
    115      * @throws IllegalArgumentException if the value exceeds 92 characters
    116      */
    117     public static void set(String key, String val) {
    118         if (key.length() > PROP_NAME_MAX) {
    119             throw new IllegalArgumentException("key.length > " + PROP_NAME_MAX);
    120         }
    121         if (val != null && val.length() > PROP_VALUE_MAX) {
    122             throw new IllegalArgumentException("val.length > " +
    123                 PROP_VALUE_MAX);
    124         }
    125         native_set(key, val);
    126     }
    127 }
    128