每日小点-Properties用法

android中Properties一般用的比较少，一般场景是用于获取系统配置键值对 System.getProperties()。其实它还有特殊功能。

解析指定格式的文件

（1）了解基本文件格式

我们可以看见android项目下会有properties文件，看下内容格式：

#
# To customize properties used by the Ant build system edit
# "ant.properties", and override values to adapt the script to your
# project structure.
#
# To enable ProGuard to shrink and obfuscate your code, uncomment this (available properties: sdk.dir, user.home):
#proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt

# Project target.
target=android-21

文件格式是目前是类似键值对的样式。

大概文件的格式，我们来看下它提供的接口能力。

（2）接口能力。

   public synchronized void load(Reader reader) throws IOException {
        load0(new LineReader(reader));
    }

    /**
     * Reads a property list (key and element pairs) from the input
     * byte stream. The input stream is in a simple line-oriented
     * format as specified in
     * {@link #load(java.io.Reader) load(Reader)} and is assumed to use
     * the ISO 8859-1 character encoding; that is each byte is one Latin1
     * character. Characters not in Latin1, and certain special characters,
     * are represented in keys and elements using Unicode escapes as defined in
     * section 3.3 of
     * <cite>The Java™ Language Specification</cite>.
     * <p>
     * The specified stream remains open after this method returns.
     *
     * @param      inStream   the input stream.
     * @exception  IOException  if an error occurred when reading from the
     *             input stream.
     * @throws     IllegalArgumentException if the input stream contains a
     *             malformed Unicode escape sequence.
     * @since 1.2
     */
    public synchronized void load(InputStream inStream) throws IOException {
        load0(new LineReader(inStream));
    }

    private void load0 (LineReader lr) throws IOException {
        ...
            String key = loadConvert(lr.lineBuf, 0, keyLen, convtBuf);
            String value = loadConvert(lr.lineBuf, valueStart, limit - valueStart, convtBuf);
            put(key, value);

我们发现原来它还具有加载数据流的能力，这就意味着它可以支持指定流的解析了，解析详细过程咱不贴代码，有兴趣的可以看源码。大致过程就是在每一行中找到 key的位置，以及value所对应的位置。然后内部键值对保存。

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每日小点-Properties用法

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