j2me 兑现 j2se 的 Properties 功能

j2me 实现 j2se 的 Properties 功能
我们知道 j2me 中没有 j2se 里边的 Properties 类，要自己实现才能像 j2se 那样读取文件的，现在 j2mepolish 里边的 de.enough.polish.util.Properties 就实现了类似 j2se 的 Properties, 加上de.enough.polish.util.ResourceStreamUtil（旧版本polish 没有这个类，要自己实现相应功能）可以让我们容易读取属性文件。关于 ResourceStreamUtil 类和 Properties 类的介绍大家可以参考 j2mepolish 里边的 api doc。

只要在把你所新建的 .properties 文件放在 resources 文件夹下(相当于一个资源文件,也可以放其他地方，但一定要把它配置成资源),就可以用相应的方法读取, 看下边例子:

test.properties文件:

name=muscle-liusex=maleage=24

读取时的部分代码：

Properties prop = new Properties();InputStream in = null;try{  byte[] sData = ResourceStreamUtil.getResourceAsByteArray("/test.properties");  System.out.println("sData.length:  "+sData.length);  in =  new ByteArrayInputStream(sData);              prop.load(in);}catch (IOException e){  e.printStackTrace();}System.out.println("prop.getProperty("name"): "+prop.getProperty("name"));System.out.println("prop.getProperty("sex"): "+prop.getProperty("sex"));System.out.println("prop.getProperty("age"): "+prop.getProperty("age"));

运行结果如下：

prop.getProperty("name"): muscle-liuprop.getProperty("sex"): maleprop.getProperty("age"): 24

在运用中我发现这个 Properties 类有个 bug，就是不支持 # 的注释(也就是说，属性文件里边除了 key-value 的内容，不能有其他的非 k-v 内容)。下边是我修改 Properties 里边的 load 方法，令它支持 # 注释:
原来的 load 方法：

public void load(InputStream in, String encoding, boolean generateIntegerValues ) throws IOException{this.isIntegerValues = generateIntegerValues;int bufferLength = 2 * 1024;byte[] buffer = new byte[ bufferLength ];int read;int start = 0;int end = 0;boolean newLineFound;while ( (read = in.read(buffer, start, bufferLength - start )) != -1) {// search for next \r or \nString line;if (encoding != null) {line = new String( buffer, 0, read + start, encoding );} else {line = new String( buffer, 0, read + start );}start = 0;newLineFound = true;while (newLineFound) {newLineFound = false;char c = '\n';for (int i = start; i < line.length(); i++) {c = line.charAt(i);if (c == '\r' || c == '\n') {end = i;newLineFound = true;break;}}if (newLineFound) {int splitPos = line.indexOf('=', start);if(splitPos == -1) {throw new IOException("no = separator: " + line.substring( start, end ));}String key = line.substring( start, splitPos );String value = line.substring( splitPos + 1, end );if (generateIntegerValues) {try {put( key, Integer.valueOf(value) );} catch(NumberFormatException ex) {throw new IOException( ex.toString() );}} else {put( key, value );}if (c == '\r') {start = end + 2;} else {start = end + 1;}}}// now all key-value pairs have been read, now move any remaining data to the beginning of the buffer:if (start < read) {System.arraycopy( buffer, start, buffer, 0, read - start );start = read - start;} else {start = 0;}}}

修改后的 load 方法:

public void load(InputStream in, String encoding, boolean generateIntegerValues ) throws IOException{this.isIntegerValues = generateIntegerValues;int bufferLength = 2 * 1024;byte[] buffer = new byte[ bufferLength ];int read;int start = 0;int end = 0;boolean newLineFound;boolean isComment;while ( (read = in.read(buffer, start, bufferLength - start )) != -1) {// search for next \r or \nString line;if (encoding != null) {line = new String( buffer, 0, read + start, encoding );} else {line = new String( buffer, 0, read + start );}start = 0;newLineFound = true;while (newLineFound) {newLineFound = false;isComment = false;char c = '\n';char firstChar = line.charAt(start);if(firstChar == '#'){isComment = true;}for (int i = start; i < line.length(); i++) {c = line.charAt(i);if (c == '\r' || c == '\n') {end = i;newLineFound = true;break;}}if (newLineFound && !isComment) {int splitPos = line.indexOf('=', start);if(splitPos == -1) {throw new IOException("no = separator: " + line.substring( start, end ));}String key = line.substring( start, splitPos );String value = line.substring( splitPos + 1, end );if (generateIntegerValues) {try {put( key, Integer.valueOf(value) );} catch(NumberFormatException ex) {throw new IOException( ex.toString() );}} else {put( key, value );}}if (c == '\r') {start = end + 2;} else {start = end + 1;}}// now all key-value pairs have been read, now move any remaining data to the beginning of the buffer:if (start < read) {System.arraycopy( buffer, start, buffer, 0, read - start );start = read - start;} else {start = 0;}}}

这样我们就可以像 j2se 那样写 properties 文件了..当然，如果你的项目中没有用 j2mepolish, 那你也可以借用这两个类到你的工程，照样可以实现 j2se 的 properties 功能 1 楼 mingkg21 2008-04-14   复杂了一些，还可以简单一点。。。。。 2 楼 jandyguan 2008-07-15   因为Properties类继承Hashmap，实现接口Externalizable,这些都是Polish的东西，所以在其它项目单用这两个类是不行的。 3 楼 muscle-liu 2008-07-30   我们可以继承j2me里边的Hashtable来实现的，而接口Externalizable 是继承Serializable的，所以完全可以改为自己的properties,在其他的j2me项目里都能用