如何在Java中的特定单词后面找到特定值

Question

我从BufferedReader中获得了一个文本，需要在特定字符串中获得一个特定值。

这是文本：

    aimtolerance = 1024;
    model = Araarrow;
    name = Bow and Arrows;
    range = 450;
    reloadtime = 3;
    soundhitclass = arrow;
    type = Ballistic;
    waterexplosionclass = small water explosion;
    weaponvelocity = 750;
        default = 213;
        fort = 0.25;
        factory = 0.25;
        stalwart = 0.25;
        mechanical = 0.5;
        naval = 0.5;

我需要得到介于默认值=和

哪个是"213"

Answer 1

类似的内容。。。。

String line;
while ((line = reader.readLine())!=null) {
   int ind = line.indexOf("default =");
   if (ind >= 0) {
      String yourValue = line.substring(ind+"default =".length(), line.length()-1).trim(); // -1 to remove de ";"
      ............
   }
}

Answer 2

如果只关心最终结果，即从'='分隔值文本文件中提取内容，您可能会发现内置的Properties对象有帮助？

http://docs.oracle.com/javase/6/docs/api/java/util/Properties.html

这能满足你的需求。当然，如果你特别想手动完成，这可能不是正确的选择。

Answer 3

您可以使用Properties类加载字符串并从中查找任何值

String readString = "aimtolerance = 1024;rn" + 
"model = Araarrow;rn" + 
"name = Bow and Arrows;rn" + 
"range = 450;rn" + 
"reloadtime = 3;rn" + 
"soundhitclass = arrow;rn" + 
"type = Ballistic;rn" + 
"waterexplosionclass = small water explosion;rn" + 
"weaponvelocity = 750;rn" + 
"default = 213;rn" + 
"fort = 0.25;rn" + 
"factory = 0.25;rn" + 
"stalwart = 0.25;rn" + 
"mechanical = 0.5;rn" + 
"naval = 0.5;rn";
readString = readString.replaceAll(";", "");
Properties properties = new Properties();
System.out.println(properties);
try {
    properties.load(new StringReader(readString));
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
System.out.println(properties);
String requiredPropertyValue = properties.getProperty("default");
System.out.println("requiredPropertyValue : "+requiredPropertyValue);

Answer 4

在"default="上拆分字符串，然后使用indexOf查找第一个出现的"；"。从0到索引做一个子字符串，你就有了自己的值。

请参阅http://docs.oracle.com/javase/7/docs/api/java/lang/String.html

Answer 5

使用正则表达式：

private static final Pattern DEFAULT_VALUE_PATTERN
        = Pattern.compile("default = (.*?);");
private String extractDefaultValueFrom(String text) {
    Matcher matcher = DEFAULT_VALUE_PATTERN.matcher(text);
    if (!matcher.find()) {
        throw new RuntimeException("Failed to find default value in text");
    }
    return matcher.group(1);
}