Java中有个比较重要的类Properties（Java.util.Properties），主要用于读取Java的配置文件，各种语言都有自己所支 持的配置文件，配置文件中很多变量是经常改变的，这样做也是为了方便用户，让用户能够脱离程序本身去修改相关的变量设置。今天，我们就开始Properties的使用。
Java中Properties的使用
Properties的文档说明：
The Properties class represents a persistent set of properties. The Properties can be saved to a stream or loaded from a stream. Each key and its corresponding value in the property list is a string.
Properties类的描述：
public class Properties extends Hashtable<Object,Object>
测试的项目结构如下：
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" alt="" />
一、在huhx.properties文件中，我们为也方便，加入一条数据：
name=huhx
二、将huhx.properties文件加载读取，得到相应的属性
Properties properties = new Properties();
FileInputStream fis = new FileInputStream("huhx.properties");
properties.load(fis);
System.out.println(properties.get("name"));
properties.load()执行之后，fis.close方法对于properties.get(key)没有什么影响。因为load方法已经将数据解析读取到了Property中。
三、Properties的list方法的使用
PrintStream printStream = System.out;
properties.list(printStream);
list方法的具体代码：
public void list(PrintStream out) {
out.println("-- listing properties --");
Hashtable h = new Hashtable();
enumerate(h);
for (Enumeration e = h.keys() ; e.hasMoreElements() ;) {
String key = (String)e.nextElement();
String val = (String)h.get(key);
if (val.length() > 40) {
val = val.substring(0, 37) + "...";
}
out.println(key + "=" + val);
}
}
四、Properties的store方法的使用
OutputStream outputStream = new FileOutputStream("huhx.txt");
properties.store(outputStream, "comments");
五、Properties的storeToXML方法的使用
OutputStream outputStream2 = new FileOutputStream("huhx.xml");
properties.storeToXML(outputStream2, "comments");
六、最终生成的文件如下：
huhx.txt：
#comments
#Thu May 19 19:19:36 CST 2016
name=huhx
huhx.xml：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<comment>comments</comment>
<entry key="name">huhx</entry>
</properties>
PropertiesTest.java：
package com.huhx.linux; import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.Properties; public class PropertiesTest { public static void main(String[] args) throws Exception {
// 一般Properties的使用
Properties properties = new Properties();
FileInputStream fis = new FileInputStream("huhx.properties");
properties.load(fis);
System.out.println(properties.get("name")); // 以下是测试的部分
PrintStream printStream = System.out;
properties.list(printStream);
OutputStream outputStream = new FileOutputStream("huhx.txt");
properties.store(outputStream, "comments");
OutputStream outputStream2 = new FileOutputStream("huhx.xml");
properties.storeToXML(outputStream2, "comments");
}
}
PropertiesTest.java
七、属性文件中占位符的使用
huhx的文件内容如下：
word=I loves {0} and {1}
java的代码如下：
String word = properties.getProperty("word");
String lovesWord = MessageFormat.format(word, "android", "linux");
System.out.println(lovesWord); // I loves android and linux