属性类：Properties

在一个属性文件中保存了多个属性，每一个属性就是直接用字符串表示出来的"key=value对"，而如果想要轻松地操作这些属性文件中的属性，可以通过Properties类方便地完成。

<1>设置和取得属性

import java.util.Properties;

//=================================================
// File Name       :	Properties_demo
//------------------------------------------------------------------------------
// Author          :	Common



//主类
//Function        : 	Properties_demo;
public class Properties_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Properties pro = new Properties();
		pro.setProperty("BJ", "Beijing");
		pro.setProperty("NJ", "Nanjing");
		pro.setProperty("TJ", "Tianjin");
		System.out.println("获得属性"+pro.getProperty("BJ"));
		System.out.println("获得属性不存在"+pro.getProperty("HB"));
		System.out.println("获得属性不存在，同时设置默认的显示值"+pro.getProperty("HB","：：：没有发现"));
	}

}

<2>将属性保存在普通文件中

import java.io.File;
import java.io.FileOutputStream;
import java.util.Properties;

//=================================================
// File Name       :	Properties_demo
//------------------------------------------------------------------------------
// Author          :	Common



//主类
//Function        : 	Properties_demo;
public class Properties_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Properties pro = new Properties();
		pro.setProperty("BJ", "Beijing");
		pro.setProperty("NJ", "Nanjing");
		pro.setProperty("TJ", "Tianjin");
		System.out.println("获得属性"+pro.getProperty("BJ"));
		System.out.println("获得属性不存在"+pro.getProperty("HB"));
		System.out.println("获得属性不存在，同时设置默认的显示值"+pro.getProperty("HB","：：：没有发现"));
		
		File f = new File("/home/common/software/coding/HelloWord/HelloWord/test.properties");//路径
		try{
			pro.store(new FileOutputStream(f),"pro info");		//保存并添加注释信息
		}catch(Exception e){
			e.printStackTrace();
		}
	}

}

<3>从普通文件中读取属性内容

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Properties;

//=================================================
// File Name       :	Properties_demo
//------------------------------------------------------------------------------
// Author          :	Common



//主类
//Function        : 	Properties_demo;
public class Properties_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Properties pro = new Properties();
		pro.setProperty("BJ", "Beijing");
		pro.setProperty("NJ", "Nanjing");
		pro.setProperty("TJ", "Tianjin");
		System.out.println("获得属性"+pro.getProperty("BJ"));
		System.out.println("获得属性不存在"+pro.getProperty("HB"));
		System.out.println("获得属性不存在，同时设置默认的显示值"+pro.getProperty("HB","：：：没有发现"));
		
		File f = new File("/home/common/software/coding/HelloWord/HelloWord/test.properties");//路径
		try{
			pro.load(new FileInputStream(f));		//读取属性文件
		}catch(Exception e){
			e.printStackTrace();
		}
		System.out.println("BJ属性值为"+pro.getProperty("BJ"));	
	}

}

<4>将属性保存在XML文件中

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Properties;

//=================================================
// File Name       :	Properties_demo
//------------------------------------------------------------------------------
// Author          :	Common



//主类
//Function        : 	Properties_demo;
public class Properties_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Properties pro = new Properties();
		pro.setProperty("BJ", "Beijing");
		pro.setProperty("NJ", "Nanjing");
		pro.setProperty("TJ", "Tianjin");
		System.out.println("获得属性"+pro.getProperty("BJ"));
		System.out.println("获得属性不存在"+pro.getProperty("HB"));
		System.out.println("获得属性不存在，同时设置默认的显示值"+pro.getProperty("HB","：：：没有发现"));
		
		File f = new File("/home/common/software/coding/HelloWord/HelloWord/test.xml");//路径
		try{
			pro.storeToXML(new FileOutputStream(f),"pro info");		//保存并添加注释信息
		}catch(Exception e){
			e.printStackTrace();
		}
		System.out.println("BJ属性值为"+pro.getProperty("BJ"));	
	}

}

<5>从XML文件中读取属性

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Properties;

//=================================================
// File Name       :	Properties_demo
//------------------------------------------------------------------------------
// Author          :	Common



//主类
//Function        : 	Properties_demo;
public class Properties_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Properties pro = new Properties();
		pro.setProperty("BJ", "Beijing");
		pro.setProperty("NJ", "Nanjing");
		pro.setProperty("TJ", "Tianjin");
		System.out.println("获得属性"+pro.getProperty("BJ"));
		System.out.println("获得属性不存在"+pro.getProperty("HB"));
		System.out.println("获得属性不存在，同时设置默认的显示值"+pro.getProperty("HB","：：：没有发现"));
		
		File f = new File("/home/common/software/coding/HelloWord/HelloWord/test.xml");//路径
		try{
			pro.loadFromXML(new FileInputStream(f));		//读取属性文件
		}catch(Exception e){
			e.printStackTrace();
		}
		System.out.println("BJ属性值为"+pro.getProperty("BJ"));	
	}

}