Java Property类使用详解

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Date;
import java.util.Properties;

public class TestProperties {
	public void writeProperties() {
		Properties properties = new Properties();
		OutputStream output = null;
		try {
			output = new FileOutputStream("config.properties");
			properties.setProperty("url", "jdbc:mysql://localhost:3306/");
			properties.setProperty("username", "root");
			properties.setProperty("password", "root");
			properties.setProperty("databases", "music_player");
			properties.store(output, "Steven1997 modify" + new Date().toString());
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			if(output!=null) {
				try {
					output.close();
				}catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		
	}
	public static void main(String[] args) {
		TestProperties t = new TestProperties();
		t.writeProperties();
	}
}

package property;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

public class LoadProperties {
	public void loadProperties() {
		Properties properties = new Properties();
		InputStream inputStream = null;
		
		try {
			inputStream = new FileInputStream("config.properties");
			properties.load(inputStream);
			System.out.println("url:" + properties.getProperty("url"));
			System.out.println("username:" + properties.getProperty("username"));
			System.out.println("password:" + properties.getProperty("password"));
			System.out.println("database:" + properties.getProperty("database"));
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			if(inputStream !=null) {
				try {
					inputStream.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		
	}
	public static void main(String[] args) {
		LoadProperties l = new LoadProperties();
		l.loadProperties();
	}
}

package property;

import java.io.InputStream;
import java.util.Enumeration;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;

public class PropertiesTest {
	public void printAll() {
		Properties prop = new Properties();
		InputStream input = null;
		try {
			String file = "config.properties";
			input = getClass().getClassLoader().getResourceAsStream(file);
			if(input == null) {
				System.out.println("无法加载文件" + file);
				return ;
			}
			prop.load(input);
			// 方法一
			Set<Object> keys = prop.keySet();
			for(Object key:keys) {
				System.out.println("key:" + key.toString() + "|" + "value:" + prop.get(key));
			}
			//方法二：
			Set<Entry<Object, Object>> entrys =	prop.entrySet();//返回的属性键值对实体
			for(Entry<Object, Object> entry:entrys){
				System.out.println("key:"+entry.getKey()+",value:"+entry.getValue());
			}
			//方法三：
			Enumeration<?> e = prop.propertyNames();
			while (e.hasMoreElements()) {
				String key = (String) e.nextElement();
				String value = prop.getProperty(key);
				System.out.println("Key:" + key + ",Value:" + value);
			}

		}catch (Exception e) {
			e.printStackTrace();
		}finally {
			if(input != null) {
				try {
					input.close();
				}catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
	}
	public static void main(String[] args) {
		PropertiesTest p = new PropertiesTest();
		p.printAll();
	}
}