java读取properties文件

关键字: java读取properties配置文件 今天要将以前一个项目的数据连接改成从properties文件中配置。找了好久，网上也不少，可就是读取文件时总是找不到文件在哪（我放在classes目录下了）。最后终于成功，记下，以做纪念。

Java代码

package com.web.connection;
 

import java.io.IOException;
 
import java.io.InputStream;
 
import java.sql.Connection;
 
import java.sql.DriverManager;
 
import java.sql.SQLException;
 
import java.util.Properties;
 
import java.util.logging.Level;
 
import java.util.logging.Logger;
 

public class Conn {
 
private String fileName="/db.properties";//这里是指放在classes下，如果有包的话，前面加包名即可。例：/com/web/db.properties
 
private String driver = "";
 
private String url = "";
 
private String username ="";
 
private String password = "";
 
Connection conn=null;
 


public  Connection  getConn(){
 
Properties p = new Properties();
 
try {
 
InputStream in = Conn.class.getResourceAsStream(fileName);// 与类在同一级，也可用/package/path/to/fileName
 
p.load(in);
 
in.close();
 
if(p.containsKey("driver")){
 
this.driver = p.getProperty("driver");
 
}
 
if(p.containsKey("url")){
 
this.url = p.getProperty("url");
 
}
 
if(p.containsKey("user")){
 
this.username = p.getProperty("user");
 
}
 
if(p.containsKey("password")){
 
this.password = p.getProperty("password");
 
}
 
} catch (IOException ex) {
 
Logger.getLogger(Conn.class.getName()).log(Level.SEVERE, null, ex);
 
}
 
System.out.println(p.getProperty("driver"));
 
try {
 
Class.forName(this.driver);
 
conn = DriverManager.getConnection(this.url,this.username,this.password);
 
} catch (SQLException ex) {
 
ex.printStackTrace();
 
System.out.print("获取连接异常");
 
} catch (ClassNotFoundException ex) {
 
System.out.print("加载驱动出错");
 
ex.printStackTrace();;
 
}
 
return conn;
 
}
 
}
 
package com.web.connection;  import java.io.IOException; import java.io.InputStream; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.util.Properties; import java.util.logging.Level; import java.util.logging.Logger;  public class Conn {     private String fileName="/db.properties";//这里是指放在classes下，如果有包的话，前面加包名即可。例：/com/web/db.properties     private String driver = "";     private String url = "";     private String username ="";     private String password = "";     Connection conn=null;           public  Connection  getConn(){         Properties p = new Properties();   try {    InputStream in = Conn.class.getResourceAsStream(fileName);//这里有人用new FileInputStream(fileName),不过这种方式找不到配置文件。有人说是在classes下，我调过了，不行。       p.load(in);       in.close();       if(p.containsKey("driver")){           this.driver = p.getProperty("driver");       }       if(p.containsKey("url")){           this.url = p.getProperty("url");       }       if(p.containsKey("user")){           this.username = p.getProperty("user");       }       if(p.containsKey("password")){           this.password = p.getProperty("password");       }   } catch (IOException ex) {       Logger.getLogger(Conn.class.getName()).log(Level.SEVERE, null, ex);   }         System.out.println(p.getProperty("driver"));        try {             Class.forName(this.driver);             conn = DriverManager.getConnection(this.url,this.username,this.password);         } catch (SQLException ex) {             ex.printStackTrace();             System.out.print("获取连接异常");         } catch (ClassNotFoundException ex) {             System.out.print("加载驱动出错");             ex.printStackTrace();;         }         return conn;     } } 
 
网上文章常见的几种读取.properties文件的方式
 
1、使用java.util.Properties类的load()方法 示例： 
 

   Java代码 
  
 
 
1. InputStream in = lnew BufferedInputStream(new
2. Properties p = new
3. p.load(in);
 
InputStream in = lnew BufferedInputStream(new FileInputStream(name));  Properties p = new Properties();  p.load(in);2、使用java.util.ResourceBundle类的getBundle()方法 
示例：  

   Java代码 
  
 
 
1. ResourceBundle rb = ResourceBundle.getBundle(name, Locale.getDefault());
 
ResourceBundle rb = ResourceBundle.getBundle(name, Locale.getDefault());用ResourceBundle读取.properties文件可避免路径问题 
我在jar里读取.properties文件时，总是找不到文件路径，后来用ResourceBundle读取.properties文件即可避免路径问题，代码如下： 


//process为文件名，切记不要加 .properties， URL是文件里的键名 

   Java代码 
  
 
 
1. getBundle("com.ihandy.smsoc.app.process");
2. "URL");
3. System.out.println(s);
4. pURL = s;
 
ResourceBundle bundle = ResourceBundle.getBundle("com.ihandy.smsoc.app.process");      String s = bundle.getString("URL");   System.out.println(s);   pURL = s;
3、使用java.util.PropertyResourceBundle类的构造函数 
示例： 

   Java代码 
  
 
 
1. InputStream in = new BufferedInputStream(new
2. ResourceBundle rb = new
 
InputStream in = new BufferedInputStream(new FileInputStream(name));  ResourceBundle rb = new PropertyResourceBundle(in);4、使用class变量的getResourceAsStream()方法 
示例：
 

   Java代码 
  
 
 
1. InputStream in = 类名.class.getResourceAsStream(name);
2. Properties p = new
3. p.load(in);
 
InputStream in = 类名.class.getResourceAsStream(name);  Properties p = new Properties();  p.load(in);5、使用class.getClassLoader()所得到的java.lang.ClassLoader的getResourceAsStream()方法 示例：
 

   Java代码 
  
 
 
1. InputStream in = 类名.class.getClassLoader().getResourceAsStream(name);
2. Properties p = new
3. p.load(in);
 
InputStream in = 类名.class.getClassLoader().getResourceAsStream(name);  Properties p = new Properties();  p.load(in);6、使用java.lang.ClassLoader类的getSystemResourceAsStream()静态方法 示例：
 

   Java代码 
  
 
 
1. InputStream in = ClassLoader.getSystemResourceAsStream(name);
2. Properties p = new
3. p.load(in);
 
InputStream in = ClassLoader.getSystemResourceAsStream(name);  Properties p = new Properties();  p.load(in);7、Servlet中可以使用javax.servlet.ServletContext的getResourceAsStream()方法 示例：
 

   Java代码 
  
 
 
1. InputStream in = context.getResourceAsStream(path);
2. Properties p = new
3. p.load(in);