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);
//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;

}

}

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

InputStream in = lnew BufferedInputStream(
new
FileInputStream(name));

Properties p = new
Properties();

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

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

ResourceBundle bundle = ResourceBundle.getBundle(
"com.ihandy.smsoc.app.process"
);

String s = bundle.getString("URL"
);

System.out.println(s);

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

InputStream in =
new
BufferedInputStream(
new
FileInputStream(name));

ResourceBundle rb = new
PropertyResourceBundle(in);

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

InputStream in = 类
名.
class
.getResourceAsStream(name);

Properties p = new
Properties();

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

InputStream in = 类
名.
class
.getClassLoader().getResourceAsStream(name);

Properties p = new
Properties();

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

InputStream in = ClassLoader.getSystemResourceAsStream(name);

Properties p = new
Properties();

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

InputStream in = context.getResourceAsStream(path);

Properties p = new
Properties();

p.load(in);