java中Properties类的使用，网上文章整理

package com.adrop.util;



import java.io.*;

import java.util.properties;

import javax.servlet.http.*;

import javax.servlet.*;

import javax.servlet.jsp.*;



public class propertiesutil {

private string filename;

private properties p;

private fileinputstream in;

private fileoutputstream out;

/**

* 根据传进的文件名载入文件

* @param filename string

*/

public propertiesutil(string filename) {

this.filename=filename;

file file = new file(filename);

try {

in = new fileinputstream(file);

p = new properties();

//载入文件

p.load(in);

in.close();

}

catch (filenotfoundexception e) {

system.err.println("设置文件config.properties未找到！！");

e.printstacktrace();

}

catch (exception e) {

system.err.println("读取设置文件config.properties错误！！");

e.printstacktrace();

}

}



/**

* 设置文件一律为config.propertities，并且统一放在web应用的根目录下。

* @return string

*/

public static string getconfigfile(httpservlet hs) {



return getconfigfile(hs,"config.properties");

}

/**

* 在servlet中使用,直接用this作为参数,httpservlet类型

* 根据设置文件名从当前web应用的根目录下找出设置文件

* @param hs httpservlet

* @param configfilename string设置文件名字

* @return string

*/

public static string getconfigfile(httpservlet hs, string configfilename) {

string configfile = "";

servletcontext sc = hs.getservletcontext();

configfile = sc.getrealpath("/" + configfilename);

if (configfile == null || configfile.equals("")) {

configfile = "/" + configfilename;

}

return configfile;

}

/**

* jsp中用pagecontext作参数

* @param hs pagecontext

* @param configfilename string 设置文件名字

* @return string

*/

public static string getconfigfile(pagecontext hs, string configfilename) {

string configfile = "";

servletcontext sc = hs.getservletcontext();

configfile = sc.getrealpath("/" + configfilename);

if (configfile == null || configfile.equals("")) {

configfile = "/" + configfilename;

}

return configfile;

}



/**

* 列出所有的设置文件内容

*/

public void list() {

p.list(system.out);

}



/**

* 指定设置项名称，返回设置值

* @param itemname string

* @return string

*/

public string getvalue(string itemname){

return p.getproperty(itemname);

}



/**

* 指定设置项名称和默认值，返回设置值

* @param itemname string

* @param defaultvalue string

* @return string

*/

public string getvalue(string itemname,

string defaultvalue){

return p.getproperty(itemname,defaultvalue);

}



/**

* 设置设置项名称及其值

* @param itemname string

* @param value string

*/

public void setvalue(string itemname,string value){

p.setproperty(itemname,value);

return;

}



/**

* 保存设置文件，指定文件名和抬头描述

* @param filename string

* @param description string

* @throws exception

*/

public void savefile(string filename,string description)throws exception{

try {

file f=new file(filename);

out

= new fileoutputstream(f);

p.store(out, description);//保存文件

out.close();

}

catch (ioexception ex) {

throw new exception

("无法保存指定的设置文件:"+filename);

}

}



/**

* 保存设置文件，指定文件名

* @param filename string

* @throws exception

*/

public void savefile(string filename)

throws exception {

savefile(filename,"");

}



/**

* 保存设置文件，采用原文件名

* @throws exception

*/

public void savefile() throws exception {

if(filename.length()==0)

throw new exception

("需指定保存的设置文件名");

savefile(filename);

}

/**

* 删除一个属性

* @param value string

*/

public void deletevalue(string value){

p.remove(value);

}

/**

* main method for test

* @param args string[]

*/

public static void main(string[] args) {

string file = "f:＼＼p.properties";

propertiesutil pu = new propertiesutil(file);

pu.list();

}

}

 

 

一个既能读又写入dbConfig.properties（数据库配置文件）java源代码

 

答案一

public class ConnectionHelper {
/**
* 通过JNDI获取数据源
*/
private static DataSource getDataSource(){
//建立JNDI的上下文
try {
InitialContext ct = new InitialContext();
DataSource source = (DataSource)ct.lookup("java:/comp/env/jdbc/shop");
return source;
} catch (Exception e) {
throw new RuntimeException("获取数据源失败",e);
}
}

//从Properties文件加载配置参数
public static Properties getConfig(){
Properties pro = new Properties();
InputStream is = ConnectionHelper.class.getResourceAsStream("/com/lxw/config/db.properties");
try {
pro.load(is);
return pro;
} catch (IOException e) {
throw new DBException("加载配置文件失败",e);
}
}

private static DataSource ds = null;
//自构建数据源
public static synchronized DataSource getMyDataSource(){
if(ds == null){
Properties pro = getConfig();
BasicDataSource bdc = new BasicDataSource();
bdc.setDriverClassName(pro.getProperty("dbDriver"));
bdc.setUrl(pro.getProperty("dbUrl"));
bdc.setUsername(pro.getProperty("dbUser"));
bdc.setPassword(pro.getProperty("dbPassword"));
String num = pro.getProperty("dbMaxActive");
if(num != null && num.equals("")){
bdc.setMaxActive(Integer.parseInt(num));
}
/*bdc.setDriverClassName("com.mysql.jdbc.Driver");
bdc.setUrl("jdbc:mysql://localhost:3306/shop");
bdc.setUsername("root");
bdc.setPassword("123");
bdc.setMaxActive(20);*/
ds = bdc;
}
return ds;
}

//获取统一的数据库连接
public static Connection getCon(){
try {
//return getDataSource().getConnection();

//通过自构建的数据源获取连接
return getMyDataSource().getConnection();
} catch (SQLException e) {
throw new DBException("获取数据库连接失败",e);
}
}

//关闭连接
public static void closeCon(Connection con){
try {
if(null != con && !con.isClosed()){
con.close();
con = null;
}
} catch (SQLException e) {
throw new DBException("关闭数据库连接失败",e);
}
}
public static void main(String[] args) {
System.out.println(getCon());
System.out.println("获取连接成功");
}
}

 

 

答案二

 

/**
* 读取属性文件
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2005</p>
* <p>Company: </p>
* @author zhanggy
* @version 1.0
*/
public class PropertyManager {

private static PropertyManager manager = null;
private static Object managerLock = new Object();

/**
* Returns a Jive property.
*
* @param name the name of the property to return.
* @return the property value specified by name.
*/
public static String getProperty(String propsName,String name) {
if (manager == null) {
synchronized(managerLock) {
if (manager == null) {
manager = new PropertyManager(propsName);
}
}
}
return manager.getProp(name);
}

private Properties properties = null;
private Object propertiesLock = new Object();
private String resourceURI;

/**
* Creates a new PropertyManager. Singleton access only.
*/
private PropertyManager(String resourceURI) {
this.resourceURI = resourceURI;
}

/**
* Gets a Jive property. Jive properties are stored in jive.properties.
* The properties file should be accesible from the classpath. Additionally,
* it should have a path field that gives the full path to where the
* file is located. Getting properties is a fast operation.
*
* @param name the name of the property to get.
* @return the property specified by name.
*/
protected String getProp(String name) {
//If properties aren't loaded yet. We also need to make this thread
//safe, so synchronize...
if (properties == null) {
synchronized(propertiesLock) {
//Need an additional check
if (properties == null) {
loadProps();
}
}
}
String property = properties.getProperty(name);
if (property == null) {
return null;
}
else {
return property.trim();
}
}

/**
* Loads Jive properties from the disk.
*/
private void loadProps() {
properties = new Properties();
InputStream in = null;
try {
in = getClass().getResourceAsStream(resourceURI);
properties.load(in);
in.close();
}
catch (Exception e) {
System.err.println("Error reading properties in PropertyManager.loadProps() " + e);
e.printStackTrace();
}
finally {
try {
in.close();
} catch (Exception e) { }
}
}

// public static void main(String[] args) {
// String dbtype = PropertyManager.getProperty("/dbconfig.properties", "dbtype");
// System.out.println("dbtype = "+dbtype);
// }
}

 

 

java获取properties配置文件

 

package test.bwl;   
  
import java.io.FileNotFoundException;   
import java.io.IOException;   
import java.io.InputStream;   
import java.util.Properties;   
  
public class Test {   
    private static Properties properties = new Properties();   
  
    public static void main(String[] args) {   
        try {   
            InputStream is = Test.class.getClassLoader().getResourceAsStream("cache.properties");   
            properties.load(is);   
            String size = properties.getProperty("cache.size");   
            writeLog("配置成功！" + size);   
        } catch (FileNotFoundException e) {   
            writeLog("配置文件不存在！" + e.getMessage());   
        } catch (IOException e) {   
            writeLog("读取配置文件IO错误！" + e.getMessage());   
        }   
    }   
  
    public static void writeLog(String strLog) {   
        System.out.println(strLog);   
    }   
}  
package test.bwl;

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

public class Test {
private static Properties properties = new Properties();

public static void main(String[] args) {
try {
InputStream is = Test.class.getClassLoader().getResourceAsStream("cache.properties");
properties.load(is);
String size = properties.getProperty("cache.size");
writeLog("配置成功！" + size);
} catch (FileNotFoundException e) {
writeLog("配置文件不存在！" + e.getMessage());
} catch (IOException e) {
writeLog("读取配置文件IO错误！" + e.getMessage());
}
}

public static void writeLog(String strLog) {
System.out.println(strLog);
}
}

 

package test.bwl;   
  
import java.io.File;   
import java.io.FileInputStream;   
import java.io.FileNotFoundException;   
import java.io.FilenameFilter;   
import java.io.IOException;   
import java.io.InputStream;   
import java.util.Collections;   
import java.util.HashMap;   
import java.util.Map;   
import java.util.Properties;   
import java.util.regex.Pattern;   
  
/**  
* 配置信息管理器  
*   
* @author      bwl   
* @version     1.0  
*/  
public class ConfigManager {   
  
    /**  
     * 提供单例对象的静态内部类  
     */  
    private static class SingletonHolder {   
        public static ConfigManager instance = new ConfigManager();   
    }   
  
    /**  
     * 获取对象实例  
     * @return  
     */  
    public static ConfigManager getInstance() {   
        return SingletonHolder.instance;   
    }   
  
    /**  
     * 存储问题列表的Map  
     */  
    private Map<String, Properties> name2properties;   
  
    /**  
     * 构造方法，请使用getInstance()获取实例  
     */  
    private ConfigManager() {   
        name2properties = Collections.synchronizedMap(new HashMap<String, Properties>());   
        doInit();   
    }   
  
    /**  
     * 初始化方法   
     */  
    private void doInit() {   
        try {   
            File path = new File("./conf/");   
            if (!path.exists()) {   
                System.out.println("ConfilgManager Init Error: There is no folder named 'conf' under src file.");   
                return;   
            }   
            File[] confFiles = path.listFiles(new DirFilter(".*//.properties"));////   
            for (int i = 0; i < confFiles.length; i++) {   
                File f = confFiles[i];   
                if (f.exists() && f.isFile()) {   
                    Properties properties = new Properties();   
                    InputStream is = new FileInputStream(f);   
                    properties.load(is);   
                    name2properties.put(f.getName(), properties);   
                }   
            }   
  
        } catch (FileNotFoundException e) {   
            e.printStackTrace();   
        } catch (IOException e) {   
            e.printStackTrace();   
        }   
    }   
  
    /**  
     * 获取配置项的值  
     * @param fileName  配置文件的名称  
     * @param key       关键码的值  
     * @return  配置项  
     */  
    public String getProperty(String fileName, String key) {   
        if (fileName == null || fileName.length() == 0) {   
            return null;   
        }   
        Properties prop = name2properties.get(fileName);   
        if (prop != null) {   
            return prop.getProperty(key);   
        }   
        return null;   
    }   
  
    /**  
     * 获取整形的配置项的值  
     * @param fileName  配置文件的名称  
     * @param keyName   关键码的值  
     * @return  如果正确则返回数字，否则返回-1  
     */  
    public int getIntProperty(String fileName, String key) {   
        String value = this.getProperty(fileName, key);   
        int result = -1;   
        if (value == null) {   
            return result;   
        }   
        try {   
            result = Integer.parseInt(value);   
            return result;   
        } catch (Exception e) {   
            //Do nothing   
        }   
        return result;   
    }   
  
    /**  
     * 过滤属性文件的内部类   
     */  
    class DirFilter implements FilenameFilter {   
  
        /**  
         * 记录文件名格式的正则对象  
         */  
        private Pattern pattern;   
  
        public DirFilter(String regex) {   
            pattern = Pattern.compile(regex);   
        }   
  
        public boolean accept(File dir, String name) {   
            return pattern.matcher(new File(name).getName()).matches();   
        }   
  
    }   
  
    public static void main(String[] args) {   
        ConfigManager config = ConfigManager.getInstance();   
        System.out.println(config.getIntProperty("cache.properties", "cache.size") + "");   
        System.out.println(config.getProperty("javagroups.properties", "bus_name") + "");   
    }