JavaWeb读取配置文件的四种方法

package com.xia.fileReader; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.text.MessageFormat; import java.util.Properties; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class FileReader extends HttpServlet {  private static final long serialVersionUID = 1L;  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  /**  * response.setContentType("text/html;charset=UTF-8");目的是控制浏览器用UTF-8进行解码；  * 这样就不会出现中文乱码了  */  response.setHeader("content-type","text/html;charset=UTF-8");  readSrcDirPropCfgFile(response);//读取src目录下的db1.properties配置文件  response.getWriter().println("<hr/>");  readWebRootDirPropCfgFile(response);//读取WebRoot目录下的db2.properties配置文件  response.getWriter().println("<hr/>");  readSrcSourcePackPropCfgFile(response);//读取src目录下的config目录中的db3.properties配置文件  response.getWriter().println("<hr/>");  readWEBINFPropCfgFile(response);//读取WEB-INF目录下的JDBC目录中的db4.properties配置文件  }  public void readSrcDirPropCfgFile(HttpServletResponse response) throws IOException {  String path = "/WEB-INF/classes/db1.properties";  InputStream in = this.getServletContext().getResourceAsStream(path);  Properties props = new Properties();  props.load(in);  String driver = props.getProperty("jdbc.driver");  String url = props.getProperty("jdbc.url");  String username = props.getProperty("jdbc.username");  String password = props.getProperty("jdbc.password");  response.getWriter().println("读取src目录下的db1.properties配置文件");  response.getWriter().println(MessageFormat.format( "driver={0},url={1},username={2},password={3}",  driver,url, username, password));  }  public void readWebRootDirPropCfgFile(HttpServletResponse response) throws IOException{  String path = "/db2.properties";  InputStream in = this.getServletContext().getResourceAsStream(path);  Properties props = new Properties();  props.load(in);  String driver = props.getProperty("jdbc.driver");  String url = props.getProperty("jdbc.url");  String username = props.getProperty("jdbc.username");  String password = props.getProperty("jdbc.password");  response.getWriter().println("读取WebRoot目录下的db2.properties配置文件");  response.getWriter().println(MessageFormat.format( "driver={0},url={1},username={2},password={3}",  driver,url, username, password));  }  public void readSrcSourcePackPropCfgFile(HttpServletResponse response) throws IOException {  String path = "/WEB-INF/classes/config/db3.properties";  String realPath = this.getServletContext().getRealPath(path);  InputStreamReader reader = new InputStreamReader(new FileInputStream(realPath),"UTF-8");  Properties props = new Properties();  props.load(reader);  String driver = props.getProperty("jdbc.driver");  String url = props.getProperty("jdbc.url");  String username = props.getProperty("jdbc.username");  String password = props.getProperty("jdbc.password");  response.getWriter().println("读取src目录下的config目录中的db3.properties配置文件");  response.getWriter().println(MessageFormat.format( "driver={0},url={1},username={2},password={3}",  driver,url, username, password));  }  public void readWEBINFPropCfgFile(HttpServletResponse response) throws IOException {  String path = "/WEB-INF/JDBC/db4.properties";  String realPath = this.getServletContext().getRealPath(path);  System.out.println("realPath："+realPath);  System.out.println("contextPath："+this.getServletContext().getContextPath());  InputStreamReader reader = new InputStreamReader(new FileInputStream(realPath),"UTF-8");  Properties props = new Properties();  props.load(reader);  String driver = props.getProperty("jdbc.driver");  String url = props.getProperty("jdbc.url");  String username = props.getProperty("jdbc.username");  String password = props.getProperty("jdbc.password");  response.getWriter().println("读取WEB-INF目录下的JDBC目录中的db4.properties配置文件");  response.getWriter().println(MessageFormat.format( "driver={0},url={1},username={2},password={3}",  driver,url, username, password));  }  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  } } 

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">  <display-name>javaReaderFile</display-name>  <welcome-file-list>  <welcome-file>index.html</welcome-file>  <welcome-file>index.htm</welcome-file>  <welcome-file>index.jsp</welcome-file>  <welcome-file>default.html</welcome-file>  <welcome-file>default.htm</welcome-file>  <welcome-file>default.jsp</welcome-file>  </welcome-file-list>  <servlet>  <servlet-name>FileReader</servlet-name>  <servlet-class>com.xia.fileReader.FileReader</servlet-class>  </servlet>  <servlet-mapping>  <servlet-name>FileReader</servlet-name>  <url-pattern>/FileReader</url-pattern>  </servlet-mapping> </web-app> 

/**  * 获取指定配置文件中所有的数据  * @param propertyName  * 调用方式：  * 1.配置文件放在resource源包下，不用加后缀  * PropertiesUtil.getAllMessage("message");  * 2.放在包里面的  * PropertiesUtil.getAllMessage("com.test.message");  * @return  */ public static List<String> getAllMessage(String propertyName) {  // 获得资源包  ResourceBundle rb = ResourceBundle.getBundle(propertyName.trim());  // 通过资源包拿到所有的key  Enumeration<String> allKey = rb.getKeys();  // 遍历key 得到 value  List<String> valList = new ArrayList<String>();  while (allKey.hasMoreElements()) {  String key = allKey.nextElement();  String value = (String) rb.getString(key);  valList.add(value);  }  return valList; } 

package com.xia.fileReader; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.Properties; public class ReadByClassLoader {  public static void main(String[] args) throws IOException {  readPropFileByClassLoad();  }  public static void readPropFileByClassLoad() throws IOException{  //读取src下面config包内的配置文件db3.properties  InputStream in = ReadByClassLoader.class.getClassLoader().getResourceAsStream("config/db3.properties");  BufferedReader br = new BufferedReader(new InputStreamReader(in));  Properties props = new Properties();  props.load(br);  for(Object s: props.keySet()){  System.out.println(s+":"+props.getProperty(s.toString()));  }  } } 

/**  * Spring 提供的 PropertiesLoaderUtils 允许您直接通过基于类路径的文件地址加载属性资源  * 最大的好处就是：实时加载配置文件，修改后立即生效，不必重启  */ private static void springUtil(){  Properties props = new Properties();  while(true){  try {  props=PropertiesLoaderUtils.loadAllProperties("message.properties");  for(Object key:props.keySet()){  System.out.print(key+":");  System.out.println(props.get(key));  }  } catch (IOException e) {  System.out.println(e.getMessage());  }  try {Thread.sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}  } } 

/**  * 传递键值对的Map，更新properties文件  *  * @param fileName  * 文件名(放在resource源包目录下)，需要后缀  * @param keyValueMap  * 键值对Map  */  public static void updateProperties(String fileName,Map<String, String> keyValueMap) {  //getResource方法使用了utf-8对路径信息进行了编码，当路径中存在中文和空格时，他会对这些字符进行转换，这样，  //得到的往往不是我们想要的真实路径，在此，调用了URLDecoder的decode方法进行解码，以便得到原始的中文及空格路径。  String filePath = PropertiesUtil.class.getClassLoader().getResource(fileName).getFile();  Properties props = null;  BufferedWriter bw = null;  try {  filePath = URLDecoder.decode(filePath,"utf-8");  log.debug("updateProperties propertiesPath:" + filePath);  props = PropertiesLoaderUtils.loadProperties(new ClassPathResource(fileName));  log.debug("updateProperties old:"+props);  // 写入属性文件  bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(filePath)));  props.clear();// 清空旧的文件  for (String key : keyValueMap.keySet())  props.setProperty(key, keyValueMap.get(key));  log.debug("updateProperties new:"+props);  props.store(bw, "");  } catch (IOException e) {  log.error(e.getMessage());  } finally {  try {  bw.close();  } catch (IOException e) {  e.printStackTrace();  }  }  }