java项目读取properties路径问题

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java项目读取properties路径问题

1.项目结构

2.方法一

/**
* 传统方式
*/
private void test1() throws FileNotFoundException, IOException {
		// FileInputStream in = new FileInputStream("src/main/resources/properties/url.properties"); // 错误写法1  java项目中这么写是正确的，web项目不行
		 //  FileInputStream in = new FileInputStream("classes/test.properties");//错误写法2
		     FileInputStream in = new FileInputStream("test.properties");//把test.properties文件copy到tomcate的bin目录下
		     Properties prop = new Properties();
		     prop.load(in);
		     String driver = prop.getProperty("driver");
		     String url = prop.getProperty("url");
		     System.out.println("driver-==-="+driver);
		     System.out.println("url-==-="+url);
	}

解析：
错误写法1：要是java项目，这么写是正确的，可以读到配置文件，但是web项目就会报找不到路径的错误，因为web项目会把test.properties文件编译到WEB-INF目录下的classes文件夹下。
错误写法2：这么看似没问题了，但是会报跟1一样的错误，因为这是相对路径，谁调用此类就是相对于谁，故这是相对于java虚拟机，本项目时用tomcate启动的java虚拟机，故回去tomcate的bin目录下去找classes/test.properties文件，找不到故报错

3.方法二

private void test2() throws IOException {
		System.out.println("test2");
		InputStream in = this.getServletContext().getResourceAsStream("WEB-INF/classes/test.properties");
		 Properties prop = new Properties();
		 prop.load(in);
		 String driver = prop.getProperty("driver");
		 String url = prop.getProperty("url");
		 System.out.println("driver-==-="+driver);
		 System.out.println("url-==-="+url);
	}

4.方法三

private void test3() throws FileNotFoundException, IOException {
		String path = this.getServletContext().getRealPath("WEB-INF/classes/test.properties");//拿到资源在硬盘上的路径
		FileInputStream in = new FileInputStream(path);
		 System.out.println("test3");
		 Properties prop = new Properties();
		 prop.load(in);
		 String driver = prop.getProperty("driver");
		 String url = prop.getProperty("url");
		 System.out.println("driver-==-="+driver);
		 System.out.println("url-==-="+url);
	}

5.方法四

private void test4() throws IOException {
		/**
		 * 读取webroot目录下的配置文件
		 */
		 System.out.println("test4");
		 InputStream in = this.getServletContext().getResourceAsStream("/WEB-INF/test11.properties");
		 Properties prop = new Properties();
		 prop.load(in);
		 String driver = prop.getProperty("driver");
		 String url = prop.getProperty("url");
		 System.out.println("driver-==-="+driver);
		 System.out.println("url-==-="+url);
	}

6.方法五

private void test5() throws IOException {
		/**
		 * 类装载器方式读取，我常用的方式
		 */
		InputStream in  = readProp.class.getClassLoader().getResourceAsStream("test.properties");
		System.out.println("类装载器方式");
		 Properties prop = new Properties();
		 prop.load(in);
		 String driver = prop.getProperty("driver");
		 String url = prop.getProperty("url");
		 System.out.println("driver-==-="+driver);
		 System.out.println("url-==-="+url);
	}

转载于:https://my.oschina.net/gaoguofan/blog/753386