ReadFileUtils

title: UtilsClass_ReadFileUtils

date: 2015-12-28 18:30:59

categories: UtilsClass_Resource

tags: Utils

xl_echo编辑整理

读取文件

读取方式一：使用类的加载器

public class ReadFileServlet extends HttpServlet {
    public void ReadFile() {
            InputStream is = ReadFileServlet.class.getClassLoader().getResourceAsStream("ReadFile.properties");
            Properties prop = new Properties();
            prop.load(is);

            String driverClass = prop.getProperty("driverClass");
            String url = prop.getProperty("url");
            String username = prop.getProperty("username");
            String password = prop.getProperty("password");

            System.out.println(driverClass + ":" + url + ":" + username + ":" + password);
        }
}

读取方式二：使用this.getServletContext();

public class ReadFileServlet1 extends HttpServlet {
    public void ReadFile() {
        //获取全局域变量ServletContext
        ServletContext context = this.getServletContext();

        //使用全局变量获取输入流
        InputStream is = context.getResourceAsStream("/WEB-INF/classes/ReadFile.properties");
        Properties prop = new Properties();
        prop.load(is);

        String driverClass = prop.getProperty("driverClass");
        String url = prop.getProperty("url");
        String username = prop.getProperty("username");
        String password = prop.getProperty("password");

        System.out.println(driverClass + ":" + url + ":" + username + ":" + password);
        }
}

读取方式三：使用context.getRealPath();

public class ReadFileServlet2 extends HttpServlet {
    public void ReadFile() {
        //获得ServletContext全局域对象
        ServletContext context = this.getServletContext();
        //得到文件在磁盘的绝对路径
        String realPath = context.getRealPath("/WEB-INF/classes/ReadFile.properties");

        //使用字节输入流加绝对路径读取文件
        InputStream is = new FileInputStream(realPath);

        Properties prop = new Properties();
        prop.load(is);

        String driverClass = prop.getProperty("driverClass");
        String url = prop.getProperty("url");
        String username = prop.getProperty("username");
        String password = prop.getProperty("password");

        System.out.println(driverClass + ":" + url + ":" + username + ":" + password);
        }
}

使用全局变量来读取配置文件中的值

配置文件信息

<context-param>
    <param-name>username</param-name>
    <param-value>root</param-value>
  </context-param>
  <context-param>
    <param-name>password</param-name>
    <param-value>123</param-value>
  </context-param>
  <context-param>
    <param-name>111</param-name>
    <param-value>222</param-value>
  </context-param>

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = this.getServletContext().getInitParameter("username");
        String password = this.getServletContext().getInitParameter("password");
        System.out.println(username + password);

        //获得枚举类型
        Enumeration<String> e = this.getServletContext().getInitParameterNames();

        //遍历枚举对象
        while(e.hasMoreElements()){
            String name = e.nextElement();
            String value = this.getServletContext().getInitParameter(name);
            System.out.println(name + "\t" + value);
        }
    }

使用全局变量来读取文件在网络上的类型

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获得文件MIME的类型（主要是判断文件在网络上的类型，用于上传和下载）
        String type = this.getServletContext().getMimeType("aa.html");
        System.out.println(type);
    }