Servlet 获取文件目录

Servlet 获取文件目录

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在web项目中，经常会用到配置文件。加载配置文件时就要需要目录

• 通过Request获取虚拟目录

@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String path = req.getContextPath();
        //如果项目发布的虚拟目录是/day12
        //则 path = "/day12"
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req,resp);
    }
}

• 通过 ServletContext对象 获取文件真实路径

1. 先说ServletContext对象的获取方式：
   1. 通过request对象获取 request.getServletContext();
   2. 通过HttpServlet获取 this.getServletContext();
   3. 通过Filter中的init的config获取 config.getServletContext();、
2. ServletContext对象的功能
   1. 获取MIME类型：
   2. 共享数据：（这也是域对象
   3. 获取文件的真实(服务器)路径 `getRealPath(“文件路径”)

文件位置	文件名	目录描述
src	a.txt	“WEB-INF/classes/a.txt”
web	b.txt	“/b.txt”
web/WEB-INF	c.txt	“WEB-INF/c.txt”

@WebServlet("/servletContextDemo5")
public class ServletContextDemo5 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /**
         * ServletContext第3个功能：
         *  3. 获取文件的真实(服务器)路径
         * 		1. 方法：String getRealPath(String path)
         */
        ServletContext context1 = this.getServletContext();
        //获取文件的服务器路径
        //1-web目录下的资源访问    "/"+文件名
        String b_path = context1.getRealPath("/b.txt");
        System.out.println(b_path);

        //2-WEB-INF下的资源访问
        String c_path = context1.getRealPath("WEB-INF/c.txt");
        System.out.println(c_path);

        //3-src目录下的资源访问
        String a_path = context1.getRealPath("WEB-INF/classes/a.txt");
        System.out.println(a_path);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req,resp);
    }
}