ServletContext对象访问文件（getResourceAsStream(String s)，getResource(String s),getRealPath(String s)）

今天药忘吃喽~ 2022-06-08 10:58 162阅读 0赞

**使用ServletContext对象访问文件：**

一、在项目web 下面创建一个文件夹file，接着创建一个test.properties文件，并输入如图信息

![Center][]

![Center 1][]

二、配置web.xml

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://java.sun.com/xml/ns/javaee"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    		  http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
             version="2.5">
    
        <servlet-mapping>
            <servlet-name>ServletFile</servlet-name>
            <url-pattern>/file</url-pattern>
        </servlet-mapping>
    
        
            
            
        
    
    </web-app>

三、servlet处理（ServletFile.java）

package com.hcq.servlet;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.*;
    import java.util.Properties;
    
    public class ServletFile extends HttpServlet {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //        应用servlet上下文读取properties文件
            readProperties();
    //        应用servlet上下文写内容到文件中
            writeProperties();
    
        }
    
        private void writeProperties() throws IOException {
            String realPath = getServletContext().getRealPath("/file/b.properties");
            FileWriter fw = new FileWriter(realPath);
            BufferedWriter bw = new BufferedWriter(fw);
            bw.write("写出到文件的内容");
            bw.flush();
            bw.close();
        }
    
        private void readProperties() throws IOException {
            String realPath = getServletContext().getRealPath("/file/test.properties");//返回该资源文件的绝对路径
            FileInputStream fis = new FileInputStream(realPath);
            InputStreamReader isr = new InputStreamReader(fis);
            Properties properties = new Properties();
            properties.load(isr);//这里我们使用字符流读取，防止出现乱码
            String db = properties.getProperty("db");
            String user = properties.getProperty("user");
            System.out.println("db:" + db);
            System.out.println("user:" + user);
            isr.close();
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request, response);
        }
    }

四、结果

![Center 2][]

![Center 3][]

注：不要忘记导入包

补充：

1. ServletContext的getResourceAsStream(String s)方法也可以读取文件  
InputStream is = getServletContext().getResourceAsStream("/file/test.properties");//返回字节输入流  
接下来的步骤与getRealPath(String s)方法一致  
  
  
2. ServletContext的getResource(String s)方法也可以读取文件  
URL urlObj = this.getServletContext().getResource("/file/test.properties");  
InputStream is = urlObj.openStream();//返回一个字节输入流。  
接下来的步骤与getRealPath(String s)方法一致

[Center]: /images/20220608/ac4d202e020c46979d9f404c3a473942.png
[Center 1]: /images/20220608/ebd0d1f7e9684855ac4e86929562bd88.png
[Center 2]: /images/20220608/d79eb76ccf9749b8ae930c740f8cb748.png
[Center 3]: /images/20220608/5695dec2e5bc489790f2635427be3df8.png