最近看了一些视频，总算把Java中关于加载路径"."的作用弄明白了
下面就详解一下关于javase和javaee中加载相对资源路径使用“.”号的区别
首先 创建一个db.properties的资源文件
设置上属性名和值，我们用eclipse去运行此代码
package ch.ksssss.it_resource;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;
public class resourceDemo {
public static void main(String[] args) throws IOException {
FileInputStream inStream=new FileInputStream(new File("./src/db.properties"));
Properties pro=new Properties();
pro.load(inStream);
String name=pro.getProperty("name");
System.out.println(name);
}
}
结果 输出 name=chenlin
然后建一个javaweb项目
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
FileInputStream inStream=new FileInputStream(new File("./src/db.properties"));
Properties prop=new Properties();
prop.load(inStream);
String name=prop.getProperty("name");
System.out.println(name);
}
运行结果如下
该项目就会找不到"./src/db.properties"这个路径，这是为什么了，一方面是因为javaee里面没有src这个文件夹
里一个方面是java 相对路径是“.”匹配的是java命令运行的目录。而JVM启动Tomcat服务器是在"tomcat\bin"目录下启动，所以找不到资源文件，当我把资源文件放进tomcat\bin\src目录下面
再一次运行代码，显示name=chenlin
但是这样比较麻烦，所以context域对象就提供了两个方法
java.lang.StringgetRealPath(java.lang.String path)
java.io.InputStreamgetResourceAsStream(java.lang.String path)
package ch.ksssss.it_resource;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
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 resourceDemo extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
// FileInputStream inStream=new FileInputStream(new File("./src/db.properties"));
//将path改为 "/WEB-INF/classes/db.properties"
InputStream inStream= this.getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");
Properties prop=new Properties();
prop.load(inStream);
String name=prop.getProperty("name");
System.out.println(name);
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
}
运行就成功了