有两种方式可以读取资源文件
* InputStream getResourceAsStream(String path) 通过文件的地址获取输入流
* String getRealPath(String path) 通过文件的地址获取文件的绝对磁盘路径
步骤：
1. 创建配置文件db.properties
2. 获取资源的输出流
3. 把输出流加载到配置文件中
db.properties
username=root33 password=12333 desc=haha33
package cn.itcast.context;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 读取资源文件
* @author Administrator
*
*/
public class ReadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
read5();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
/**
* 通过ServletContext对象获取文件的绝对磁盘路径
* 获取src目录下文件
* @throws IOException
*/
public void read5() throws IOException{
// 获取对象
String path = getServletContext().getRealPath("/WEB-INF/classes/db.properties");
// System.out.println(path);
// C:\apache-tomcat-6.0.14\webapps\day09\WEB-INF\classes\db.properties
// 获取输入流
InputStream in = new FileInputStream(path);
print(in);
}
/**
* 获取WebRoot目录目录下db.properties文件
* @throws IOException
*/
public void read4() throws IOException{
// ServletContext读取文件
InputStream in = getServletContext().getResourceAsStream("/db.properties");
// 打印方式
print(in);
}
/**
* 获取包目录下db.properties文件
* @throws IOException
*/
public void read3() throws IOException{
// ServletContext读取文件
InputStream in = getServletContext().getResourceAsStream("/WEB-INF/classes/cn/itcast/context/db.properties");
// 打印方式
print(in);
}
/**
* 获取src目录下db.properties文件
* @throws IOException 编译后，src文件不见了，全都放在class文件里
*/
public void read2() throws IOException{
// ServletContext读取文件
InputStream in = getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");
// 打印方式
print(in);
}
/**
* 传统方式读取资源文件
* 交给服务器处理，相对的位置tomcat/bin
* @throws IOException
*/
public void read1() throws IOException{
// 获取输入流
InputStream in = new FileInputStream("src/db.properties");
print(in);
}
/**
* 在控制台打印内容
* @param in
* @throws IOException
*/
public void print(InputStream in) throws IOException{
Properties pro = new Properties();
// 加载
pro.load(in);
// 获取文件中的内容
String username = pro.getProperty("username");
String password = pro.getProperty("password");
String desc = pro.getProperty("desc");
System.out.println("用户名："+username);
System.out.println("密码："+password);
System.out.println("描述："+desc);
}
}
1.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h3>1.html的相对路径</h3>
<a href="./demo5">demo5</a>
<a href="demo5">demo5</a>
<h3>1.html的绝对路径</h3>
<a href="http://localhost/day09/demo5">demo5</a>
<a href="/day09/demo5">demo5</a>
</body>
</html>
Servlet配置web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
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">
<servlet>
<servlet-name>ReadServlet</servlet-name>
<servlet-class>cn.itcast.context.ReadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ReadServlet</servlet-name>
<url-pattern>/read</url-pattern>
</servlet-mapping>
</web-app>
Servlet和location、302一起完成重定向
package cn.itcast.http;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 页面定时跳转
* @author Administrator
*
*/
public class RefreshServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
response.getWriter().write("访问到了...");
// 页面5秒会跳转到ServletDmo1
response.setHeader("refresh", "5;url=/day09/1.html");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
package cn.itcast.http;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 和location和302一起完成重定向
* @author Administrator
*
*/
public class ServletDmo1 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 向页面输出内容
response.setContentType("text/html;charset=UTF-8");
// response.getWriter().write("向班长借钱...");
// 我没钱
response.setStatus(302);
// 告诉我富班长的地址（重定向都是客户端的，带项目名）
response.setHeader("location", "/day09/1.html");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
web.xml配置文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
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">
<servlet>
<servlet-name>ServletDmo1</servlet-name>
<servlet-class>cn.itcast.http.ServletDmo1</servlet-class>
</servlet>
<servlet>
<servlet-name>RefreshServlet</servlet-name>
<servlet-class>cn.itcast.http.RefreshServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletDmo1</servlet-name>
<url-pattern>/servlet1</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>RefreshServlet</servlet-name>
<url-pattern>/refresh</url-pattern>
</servlet-mapping>
</web-app>
原文地址：https://www.cnblogs.com/zsj03180204/p/11025252.html
时间： 2024-11-10 00:01:05