ServletContext对象读取资源文件以及重定向
Posted zsj03180204
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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>
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