教学目标 | 掌握response设置响应头 掌握response重定向和转发的区别 掌握request接收请求参数 掌握request域的作用范围 |
教学方法 | 案例驱动法 |
/**
* 使用ServletContext中的getResourceAsStream读取.
* @throws FileNotFoundException
* @throws IOException
*/
private void test2() throws FileNotFoundException, IOException {
// 获得ServletContext:
ServletContext context = this.getServletContext();
InputStream is = context.getResourceAsStream("/WEB-INF/classes/db.properties");
Properties properties = new Properties();
properties.load(is);
String driverClass = properties.getProperty("driverClass");
String url = properties.getProperty("url");
String username = properties.getProperty("username");
String password = properties.getProperty("password");
System.out.println(driverClass);
System.out.println(url);
System.out.println(username);
System.out.println(password);
}
/**
* 使用ServletContext中的getRealPath读取.
* @throws FileNotFoundException
* @throws IOException
*/
private void test3() throws FileNotFoundException, IOException {
// 获得ServletContext:
ServletContext context = this.getServletContext();
String realPath = context.getRealPath("/WEB-INF/classes/db.properties");
// 获得该文件的磁盘绝对路径.
System.out.println(realPath);
InputStream is = new FileInputStream(realPath);
Properties properties = new Properties();
properties.load(is);
String driverClass = properties.getProperty("driverClass");
String url = properties.getProperty("url");
String username = properties.getProperty("username");
String password = properties.getProperty("password");
System.out.println(driverClass);
System.out.println(url);
System.out.println(username);
System.out.println(password);
}
配置全局初始化参数:
<context-param>
<param-name>username</param-name>
<param-value>root</param-value>
</context-param>
<context-param>
<param-name>password</param-name>
<param-value>123</param-value>
</context-param>
代码:
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = this.getServletContext().getInitParameter("username");
String password = this.getServletContext().getInitParameter("password");
System.out.println(username+" "+password);
Enumeration<String> e = this.getServletContext().getInitParameterNames();
while(e.hasMoreElements()){
String name = e.nextElement();
String value = this.getServletContext().getInitParameter(name);
System.out.println(name+" "+value);
}
}
public static void readFile() throws IOException{
// 使用类的加载器来读取文件.
// 类的加载器用来加载class文件,将class文件加载到内存.
InputStream is = ReadFileUtils.class.getClassLoader().getResourceAsStream("db.properties");
Properties properties = new Properties();
properties.load(is);
String driverClass = properties.getProperty("driverClass");
String url = properties.getProperty("url");
String username = properties.getProperty("username");
String password = properties.getProperty("password");
System.out.println(driverClass);
System.out.println(url);
System.out.println(username);
System.out.println(password);
}
public class DownloadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1.接收参数
String filename = request.getParameter("filename");
// 2.完成文件下载:
// 2.1设置Content-Type头
String type = this.getServletContext().getMimeType(filename);
response.setHeader("Content-Type", type);
// 2.2设置Content-Disposition头
response.setHeader("Content-Disposition", "attachment;filename="+filename);
// 2.3设置文件的InputStream.
String realPath = this.getServletContext().getRealPath("/download/"+filename);
InputStream is = new FileInputStream(realPath);
// 获得response的输出流:
OutputStream os = response.getOutputStream();
int len = 0;
byte[] b = new byte[1024];
while((len = is.read(b))!= -1){
os.write(b, 0, len);
}
is.close();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}Ø IE浏览器下载中文文件的时候采用的URL的编码.
Ø Firefox浏览器下载中文文件的时候采用的是Base64的编码.
/**
* 文件下载的Servlet
*/
public class DownloadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1.接收参数
String filename = new String(request.getParameter("filename").getBytes("ISO-8859-1"),"UTF-8");
System.out.println(filename);
// 2.完成文件下载:
// 2.1设置Content-Type头
String type = this.getServletContext().getMimeType(filename);
response.setHeader("Content-Type", type);
// 2.3设置文件的InputStream.
String realPath = this.getServletContext().getRealPath("/download/"+filename);
// 根据浏览器的类型处理中文文件的乱码问题:
String agent = request.getHeader("User-Agent");
System.out.println(agent);
if(agent.contains("Firefox")){
filename = base64EncodeFileName(filename);
}else{
filename = URLEncoder.encode(filename,"UTF-8");
}
// 2.2设置Content-Disposition头
response.setHeader("Content-Disposition", "attachment;filename="+filename);
InputStream is = new FileInputStream(realPath);
// 获得response的输出流:
OutputStream os = response.getOutputStream();
int len = 0;
byte[] b = new byte[1024];
while((len = is.read(b))!= -1){
os.write(b, 0, len);
}
is.close();
}
public static String base64EncodeFileName(String fileName) {
BASE64Encoder base64Encoder = new BASE64Encoder();
try {
return "=?UTF-8?B?"
+ new String(base64Encoder.encode(fileName
.getBytes("UTF-8"))) + "?=";
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
public class RequestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 获得请求方式：
String method = request.getMethod();
System.out.println("请求方式:"+method);
// 获得客户机的IP地址：
String ip = request.getRemoteAddr();
System.out.println("IP地址:"+ip);
// 获得用户的请求的路径:
String url = request.getRequestURL().toString();
String uri = request.getRequestURI();
System.out.println("获得请求的URL:"+url);
System.out.println("获得请求的URI:"+uri);
// 获得发布的工程名：
String contextPath = request.getContextPath();
System.out.println("工程名:"+contextPath);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}create database day10;
use day10;
create table user(
id int primary key auto_increment,
username varchar(20),
password varchar(20),
email varchar(20),
name varchar(20),
sex varchar(10),
telephone varchar(20)
);
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