Servlet接口应用(开发servlet三种方式)
第一种：实现Servlet接口
public class ServletDemo1 implements Servlet {
@Override
public void init(ServletConfig config) throws ServletException {
// TODO Auto-generated method stub
}
@Override
public ServletConfig getServletConfig() {
// TODO Auto-generated method stub
return null;
}
@Override
public void service(ServletRequest req, ServletResponse res)
throws ServletException, IOException {
HttpServletRequest request=(HttpServletRequest) req; //类型转换
HttpServletResponse response=(HttpServletResponse) res;
//获取请求的类型
String type=request.getMethod();
//判断类型GET/POST
if("GET".equals(type)){
this.doGet(request,response);
}else{
this.doPost(request,response);
}
}
private void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
// TODO Auto-generated method stub
response.setContentType("text/html;charset=utf-8");//设置response 字符编码
PrintWriter writer = response.getWriter();//得到打印流对象
writer.print("实现Servlet类的方式1，实现Servlet接口");//浏览器打印
}
private void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
// TODO Auto-generated method stub
doPost(request, response);//执行调用doPost,因为默认是doGet
}
@Override
public String getServletInfo() {
// TODO Auto-generated method stub
return null;
}
@Override
public void destroy() {
// TODO Auto-generated method stub
}
}
XML配置
<?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>ServletDemos</servlet-name>
<servlet-class>cn.itcast.servlet.demo.ServletDemo1</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletDemos</servlet-name>
<url-pattern>/servletdemo1</url-pattern>
</servlet-mapping>
</web-app>
第二种：继承抽象类形式 GenericServlet
//通过继承GenericServlet类实现 Servlet开发
public class ServletDemo2 extends GenericServlet {
//必须实现GenericServlet方法
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
response.getWriter().write("hello GenericServlet");
//直接往浏览器输出
}
}
XML配置
<servlet>
<servlet-name>ServletDemo2</servlet-name>
<servlet-class>cn.itcast.servlet.demo.ServletDemo2</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletDemo2</servlet-name>
<url-pattern>/servletdemo2</url-pattern>
</servlet-mapping>
第三种：继承抽象类 HttpServlet (推荐)
//通过继承HttpServlet 开发Servlet
//最常用的
public class ServletDemo3 extends HttpServlet {
//重写方法
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
//重写方法
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");//设置编码
PrintWriter pw=response.getWriter();
pw.write("第三种继承HttpServlet(推荐)");//输出
}
}
XML配置
<servlet>
<servlet-name>ServletDemo3</servlet-name>
<servlet-class>cn.itcast.servlet.demo.ServletDemo3</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletDemo3</servlet-name>
<url-pattern>/servletdemo3</url-pattern>
</servlet-mapping>
