javaWeb中servlet开发(4)——servlet跳转

servlet跳转

1、跳转类型

客户端跳转：跳转后地址栏改变，无法传递request范围内属性，是在所有的操作都执行完毕之后才发生跳转的操作，跳转语法是，response.sendRedict()

服务器端跳转：地址栏不改变，可以传递request范围内属性，属于无条件跳转，只要执行到了，就立即执行跳转操作，语法是：<jsp:forward></jsp:forward>

2、servlet跳转

2.1 客户端跳转

servlet 中也是可以完成跳转的，servlet本身已经存在HttpServletResponse对象，所有可以直接通过此对象完成sendRedirect跳转操作。

代码如下：

public class ClientRedirectDemo extends HttpServlet {
    public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
        req.getSession().setAttribute("name","李李") ;
        req.setAttribute("info","JAVA") ;
        resp.sendRedirect("get_info.jsp") ;
    }
    public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
        this.doGet(req,resp) ;
    }
}

xml配置：

<servlet>
		<servlet-name>client</servlet-name>
		<servlet-class>
			com.alice.servletdemo.ClientRedirectDemo
		</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>client</servlet-name>
		<url-pattern>/forward/ClientRedirectDemo</url-pattern>
	</servlet-mapping>

get—info.jsp

<body>
<%	request.setCharacterEncoding("GBK") ;	%>
<h2>sesion属性：<%=session.getAttribute("name")%></h2>
<h2>request属性：<%=request.getAttribute("info")%></h2>
</body>

2.2 服务器端跳转

代码实现：

public class ServerRedirectDemo extends HttpServlet {
    public void doGet(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
        req.getSession().setAttribute("name","李兴华") ;
        req.setAttribute("info","MLDNJAVA") ;
        RequestDispatcher rd = req.getRequestDispatcher("get_info.jsp") ;    // 准备好了跳转操作
        rd.forward(req,resp) ;    // 完成跳转
    }
    public void doPost(HttpServletRequest req,HttpServletResponse resp) throws ServletException,IOException{
        this.doGet(req,resp) ;
    }
}

xml配置：

<servlet>
        <servlet-name>server</servlet-name>
        <servlet-class>
            com.alice.servletdemo.ServerRedirectDemo
        </servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>server</servlet-name>
        <url-pattern>/forward/ServerRedirectDemo</url-pattern>
    </servlet-mapping>