Servlet 转发、包含、重定向对比

Bertha 。 2022-06-07 05:21 195阅读 0赞

**Servlet 转发、包含、重定向对比**

**1、转发**  
在index.jsp页面中有一个form表单，提交到TestASerlvet处理，在TestASerlvet我们将请求转发到TestBSerlvet  
示例代码：  
index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    	pageEncoding="UTF-8"%>
    <!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></title>
    </head>
    <body>
    	<form action="TestASerlvet" method="post">
    		姓名：<input type="text" name="name" />
    		<button>提交</button>
    	</form>
    </body>
    </html>

web.xml

<servlet>
    
    		<servlet-name>TestASerlvet</servlet-name>
    		<servlet-class>cn.sz.hcq.servlet.TestASerlvet</servlet-class>
    	</servlet>
    	<servlet-mapping>
    		<servlet-name>TestASerlvet</servlet-name>
    		<url-pattern>/TestASerlvet</url-pattern>
    	</servlet-mapping>
    
    	<servlet>
    
    		<servlet-name>TestBSerlvet</servlet-name>
    		<servlet-class>cn.sz.hcq.servlet.TestBSerlvet</servlet-class>
    	</servlet>
    	<servlet-mapping>
    		<servlet-name>TestBSerlvet</servlet-name>
    		<url-pattern>/TestBSerlvet</url-pattern>
    	</servlet-mapping>

TestASerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestASerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		PrintWriter out = response.getWriter();
    		out.println("这里是TestASerlvet...");// 这里不能关闭输出流
    		// 转发到TestBSerlvet
    		request.getRequestDispatcher("TestBSerlvet").forward(request, response);
    	}
    
    }

TestBSerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestBSerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		String name = request.getParameter("name");// 获取到提交的数据
    		PrintWriter out = response.getWriter();
    		out.println("name: " + name);
    		out.println("这里是TestBSerlvet...");
    		out.flush();
    		out.close();
    	}
    
    }

结果截图：

![Center][]

![Center 1][]

部署运行项目后，我们提交表单我们发现地址栏的URL没有改变还是TestASerlvet，页面的内容只显示了TestBSerlvet的内容并且能够接受到传递的数据。得出结论：转发地址栏URL不会改变，显示的内容为转发到的Servlet内容，数据能够共享。

**2、包含**

**示例代码：**

index.jsp

web.xml

TestASerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestASerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		PrintWriter out = response.getWriter();
    		out.println("这里是TestASerlvet...");// 这里不能关闭输出流
    		// 包含TestBSerlvet
    		request.getRequestDispatcher("TestBSerlvet").include(request, response);
    	}
    
    }

TestBSerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestBSerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		String name = request.getParameter("name");// 获取到提交的数据
    		PrintWriter out = response.getWriter();
    		out.println("name: " + name);
    		out.println("这里是TestBSerlvet...");
    		out.flush();
    		out.close();
    	}
    
    }

结果截图：

![Center 2][]

![Center 3][]

提交表单后，我们发现地址栏的URL没有改变还是TestASerlvet，页面的内容不仅显示了TestASerlvet的内容，还显示了TestBSerlvet的内容，并且能够接受到传递的数据。得出结论：包含地址栏URL不会改变，显示的内容为转发到的Servlet内容和原来servlet共同的内容，数据能够共享。

**3、重定向**

**示例代码：**

index.jsp

web.xml

TestASerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestASerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		PrintWriter out = response.getWriter();
    		out.println("这里是TestASerlvet...");// 这里不能关闭输出流
    		//重定向到TestBSerlvet
    		
    		response.sendRedirect("TestBSerlvet");
    	}
    
    }

TestBSerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestBSerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		String name = request.getParameter("name");// 获取到提交的数据
    		PrintWriter out = response.getWriter();
    		out.println("name: " + name);
    		out.println("这里是TestBSerlvet...");
    		out.flush();
    		out.close();
    	}
    
    }

截图：

![Center 4][]

![Center 5][]

提交表单后，地址栏发送改变（默认提交后的地址栏是http://localhost:8080/MyServlet\_js/TestASerlvet），不能接收到传递的数据（数据不能共享），只显示重定向后的servlet。

**注：转发、包含发送在一次请求内 ，重定向发送在两次请求上**

web.xml

TestASerlvet

TestBSerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestBSerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		String name = request.getParameter("name");// 获取到提交的数据
    		PrintWriter out = response.getWriter();
    		out.println("name: " + name);
    		out.println("这里是TestBSerlvet...");
    		out.flush();
    		out.close();
    	}
    
    }

TestASerlvet

TestBSerlvet

package cn.sz.hcq.servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class TestBSerlvet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		this.doPost(request, response);
    	}
    
    	protected void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		request.setCharacterEncoding("UTF-8");// 处理Post请求中文乱码
    		response.setHeader("Content-Type", "text/html;charset=utf-8");/* 处理中文响应乱码 */
    		String name = request.getParameter("name");// 获取到提交的数据
    		PrintWriter out = response.getWriter();
    		out.println("name: " + name);
    		out.println("这里是TestBSerlvet...");
    		out.flush();
    		out.close();
    	}
    
    }

[Center]: /images/20220607/1d802e80dc7f4915a442b1ac6b10d748.png
[Center 1]: /images/20220607/aad98976866446ab907fd7cc2269f4a1.png
[Center 2]: /images/20220607/03968528647741f39ccf6789e6c41096.png
[Center 3]: /images/20220607/439b287346e340b98c6fc33780690b16.png
[Center 4]: /images/20220607/7911237cbe764dbf8ccbbb075ec0ca52.png
[Center 5]: /images/20220607/3f4f22a77cbb441f8931f1462c497fe3.png