页面跳转之转发和重定向+Servlet中文乱码问题

一、页面跳转

welcome.html

1.页面跳页面

知识点：跳转
页面跳页面
跳转到Page01页面

账号：
密码：

Page01页面

2.页面跳Servlet

页面跳Servlet
跳转到Servlet01

账号：
密码：

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/Servlet01")
public class Servlet01 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");response.setContentType("text/html;charset=UTF-8");String username = request.getParameter("username");String password = request.getParameter("password");System.out.println("Servlet01接收到客户的请求了：" + username + "--" + password);}
}

3.Servlet跳Servlet

1.转发

request.getRequestDispatcher(“页面.html”).forward(request, response);

2.重定向

response.sendRedirect(“页面.html”);

Servlet跳Servlet
向Servlet02发送请求 -- 转发
向Servlet03发送请求 -- 重定向

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/Servlet02")
public class Servlet02 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");response.setContentType("text/html;charset:UTF-8");//转发request.getRequestDispatcher("OtherServlet").forward(request,response);}
}

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/OtherServlet")
public class OtherServlet 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");response.setContentType("text/html;charset=UTF-8");System.out.println("OtherServlet接受到请求了...");}
}

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/Servlet03")
public class Servlet03 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");response.setContentType("text/html;charset=UTF-8");//重定向response.sendRedirect("OtherServlet");}
}

4.Servlet跳页面

Servlet跳页面
向Servlet04发送请求 -- 转发
向Servlet05发送请求 -- 重定向

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/Servlet04")
public class Servlet04 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");response.setContentType("text/html;charset=UTF-8");//转发request.getRequestDispatcher("page02.html").forward(request,response);}
}

Page02页面

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet( "/Servlet05")
public class Servlet05 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");response.setContentType("text/html;charset=UTF-8");//重定向response.sendRedirect("page02.html");}
}

二、转发与重定向的区别

区别1：转发是发送1次请求，重定向是发送2次请求

区别2：转发可以访问WEB-INF下的页面（受保护的页面）,重定向不可以访问

区别3：重定向可以访问外部服务器，转发不可以访问

向Servlet06发送请求 -- 做实验

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/Servlet06")
public class Servlet06 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");response.setContentType("text/html;charset=UTF-8");//跳转普通页面(web文件夹下的页面)//转发 -- yes//request.getRequestDispatcher("page02.html").forward(request,response);//重定向 -- yes//response.sendRedirect("page02.html");//跳转受保护的页面(WEB-INF文件夹下的页面)//注意：WEB-INF文件夹下的页面只能服务器内部访问//转发 -- yes//request.getRequestDispatcher("WEB-INF/page03.html").forward(request,response);//重定向 -- no（原因：客户端不能直接访问WEB-INF文件夹下的页面）//response.sendRedirect("WEB-INF/page03.html");//跳转外部服务器//注意：当前服务器不能访问外部服务器//转发 -- no//request.getRequestDispatcher("http://www.baidu.com").forward(request,response);//重定向 -- yes(原因：重定向是发送两次请求，告诉客户端去访问外部服务器)response.sendRedirect("http://www.baidu.com");}
}

page03页面

三、Servlet中文乱码问题

1.出现原因

前端后端编码不一致

浏览器默认使用UTF-8码表进行编码 ，Servlet使用ISO-8859-1码表进行编码

传输和接收方编码不一致导致乱码的产生

2.Request乱码

Request请求分为post和get，分别有不同的解决方案

1.Request乱码 - POST请求

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);
}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//给请求中的参数设置编码格式request.setCharacterEncoding("UTF-8");String parameter1 = request.getParameter("parameter1");String parameter2 = request.getParameter("parameter2");System.out.println(parameter1);System.out.println(parameter2);
}

作用：设置从 request 中取得的值,用来指定对浏览器发送来的数据进行重新编码时，使用的编码。

使用注意事项：

• 在执行 setCharacterEncoding()之前，不能执行任何 getParameter()操作
• 通过 setCharacterEncoding 设置的编码方式只对 POST 方式提交的表单有效，对 GET 方式无效

2.Request乱码 - GET请求(Tomcat7.X版本)

解决方案1

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);
}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String parameter1 = request.getParameter("parameter1");parameter1 = new String(parameter1.getBytes("ISO-8859-1"),"UTF-8");String parameter2 = request.getParameter("parameter2");parameter2 = new String(parameter2.getBytes("ISO-8859-1"),"UTF-8");System.out.println(parameter1);System.out.println(parameter2);
}

解决方案2

在Tomcat根目录/conf/server.xml中设置编码格式

那么在启动服务器的时候就会读取到URIEncoding的属性配置,然后再调用自己的一个setURIEncoding方法完成设置,形参的值为我们设置的UTF-8

protected String URIEncoding = null;
public void setURIEncoding(String URIEncoding) {this.URIEncoding = URIEncoding;setProperty("URIEncoding", URIEncoding);
}

3.Request乱码 - GET请求(Tomcat8.X版本)

Tomcat8.x的服务器在接收GET请求时,即使参数中有中文,也不会出现乱码，作者在底层设计上的一些改动

Tomcat的连接器组件(Connector) ，Connector是Tomcat中的一个重要的组件，它负责监听Tomcat收到的请求信息，并将这些请求信息传递给Servlet规范中所定义的Request，然后将转换后的请求交给Engine组件

去处理，最后将Engine返回的Response返回给客户端 。源码中我们可以看到, URIEncoding的默认值为UTF-8,所以在Tomcat8.x中,即使GET请求包含了中文的数据,也不会出现乱码了

public class Connector extends LifecycleMBeanBase  {private Charset uriCharset = StandardCharsets.UTF_8;//查询Tomcat根目录/conf/catalina.properties配置文件中的属性public static final boolean RECYCLE_FACADES =
Boolean.parseBoolean(System.getProperty("org.apache.catalina.connector.RECYCLE_FACADES", "false"));   public Connector() {this(null);}public Connector(String protocol) {setProtocol(protocol);ProtocolHandler p = null;try {Class clazz = Class.forName(protocolHandlerClassName);p = (ProtocolHandler) clazz.getConstructor().newInstance();} catch (Exception e) {log.error(sm.getString("coyoteConnector.protocolHandlerInstantiationFailed"), e);} finally {this.protocolHandler = p;}if (Globals.STRICT_SERVLET_COMPLIANCE) {uriCharset = StandardCharsets.ISO_8859_1;} else {uriCharset = StandardCharsets.UTF_8;}}
}

4.Response乱码

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);
}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置响应内容的编码格式response.setContentType("text/html;charset=UTF-8");response.getWriter().println("千锋吴彦祖");
}

5.跳转到中文页面路径乱码

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);
}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.sendRedirect(URLEncoder.encode("详情页面.html", "UTF-8"));
}

四、跳转到中文名的页面

知识点：跳转到中文名的页面
跳转到中文名的页面

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;@WebServlet( "/Servlet07")
public class Servlet07 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");response.setContentType("text/html;charset=UTF-8");//注意：中文名的网页一定要设置编码格式response.sendRedirect(URLEncoder.encode("用良心做教育.html","UTF-8"));}
}

用真心待人