string boot 与自定义interceptor的实例讲解

前面学习过过滤器, 但是过滤器是针对servlet的, 用在springmvc和spring boot里面, 功能上, 感觉并不是很好用.

那这里来学习一下拦截器.

一. 拦截器的执行顺序

1. 目录

2. 拦截器

拦截器里面, 我加了三个(First,Two,Third), 但是内容都差不多.

package org.elvin.boot.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class FirstInterceptor implements HandlerInterceptor {
  @Override
  public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
    System.out.println("FirstInterceptor preHandle");
    return true;
  }
  @Override
  public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
    System.out.println("FirstInterceptor postHandle");
  }
  @Override
  public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
    System.out.println("FirstInterceptor afterCompletion");
  }
}

preHandle 返回true, 才会继续下面的执行.

拦截器注册:

package org.elvin.boot.interceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
@Configuration
public class RegisterInterceptor extends WebMvcConfigurerAdapter {
  @Override
  public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(new FirstInterceptor());
    registry.addInterceptor(new TwoInterceptor());
    registry.addInterceptor(new ThirdInterceptor());
    super.addInterceptors(registry);
  }
}

为了验证执行顺序, 这里使用了 thymeleaf, 然后在前台访问了我后台传过去的属性, 在访问的时候, 就会打印信息到控制台

package org.elvin.boot.pojo;
public class Book {
  private String name ;
  public String getName() {
    System.out.println("view : Book'name is " + name);
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
}

Controller:

package org.elvin.boot.Controller;
import org.elvin.boot.pojo.Book;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("first")
public class FirstController {
  private String controllerPath = "first/";
  @GetMapping("index")
  public String index(Model model){
    System.out.println("controller : FirstController index doing...");
    Book book = new Book();
    book.setName("spring boot");
    model.addAttribute("book", book);
    return controllerPath + "index";
  }
}

View:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <title>Title</title>
</head>
<body>
  <h1 th:text="${book.name}"></h1>
</body>
</html>

在访问 localhost:8080/first/index 的时候, 就会在控制台输出响应的信息.

这样, 就能看出单个拦截器的执行顺序.

1. 在控制器方法执行之前, 执行的 preHandle 方法

2. 执行控制器的action方法

3. 执行完action, 解析view之前(如果有的话), 执行拦截器的 posthandle 方法

4. 解析view

5. 解析完之后, 执行 afterCompletion 方法

当注册多个拦截器的时候, 执行顺序, 如图上所示了.

二. 拦截器实现权限验证

同样的, 先加入权限拦截器

package org.elvin.boot.interceptor;
import org.elvin.boot.annotation.NoLogin;
import org.springframework.util.StringUtils;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LoginInterceptor implements HandlerInterceptor {
  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handle) throws Exception {
    HandlerMethod method = (HandlerMethod ) handle;
    Class<?> controllerType = method.getBeanType();
    if(method.getMethodAnnotation(NoLogin.class) != null || controllerType.getAnnotation(NoLogin.class) != null){
      return true;
    }
    HttpSession session = request.getSession();
    String token = (String)session.getAttribute("token");
    if(!StringUtils.isEmpty(token)){
      return true;
    }
    response.sendRedirect("/login/index");
    return false;
  }
  @Override
  public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
  }
  @Override
  public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
  }
}

然后注册权限拦截器

package org.elvin.boot.interceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
@Configuration
public class RegisterInterceptor extends WebMvcConfigurerAdapter {
  @Override
  public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(new LoginInterceptor());
    super.addInterceptors(registry);
  }
}

在控制器中加入登录控制器, 提供登录页面和注销方法

package org.elvin.boot.Controller;
import org.elvin.boot.annotation.NoLogin;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@NoLogin
@Controller
@RequestMapping("login")
public class LoginController {
  @Autowired
  private HttpServletRequest request;
  @Autowired
  private HttpServletResponse response;
  private String controllerPath = "login/";
  //@NoLogin
  @GetMapping("index")
  public String index(){
    HttpSession session = request.getSession();
    session.setAttribute("token", "token");
    return controllerPath + "index";
  }
  //@NoLogin
  @PostMapping("checkOut")
  @ResponseBody
  public String checkOut(){
    HttpSession session = request.getSession();
    session.setAttribute("token", null);
    return "ok";
  }
}

这里我做了一个免登录注解, 可以加在Controller上, 也可以加在 action 上.

package org.elvin.boot.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface NoLogin {
}

注解里面, 并不需要任何内容.

登录页面(这里登录页面只是为了注销用的, 所以访问过这个页面之后, 就表示登录成功了).

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
  <meta charset="UTF-8"/>
  <title>Title</title>
</head>
<body>
<div class="container">
  <input type="button" value="注销" id="checkOut"/>
</div>

<script th:src="@{/js/jquery-1.11.1.js}"></script>
<script th:inline="javascript">
  $(function () {
    $(".container").delegate("#checkOut", "click", function () {
      $.ajax({
        url: [[@{/login/checkOut}]],
        type: 'post',
        data: {},
        success: function (res) {
          if (res == "ok") {
            alert("注销成功");
          }
        }
      });
    });
  });
</script>
</body>
</html>

结果演示方式:

在浏览器中, 先打开 http://localhost:8080/login/index 页面, 然后在新标签中访问 http://localhost:8080/first/index 页面.

你会发现访问 first/index 的时候, 是可以访问的.

此时, 在login/index页面中, 点击注销按钮之后, 再刷新 first/index 页面, 就会直接跳去登录页面.

以上这篇string boot 与自定义interceptor的实例讲解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。

string boot 与 自定义interceptor的实例讲解

string boot 与自定义interceptor的实例讲解