拦截器
1.简介
Spring MVC 中的拦截器（Interceptor）类似于 Servlet 开发中的过滤器 Filter，它主要用于拦截用户请求并作相应的处理,它也是 AOP 编程思想的体现,底层通过动态代理模式完成。
2.定义实现类
拦截器有两种实现方式：
1.实现 HandlerInterceptor 接口
2.继承 HandlerInterceptorAdapter 抽象类（看源码最底层也是通过 HandlerInterceptor 接口 实现）
3.HandlerInterceptor方法介绍
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
//进行逻辑判断，如果ok就返回true，不行就返回false，返回false就不会处理请求
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
}
preHandle：在业务处理器处理请求之前被调用。预处理，可以进行编码、安全控制、权限校验等处理；
postHandle：在业务处理器处理请求执行完成后，生成视图之前执行。
afterCompletion：在 DispatcherServlet 完全处理完请求后被调用，可用于清理资源等。
4.应用场景
5.与 Filter 过滤器的区别
具体实现
单个拦截器
1.新建拦截器
public class Test1Interceptor implements HandlerInterceptor{
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
System.out.println("执行preHandle方法-->01");
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
System.out.println("执行postHandle方法-->02");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
System.out.println("执行afterCompletion方法-->03");
}
}
2.配置拦截器
@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {
/*
* 拦截器配置
*/
@Override
public void addInterceptors(InterceptorRegistry registry) {
// 注册自定义拦截器，添加拦截路径和排除拦截路径
registry.addInterceptor(new Test1Interceptor()) // 添加拦截器
.addPathPatterns("/**") // 添加拦截路径
.excludePathPatterns(// 添加排除拦截路径
"/hello").order(0);//执行顺序
super.addInterceptors(registry);
}
}
3.测试拦截器
@RestController
public class TestController {
@RequestMapping("/hello")
public String getHello() {
System.out.println("这里是Hello");
return "hello world";
}
@RequestMapping("/test1")
public String getTest1() {
System.out.println("这里是Test1");
return "test1 content";
}
@RequestMapping("/test2")
public String getTest2() {
System.out.println("这里是Test2");
return "test2 content";
}
}
4.单个拦截器的执行流程
通过浏览器测试：
http://127.0.0.1:8080/hello
结果：
这里是Hello
http://127.0.0.1:8080/test1 、http://127.0.0.1:8080/test2
结果：
执行preHandle方法-->01
这里是Test1
执行postHandle方法-->02
执行afterCompletion方法-->03
多个拦截器
1.新建两个拦截器
Test1Interceptor
public class Test1Interceptor implements HandlerInterceptor{
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
System.out.println("执行Test1Interceptor preHandle方法-->01");
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
System.out.println("执行Test1Interceptor postHandle方法-->02");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
System.out.println("执行Test1Interceptor afterCompletion方法-->03");
}
}
Test2Interceptor
public class Test2Interceptor extends HandlerInterceptorAdapter{
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
System.out.println("执行Test2Interceptor preHandle方法-->01");
return true;
}
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
System.out.println("执行Test2Interceptor postHandle方法-->02");
}
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
System.out.println("执行Test2Interceptor afterCompletion方法-->03");
}
}
2.配置拦截器
@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {
/*
* 拦截器配置
*/
@Override
public void addInterceptors(InterceptorRegistry registry) {
// 注册自定义拦截器，添加拦截路径和排除拦截路径
registry.addInterceptor(new Test1Interceptor()) // 添加拦截器1
.addPathPatterns("/**") // 添加拦截路径
.excludePathPatterns(// 添加排除拦截路径
"/hello")
.order(0);
registry.addInterceptor(new Test2Interceptor()) // 添加拦截器2
.addPathPatterns("/**") // 添加拦截路径
.excludePathPatterns(// 添加排除拦截路径
"/test1")
.order(1);
super.addInterceptors(registry);
}
}
3.测试拦截器
@RestController
public class TestController {
@RequestMapping("/hello")
public String getHello() {
System.out.println("这里是Hello");
return "hello world";
}
@RequestMapping("/test1")
public String getTest1() {
System.out.println("这里是Test1");
return "test1 content";
}
@RequestMapping("/test2")
public String getTest2() {
System.out.println("这里是Test2");
return "test2 content";
}
}
4.多个拦截器的执行流程
通过浏览器测试：
http://127.0.0.1:8080/test2
结果：
执行Test1Interceptor preHandle方法-->01
执行Test2Interceptor preHandle方法-->01
这里是Test2
执行Test2Interceptor postHandle方法-->02
执行Test1Interceptor postHandle方法-->02
执行Test2Interceptor afterCompletion方法-->03
执行Test1Interceptor afterCompletion方法-->03
通过示例，简单的说多个拦截器执行流程就是先进后出。
简单的 token 判断示例
1.拦截器
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
System.out.println("执行Test1Interceptor preHandle方法-->01");
String token = request.getParameter("token");
if (StringUtils.isEmpty(token)) {
response.setContentType("text/html");
response.setCharacterEncoding("UTF-8");
response.getWriter().println("token不存在");
return false;
}
return true;
}
2.测试及结果
未传token：
执行Test1Interceptor preHandle方法-->01
传token：
执行Test1Interceptor preHandle方法-->01
页码：1
页码大小：10
执行Test1Interceptor postHandle方法-->02
执行Test1Interceptor afterCompletion方法-->03
示例代码
非特殊说明，本文版权归 朝雾轻寒 所有，转载请注明出处.
原文标题：Spring Boot 2.X(九)：Spring MVC - 拦截器（Interceptor）
原文地址：https://www.zwqh.top/article/info/18
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