spring boot 實現監聽器、過濾器、全域性異常處理

竹林聽雨行發表於2018-12-03
Spring Boot過濾器

Spring boot實現監聽器

package com.example.demo.listener.test;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

/**
 * 使用@WebListener註解，實現ServletContextListener介面
 * 在啟動器處加註解@ServletComponentScan
 * @author cxx
 */
@WebListener
public class MyServletContextListener implements ServletContextListener{
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        System.out.println("ServletContext初始化");
        System.out.println(servletContextEvent.getServletContext().getServerInfo());
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        System.out.println("ServletContext銷燬");
    }
}

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@MapperScan(value = "com.example.demo.mapper")
//filter和listener監聽器註解需要用的
@ServletComponentScan
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}
}
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Spring Boot實現過濾器

第一步：定義MyFilter過濾器

package com.example.demo.filter.test;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

/**
 * 使用註解過濾器
 * @WebFilter將一個實現了import javax.servlet.Filter介面的類定義為過濾器
 * 屬性filterName生命過濾器的名稱，可選
 * 屬性urlPatterns指定要過濾的URL模式，也可使用屬性value來宣告（指定要過濾的URL是必選屬性）
 */
@WebFilter(filterName = "MyFilter",urlPatterns = "/*")
public class MyFilter implements Filter{
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("過濾器初始化");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("執行過濾操作");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {
        System.out.println("過濾器銷燬");
    }
}
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第二部：在入口處新增@ServletComponentScan註解

package com.example.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@MapperScan(value = "com.example.demo.mapper")
//filter和listener監聽器註解需要用的
@ServletComponentScan
public class DemoApplication {

   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}
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Spring Boot全域性異常處理

全域性異常處理：@ControllerAdvice：包含@Componet,可以被掃描到

統一異常處理：@ExceptionHandler（Exception.class）:用在方法上面表示遇到這個異常就執行以下方法。

package com.example.demo.global.exception.test;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ExceptionTestController {
    @RequestMapping(value = "ExceptionTest",method = RequestMethod.GET)
    public String index(){
        String str=null;
        str.split("1");
        return "ExceptionTestController";
    }
}

package com.example.demo.global.exception.test;

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import java.util.Date;

@ControllerAdvice
//如果返回的為json資料或其他物件，新增該註解
@ResponseBody
public class GlobalDefaultExceptionHandler {
    public static final String DEFAULT_ERROR_VIEW="error";
    @ExceptionHandler({NullPointerException.class,NumberFormatException.class})
    public ModelAndView formatErrorHandler(HttpServletRequest request,Exception ex){
        System.out.println("已經捕獲到異常");
        ModelAndView mv=new ModelAndView();
        mv.addObject("exception",ex);
        mv.addObject("timeStamp",new Date());
        mv.setViewName(DEFAULT_ERROR_VIEW);
        return mv;
    }
}
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