文章：
https://github.com/Snailclimb/springboot-guide/blob/master/docs/basis/springboot-filter.md
https://blog.csdn.net/weixin_39933264/article/details/100181291
demo源碼：https://github.com/FDzhang/demo-study/tree/master/demo-springboot/demo-filter
2020-02-19
- 1 pom.xml 依賴
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
- 2 springboot的啟動類添加注解
@ServletComponentScan
@SpringBootApplication
@ServletComponentScan
public class DemoFilterApplication {
public static void main(String[] args) {
SpringApplication.run(DemoFilterApplication.class, args);
}
}
- 3 簡單使用
/**
* order(number) : 過濾器的順序
* filterName : 過濾器名稱
* urlPatterns : 需要過濾的路徑
* initParams : 初始化參數(shù)，存于FilterConfig中
*/
@Order(1)
@WebFilter(filterName = "DemoFilter1", urlPatterns = "/*" , initParams = {})
public class DemoFilter1 implements Filter {
/**
* filter對象只會創(chuàng)建一次心墅，init方法也只會執(zhí)行一次。
*/
@Override
public void init(FilterConfig filterConfig) {
}
/**
* 主要的業(yè)務(wù)代碼編寫方法
*/
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
// 獲取請求參數(shù)中的cityCode
String cityCode = request.getParameter("cityCode");
// 如果 cityCode==001 則通過
if ("001".equals(cityCode)){
// 放行
filterChain.doFilter(servletRequest,servletResponse);
}else {
// 返回錯誤信息
Map<String,Object> map = new HashMap<>(4);
map.put("code","301");
map.put("message","cityCode錯誤");
// 設(shè)置編碼 和 數(shù)據(jù)格式
response.setCharacterEncoding("UTF-8");
response.setContentType("application/json; charset=utf-8");
Gson gson = new Gson();
response.getWriter().write(gson.toJson(map));
}
}
/**
* 在銷毀Filter時自動調(diào)用。
*/
@Override
public void destroy() {
}
}
