Mybatis里使用Filter

1. 拦截请求

1.1. 使用注解 @WebFilter("/*")

@WebFilter("/*")
public class OpenSessioInView implements Filter {
...
}

1.2. 配置文件 web.xml

<filter>
	<filter-name>opensession</filter-name>
	<filter-name>com.filter.OpenSessioInView.java</filter-name>
</filter>
<filter-mapping>
	<filter-name>opensession</filter-name>
	<url-pattern> /*</url-pattern>
</filter-mapping>

2. 自定义过滤器

@WebFilter("/*")
public class OpenSessioInView implements Filter {
    private static final Logger logger = Logger.getLogger(OpenSessioInView.class);

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		logger.info("初始化过滤器：");
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
//		InputStream resourceAsStream = Resources.getResourceAsStream("mybatis.xml");
//		SqlSessionFactory build = new SqlSessionFactoryBuilder().build(resourceAsStream);
//		SqlSession session = build.openSession();
		SqlSession session = MyBatisUtil.getSession();
		System.out.println("opensession");
		try {
			logger.info("过滤器开始;");
			chain.doFilter(request, response);
			session.commit();
	        logger.info("过滤器结束;");
		} catch (Exception e) {
			e.printStackTrace();
			session.rollback();
			System.out.println("roolback");
		} finally {
			MyBatisUtil.closeSession();
			System.out.println("commit");
			System.out.println("closesession");
			System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
		}
//		session.commit();
//		session.close();
	}

	@Override
	public void destroy() {
		logger.info("销毁过滤器");
	}
}

使用

public class MyBatisUtil {
    //3. factory实例化的过程是一个比较费性能的过程，做项目的时候都是保证有且仅有一个factory，因为没必要频繁创建工厂
	private static SqlSessionFactory factory;// 2.静态代码块调用的东西也是静态的，所以这里是 static
	private static ThreadLocal<SqlSession> tl = new ThreadLocal<>();
	//1. 希望类在加载的时候就会产生factory对象，所以用静态块
	static {
		try {
			InputStream resourceAsStream = Resources.getResourceAsStream("mybatis.xml");
			factory = new SqlSessionFactoryBuilder().build(resourceAsStream);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static SqlSession getSession() {
		SqlSession sin = tl.get();
		if (sin == null) {
			SqlSession session = factory.openSession();
			tl.set(session);
		}
		return tl.get();
	}

	public static void closeSession() {
		SqlSession sl = tl.get();
		if (sl != null) {
			sl.close();
		}
		tl.set(null);
	}
}

@WebServlet("/inssssss")
public class LogServlet extends HttpServlet {
	LogService logService = new LogServiceImpl();

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		req.setCharacterEncoding("utf-8");
		
		String accOut = req.getParameter("accOut");
		String accIn = req.getParameter("accIn");
		String money = req.getParameter("money");
		
		LogInfo loginfo = new LogInfo();
		loginfo.setAccOut(accOut);
		loginfo.setAccIn(accIn);
		loginfo.setMoney(Double.parseDouble(money));
		
		int index = logService.insert(loginfo);
		
		if (index > 0) {
			resp.sendRedirect("success.jsp");
		} else {
			resp.sendRedirect("error.jsp");
		}
	}
}

public class LogServiceImpl implements LogService {

	@Override
	public int insert(LogInfo loginfo) {
		SqlSession session = MyBatisUtil.getSession();
		LogMapper logmapper = session.getMapper(LogMapper.class);
		int index = logmapper.ins(loginfo);
		return index;
	}

tomcat 一启动机会初始化过滤器

Filter是如何实现拦截的？

SpringBoot里使用Filter

1. 手动注册配置实现

@Component
public class MyFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) {
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String requestUri = request.getRequestURI();
        
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {
    }
}

@Configuration
public class MyFilterConfig {
    @Autowired
    MyFilter myFilter;
    @Bean
    public FilterRegistrationBean<MyFilter> thirdFilter() {
    
        FilterRegistrationBean<MyFilter> filterRegistrationBean = new FilterRegistrationBean<>();
        
        filterRegistrationBean.setFilter(myFilter);
        filterRegistrationBean.setUrlPatterns(new ArrayList<>(Arrays.asList("/api/*")));

        return filterRegistrationBean;
    }
}

注解实现

为了能让 Spring 找到它，你需要在启动类上加上 @ServletComponentScan 注解

@WebFilter(filterName = "MyFilterWithAnnotation", urlPatterns = "/api/*")
public class MyFilterWithAnnotation implements Filter {
   ......
}

定义多个拦截器，并决定它们的执行顺序

@Component
public class MyFilter2 implements Filter {

    @Override
    public void init(FilterConfig filterConfig) {
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        String requestUri = request.getRequestURI();
        
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override
    public void destroy() {
    }
}

@Configuration
public class MyFilterConfig {
    @Autowired
    MyFilter myFilter;

    @Autowired
    MyFilter2 myFilter2;

    @Bean
    public FilterRegistrationBean<MyFilter> setUpMyFilter() {
        
        FilterRegistrationBean<MyFilter> filterRegistrationBean = new FilterRegistrationBean<>();
        
        filterRegistrationBean.setOrder(2);
        filterRegistrationBean.setFilter(myFilter);
        filterRegistrationBean.setUrlPatterns(new ArrayList<>(Arrays.asList("/api/*")));

        return filterRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean<MyFilter2> setUpMyFilter2() {
       
        FilterRegistrationBean<MyFilter2> filterRegistrationBean = new FilterRegistrationBean<>();
       
        filterRegistrationBean.setOrder(1);
        filterRegistrationBean.setFilter(myFilter2);
        filterRegistrationBean.setUrlPatterns(new ArrayList<>(Arrays.asList("/api/*")));
        return filterRegistrationBean;
    }
}

最后

以上就是大气大叔为你收集整理的如何自定义一个Filter 过滤器？Mybatis里使用FilterFilter是如何实现拦截的？SpringBoot里使用Filter定义多个拦截器，并决定它们的执行顺序的全部内容，希望文章能够帮你解决如何自定义一个Filter 过滤器？Mybatis里使用FilterFilter是如何实现拦截的？SpringBoot里使用Filter定义多个拦截器，并决定它们的执行顺序所遇到的程序开发问题。

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