解决过滤器和拦截器里面注入redisTemplate 为null

最新推荐文章于 2024-09-27 15:10:58 发布

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#java #过滤器

博客主要讨论Spring中拦截器或过滤器直接注入IOC管理的普通bean为null的情况。指出过滤器可在init方法中从上下文获取bean，若要获取jar里的bean，如在过滤器中使用Redis，可采用构造器注入方式，拦截器同理。

关于spring中在拦截器或者过滤器中直接注入由ioc管理的普通bean 为null的情况

过滤器可以在init方法中从上下文获取

public class TestFilter implements Filter {

    private TestService testService;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        ServletContext servletContext = filterConfig.getServletContext();
        WebApplicationContext cxt = WebApplicationContextUtils.getWebApplicationContext(servletContext);
        if (testService == null) {
            testService = (TestService) cxt.getBean("testService");
        }
    }

}

如果想获取jar里面带的bean 比如在过滤器里面想使用redis的话采用上述方式是不行的，我们采用构造器注入的方式

先注入redis

@Configuration
public class TestConfig {

    @Bean
    public JedisConnectionFactory getJedisConnectionFactory(){
        JedisConnectionFactory connectionFactory = new JedisConnectionFactory();
        connectionFactory.setHostName("127.0.0.1");
        connectionFactory.setPort(6379);
        return connectionFactory;
    }

    @Bean
    public StringRedisTemplate getRedisTemplate(){
        StringRedisTemplate redisTemplate = new StringRedisTemplate();
        redisTemplate.setConnectionFactory(getJedisConnectionFactory());
        return redisTemplate;
    }

    @Bean
    public FilterRegistrationBean getFilterRegistrationBean(){
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();
        //通过构造器传入StringRedisTemplate 
        registrationBean.setFilter(new TestFilter(getRedisTemplate()));
        registrationBean.setUrlPatterns(new ArrayList<>(Arrays.asList("/*")));
        return registrationBean
    }
}

public class TestFilter implements Filter {

    private TestService testService;

    private StringRedisTemplate redisTemplate;

    //通过构造器实例化redisTemplate 就可以直接使用了
    public TestFilter(StringRedisTemplate redisTemplate) {
        this.redisTemplate = redisTemplate;
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        ServletContext servletContext = filterConfig.getServletContext();
        WebApplicationContext cxt = WebApplicationContextUtils.getWebApplicationContext(servletContext);
        if (testService == null) {
            testService = (TestService) cxt.getBean("testService");
        }
    }
}

2.拦截器也是同样的道理可以通过构造器注入

@Configuration
public class TestConfig extends WebMvcConfigurationSupport {

    @Bean
    public JedisConnectionFactory getJedisConnectionFactory() {
        JedisConnectionFactory connectionFactory = new JedisConnectionFactory();
        connectionFactory.setHostName("127.0.0.1");
        connectionFactory.setPort(6379);
        return connectionFactory;
    }

    @Bean
    public StringRedisTemplate getRedisTemplate() {
        StringRedisTemplate redisTemplate = new StringRedisTemplate();
        redisTemplate.setConnectionFactory(getJedisConnectionFactory());
        return redisTemplate;
    }

    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        //通过构造器注入
        registry.addInterceptor(new TestInterceptor(getRedisTemplate())).addPathPatterns("/**").excludePathPatterns("/emp/toLogin", "/emp/login", "/js/**", "/css/**", "/images/**");
        super.addInterceptors(registry);
    }
}

public class TestInterceptor implements HandlerInterceptor {

    private StringRedisTemplate stringRedisTemplate;

    //通过构造注入
    public TestInterceptor(StringRedisTemplate stringRedisTemplate){
        this.stringRedisTemplate=stringRedisTemplate;
    }

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
    }
}