# java-SpringBoot自定義參數(shù)解析器實(shí)現(xiàn)對(duì)象自動(dòng)注入
解析器邏輯流程圖表
后臺(tái)解析注解的解析器
首先，我在java后臺(tái)編寫了一個(gè)解析器，代碼如下
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import com.ruoyi.framework.interceptor.annotation.LoginUser;import com.ruoyi.project.WebMoudle.WebUser.domain.WebUser;import com.ruoyi.project.WebMoudle.WebUser.service.IWebUserService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.core.MethodParameter;import org.springframework.stereotype.Service;import org.springframework.web.bind.support.WebDataBinderFactory;import org.springframework.web.context.request.NativeWebRequest;import org.springframework.web.context.request.RequestAttributes;import org.springframework.web.method.support.HandlerMethodArgumentResolver;import org.springframework.web.method.support.ModelAndViewContainer;/** * 有@LoginUser注解的controller方法會(huì)進(jìn)入到解析器中 * 通過(guò)解析器查詢到當(dāng)前用戶，并返回給controller * * @author yangz */@Servicepublic class LoginUserHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver { //用戶service @Autowired private IWebUserService webUserService; @Override public boolean supportsParameter(MethodParameter parameter) { return parameter.getParameterType().isAssignableFrom(WebUser.class) && parameter.hasParameterAnnotation(LoginUser.class); } @Override public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer container, NativeWebRequest request, WebDataBinderFactory factory) throws Exception { //從request作用域中獲取登錄時(shí)存入的用戶ID，不明白的可以查看我的博客springBoot攔截器一文 Object object = request.getAttribute(AuthorizationInterceptor.LOGIN_USER_KEY, RequestAttributes.SCOPE_REQUEST); if (object == null) { return null; } //獲取用戶信息 Long userId=(Long) object; WebUser user = webUserService.selectWebUserById(userId); return user; }} |
其次，我編寫一個(gè)攔截器配置類，將攔截器注入到spring容器中
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import com.ruoyi.framework.interceptor.LoginUserHandlerMethodArgumentResolver;import org.springframework.context.annotation.Configuration;import org.springframework.web.method.support.HandlerMethodArgumentResolver;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;import java.util.List;@Configurationpublic class LoginUserConfig extends WebMvcConfigurerAdapter { /** * 此處獲取攔截器實(shí)例化對(duì)象，同理攔截器 * @return */ @Bean public LoginUserHandlerMethodArgumentResolver getLoginUserHandlerMethodArgumentResolver(){ return new LoginUserHandlerMethodArgumentResolver(); } @Override public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers){ super.addArgumentResolvers(argumentResolvers); argumentResolvers.add(getLoginUserHandlerMethodArgumentResolver()); }} |
最后是我們的開關(guān)，也就是自定義的注解LoginUser注解，當(dāng)在controller方法中參數(shù)有使用此注解，就會(huì)觸發(fā)我們的解析器進(jìn)行對(duì)象注入，那么我就得自己定義一個(gè)屬于自己的注解
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import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;/** * 注入用戶信息注解， *比較簡(jiǎn)單，沒(méi)有聲明更多的屬性 * @author lipengjun * @email 939961241@qq.com * @date 2017-03-23 20:39 */@Target(ElementType.PARAMETER)@Retention(RetentionPolicy.RUNTIME)public @interface LoginUser {} |
然后就是一小個(gè)演示使用的方法
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@RequestMapping(value = "/prepay")@ResponseBodypublic Map<String,Object> prepay(@LoginUser WebUser webUser){ //此間，從request中獲取到userId信息就會(huì)在進(jìn)入controller之前將webuser對(duì)象查出并注入到webUser參數(shù)中} |
補(bǔ)充知識(shí)：Springboot基于自定義注解的自動(dòng)裝配
1.定義java bean
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@Data //lombok注解public class User { private Integer userId; private String userName;} |
2.創(chuàng)建configuration類
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public class UserConfig { @Bean public User getUser(){ User user = new User(); user.setUserId(1); user.setUserName("你好啊 哈哈哈哈"); return user; }} |
3.定義注解
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@Target({ElementType.TYPE})@Retention(RetentionPolicy.RUNTIME)@Documented@Inherited@AutoConfigurationPackage@Import(UserConfig.class)public @interface EnableAutoImport {} |
4.調(diào)用
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@SpringBootApplication@EnableAutoImport //打上你自定義的注解public class DemoApplication implements InitializingBean {//這里實(shí)現(xiàn)了InitializingBean 在初始化bean的時(shí)候都會(huì)執(zhí)行afterPropertiesSet @Autowired private User user; //注入 user類 public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } @Override public void afterPropertiesSet() throws Exception { //在這里調(diào)用了裝配進(jìn)來(lái)的類 System.out.println(user.getUserName()); }} |
以上這篇java SpringBoot自定義注解,及自定義解析器實(shí)現(xiàn)對(duì)象自動(dòng)注入操作就是小編分享給大家的全部?jī)?nèi)容了，希望能給大家一個(gè)參考，也希望大家多多支持服務(wù)器之家。
原文鏈接：https://blog.csdn.net/nishiwodebocai21/article/details/100045494
