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自定义@ResponseBody以及SpringMVC总结

news 来源：原创 2024/9/20 7:51:41

文章目录

- 1.需求分析
- 2.目录
- 3.自定义ResponseBody注解
- 4.MonsterController.java
- 5.Monster.java 实现序列化接口
- 6.引入jackson
- 7.Adapter.java 如果有@ResponseBody注解就返回json
- 8.测试
- 9.SpringMVC执行流程

1.需求分析

CleanShot 2024-08-08 at 14.23.16@2x

2.目录

CleanShot 2024-08-08 at 14.52.19@2x

3.自定义ResponseBody注解

package com.sunxiansheng.springmvc.annotation;import java.lang.annotation.*;/*** Description: 自定义ResponseBody注解* @Author sun* @Create 2024/8/6 16:09* @Version 1.0*/
@Retention(value = RetentionPolicy.RUNTIME) // 运行时生效
@Target(value = ElementType.METHOD) // 作用在方法上
@Documented // 生成文档
public @interface ResponseBody {}

4.MonsterController.java

    /*** 返回JSON数据的格式*/@ResponseBody // 返回JSON数据@RequestMapping(url = "/json/monster")public List<Monster> jsonMonster(HttpServletResponse response) {// 设置响应类型// 获取怪物列表List<Monster> monsters = monsterService.listMonster();// 日志打印monsterslog.info("monsters: {}", monsters);// 响应JSON数据return monsters;}

5.Monster.java 实现序列化接口

CleanShot 2024-08-08 at 14.53.48@2x

6.引入jackson

        <dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.13.4</version> </dependency>

7.Adapter.java 如果有@ResponseBody注解就返回json

package com.sunxiansheng.springmvc.adaptor;import com.fasterxml.jackson.databind.ObjectMapper;
import com.sunxiansheng.springmvc.annotation.ResponseBody;
import com.sunxiansheng.springmvc.handler.HandlerMapping;
import com.sunxiansheng.springmvc.handler.SunHandler;
import com.sunxiansheng.springmvc.viewparser.ViewParser;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;/*** Description: 适配器** @Author sun* @Create 2024/8/8 14:13* @Version 1.0*/
public class Adapter {private static final Logger log = LoggerFactory.getLogger(Adapter.class);/*** 3.适配器请求分发** @param request* @param response*/public static void executeDispatch(HttpServletRequest request, HttpServletResponse response) {// 4.调用映射器获取映射关系HandlerMapping handlerMapping = SunHandler.getHandlerMapping(request);// 如果没有找到映射器，就返回404if (handlerMapping == null) {try {response.getWriter().write("404 NOT FOUND");} catch (Exception e) {throw new RuntimeException(e);}return;}// 匹配成功，调用目标方法Object controller = handlerMapping.getController();Method method = handlerMapping.getMethod();// 5.调用参数解析器，解析参数Object[] args = ResolveArguments.resolveMethodArguments(request, response, method);// 日志，打印实参列表数组List<Class<?>> argsList = new ArrayList<>();for (Object arg : args) {argsList.add(arg.getClass());}log.info("实参列表：{}", argsList);try {// 反射调用方法Object invoke = method.invoke(controller, args);// 先判断有没有@ResponseBody注解，如果有则返回JSONif (method.isAnnotationPresent(ResponseBody.class)) {// 使用 Jackson 进行 JSON 序列化ObjectMapper objectMapper = new ObjectMapper();String jsonResponse = objectMapper.writeValueAsString(invoke);// 设置响应内容类型和编码response.setContentType("application/json;charset=utf-8");response.setCharacterEncoding("UTF-8");// 将 JSON 响应数据写入到响应输出流response.getOutputStream().write(jsonResponse.getBytes());} else {// 6.调用视图解析器，进行视图解析if (invoke instanceof String) {ViewParser.parse(invoke.toString(), request, response);}}} catch (Exception e) {throw new RuntimeException(e);}}}