feat(response): 统一返回结果

src/main/java/org/linker/springboot/controller/UserController.java

 package org.linker.springboot.controller;
 
+import org.linker.springboot.core.vo.CommonResult;
 import org.linker.springboot.dto.UserAddDTO;
 import org.linker.springboot.dto.UserUpdateDTO;
 import org.linker.springboot.service.UserService;
@@ -9,6 +10,7 @@ import org.springframework.web.bind.annotation.*;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.UUID;
 
 /**
  * 用户 Controller
@@ -104,4 +106,20 @@ public class UserController {
         return success;
     }
 
+    /**
+     * 获得指定用户编号的用户
+     *
+     * 提供使用 CommonResult 包装
+     *
+     * @param id 用户编号
+     * @return 用户
+     */
+    @GetMapping("/getWithCommonResult")
+    public CommonResult<UserVO> getWithCommonResult(@RequestParam("id") Integer id) {
+        // 查询用户
+        UserVO user = new UserVO().setId(id).setUsername(UUID.randomUUID().toString());
+        // 返回结果
+        return CommonResult.success(user);
+    }
+
 }

src/main/java/org/linker/springboot/core/vo/CommonResult.java

+package org.linker.springboot.core.vo;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import org.springframework.util.Assert;
+
+import java.io.Serializable;
+
+/**
+ * 通用返回结果
+ *
+ * @param <T> 结果泛型
+ */
+public class CommonResult<T> implements Serializable {
+
+    public static Integer CODE_SUCCESS = 0;
+
+    /**
+     * 错误码
+     */
+    private Integer code;
+    /**
+     * 错误提示
+     */
+    private String message;
+    /**
+     * 返回数据
+     */
+    private T data;
+
+    /**
+     * 将传入的 result 对象，转换成另外一个泛型结果的对象
+     *
+     * 因为 A 方法返回的 CommonResult 对象，不满足调用其的 B 方法的返回，所以需要进行转换。
+     *
+     * @param result 传入的 result 对象
+     * @param <T> 返回的泛型
+     * @return 新的 CommonResult 对象
+     */
+    public static <T> CommonResult<T> error(CommonResult<?> result) {
+        return error(result.getCode(), result.getMessage());
+    }
+
+    public static <T> CommonResult<T> error(Integer code, String message) {
+        Assert.isTrue(!CODE_SUCCESS.equals(code), "code 必须是错误的！");
+        CommonResult<T> result = new CommonResult<>();
+        result.code = code;
+        result.message = message;
+        return result;
+    }
+
+    public static <T> CommonResult<T> success(T data) {
+        CommonResult<T> result = new CommonResult<>();
+        result.code = CODE_SUCCESS;
+        result.data = data;
+        result.message = "";
+        return result;
+    }
+
+    public Integer getCode() {
+        return code;
+    }
+
+    public void setCode(Integer code) {
+        this.code = code;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public T getData() {
+        return data;
+    }
+
+    public void setData(T data) {
+        this.data = data;
+    }
+
+    @JsonIgnore
+    public boolean isSuccess() {
+        return CODE_SUCCESS.equals(code);
+    }
+
+    @JsonIgnore
+    public boolean isError() {
+        return !isSuccess();
+    }
+
+    @Override
+    public String toString() {
+        return "CommonResult{" +
+                "code=" + code +
+                ", message='" + message + '\'' +
+                ", data=" + data +
+                '}';
+    }
+
+}
\ No newline at end of file

src/main/java/org/linker/springboot/core/web/GlobalResponseBodyHandler.java

+package org.linker.springboot.core.web;
+
+import org.linker.springboot.core.vo.CommonResult;
+import org.springframework.core.MethodParameter;
+import org.springframework.http.MediaType;
+import org.springframework.http.server.ServerHttpRequest;
+import org.springframework.http.server.ServerHttpResponse;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
+
+// 只拦截我们的 Controller 所在包，避免其它类似 swagger 提供的 API 被切面拦截
+@ControllerAdvice(basePackages = "org.linker.springboot.controller")
+public class GlobalResponseBodyHandler implements ResponseBodyAdvice {
+
+    @Override
+    public boolean supports(MethodParameter returnType, Class converterType) {
+        return true;
+    }
+
+    @Override
+    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class selectedConverterType,
+                                  ServerHttpRequest request, ServerHttpResponse response) {
+        // 如果已经是 CommonResult 类型，则直接返回
+        if (body instanceof CommonResult) {
+            return body;
+        }
+        // 如果不是，则包装成 CommonResult 类型
+        return CommonResult.success(body);
+    }
+
+}