无侵入式 统一返回JSON格式接口开发demo

参考
https://github.com/galaxy-sea/galaxy-blogs/tree/master/code/responseResult

自己copy了一份发现使用eureka或者直接引入如下依赖，接口浏览器访问返回xml格式结果

<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
</dependency>

如图：
百度一下，Eureka依赖自动引入的

所以只需要在eureka依赖中使用 排除该依赖就行。

 <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        <exclusions>
            <exclusion>
                <groupId>com.fasterxml.jackson.dataformat</groupId>
                <artifactId>jackson-dataformat-xml</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

具体统一json代码实现如下：

==========================================
ResponseResultBody.java

package com.wwy.newapi.result;

import org.springframework.web.bind.annotation.ResponseBody;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
@Documented
@ResponseBody
public @interface ResponseResultBody {

}

==========================================
ResponseResultBodyAdvice.java

package com.wwy.newapi.result;

import java.lang.annotation.Annotation;

import org.springframework.core.MethodParameter;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;
import org.springframework.web.util.WebUtils;

import com.wwy.newapi.result.exception.ResultException;

import lombok.extern.slf4j.Slf4j;

/**
 * 使用这个注解就可以返回统一的json格式,  用于类和方法上
 * @author wangwenying
 *
 */
@Slf4j
@RestControllerAdvice
public class ResponseResultBodyAdvice implements ResponseBodyAdvice<Object> {

    private static final Class<? extends Annotation> ANNOTATION_TYPE = ResponseResultBody.class;

    /** 判断类或者方法是否使用了 @ResponseResultBody */
    @Override
    public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
        return AnnotatedElementUtils.hasAnnotation(returnType.getContainingClass(), ANNOTATION_TYPE) || returnType.hasMethodAnnotation(ANNOTATION_TYPE);
    }

    /** 当类或者方法使用了 @ResponseResultBody 就会调用这个方法 */
    @Override
    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
        if (body instanceof Result) {
            return body;
        }
        return Result.success(body);
    }


    /**
     * 提供对标准Spring MVC异常的处理
     *
     * @param ex      the target exception
     * @param request the current request
     */
    @ExceptionHandler(Exception.class)
    public final ResponseEntity<Result<?>> exceptionHandler(Exception ex, WebRequest request) {
        HttpHeaders headers = new HttpHeaders();
        if (ex instanceof ResultException) {
            return this.handleResultException((ResultException) ex, headers, request);
        }
        // TODO: 2019/10/05 galaxy 这里可以自定义其他的异常拦截
        return this.handleException(ex, headers, request);
    }

    /** 对ResultException类返回返回结果的处理 */
    protected ResponseEntity<Result<?>> handleResultException(ResultException ex, HttpHeaders headers, WebRequest request) {
        Result<?> body = Result.failure(ex.getResultStatus());
        HttpStatus status = ex.getResultStatus().getHttpStatus();
        return this.handleExceptionInternal(ex, body, headers, status, request);
    }

    /** 异常类的统一处理 */
    protected ResponseEntity<Result<?>> handleException(Exception ex, HttpHeaders headers, WebRequest request) {
        Result<?> body = Result.failure();
        HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
        return this.handleExceptionInternal(ex, body, headers, status, request);
    }

    /**
     * org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler#handleExceptionInternal(java.lang.Exception, java.lang.Object, org.springframework.http.HttpHeaders, org.springframework.http.HttpStatus, org.springframework.web.context.request.WebRequest)
     * <p>
     * A single place to customize the response body of all exception types.
     * <p>The default implementation sets the {@link WebUtils#ERROR_EXCEPTION_ATTRIBUTE}
     * request attribute and creates a {@link ResponseEntity} from the given
     * body, headers, and status.
     */
    protected ResponseEntity<Result<?>> handleExceptionInternal(
            Exception ex, Result<?> body, HttpHeaders headers, HttpStatus status, WebRequest request) {

        if (HttpStatus.INTERNAL_SERVER_ERROR.equals(status)) {
            request.setAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE, ex, WebRequest.SCOPE_REQUEST);
        }
        return new ResponseEntity<>(body, headers, status);
    }
}

==========================================
Result.java

package com.wwy.newapi.result;

/**
 * 后端返回给前端的json格式
 *  todo 返回格式参考 org.springframework.boot.web.servlet.error.DefaultErrorAttributes
 *
 * @author galaxy
 * @date 2019/10/05 16:19
 */
public class Result<T> {
    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;
	}

	/** 业务错误码 */
    private Integer code;
    /** 信息描述 */
    private String message;
    /** 返回参数 */
    private T data;

    private Result(ResultStatus resultStatus, T data) {
        this.code = resultStatus.getCode();
        this.message = resultStatus.getMessage();
        this.data = data;
    }

    /** 业务成功返回业务代码和描述信息 */
    public static Result<Void> success() {
        return new Result<Void>(ResultStatus.SUCCESS, null);
    }

    /** 业务成功返回业务代码,描述和返回的参数 */
    public static <T> Result<T> success(T data) {
        return new Result<T>(ResultStatus.SUCCESS, data);
    }

    /** 业务成功返回业务代码,描述和返回的参数 */
    public static <T> Result<T> success(ResultStatus resultStatus, T data) {
        if (resultStatus == null) {
            return success(data);
        }
        return new Result<T>(resultStatus, data);
    }

    /** 业务异常返回业务代码和描述信息 */
    public static <T> Result<T> failure() {
        return new Result<T>(ResultStatus.INTERNAL_SERVER_ERROR, null);
    }

    /** 业务异常返回业务代码,描述和返回的参数 */
    public static <T> Result<T> failure(ResultStatus resultStatus) {
        return failure(resultStatus, null);
    }

    /** 业务异常返回业务代码,描述和返回的参数 */
    public static <T> Result<T> failure(ResultStatus resultStatus, T data) {
        if (resultStatus == null) {
            return new Result<T>(ResultStatus.INTERNAL_SERVER_ERROR, null);
        }
        return new Result<T>(resultStatus, data);
    }
}

==========================================
ResultStatus.java

package com.wwy.newapi.result;

import org.springframework.http.HttpStatus;

public enum ResultStatus {

    SUCCESS(HttpStatus.OK, 200, "OK"),
    BAD_REQUEST(HttpStatus.BAD_REQUEST, 400, "Bad Request"),
    INTERNAL_SERVER_ERROR(HttpStatus.INTERNAL_SERVER_ERROR, 500, "Internal Server Error"),
    ;

    /** 返回的HTTP状态码,  符合http请求 */
    private HttpStatus httpStatus;
    /** 业务异常码 */
    private Integer code;
    /** 业务异常信息描述 */
    private String message;

    ResultStatus(HttpStatus httpStatus, Integer code, String message) {
        this.httpStatus = httpStatus;
        this.code = code;
        this.message = message;
    }

	public HttpStatus getHttpStatus() {
		return httpStatus;
	}

	public void setHttpStatus(HttpStatus httpStatus) {
		this.httpStatus = httpStatus;
	}

	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;
	}
}

==========================================
WebMvcConfiguration.java

package com.wwy.newapi.result;

import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.util.List;

/**
 * @author changjinwei
 * @date 2020/11/10
 */
@Configuration
public class WebMvcConfiguration implements WebMvcConfigurer {


    /**
     * // 这里是修复 com.galaxy.controller.HelloResultController.testString 方法， 解决方案有两个
     * // 1。 重写 org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(T, org.springframework.core.MethodParameter, org.springframework.http.server.ServletServerHttpRequest, org.springframework.http.server.ServletServerHttpResponse)
     * // 2。 实现WebMvcConfigurer或者继承WebMvcConfigurationSupport 重写 #extendMessageConverters(java.util.List)方法,
     * // 第二个方法实现如下
     */
    @Override
    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.removeIf(converter -> converter instanceof StringHttpMessageConverter);
    }
}

==========================================
ResultException.java

package com.wwy.newapi.result.exception;

import com.wwy.newapi.result.ResultStatus;

/**
 * 业务异常类
 *
 * @author galaxy
 * @date 2019/10/05 16:19
 */

@SuppressWarnings("serial")
public class ResultException extends Exception {

    /**
     * 业务异常信息信息
     */
    ResultStatus resultStatus;

    public ResultException() {
        this(ResultStatus.INTERNAL_SERVER_ERROR);
    }

    public ResultStatus getResultStatus() {
		return resultStatus;
	}

	public void setResultStatus(ResultStatus resultStatus) {
		this.resultStatus = resultStatus;
	}

	public ResultException(ResultStatus resultStatus) {
        super(resultStatus.getMessage());
        this.resultStatus = resultStatus;
    }
}

==========================================
HelloResultController.java

package com.wwy.newapi.controller;

import java.util.HashMap;
import java.util.Map;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.wwy.newapi.result.ResponseResultBody;
import com.wwy.newapi.result.Result;
import com.wwy.newapi.result.exception.ResultException;

/**
 * @author galaxy
 * @date 2019/10/05 16:19
 */

@RestController
@RequestMapping("/helloResult")
@ResponseResultBody
public class HelloResultController {

    private static final HashMap<String, Object> INFO;

    static {
        INFO = new HashMap<String, Object>();
        INFO.put("name", "galaxy");
        INFO.put("age", "70");
    }

    @GetMapping("hello")
    public HashMap<String, Object> hello() {
        return INFO;
    }

    @GetMapping("result")
    public Result<Map<String, Object>> helloResult() {
        return Result.success(INFO);
    }

    @GetMapping("helloError")
    public HashMap<String, Object> helloError() throws Exception {
        throw new Exception("helloError");
    }

    @GetMapping("helloMyError")
    public HashMap<String, Object> helloMyError() throws Exception {
        throw new ResultException();
    }

    @GetMapping(value = "testString")
    public String testString() {
        return "helloString";
    }

    @GetMapping(value = "testInt")
    public Integer testInt() {
        return 123;
    }
}

==========================================
pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.galaxy</groupId>
    <artifactId>response-result</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>response-result</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.10</version>
            <scope>provided</scope>
        </dependency>



        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

结果如下：