【问题记录】fastjson序列化MultipartFile接口入参导致的异常

﹏ヽ暗。殇╰゛Y 2024-03-17 23:59 32阅读 0赞

#### 目录 ####

*  一、异常场景复现
 *   *  1、maven
     *  2、java
     *   *  2-1、Java-aspect
         *  2-2、java-controller
     *  3、触发
 *  二、异常堆栈
 *  三、堆栈分析
 *  四、问题定位
 *  五、问题解决
 *   *  1、思路分析
     *  2、代码实现
     *   *  2-1、controller
         *  2-2、FileParam
 *  六、再次调用，无异常

## 一、异常场景复现 ##

### 1、maven ###

<dependency>
        <groupId>com.fasterxml.jackson.jaxrs</groupId>
        <artifactId>jackson-jaxrs-json-provider</artifactId>
        <version>2.13.3</version>
    </dependency>
    
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.24</version>
        <scope>provided</scope>
    </dependency>
    
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-aop</artifactId>
        <version>2.6.2</version>
    </dependency>

### 2、java ###

#### 2-1、Java-aspect ####

package com.example.temp.apo;
    
    import com.alibaba.fastjson.JSON;
    import lombok.extern.slf4j.Slf4j;
    import org.aspectj.lang.JoinPoint;
    import org.aspectj.lang.annotation.*;
    import org.springframework.stereotype.Component;
    
    @Aspect
    @Component
    @Slf4j
    public class LogAspect {
        
    
        @Pointcut("execution(public * com.example.temp.controller..*.*(..))")
        public void logPointCut() {
        
        }
    
        @Before("logPointCut()")
        public void doBefore(JoinPoint joinPoint) {
        
            log.info(" |---- 请求体: {}", JSON.toJSONString(joinPoint.getArgs()));
        }
    
        @After("logPointCut()")
        public void doAfter() {
        
        }
    
        @AfterThrowing(value = "logPointCut()", throwing = "e")
        public void afterThrowing(Throwable e) {
        
        }
    }

#### 2-2、java-controller ####

package com.example.temp.controller;
    
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.bind.annotation.PostMapping;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.multipart.MultipartFile;
    
    @RestController
    @RequestMapping("file")
    public class FileController {
        
        @PostMapping(value = "/upload")
        public Object importLicense(@RequestParam("file") MultipartFile file) {
        
            if (file == null || file.isEmpty()) {
        
                return "上传文件不能为空";
            }
            return null;
        }
    }

### 3、触发 ###

![postman][]

## 二、异常堆栈 ##

2023-07-23 07:03:49.148 [traceId:]  ERROR o.a.c.c.C.[.[.[.[dispatcherServlet] -175 -Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is com.alibaba.fastjson.JSONException: write javaBean error, fastjson version 1.2.83, class org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile, fieldName : 0, write javaBean error, fastjson version 1.2.83, class org.springframework.web.multipart.MultipartFileResource, fieldName : resource] with root cause
    java.io.FileNotFoundException: MultipartFile resource [file] cannot be resolved to absolute file path
    	at org.springframework.core.io.AbstractResource.getFile(AbstractResource.java:138)
    	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at com.alibaba.fastjson.util.FieldInfo.get(FieldInfo.java:571)
    	at com.alibaba.fastjson.serializer.FieldSerializer.getPropertyValueDirect(FieldSerializer.java:143)
    	at com.alibaba.fastjson.serializer.JavaBeanSerializer.write(JavaBeanSerializer.java:284)
    	at com.alibaba.fastjson.serializer.JavaBeanSerializer.write(JavaBeanSerializer.java:154)
    	at com.alibaba.fastjson.serializer.FieldSerializer.writeValue(FieldSerializer.java:318)
    	at com.alibaba.fastjson.serializer.JavaBeanSerializer.write(JavaBeanSerializer.java:472)
    	at com.alibaba.fastjson.serializer.JavaBeanSerializer.write(JavaBeanSerializer.java:154)
    	at com.alibaba.fastjson.serializer.JSONSerializer.writeWithFieldName(JSONSerializer.java:360)
    	at com.alibaba.fastjson.serializer.JSONSerializer.writeWithFieldName(JSONSerializer.java:338)
    	at com.alibaba.fastjson.serializer.ObjectArrayCodec.write(ObjectArrayCodec.java:118)
    	at com.alibaba.fastjson.serializer.JSONSerializer.write(JSONSerializer.java:312)
    	at com.alibaba.fastjson.JSON.toJSONString(JSON.java:793)
    	at com.alibaba.fastjson.JSON.toJSONString(JSON.java:731)
    	at com.alibaba.fastjson.JSON.toJSONString(JSON.java:688)
    	at com.example.temp.apo.LogAspect.doBefore(LogAspect.java:20)
    	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)

## 三、堆栈分析 ##

1.  **nested exception is com.alibaba.fastjson.JSONException: write javaBean error** ，提示到fastjson序列化javaBean时出错，且后面提示**class org.springframework.web.multipart.MultipartFileResource**，指出MultipartFile相关。
2.  \*\*at com.example.temp.apo.LogAspect.doBefore(LogAspect.java:20)\*\*指明了异常所在代码位置，该行代码为：

log.info(" |---- 请求体: {}", JSON.toJSONString(joinPoint.getArgs()));

## 四、问题定位 ##

基本可以断定，异常源自于**JSON.toJSONString(joinPoint.getArgs())**，该语句目的是为了打印接口参数信息，但【上传】接口的参数为**MultipartFile file**，导致fastjson序列化异常。

## 五、问题解决 ##

### 1、思路分析 ###

由于日志切面是公共切面，去除\*\*JSON.toJSONString(joinPoint.getArgs())**参数打印信息，属于因噎废食下下策，那么只能从【上传】文件接口入手了。  
既然fastjson与MultipartFile不合，那么我们可以考虑将MultipartFile封装入一个Po对象中，并在MultipartFile属性字段上加上注解**@JSONField(serialize = false)\*\*这样一来，对于日志切面而言，【上传】  
接口的参数就不是MultipartFile，而是一个自定义的普通java对象，且MultipartFile不必序列化。

### 2、代码实现 ###

#### 2-1、controller ####

@PostMapping(value = "/upload")
        public Object importLicense(FileParam fileParam) {
        
    
            if (fileParam == null
                    || fileParam.getFile() == null
                    || fileParam.getFile().isEmpty()) {
        
                return "上传文件不能为空";
            }
            return null;
        }

#### 2-2、FileParam ####

package com.example.temp.param;
    
    import com.alibaba.fastjson.annotation.JSONField;
    import lombok.Data;
    import org.springframework.web.multipart.MultipartFile;
    
    @Data
    public class FileParam {
        
        @JSONField(serialize = false)
        private MultipartFile file;
        private String Context;
    }

## 六、再次调用，无异常 ##

[postman]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/14/62fac72f21584f93ab66bb342f57631c.png