# RestTemplate

**Repository Path**: qplo/rest-template

## Basic Information

- **Project Name**: RestTemplate
- **Description**: No description available
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-12-26
- **Last Updated**: 2022-02-22

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README



# http请求参数中巨坑的“+”被转为空格的问题

​	我在工作中遇到一个问题，我们在通过 SpringBoot 提供的（客户端请求） RestTemplate 方法去请求其他服务的接口时，所带参数携带 “+” 号被转换成空格的问题

## 1.前提

- 前提我们得先知道HTTP请求中携带的参数中带 “+” 请求后端时，在经过 tomcat 时，会被替换成空格。

通过debug我们来到

- public final class Parameters 类中的 processParameters 方法
  

![image-20211225232948655](C:\Users\deku\AppData\Roaming\Typora\typora-user-images\image-20211225232948655.png)

经过层层套娃之后他就会进入下面的方法中

- public final class UDecoder{} 类中的 convert 方法


![image-20211225232414184](C:\Users\deku\AppData\Roaming\Typora\typora-user-images\image-20211225232414184.png)

这里详细看https://www.cnblogs.com/thisiswhy/p/12119126.html



上面我们知道 “+” 在经过 tomcat 处理过后会变成空格

## 2.了解转码,解码

```java
	String encode = URLEncoder.encode("come +here=", "UTF-8");
        System.out.println(encode);
        String decode = URLDecoder.decode(encode, "UTF-8");
        System.out.println(decode);
        String decodeDemo = URLDecoder.decode("come +here=/yuftujy", "UTF-8");
        System.out.println(decodeDemo);
/*
*	输出
*	come+%2Bhere%3D
*	come +here=
*	come  here=/yuftujy
*/
```


|  | tomcat | 转码 | 解码 |
| ----- | --------- | ----------- | ------- |
| “ ” | “ ” | “+” | “ ” |
| “+” | “ ”  | “%2B” | “+” |
| “=” | “=” | “%3D” | "=" |



我们这就发现一个空格的问题，他在转码后没有变成我们所预期的 "%20",而是变成了 ”+“，而 ”+” 号在经过 tomcat 时又会变成 空格？

这会导致什么问题，后端

这就是一个巨大的坑！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！




## 3.发现问题



现在我们结合工作中的问题，在客户端，用SpringBoot提供的 RestTemplate 请求其他服务参数带 ”+“ 的问题、

- 得知 admId 从请求开始到结束一共经过了两次 tomcat

在调试中我发现三种情况

1、正常请求：http://localhost:8080/cdata?admId=S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=

```java
@GetMapping("/cdata")
public Object cdata(@RequestParam String admId) throws Exception{
    
    System.out.println("tomcat转："+admId);//admId S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=

    String url="http://localhost:8080/hello";
    UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromHttpUrl(url)
            .queryParam("admId", encode);
    String urls = uriComponentsBuilder.build().toUriString();

    HttpEntity<Map<String, Object>> requestEntity = new HttpEntity<>(null, null);
    ResponseEntity<ResponsVO> response = restTemplate.exchange(urls, HttpMethod.GET, requestEntity,
            new ParameterizedTypeReference<ResponsVO>() {
            });

    return response.getBody().getData();
}

@GetMapping("hello")
public Object cdataDemo(String admId) throws Exception{
    
    System.out.println(admId);//S9Y qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
    
    ResponsVO<Object> responsVO = new ResponsVO<>();
    responsVO.setCode(200);
    responsVO.setMsg("成功");
    User user = new User();
    user.setId(1);
    user.setName("汪镇威");
    responsVO.setData(user);
    return responsVO;
}

//正常请求我们可以看到参数 admId 第一次进过tomcat的时候 “+” 就变成了空格
```



2.第二种：加上转码解码

```java
 @GetMapping("/cdata")
    public Object cdata(@RequestParam String admId) throws Exception{
        
        System.out.println("转码前："+admId);//转码前：S9Y qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=

        String encode = URLEncoder.encode(admId, "UTF-8");
        
        System.out.println("转码后："+encode);//转码后：S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D

        String url="http://localhost:8080/hello";
        UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromHttpUrl(url)
                .queryParam("admId", encode);
        String urls = uriComponentsBuilder.build().toUriString();
        HttpEntity<Map<String, Object>> requestEntity = new HttpEntity<>(null, null);
        ResponseEntity<ResponsVO> response = restTemplate.exchange(urls, HttpMethod.GET, requestEntity,
                new ParameterizedTypeReference<ResponsVO>() {
                });

        return response.getBody().getData();
    }

    @GetMapping("hello")
    public Object cdataDemo(String admId) throws Exception{
        
        System.out.println("解码前："+admId);
        //解码前：S9Y qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D
        System.out.println("解码后："+URLDecoder.decode(admId,"UTF-8"));
        //解码后：S9Y qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
        
        ResponsVO<Object> responsVO = new ResponsVO<>();
        responsVO.setCode(200);
        responsVO.setMsg("成功");
        User user = new User();
        user.setId(1);
        user.setName("汪镇威");
        responsVO.setData(user);
        return responsVO;
    }
} 
/**
 * 转码前：S9Y qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
 * 转码后：S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D
 * 解码前：S9Y qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D
 * 解码后：S9Y qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
 */
```

- 还是不行，因为 admId经过第一次 tomcat的时候就已经把“+”替换成了空格，转码后“=”被符合预期的转成了"%3D",但是 空格 被转码后又变成了 “+” ，不是我们所预期的“%20”，这导致在第二次请求接口的时候 “+” 又被替换成了空格。
- 这么一看，那他不是无解了吗？？？



3.第三种：前端传参时进行转码-S9Y%2BqEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D

```java
@GetMapping("/cdata")
    public Object cdata(@RequestParam String admId) throws Exception{
//        admId="admId%2BS9Y%2BqEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D";
        
        System.out.println("转码前："+admId);//转码前：S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
        String encode = URLEncoder.encode(admId, "UTF-8");
        System.out.println("转码后："+encode);//转码后：S9Y%2BqEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D

        String url="http://localhost:8080/hello";
        UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromHttpUrl(url)
                .queryParam("admId", encode);
        String urls = uriComponentsBuilder.build().toUriString();
        HttpEntity<Map<String, Object>> requestEntity = new HttpEntity<>(null, null);
        ResponseEntity<ResponsVO> response = restTemplate.exchange(urls, HttpMethod.GET, requestEntity,
                new ParameterizedTypeReference<ResponsVO>() {
                });

        return response.getBody().getData();
    }

    @GetMapping("hello")
    public Object cdataDemo(String admId) throws Exception{
        System.out.println("解码前："+admId);
        //解码前：S9Y%2BqEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D
        System.out.println("解码后："+URLDecoder.decode(admId,"UTF-8"));
        //解码后：S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
        ResponsVO<Object> responsVO = new ResponsVO<>();
        responsVO.setCode(200);
        responsVO.setMsg("成功");
        User user = new User();
        user.setId(1);
        user.setName("汪镇威");
        responsVO.setData(user);
        return responsVO;
    }
/**
 * 转码前：S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
 * 转码后：S9Y%2BqEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D
 * 解码前：S9Y%2BqEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w%3D
 * 解码后：S9Y+qEERxxGVFo0DE8mruGVGmVYNJraVwZyijimEv6w=
 */
```

- 从输出结果中我们可以看出，前端对参数进行转码后，“+” 被符合预期的转成了 “%2B”，进过tomcat的解码之后，再对其进行转码，在其他服务接口对其进行接码之后就能返回正常数据