RestTemplate传递对象乱码问题及实例调用

Bertha 。 2022-06-01 13:35 750阅读 0赞

最近在优化项目，将里面的交易日志插入部分分离了出来，现在就要将主系统得到的日志发送到
    日志系统，来减轻主项目对数据库的压力，现将日志发送给日志系统的方案有三个，其一为
    RestTemplate发送，其二为kafka，其三为PostMethod。此处仅讲解RestTemplate的具体用
    法，以备后用。

**服务端代码**

@RequestMapping("/json.do")
    	public void myJson(@RequestParam("repo") String repo, HttpServletResponse po) throws Exception {
    		System.out.println(repo);
    		JSONObject jo = new JSONObject();
    		jo.put("message",
    				"{ringDialTime=\"1111122\", ringdialTimestamp=\"1513059248647\", establishedTimestamp=\"1513099248647\"}");
    		po.getWriter().write(jo.toString());
    
    	}
    
    	@RequestMapping("/getEntity.do")
    	public void getEntity(@RequestBody User user, HttpServletResponse po) throws Exception {
    		System.out.println(user.getName());
    		JSONObject jo = new JSONObject();
    		jo.put("message",
    				"{ringDialTime=\"1111122\", ringdialTimestamp=\"1513059248647\", establishedTimestamp=\"1513099248647\"}");
    		po.getWriter().write(jo.toString());
    
    	}

***客户端代码***

public static void main(String[] args) throws HttpException, IOException {
    		RestTemplate pp =new RestTemplate();
    		User a = new User();
    		a.setEmail("email");
    		a.setName("ljp");
    		ResponseEntity<String> postForEntity = pp.postForEntity("http://127.0.0.1:8081/SpringMVC-T/inde/getEntity.do",a,String.class);//传递实体
    		ResponseEntity<String> postForEntity2 = pp.postForEntity("http://127.0.0.1:8081/SpringMVC-T/inde/json.do?repo=ljp",null,String.class);//传参
    		System.out.println(postForEntity+"\n"+postForEntity2);
    		System.out.println(postForEntity.getBody());
    	}

**客户端接收的返回值**  
可以看到服务器端返回的json串，可以通过`postForEntity.getBody()` 获取得到`{"message":"{ringDialTime=\"1111122\"}"}`，具体返回的数据可以做交互验证之类的操作

![这里写图片描述][SouthEast]

服务器端接收到的数据展示

由此可以看到服务器端完全接收到了传递的参数和对象  
![这里写图片描述][SouthEast 1]

\*\*

## 解决方案 ##

\*\*  
跨域传输的对象参数之间难免有汉字，但是restTemplate 的请求默认的参数是iso-9958-1,这个时候就出现了乱码的问题，我在网上也找了不少方法，很多的都是如下

RestTemplate restTemplate = new RestTemplateBuilder().additionalMessageConverters(m).build();
            HttpHeaders headers = new HttpHeaders();
            MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
            headers.setContentType(type);
            headers.add("Accept", MediaType.APPLICATION_JSON.toString());
            
            String jsonStr = JSONObject.toJSONString(params);
            
            HttpEntity formEntity = new HttpEntity( headers);
            String result = restTemplate.getForObject("http://www.baidu.com", String.class);

**但是**我的并不行，依然是乱码，然后只好用了个笨方法，重写了 **StringHttpMessageConverter** 这个类，这个效果是立竿见影，立马就好了

package org.springframework.http.converter;
          
          import java.io.IOException;
          import java.io.UnsupportedEncodingException;
          import java.nio.charset.Charset;
          import java.util.ArrayList;
          import java.util.List;
          import java.util.SortedMap;
          import org.springframework.http.HttpHeaders;
          import org.springframework.http.HttpInputMessage;
          import org.springframework.http.HttpOutputMessage;
          import org.springframework.http.MediaType;
          import org.springframework.util.StreamUtils;
    
          public class StringHttpMessageConverter
            extends AbstractHttpMessageConverter<String>
          {
          public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
            
            private final Charset defaultCharset;
            
            private final List<Charset> availableCharsets;
            
          private boolean writeAcceptCharset = true;
            
            public StringHttpMessageConverter()
            {
            this(DEFAULT_CHARSET);
            }
            
          
            public StringHttpMessageConverter(Charset defaultCharset)
            {
            super(new MediaType[] { new MediaType("text", "plain", defaultCharset), MediaType.ALL });
            this.defaultCharset = defaultCharset;
            this.availableCharsets = new ArrayList(Charset.availableCharsets().values());
            }
            
            public void setWriteAcceptCharset(boolean writeAcceptCharset)
            {
            this.writeAcceptCharset = writeAcceptCharset;
            }
            
            public boolean supports(Class<?> clazz)
            {
            return String.class.equals(clazz);
            }
            
            protected String readInternal(Class<? extends String> clazz, HttpInputMessage inputMessage) throws IOException
            {
            Charset charset = getContentTypeCharset(inputMessage.getHeaders().getContentType());
            return StreamUtils.copyToString(inputMessage.getBody(), charset);
            }
            
            protected Long getContentLength(String s, MediaType contentType)
            {
            Charset charset = getContentTypeCharset(contentType);
              try {
              return Long.valueOf(s.getBytes(charset.name()).length);
              }
              catch (UnsupportedEncodingException ex)
              {
              throw new IllegalStateException(ex);
              }
            }
            protected void writeInternal(String s, HttpOutputMessage outputMessage) throws IOException
            {
           if (this.writeAcceptCharset) {
             outputMessage.getHeaders().setAcceptCharset(getAcceptedCharsets());
              }
          Charset charset = getContentTypeCharset(outputMessage.getHeaders().getContentType());
           StreamUtils.copy(s, charset, outputMessage.getBody());
            }
            
            protected List<Charset> getAcceptedCharsets()
            {
           return this.availableCharsets;
            }
            
            private Charset getContentTypeCharset(MediaType contentType) {
           if ((contentType != null) && (contentType.getCharSet() != null)) {
             return contentType.getCharSet();
              }
              
           return this.defaultCharset;
            }
          }

我们知道，调用reseful接口传递的数据内容是json格式的字符串，返回的响应也是json格式的字符串。然而restTemplate.postForObject方法的请求参数RequestBean和返回参数ResponseBean却都是java类。是RestTemplate通过HttpMessageConverter自动帮我们做了转换的操作。想要详细了解的可以看看这篇：[https://www.jianshu.com/p/c9644755dd5e，][https_www.jianshu.com_p_c9644755dd5e]

[SouthEast]: /images/20220601/4519e17573cc4458b22893c9f8395216.png
[SouthEast 1]: /images/20220601/d23bfa83d95f431c9557ab5813214739.png
[https_www.jianshu.com_p_c9644755dd5e]: https://www.jianshu.com/p/c9644755dd5e%EF%BC%8C