RestTemplate json 转成实体类

有时候我们需要使用RestTemplate在java服务器访问其他url的资源，但是因为毕竟是处于两台服务器（jvm）中的类，如何进行实体类的传输呢？

• 约定实体类
  本例子以 AgreementApproveForOA 为结果返回的实体类
• 接受请求的代码

 @ApiOperation(value = "获取框架协议")
 @PostMapping("/getAgreementApprove")
 public ResponseEntity<AgreementApproveDTO> getAgreementApprove(@RequestParam Integer fcompanyId, @RequestParam Integer fcompanyType, @RequestHeader("fuid") Integer faid) {
      return xxx;
 }

• 转化实例

  public static AgreementApproveForOA getData() throws IOException {
        HttpHeaders headers = new HttpHeaders();
        headers.add("fuid", "2");//设置header
        String url = "http://localhost:8481/admin/admin/agreementApprove/getAgreementApprove?fcompanyId=174&fcompanyType=1";
        ResponseEntity<String> data = restTemplate.postForEntity(url, new HttpEntity<String>(headers), String.class);//获取json串
        AgreementResponseEntity agreementResponseEntity;
        //readValue(json字符串，json串对应装配的实体类)
        agreementResponseEntity = mapper.readValue(data.getBody(), AgreementResponseEntity.class); 
        return agreementResponseEntity.getRetEntity();
    }

• 附上依赖pom.xml

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.5</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.10.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>5.1.10.RELEASE</version>
        </dependency>

• 踩过的坑
  • jackson包不支持 2019-01-05 13:25:10 这种格式，会出现以下错误

 Cannot deserialize value of type `java.util.Date` from String "2019-10-03 00:00:00": not a valid representation (error: Failed to parse Date value '2019-10-03 00:00:00': Cannot parse date "2019-10-03 00:00:00": while it seems to fit format 'yyyy-MM-dd'T'HH:mm:ss.SSSZ', parsing fails (leniency? null))

• 解决方法：自定义日期解析器

解决方法引用自：链接

Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder = new Jackson2ObjectMapperBuilder();
mapper = jackson2ObjectMapperBuilder.build();
DateFormat dateFormat = mapper.getDateFormat();
mapper.setDateFormat(new MyDateFormat(dateFormat));

MyDateFormat.java

public class MyDateFormat extends DateFormat {
 
	private DateFormat dateFormat;
 
	private SimpleDateFormat format1 = new SimpleDateFormat("yyy-MM-dd HH:mm:ss");
 
	public MyDateFormat(DateFormat dateFormat) {
		this.dateFormat = dateFormat;
	}
 
	@Override
	public StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition) {
		return dateFormat.format(date, toAppendTo, fieldPosition);
	}
 
	@Override
	public Date parse(String source, ParsePosition pos) {
 
		Date date = null;
 
		try {
 
			date = format1.parse(source, pos);
		} catch (Exception e) {
 
			date = dateFormat.parse(source, pos);
		}
 
		return date;
	}
 
	// 主要还是装饰这个方法
	@Override
	public Date parse(String source) throws ParseException {
 
		Date date = null;
 
		try {
			
			// 先按我的规则来
			date = format1.parse(source);
		} catch (Exception e) {
 
			// 不行，那就按原先的规则吧
			date = dateFormat.parse(source);
		}
 
		return date;
	}
 
	// 这里装饰clone方法的原因是因为clone方法在jackson中也有用到
	@Override
	public Object clone() {
		Object format = dateFormat.clone();
		return new MyDateFormat((DateFormat) format);
	}
}

这样就可以把json转成相对应的实体类了。

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