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java - jsckson - 深拷贝时 java 8 LocalDateTime 报错解决

1. 报错

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Java 8 date/time type `java.time.LocalDateTime` not supported by
default: add Module "com.fasterxml.jackson.datatype:jackson-datatype-jsr310" to enable handling
 at [Source

 

 已经提示了，jackson 不支持 java8 的  LocalDateTime 类型

需要引入依赖添加模块

2. 解决

引入依赖

  <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-jsr310</artifactId>
            <version>2.13.0</version>
        </dependency>

在使用时需要引入该模块即可

【注意，必须使用 jackson 转 json 的字符串才可以使用 jsckson 恢复为对象，否则会报错，如果没有 java 8 的 LocalDateTime 类型，则可以与其他插件工具混用，如 gson】

 封装的 json 工具

    private static final ObjectMapper objectMapper = new ObjectMapper();

</span><span style="color: rgba(0, 0, 255, 1)">static</span><span style="color: rgba(0, 0, 0, 1)"> {
    objectMapper.registerModule(</span><span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> JavaTimeModule());
}

</span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">使用jaskon转换为json串</span>
<span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span> String beanToJsonByJaskon(Object <span style="color: rgba(0, 0, 255, 1)">object</span><span style="color: rgba(0, 0, 0, 1)">) {
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> (<span style="color: rgba(0, 0, 255, 1)">null</span> == <span style="color: rgba(0, 0, 255, 1)">object</span><span style="color: rgba(0, 0, 0, 1)">) {
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    }
    </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)"> {
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> objectMapper.writeValueAsString(<span style="color: rgba(0, 0, 255, 1)">object</span><span style="color: rgba(0, 0, 0, 1)">);
    } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (Exception e) {
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    }
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span> &lt;T&gt; T jsonToBean(String <span style="color: rgba(0, 0, 255, 1)">string</span>, Class&lt;T&gt;<span style="color: rgba(0, 0, 0, 1)"> clazz) {
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> (<span style="color: rgba(0, 0, 255, 1)">null</span> == <span style="color: rgba(0, 0, 255, 1)">string</span><span style="color: rgba(0, 0, 0, 1)">) {
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    }
    </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)"> {
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> objectMapper.readValue(<span style="color: rgba(0, 0, 255, 1)">string</span><span style="color: rgba(0, 0, 0, 1)">, clazz);
    } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (Exception e) {
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    }
}</span></pre>
View Code

3. 使用

我一般将其写在实体里，写一个 clone 的方法

 

 

 对 实例对象直接调用即可