使用Base64值的Webservice POST调用抛出异常“com.fasterxml.jackson.databind.JsonMappingException”

Question

我有一个简单的课程。

public class SolrModel {
    private Base64 param;
    //setter
    public Base64 getParam() {
        return param;
    }
    //getter
    public void setParam(Base64 param) {
        this.param = param;
    }
    public SolrModel(Base64 param) {
        this.param = param;
    }
    public SolrModel() {
    }
}

这是一个处理POST请求的控制器类。

@RestController
public class SolrController {

@RequestMapping(value = "/getdata", method = RequestMethod.POST)
    public SolrDocumentList getStatus(@RequestBody SolrModel sm) {
        SolrAction sa = new SolrActionImpl();
        return sa.getSearchData(sm.getName());
    }
}

在我进行REST调用之后，服务抛出异常。

WARNING: Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not instantiate value of type [simple type, class java.util.Base64] from String value ('dmlub2Q='); no single-String constructor/factory method
    at [Source: java.io.PushbackInputStream@4d809754; line: 2, column: 18] (through reference chain: test.solr.models.SolrModel["param"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not instantiate value of type [simple type, class java.util.Base64] from String value ('dmlub2Q='); no single-String constructor/factory method
    at [Source: java.io.PushbackInputStream@4d809754; line: 2, column: 18] (through reference chain: test.solr.models.SolrModel["param"])
Aug 12, 2015 7:22:40 PM org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver logException
WARNING: Handler execution resulted in exception: Could not read document: Can not instantiate value of type [simple type, class java.util.Base64] from String value ('dmlub2Q='); no single-String constructor/factory method
    at [Source: java.io.PushbackInputStream@4d809754; line: 2, column: 18] (through reference chain: test.solr.models.SolrModel["param"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not instantiate value of type [simple type, class java.util.Base64] from String value ('dmlub2Q='); no single-String constructor/factory method
    at [Source: java.io.PushbackInputStream@4d809754; line: 2, column: 18] (through reference chain: test.solr.models.SolrModel["param"])

解决这个问题的方法是什么？