文章标题

Java中用流程框架activiti5，查询流程定义数据时，如果查询的表为自关联的表，就会出现死循环的情况

例如：

@RestController

public class ActivitiController extends BaseController {

@Autowired
private RepositoryService repositoryService;

@RequestMapping("/act/queryDataList/{startindex}/{pagesize}")
public List<ProcessDefinition> queryDataList(@PathVariable("startindex") Integer startindex,
@PathVariable("pagesize") Integer pagesize) {
ProcessDefinitionQuery definitionQuery = repositoryService.createProcessDefinitionQuery();
List<ProcessDefinition> listPage = definitionQuery.listPage(startindex, pagesize);

return listPage;
}

｝

报错如下：

Failed to write HTTP message: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Direct self-reference leading to cycle; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Direct self-reference leading to cycle (through reference chain: java.util.ArrayList[0]->org.activiti.engine.impl.persistence.entity.ProcessDefinitionEntity[“processDefinition”])

解决办法：将查询出来的数据遍历出来再封装成Map集合形式

@RestController

public class ActivitiController extends BaseController {

@Autowired
private RepositoryService repositoryService;

@RequestMapping("/act/queryDataList/{startindex}/{pagesize}")
public List<Map<String,Object>> queryDataList(@PathVariable("startindex") Integer startindex,
@PathVariable("pagesize") Integer pagesize) {
ProcessDefinitionQuery definitionQuery = repositoryService.createProcessDefinitionQuery();
List<ProcessDefinition> listPage = definitionQuery.listPage(startindex, pagesize);

List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();

for (ProcessDefinition processDefinition : listPage) {
Map<String,Object> obj = new HashMap<String,Object>();
obj.put("id", processDefinition.getId());
obj.put("name", processDefinition.getName());
obj.put("version", processDefinition.getVersion());
obj.put("key", processDefinition.getId());
obj.put("deployid", processDefinition.getDeploymentId());

list.add(obj);
}

return list;
}

}