//1.获取仓库对象

RepositoryService rs = processEngine.getRepositoryService();

//2.使用部署ID查询，此处默认为601

String deploymentId = "601";

//3.获取该部署下的所有资源名称

List<String> list = rs.getDeploymentResourceNames(deploymentId);

//4.查询结尾是PNG的资源名称

//定义图片资源的名称，后缀为PNG的是我们要查找的资源

String resourceName = "";
if(list!=null && list.size()>0){
    for(String name:list){
        if(name.indexOf(".png")>=0){
            resourceName = name;
        }
    }
}

//5.获取图片的输入流
InputStream in = rs.getResourceAsStream(deploymentId, resourceName);

//6.将图片生成到D盘的目录下
File file = new File("D:/" + resourceName);
FileUtils.copyInputStreamToFile(in, file);