com.mongodb.DBCursor#batchSize ( )源码实例Demo

@Override
public void importCollection() {
    DBCursor cursor = mongo.getCollection("studentSectionAssociation").find();
    cursor.batchSize(BATCH_SIZE);
    while (cursor.hasNext()) {
        DBObject spa = cursor.next();
        @SuppressWarnings("unchecked")
        Map<String, Object> body = (Map<String, Object>) spa.get("body");
        String studentId = (String) body.get("studentId");
        String sectionId = (String) body.get("sectionId");
        for (Vertex student : graph.getVertices("mongoid", studentId)) {
            for (Vertex section : graph.getVertices("mongoid", sectionId)) {
                Edge e = graph.addEdge(null, section, student, "studentSection");
                e.setProperty("mongoid", spa.get("_id"));

                if (body.containsKey("endDate")) {
                    e.setProperty("endDate", body.get("endDate"));
                }
                
                logger.log(Level.INFO, "Adding an edge between section: " + sectionId + " --> student: " + studentId);
            }
        }            
    }        
}
 

public static void getSamplesFromCursor(DBCursor cursor, int limit, List<Sample> outList){
    try{
        // exhaust the cursor adding each sample
		cursor.batchSize(limit);
		cursor.limit(limit);
        while(cursor.hasNext()) {
        	outList.add(new Sample(cursor.next()));
        }
    } finally {
        // ensure cursor is closed
        cursor.close();
    }
}
 

public void importEducationOrganizations(String type) {
    logger.log(Level.INFO, "Importing education organizations into graph: " + type);
    
    DBObject query = new BasicDBObject();
    query.put("type", type);
    
    DBCursor cursor = mongo.getCollection(EDUCATION_ORGANIZATION).find(query);
    cursor.batchSize(BATCH_SIZE);
    while (cursor.hasNext()) {
        DBObject edOrg = cursor.next();
        String currentEdOrgId = (String) edOrg.get("_id");
        
        Vertex v = graph.addVertex(null);
        logger.log(Level.INFO, "Adding vertex for {0}#{1} \t {2}", new String[] { type,
                currentEdOrgId, v.getId().toString() });
        
        v.setProperty("mongoid", currentEdOrgId);
        
        @SuppressWarnings("unchecked")
        Map<String, Object> body = (Map<String, Object>) edOrg.get("body");
        if (body.containsKey("parentEducationAgencyReference")) {
            String parentId = (String) body.get("parentEducationAgencyReference");
            for (Vertex child : graph.getVertices("mongoid", currentEdOrgId)) {
                for (Vertex parent : graph.getVertices("mongoid", parentId)) {
                    graph.addEdge(null, parent, child, EDUCATION_ORGANIZATION_ASSOCIATION);
                    logger.log(Level.INFO, "Adding an edge between ed org: " + parentId + " --> " + currentEdOrgId);
                }
            }
        }
    }
}
 

/**
 * Imports student school associations (as edges) into the graph structure.
 */
@Override
public void importCollection() {
    logger.log(Level.INFO, "Importing collection into graph: " + STUDENT_SCHOOL_ASSOCIATION);
    
    DBCursor cursor = mongo.getCollection(STUDENT_SCHOOL_ASSOCIATION).find();
    cursor.batchSize(BATCH_SIZE);
    while (cursor.hasNext()) {
        DBObject association = cursor.next();
        
        @SuppressWarnings("unchecked")
        Map<String, Object> body = (Map<String, Object>) association.get("body");
        String studentId = (String) body.get("studentId");
        String schoolId = (String) body.get("schoolId");
        for (Vertex student : graph.getVertices("mongoid", studentId)) {
            for (Vertex school : graph.getVertices("mongoid", schoolId)) {
                Edge e = graph.addEdge(null, school, student, "studentSchoolAssociation");
                e.setProperty("mongoid", association.get("_id"));
                
                if (body.containsKey("exitWithdrawDate")) {
                    e.setProperty("exitWithdrawDate", body.get("exitWithdrawDate"));
                }
                
                logger.log(Level.INFO, "Adding an edge between school: " + schoolId + " --> student: " + studentId);
            }
        }            
    }
}