本文实现一个通用泛型封装实现类，需要给定一个集合对象，类似mysql中与java对应的表；思想就是把给定的对象解析出所有非空字段，保存到一个BasicDBObject中，这里一定要保证java对象与mongodb中的文档字段名字一样，因为代码为了实现通用，是默认以java对象的字段为BasicDBObject的查询字段。
核心代码1：这是将java对象转换为查询条件。
/** * 通过反射获取非空字段信息 * @param record * @param* @return */ privateBasicDBObject getCondition(Q record) { BasicDBObject cond = new BasicDBObject(); Class clazz = record.getClass(); Field[] fields = clazz.getDeclaredFields(); for (Field field : fields) { try { field.setAccessible(true); Object value = field.get(record); if (value != null) cond.put(field.getName(), value); } catch (IllegalAccessException e) { e.printStackTrace(); } } return cond; }
核心代码2：这是将查询到的文档转换为java对象，这里也是默认java对象的字段和数据库文档字段一样，也是利用java的反射动态获取用户自定义对象的所有字段，然后进行赋值，我在赋值过程中单独判断了int和long型，因为插入mongodb的时候一般是以double存的，这样就会造成转型错误。
/** * 将结果转化为自定义对象 * @param document * @param target * @param* @return */ privateQ parseToObject(Document document, Classtarget) { try { Q result = target.newInstance(); Field[] fields = target.getDeclaredFields(); for (Field f : fields) { f.setAccessible(true); Object value = document.get(f.getName()); if (value == null) continue; else if (f.getType() == Integer.class) f.set(result, ((Number) value).intValue()); else if (f.getType() == Long.class) f.set(result, ((Number) value).longValue()); else f.set(result, document.get(f.getName(), f.getType())); } return result; } catch (IllegalAccessException e) { e.printStackTrace(); return null; } catch (InstantiationException e) { e.printStackTrace(); return null; } }
调用方法：先转换查询参数，查询的时候是以id来判断正序倒序，所以默认数据库中一定要有id的标识字段。
publicListqueryByCondition(BaseQueryquery,boolean up) { Q record = query.getQuery(); BasicDBObject cond = getCondition(record); FindIterablefindIterable; if (query.getStart() != null && query.getRows() != null) findIterable = thisCollection().find(cond) .sort(new BasicDBObject("id", up ? 1 : -1)) .skip((query.getStart() - 1) * query.getRows()) .limit(query.getRows()); else findIterable = thisCollection().find(cond) .sort(new BasicDBObject("id", up ? 1 : -1)); MongoCursor iterator = findIterable.iterator(); List result = new ArrayList<>(); while (iterator.hasNext()) { Document document = iterator.next(); result.add((Q) parseToObject(document, record.getClass())); } iterator.close(); return result; }
这里传入的BaseQuery如下：里面的query就是个需要查询的java对象，start&rows是为了用来分页的。这里是用到了lombok的插件，这样简化很多的gettter&setter等代码。
@Setter @Getter @NoArgsConstructor @AllArgsConstructor @Data @Accessors(chain = true) public class BaseQuery{ private Integer start; private Integer rows; private Q query; public BaseQuery(Class clazz) { try { this.query = (Q) clazz.newInstance(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } } }
测试条件查询方法：这里用到的实体如下：
@Data @AllArgsConstructor @NoArgsConstructor @Accessors(chain = true) public class User_info { private Integer id; private String name; private Integer age; private Integer role; }
public static void main(String[] args) { User_info record = new User_info(); BaseQuery query = new BaseQuery<>(); query.setQuery(record); BaseMongoDao dao = new BaseMongoDao("test"); List result = dao.queryByCondition(query, true); for (User_info user : result) { System.out.println(user); } }
因为这里用到的查询条件为空，所有会匹配数据库的所有项：
现在测试一下设置权限为1的数据：
public static void main(String[] args) { User_info record = new User_info(); record.setRole(1); BaseQuery query = new BaseQuery<>(); query.setQuery(record); BaseMongoDao dao = new BaseMongoDao("test"); List result = dao.queryByCondition(query, true); for (User_info user : result) { System.out.println(user); } }
输出：
这个条件查询方法是一个例子，其他的删除，增加，修改都是这个原理，下面带有：
1.publicList
queryByCondition(BaseQuery
query,boolean up)
2.publicInteger queryCoditionCount(BaseQuery
query)
3.publicboolean insertOne(Q record)
4.publicboolean insertList(List
records)
5.public boolean deleteById(Integer id)
6.public boolean deleteByIds(List
7.publicvoid updateById(Q record)
放上所有代码：
package cn.wzy.dao; import com.mongodb.*; import com.mongodb.client.FindIterable; import com.mongodb.client.MongoCollection; import com.mongodb.client.MongoCursor; import com.mongodb.client.MongoDatabase; import org.bson.Document; import org.cn.wzy.query.BaseQuery; import org.cn.wzy.util.PropertiesUtil; import java.lang.reflect.Field; import java.util.ArrayList; import java.util.List; /** * Create by Wzy * on 2018/7/28 18:15 * 不短不长八字刚好 */ public class BaseMongoDao { private static final MongoClient mongoClient; private static final MongoDatabase mongo; static { MongoClientOptions options = MongoClientOptions.builder() .connectionsPerHost(150) .maxWaitTime(2000) .socketTimeout(2000) .maxConnectionLifeTime(5000) .connectTimeout(5000).build(); ServerAddress serverAddress = new ServerAddress(PropertiesUtil.StringValue("mongo.host"), PropertiesUtil.IntegerValue("mongo.port")); List
addrs = new ArrayList<>(); addrs.add(serverAddress); MongoCredential credential = MongoCredential.createScramSha1Credential( PropertiesUtil.StringValue("mongo.user") , PropertiesUtil.StringValue("mongo.db") , PropertiesUtil.StringValue("mongo.pwd").toCharArray()); mongoClient = new MongoClient(addrs, credential, options); mongo = mongoClient.getDatabase(PropertiesUtil.StringValue("mongo.db")); } public BaseMongoDao(String colName) { this.colName = colName; } private String colName; private MongoCollection
thisCollection() { return mongo.getCollection(colName); } public List queryByCondition(BaseQuery query,boolean up) { Q record = query.getQuery(); BasicDBObject cond = getCondition(record); FindIterable findIterable; if (query.getStart() != null && query.getRows() != null) findIterable = thisCollection().find(cond) .sort(new BasicDBObject("id", up ? 1 : -1)) .skip((query.getStart() - 1) * query.getRows()) .limit(query.getRows()); else findIterable = thisCollection().find(cond) .sort(new BasicDBObject("id", up ? 1 : -1)); MongoCursor iterator = findIterable.iterator(); List result = new ArrayList<>(); while (iterator.hasNext()) { Document document = iterator.next(); result.add((Q) parseToObject(document, record.getClass())); } iterator.close(); return result; } public
Integer queryCoditionCount(BaseQueryquery) { Q record = query.getQuery(); BasicDBObject cond = getCondition(record); return (int) thisCollection().countDocuments(cond); } publicboolean insertOne(Q record) { BasicDBObject cond = getCondition(record); try { int top = getTop(); cond.put("id",++top); thisCollection().insertOne(new Document(cond)); return true; } catch (Exception e) { e.printStackTrace(); return false; } } publicboolean insertList(Listrecords) { try { List
list = new ArrayList<>(records.size()); if (!changeIds(records)) return false; for (Q record : records) { list.add(new Document(getCondition(record))); } thisCollection().insertMany(list); return true; }catch (Exception e) { e.printStackTrace(); return false; } } public boolean deleteById(Integer id) { try { if (id == null) return false; thisCollection().deleteOne(new BasicDBObject("id",id)); return true; } catch (Exception e) { e.printStackTrace(); return false; } } public boolean deleteByIds(List
ids) { BasicDBObject cond = new BasicDBObject("id",new BasicDBObject("$in",ids.toArray())); try { thisCollection().deleteMany(cond); return true; } catch (Exception e) { e.printStackTrace(); return false; } } /** * 只通过id更改，查询就只是搜索id * @param record * @param
*/ publicvoid updateById(Q record) { BasicDBObject cond = getCondition(record); BasicDBObject update = new BasicDBObject("$set",cond); BasicDBObject query = new BasicDBObject("id",cond.get("id")); thisCollection().updateOne(query,update); } /** * 通过反射获取非空字段信息 * @param record * @param * @return */ private BasicDBObject getCondition(Q record) { BasicDBObject cond = new BasicDBObject(); Class clazz = record.getClass(); Field[] fields = clazz.getDeclaredFields(); for (Field field : fields) { try { field.setAccessible(true); Object value = field.get(record); if (value != null) cond.put(field.getName(), value); } catch (IllegalAccessException e) { e.printStackTrace(); } } return cond; } /** * 将结果转化为自定义对象 * @param document * @param target * @param * @return */ private Q parseToObject(Document document, Class target) { try { Q result = target.newInstance(); Field[] fields = target.getDeclaredFields(); for (Field f : fields) { f.setAccessible(true); Object value = document.get(f.getName()); if (value == null) continue; else if (f.getType() == Integer.class) f.set(result, ((Number) value).intValue()); else if (f.getType() == Long.class) f.set(result, ((Number) value).longValue()); else f.set(result, document.get(f.getName(), f.getType())); } return result; } catch (IllegalAccessException e) { e.printStackTrace(); return null; } catch (InstantiationException e) { e.printStackTrace(); return null; } } /** * 使id自增 * @param records * @param* @return */ privateboolean changeIds(Listrecords) { if (records == null || records.size() == 0) return false; Class clazz = records.get(0).getClass(); try { Field id = clazz.getDeclaredField("id"); id.setAccessible(true); int top = getTop(); for (Q record: records) { id.set(record,++top); } } catch (NoSuchFieldException e) { e.printStackTrace(); return false; } catch (IllegalAccessException e) { e.printStackTrace(); return false; } return true; } /** * 查找顶针 * @return */ private int getTop() { return ((Number) thisCollection().find().sort(new BasicDBObject("id",-1)).first().get("id")).intValue(); } }
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