搜尋

首頁  >  文章  >  Java  >  java實作對mongodb，泛型封裝增刪查改、條件查詢等操作

java實作對mongodb，泛型封裝增刪查改、條件查詢等操作

php是最好的语言
php是最好的语言原創
2018-07-30 13:47:343535瀏覽

本文實作一個通用泛型封裝實作類，需要給定一個集合對象，類似mysql中與java對應的表；思想就是把給定的對象解析出所有非空字段，保存到一個BasicDBObject中，這裡一定要保證java物件與mongodb中的文件欄位名字一樣，因為程式碼為了實現通用，就是預設以java物件的欄位為BasicDBObject的查詢欄位。

核心程式碼1：這是將java物件轉換為查詢條件。 

/**
     * 通过反射获取非空字段信息
     * @param record
     * @param <Q>
     * @return
     */
    private <Q> 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;
    }

核心程式碼2：這是將查詢到的文檔轉換為java對象，這裡也是預設java對象的字段和資料庫文檔字段一樣，也是利用java的反射動態獲取用戶自訂對象的所有字段，然後進行賦值，我在賦值過程中單獨判斷了int和long型，因為插入mongodb的時候一般是以double存的，這樣就會造成轉型錯誤。 

/**
     * 将结果转化为自定义对象
     * @param document
     * @param target
     * @param <Q>
     * @return
     */
    private <Q> Q parseToObject(Document document, Class<Q> 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;
        }
    }

呼叫方法：先轉換查詢參數，查詢的時候是以id來判斷正序倒序，所以預設資料庫中一定要有id的識別欄位。 

public <Q> List<Q> queryByCondition(BaseQuery<Q> query,boolean up) {
        Q record = query.getQuery();
        BasicDBObject cond = getCondition(record);
        FindIterable<Document> 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<Document> iterator = findIterable.iterator();
        List<Q> result = new ArrayList<>();
        while (iterator.hasNext()) {
            Document document = iterator.next();
            result.add((Q) parseToObject(document, record.getClass()));
        }
        iterator.close();
        return result;
    }

這裡傳入的BaseQuery如下：裡面的query就是個需要查詢的java對象，start&rows是為了用來分頁的。這裡是用到了lombok的插件，這樣簡化很多的gettter&setter等程式碼。 

@Setter
@Getter
@NoArgsConstructor
@AllArgsConstructor
@Data
@Accessors(chain = true)
public class BaseQuery<Q> {
    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();
        }
    }
}

測試條件查詢方法：這裡用到的實體如下：

@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<User_info> query = new BaseQuery<>();
        query.setQuery(record);

        BaseMongoDao dao = new BaseMongoDao("test");
        List<User_info> result = dao.queryByCondition(query, true);
        for (User_info user : result) {
            System.out.println(user);
        }
    }

#因為這裡用到的查詢條件為空，所有會符合資料庫的所有項目：

java實作對mongodb，泛型封裝增刪查改、條件查詢等操作

現在測試設定權限為1的資料：

public static void main(String[] args) {
        User_info record = new User_info();
        record.setRole(1);
        BaseQuery<User_info> query = new BaseQuery<>();
        query.setQuery(record);

        BaseMongoDao dao = new BaseMongoDao("test");
        List<User_info> result = dao.queryByCondition(query, true);
        for (User_info user : result) {
            System.out.println(user);
        }
    }

輸出：

java實作對mongodb，泛型封裝增刪查改、條件查詢等操作

這個條件查詢方法就是一個例子，其他的刪除，增加，修改都是這個原理，下面帶有：

1.public List queryByCondition(BaseQuery query,boolean up)

2.public Integer queryCoditionCount(BaseQuery query)

3.public boolean insertOne(Q record)

4.public booleanOne(Q record)

4.public boolean insertList(List records)

5.public boolean deleteById(Integer id)

6.public  boolean deleteByIds(List ids)

7.public void updateById(Q record)

放上所有程式碼：

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 <Q> List<Q> queryByCondition(BaseQuery<Q> query,boolean up) {
        Q record = query.getQuery();
        BasicDBObject cond = getCondition(record);
        FindIterable<Document> 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<Document> iterator = findIterable.iterator();
        List<Q> result = new ArrayList<>();
        while (iterator.hasNext()) {
            Document document = iterator.next();
            result.add((Q) parseToObject(document, record.getClass()));
        }
        iterator.close();
        return result;
    }

    public  Integer queryCoditionCount(BaseQuery query) {
        Q record = query.getQuery();
        BasicDBObject cond = getCondition(record);
        return (int) thisCollection().countDocuments(cond);
    }

    public  boolean 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;
        }
    }

    public  boolean insertList(List records) {
        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 
     */
    public  void 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 <Q>
     * @return
     */
    private <Q> 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 <Q>
     * @return
     */
    private <Q> Q parseToObject(Document document, Class<Q> 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
     */
    private  boolean changeIds(List records) {
        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();
    }

}

 相關文章：##java運算mongodb：基本的增刪改查

MongoDB（六）java操作mongodb增刪改查

相關影片：

##黑馬雲課堂mongodb實操影片教學

以上是java實作對mongodb，泛型封裝增刪查改、條件查詢等操作的詳細內容。更多資訊請關注PHP中文網其他相關文章！

陳述：
本文內容由網友自願投稿，版權歸原作者所有。本站不承擔相應的法律責任。如發現涉嫌抄襲或侵權的內容，請聯絡admin@php.cn
上一篇：簡單介紹Java循環結構：while循環和do while循環下一篇：簡單介紹Java循環結構：while循環和do while循環

相關文章

看更多