java对mongoDB的基本操作 ，游标使用

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<br>package com.mongodb.text;   import java.net.UnknownHostException; import java.util.List;   import org.bson.types.ObjectId;   import com.mongodb.BasicDBObject; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.DBCursor; import com.mongodb.DBObject; import com.mongodb.Mongo; import com.mongodb.MongoException;   public class MongoDb { //1.建立一个Mongo的数据库连接对象 static Mongo connection = null; //2.创建相关数据库的连接 static DB db = null; public MongoDb(String dbName) throws UnknownHostException, MongoException{ connection = new Mongo("127.0.0.1:27017"); db = connection.getDB(dbName); } public static void main(String[] args) throws UnknownHostException, MongoException { //实例化 MongoDb mongoDb = new MongoDb("foobar"); /** * 1.创建一个名字叫javadb的数据库 */ //  mongoDb.createCollection("javadb"); /** * 2.为集合javadb添加一条数据 */ //  DBObject dbs = new BasicDBObject(); //  dbs.put("name", "uspcat.com"); //  dbs.put("age", 2); //  List<String> books = new ArrayList<String>(); //  books.add("EXTJS"); //  books.add("MONGODB"); //  dbs.put("books", books); //  mongoDb.insert(dbs, "javadb"); /** * 3.批量插入数据 */ //  List<DBObject> dbObjects = new ArrayList<DBObject>(); //  DBObject jim = new BasicDBObject("name","jim"); //  DBObject lisi = new BasicDBObject("name","lisi"); //  dbObjects.add(jim); //  dbObjects.add(lisi); //  mongoDb.insertBatch(dbObjects, "javadb"); /** * 4.根据ID删除数据 */ //  mongoDb.deleteById("502870dab9c368bf5b151a04", "javadb"); /** * 5.根据条件删除数据 */ //  DBObject lisi = new BasicDBObject(); //  lisi.put("name", "lisi"); //  int count = mongoDb.deleteByDbs(lisi, "javadb"); //  System.out.println("删除数据的条数是: "+count); /** * 6.更新操作,为集合增加email属性 */ //  DBObject update = new BasicDBObject(); //  update.put("$set", //  new BasicDBObject("eamil","uspcat@126.com")); //  mongoDb.update(new BasicDBObject(), //  update,false,true,"javadb"); /** * 7.查询出persons集合中的name和age */ //  DBObject keys = new BasicDBObject(); //  keys.put("_id", false); //  keys.put("name", true); //  keys.put("age", true); //  DBCursor cursor = mongoDb.find(null, keys, "persons"); //  while (cursor.hasNext()) { //  DBObject object = cursor.next(); //  System.out.println(object.get("name")); //  } /** * 7.查询出年龄大于26岁并且英语成绩小于80分 */ //  DBObject ref = new BasicDBObject(); //  ref.put("age", new BasicDBObject("$gte",26)); //  ref.put("e", new BasicDBObject("$lte",80)); //  DBCursor cursor = mongoDb.find(ref, null, "persons"); //  while (cursor.hasNext()) { //  DBObject object = cursor.next(); //  System.out.print(object.get("name")+"-->"); //  System.out.print(object.get("age")+"-->"); //  System.out.println(object.get("e")); //  } /** * 8.分页例子 */ DBCursor cursor = mongoDb.find(null, null, 0, 3, "persons"); while (cursor.hasNext()) { DBObject object = cursor.next(); System.out.print(object.get("name")+"-->"); System.out.print(object.get("age")+"-->"); System.out.println(object.get("e")); }   //关闭连接对象 connection.close(); } /** * 穿件一个数据库集合 * @param collName 集合名称 * @param db 数据库实例 */ public void createCollection(String collName){ DBObject dbs = new BasicDBObject(); db.createCollection("javadb", dbs); } /** * 为相应的集合添加数据 * @param dbs * @param collName */ public void insert(DBObject dbs,String collName){ //1.得到集合 DBCollection coll = db.getCollection(collName); //2.插入操作 coll.insert(dbs); } /** * 为集合批量插入数据 * @param dbses * @param collName */ public void insertBatch(List<DBObject> dbses,String collName){ //1.得到集合 DBCollection coll = db.getCollection(collName); //2.插入操作 coll.insert(dbses); } /** * 根据id删除数据 * @param id * @param collName * @return 返回影响的数据条数 */ public int deleteById(String id,String collName){ //1.得到集合 DBCollection coll = db.getCollection(collName); DBObject dbs = new BasicDBObject("_id", new ObjectId(id)); int count = coll.remove(dbs).getN(); return count; } /** * 根据条件删除数据 * @param id * @param collName * @return 返回影响的数据条数 */  public int deleteByDbs(DBObject dbs,String collName){ //1.得到集合 DBCollection coll = db.getCollection(collName); int count = coll.remove(dbs).getN(); return count; } /** * 更新数据 * @param find 查询器 * @param update 更新器 * @param upsert 更新或插入 * @param multi 是否批量更新 * @param collName 集合名称 * @return 返回影响的数据条数 */ public int update(DBObject find, DBObject update, boolean upsert, boolean multi, String collName){ //1.得到集合 DBCollection coll = db.getCollection(collName); int count = coll.update(find, update, upsert, multi).getN(); return count; } /** * 查询器(分页) * @param ref * @param keys * @param start * @param limit * @return */ public DBCursor find(DBObject ref, DBObject keys, int start, int limit, String collName){ DBCursor cur = find(ref, keys, collName); return cur.limit(limit).skip(start); } /** * 查询器(不分页) * @param ref * @param keys * @param start * @param limit * @param collName * @return */ public DBCursor find(DBObject ref, DBObject keys, String collName){ //1.得到集合 DBCollection coll = db.getCollection(collName); DBCursor cur = coll.find(ref, keys); return cur; }   }

 

 

<dependency>
        <groupId>org.mongodb</groupId>
        <artifactId>mongodb-driver</artifactId>
        <version>3.2.2</version>
    </dependency>

 

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import java.util.ArrayList;    import org.bson.Document; import java.util.List;  import com.mongodb.MongoClient;  import com.mongodb.MongoCredential;  import com.mongodb.ServerAddress; import com.mongodb.client.MongoCollection; import com.mongodb.client.MongoCursor; import com.mongodb.client.MongoDatabase;  import com.mongodb.client.FindIterable;    public class MongodbAppHbaseTest {      public static void main(String[] args){          try {              //连接到MongoDB服务 如果是远程连接可以替换“localhost”为服务器所在IP地址              //ServerAddress()两个参数分别为 服务器地址 和 端口              ServerAddress serverAddress = new ServerAddress("1.1.1.1",27017);              List<ServerAddress> addrs = new ArrayList<ServerAddress>();              addrs.add(serverAddress);                              //MongoCredential.createScramSha1Credential()三个参数分别为 用户名 数据库名称 密码              MongoCredential credential = MongoCredential.createScramSha1Credential("xxx", "xxx", "xxx".toCharArray());              List<MongoCredential> credentials = new ArrayList<MongoCredential>();              credentials.add(credential);                              //通过连接认证获取MongoDB连接              MongoClient mongoClient = new MongoClient(addrs, credentials);                              //连接到数据库              MongoDatabase mongoDatabase = mongoClient.getDatabase("name");              System.out.println("Connect to database successfully");                //            mongoDatabase.createCollection("xxx"); //            System.out.println("集合创建成功");                           MongoCollection<Document> collection = mongoDatabase.getCollection("xxx");             System.out.println("集合 xxx选择成功");                         //检索所有文档              /**             * 1. 获取迭代器FindIterable<Document>             * 2. 获取游标MongoCursor<Document>             * 3. 通过游标遍历检索出的文档集合             * */              FindIterable<Document> findIterable = collection.find();              MongoCursor<Document> mongoCursor = findIterable.iterator();             int i=0;             while(mongoCursor.hasNext()){                 System.out.println(mongoCursor.next());                 i++;             }              System.out.println("i="+i);                       } catch (Exception e) {              System.err.println( e.getClass().getName() + ": " + e.getMessage() );          }      }  }

 

 

 

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上篇博客介绍了java操作mongoDB进行对文件的处理。现在来介绍一下对文档的处理。和对文件的处理一样，也是通过java驱动中提供的几个类相互作用完成的。这几个类分别是：         DBCollection类：指定数据库中指定集合的实例，提供了增删改查等一系列操作。在关系型数据库中，对数据的增删改查操作是建立在表的基础上的，在mongodb中是建立在集合的基础上进行的。         DBObject接口：DBObject是键值的映射，因此，可以将DBObject的实现类作为查询的返回结果，也可以作为查询条件         DBCursor：游标，返回结果的集合。       下面是部分实例：     Mongo mongo = new Mongo(); DB db = mongo.getDB("myMongoDB"); DBCollection course = db.getCollection("course");//对myMongoDB数据库中course集合进行操作       //添加操作 //下面分别是创建文档的几种方式：1. .append()  2. .put()   3. 通过map   4. 将json转换成DBObject对象 DBObject english = new BasicDBObject().append("name","english").append("score", 5).append("id",1); course.insert(english);           DBObject math = new BasicDBObject(); math.put("id", 2); math.put("name", "math"); math.put("score", 10); course.insert(math);           Map<String,Object> map = new HashMap<String,Object>(); map.put("name","physics" ); map.put("score", 10); map.put("id", 3); DBObject physics= new BasicDBObject(map); course.insert(physics);           String json ="{'name':'chemistry','score':10,'id':4}"; DBObject chemistry =(DBObject)JSON.parse(json); course.insert(chemistry);           List<DBObject> courseList = new ArrayList<DBObject>(); DBObject chinese = new BasicDBObject().append("name","chinese").append("score", 10).append("id", 5); DBObject history = new BasicDBObject().append("name", "history").append("score", 10).append("id", 6); courseList.add(chinese); courseList.add(history); course.insert(courseList);           //添加内嵌文档 String json2 =" {'name':'english','score':10,'teacher':[{'name':'柳松','id':'1'},{'name':'柳松松','id':2}]}"; DBObject english2= (DBObject)JSON.parse(json); course.insert(english2);           List<DBObject> list = new ArrayList<DBObject>(); list.add(new BasicDBObject("name","柳松").append("id",1)); list.add(new BasicDBObject("name","柳松松").append("id",2)); DBObject english3= new BasicDBObject().append("name","english").append("score",10).append("teacher",list);                     //查询 //查询所有、查询一个文档、条件查询 DBCursor cur = course.find(); while(cur.hasNext()){       DBObject document = cur.next();       System.out.println(document.get("name"));   }           DBObject document = course.findOne(); String name=(String)document.get("name"); System.out.println(name);                     //查询学分=5的 DBObject query1 = new BasicDBObject("score",5); DBObject query2 = new BasicDBObject("score",new BasicDBObject("$gte",5)); DBCursor cur2 = course.find(query2); //条件表达式：$ge(>)  $get(>=)  $lt(<)  $lte(<=)  $ne(<>)  $in  $nin  $all $exists $or  $nor $where $type等等             //查找并修改     DBObject newDocument = course.findAndModify(new BasicDBObject("score",5), new BasicDBObject("score",15));   //更新操作      //q：更新条件  o:更新后的对象 course.update(new BasicDBObject("score",10), new BasicDBObject("test",15)); course.update(new BasicDBObject("score",15), new BasicDBObject("$set",new BasicDBObject("isRequired",true))); //两个的区别是，第一个更新是将{"test":15}这个文档替换原来的文档， //第二个更新添加了条件表达式$set，是在原来文档的基础上添加"isRequired"这个键 //条件表达式：$set  $unset  $push  $inc  $push $push  $addToSet  $pull $pullAll  $pop等等   //当_id相同时，执行save方法相当于更新操作 course.save(new BasicDBObject("name","math").append("_id", 1)); course.save(new BasicDBObject("name","数学").append("_id", 1));                       //删除符合条件的文档 course.remove(new BasicDBObject("score",15));           //删除集合及所有文档 course.drop();         上面只是介绍了一些简单的操作，具体复杂的查询更新可以根据需求再去查找文档资料。其实，不管操作简单还是复杂，其核心都是对DBObject和DBCollection的操作，主要掌握DBObject如何构造键值对，以及一些条件表达式。