mongodb是非关系型数据库,对于数据的操作跟关系型数据库有很大的区别,非通用sql,
那么在java中是如何进行数据读取呢?详情如下:
(聚合函数部分见下期<mongodb在java中常见的查询(二)>)
ps: mongodb不适合做业务系统,,只适合做缓存为主的key-value读取形式存放的 或者是静态缓存数据,或者 不太重要的数据(mongodb不支持事务处理)
和java的契合度不好,一样会写大量繁琐的代码,还不如两三行sql来得痛快,不过话说回来如果只是用key来取值确实方便.,..
package com.9203.mongo; import java.net.UnknownHostException; import java.util.ArrayList; import java.util.List; import java.util.Set; import java.util.regex.Pattern; import org.junit.Test; import com.mongodb.AggregationOutput; import com.mongodb.BasicDBList; import com.mongodb.BasicDBObject; import com.mongodb.BasicDBObjectBuilder; import com.mongodb.DB; import com.mongodb.DBCollection; import com.mongodb.DBCursor; import com.mongodb.DBObject; import com.mongodb.MapReduceCommand; import com.mongodb.MapReduceOutput; import com.mongodb.Mongo; import com.mongodb.QueryBuilder; import com.mongodb.WriteConcern; public class TestCase { @Test /** * 获取所有数据库实例 */ public void testGetDBS() { List<String> dbnames = MongoUtil.getMong().getDatabaseNames(); for (String dbname : dbnames) { System.out.println("dbname:" + dbname); } } @Test /** * 删除数据库 */ public void dropDatabase() { MongoUtil.getMong().dropDatabase("my_new_db"); } @Test /** * 查询所有表名 */ public void getAllCollections() { Set<String> colls = MongoUtil.getDB().getCollectionNames(); for (String s : colls) { System.out.println(s); } } @Test public void dropCollection() { MongoUtil.getColl("jellonwu").drop(); } /** * 添加一条记录 */ @Test public void addData() { DBCollection coll = MongoUtil.getColl("wujintao"); BasicDBObject doc = new BasicDBObject(); doc.put("name", "MongoDB"); doc.put("type", "database"); doc.put("count", 1); BasicDBObject info = new BasicDBObject(); info.put("x", 203); info.put("y", 102); doc.put("info", info); coll.insert(doc); // 设定write concern，以便操作失败时得到提示 coll.setWriteConcern(WriteConcern.SAFE); } @Test /** * 创建索引 */ public void createIndex() { MongoUtil.getColl("wujintao").createIndex(new BasicDBObject("i", 1)); } @Test /** * 获取索引信息 */ public void getIndexInfo() { List<DBObject> list = MongoUtil.getColl("hems_online").getIndexInfo(); for (DBObject o : list) { System.out.println(o); } } @Test /** * 添加多条记录 */ public void addMultiData() { for (int i = 0; i < 100; i++) { MongoUtil.getColl("wujintao").insert( new BasicDBObject().append("i", i)); } List<DBObject> docs = new ArrayList<DBObject>(); for (int i = 0; i < 50; i++) { docs.add(new BasicDBObject().append("i", i)); } MongoUtil.getColl("wujintao").insert(docs); // 设定write concern，以便操作失败时得到提示 MongoUtil.getColl("wujintao").setWriteConcern(WriteConcern.SAFE); } @Test /** * 查找第一条记录 */ public void findOne() { DBObject myDoc = MongoUtil.getColl("wujintao").findOne(); System.out.println(myDoc); } @Test /** * 获取表中所有记录条数 */ public void count() { System.out.println(MongoUtil.getColl("wujintao").getCount()); System.out.println(MongoUtil.getColl("wujintao").count()); } @Test /** * 获取查询结果集的记录数 */ public void getCount() { DBObject query = new BasicDBObject("name", "a"); long count = MongoUtil.getColl("wujintao").count(query); System.out.println(count); } @Test /** * 查询所有结果 */ public void getAllDocuments() { DBCursor cursor = MongoUtil.getColl("wujintao").find(); try { while (cursor.hasNext()) { System.out.println(cursor.next()); } } finally { cursor.close(); } } @Test /** * 按照一个条件查询 */ public void queryByConditionOne() { BasicDBObject query = new BasicDBObject(); query.put("name", "MongoDB"); DBCursor cursor = MongoUtil.getColl("wujintao").find(query); try { while (cursor.hasNext()) { System.out.println(cursor.next()); } } finally { cursor.close(); } } @Test /** * AND多条件查询,区间查询 */ public void queryMulti() { BasicDBObject query = new BasicDBObject(); // 查询j不等于3,k大于10的结果集 query.put("j", new BasicDBObject("$ne", 3)); query.put("k", new BasicDBObject("$gt", 10)); DBCursor cursor = MongoUtil.getColl("wujintao").find(query); try { while (cursor.hasNext()) { System.out.println(cursor.next()); } } finally { cursor.close(); } } @Test /** * 区间查询 * select * from table where i >50 */ public void queryMulti2() { BasicDBObject query = new BasicDBObject(); query = new BasicDBObject(); query.put("i", new BasicDBObject("$gt", 50)); // e.g. find all where i > DBCursor cursor = MongoUtil.getColl("wujintao").find(query); try { while (cursor.hasNext()) { System.out.println(cursor.next()); } } finally { cursor.close(); } } @Test /** * 区间查询 * select * from table where 20 < i <= 30 //比较符 //"$gt"： 大于 //"$gte"：大于等于 //"$lt"： 小于 //"$lte"：小于等于 //"$in"： 包含 */ public void queryMulti3() { BasicDBObject query = new BasicDBObject(); query = new BasicDBObject(); query.put("i", new BasicDBObject("$gt", 20).append("$lte", 30)); DBCursor cursor = MongoUtil.getColl("wujintao").find(query); try { while (cursor.hasNext()) { System.out.println(cursor.next()); } } finally { cursor.close(); } } /** * 组合in和and select * from test_Table where (a=5 or b=6) and (c=5 or d = 6) */ public void queryMulti4() { BasicDBObject query11 = new BasicDBObject(); query11.put("a", 1); BasicDBObject query12 = new BasicDBObject(); query12.put("b", 2); List<BasicDBObject> orQueryList1 = new ArrayList<BasicDBObject>(); orQueryList1.add(query11); orQueryList1.add(query12); BasicDBObject orQuery1 = new BasicDBObject("$or", orQueryList1); BasicDBObject query21 = new BasicDBObject(); query21.put("c", 5); BasicDBObject query22 = new BasicDBObject(); query22.put("d", 6); List<BasicDBObject> orQueryList2 = new ArrayList<BasicDBObject>(); orQueryList2.add(query21); orQueryList2.add(query22); BasicDBObject orQuery2 = new BasicDBObject("$or", orQueryList2); List<BasicDBObject> orQueryCombinationList = new ArrayList<BasicDBObject>(); orQueryCombinationList.add(orQuery1); orQueryCombinationList.add(orQuery2); BasicDBObject finalQuery = new BasicDBObject("$and", orQueryCombinationList); DBCursor cursor = MongoUtil.getColl("wujintao").find(finalQuery); } @Test /** * IN查询 * if i need to query name in (a,b); just use { name : { $in : ['a', 'b'] } } * select * from things where name='a' or name='b' * @param coll */ public void queryIn() { BasicDBList values = new BasicDBList(); values.add("a"); values.add("b"); BasicDBObject in = new BasicDBObject("$in", values); DBCursor cursor = MongoUtil.getColl("wujintao").find( new BasicDBObject("name", in)); try { while (cursor.hasNext()) { System.out.println(cursor.next()); } } finally { cursor.close(); } } @Test /** * 或查询 * select * from table where name = '12' or title = 'p' * @param coll */ public void queryOr() { QueryBuilder query = new QueryBuilder(); query.or(new BasicDBObject("name", 12), new BasicDBObject("title", "p")); DBCursor cursor = MongoUtil.getColl("wujintao").find(query.get()).addSpecial("$returnKey", ""); try { while (cursor.hasNext()) { System.out.println(cursor.next()); } } finally { cursor.close(); } } @Test public void customQueryField() throws UnknownHostException{ Mongo mongo = new Mongo("localhost", 27017); DB db = mongo.getDB("zhongsou_ad"); BasicDBObjectBuilder bulder = new BasicDBObjectBuilder(); bulder.add("times",1); bulder.add("aid",1); DBCursor cusor = db.getCollection("ad_union_ad_c_1").find(new BasicDBObject(),bulder.get()); for (DBObject dbObject : cusor) { System.out.println(dbObject); } } @Test public void mapReduce() throws UnknownHostException{ Mongo mongo = new Mongo("localhost", 27017); DB db = mongo.getDB("zhongsou_ad"); try { DBCollection books = db.getCollection("books"); BasicDBObject book = new BasicDBObject(); book.put("name", "Understanding JAVA"); book.put("pages", 100); books.insert(book); book = new BasicDBObject(); book.put("name", "Understanding JSON"); book.put("pages", 200); books.insert(book); book = new BasicDBObject(); book.put("name", "Understanding XML"); book.put("pages", 300); books.insert(book); book = new BasicDBObject(); book.put("name", "Understanding Web Services"); book.put("pages", 400); books.insert(book); book = new BasicDBObject(); book.put("name", "Understanding Axis2"); book.put("pages", 150); books.insert(book); String map = "function() { "+ "var category; " + "if ( this.pages >= 250 ) "+ "category = 'Big Books'; " + "else " + "category = 'Small Books'; "+ "emit(category, {name: this.name});}"; String reduce = "function(key, values) { " + "var sum = 0; " + "values.forEach(function(doc) { " + "sum += 1; "+ "}); " + "return {books: sum};} "; MapReduceCommand cmd = new MapReduceCommand(books, map, reduce, null, MapReduceCommand.OutputType.INLINE, null); MapReduceOutput out = books.mapReduce(cmd); for (DBObject o : out.results()) { System.out.println(o.toString()); } } catch (Exception e) { e.printStackTrace(); } } @Test public void GroupByManyField() throws UnknownHostException{ //此方法没有运行成功 Mongo mongo = new Mongo("localhost", 27017); DB db = mongo.getDB("libary"); DBCollection books = db.getCollection("books"); BasicDBObject groupKeys = new BasicDBObject(); groupKeys.put("total", new BasicDBObject("$sum","pages")); BasicDBObject condition = new BasicDBObject(); condition.append("pages", new BasicDBObject().put("$gt", 0)); String reduce = "function(key, values) { " + "var sum = 0; " + "values.forEach(function(doc) { " + "sum += 1; "+ "}); " + "return {books: sum};} "; /** BasicDBList basicDBList = (BasicDBList)db.getCollection("mongodb中集合编码或者编码") .group(DBObject key, --分组字段，即group by的字段 DBObject cond, --查询中where条件 DBObject initial, --初始化各字段的值 String reduce, --每个分组都需要执行的Function String finial --终结Funciton对结果进行最终的处理 */ DBObject obj = books.group(groupKeys, condition, new BasicDBObject(), reduce); System.out.println(obj); AggregationOutput ouput = books.aggregate(new BasicDBObject("$group",groupKeys)); System.out.println(ouput.getCommandResult()); System.out.println(books.find(new BasicDBObject("$group",groupKeys))); } @Test /** * 分页查询 */ public void pageQuery() { DBCursor cursor = MongoUtil.getColl("wujintao").find().skip(0) .limit(10); while (cursor.hasNext()) { System.out.println(cursor.next()); } } /** * 模糊查询 */ public void likeQuery() { Pattern john = Pattern.compile("joh?n"); BasicDBObject query = new BasicDBObject("name", john); // finds all people with "name" matching /joh?n/i DBCursor cursor = MongoUtil.getColl("wujintao").find(query); } @Test /** * 条件删除 */ public void delete() { BasicDBObject query = new BasicDBObject(); query.put("name", "xxx"); // 找到并且删除，并返回删除的对象 DBObject removeObj = MongoUtil.getColl("wujintao").findAndRemove(query); System.out.println(removeObj); } @Test /** * 更新 */ public void update() { BasicDBObject query = new BasicDBObject(); query.put("name", "liu"); DBObject stuFound = MongoUtil.getColl("wujintao").findOne(query); stuFound.put("name", stuFound.get("name") + "update_1"); MongoUtil.getColl("wujintao").update(query, stuFound); } }