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);
}
}