我正在尝试使用MongoDB中的某些条件(使用Java驱动程序).这就是我正在做的事情:
Pattern regex = Pattern.compile("title");
DBCollection coll = MongoDBUtil.getDB().getCollection("post_details");
BasicDBObject query = new BasicDBObject();
query.put("category_title", "myCategory");
query.append("post_title", regex);
query.append("post_description", regex);
DBCursor cur = coll.find(query);
while(cur.hasNext()) {
System.out.println(cur.next().get("post_id"));
}
我想$or在这些条件下使用操作数,但我猜默认是"和",我不知道如何更改它.在上面的代码中,如果其中一个条件返回null,结果也是null如此.
我现在试图找出这个代码大约两个小时,例如在下面的类中这些字段代表什么？
import java.util.Date;
import javax.persistence.metamodel.ListAttribute;
import javax.persistence.metamodel.SingularAttribute;
import javax.persistence.metamodel.StaticMetamodel;
import java.util.UUID;
@StaticMetamodel(Address.class)
public class Address_ extends {
public static volatile SingularAttribute<Address, Long> id;
public static volatile SingularAttribute<Address, UUID> personId;
public static volatile SingularAttribute<Address, Person> person;
}
这Address.class是一个java类,它具有以下定义:
@Entity
@Table(name = "address", schema = "public")
public class Address{
private Long id;
private Person person;
private UUID personId;
//....
}
请问您能解释一下使用的注释@StaticMetamodel和@SingularAttribute注释吗？这可能很简单,但我无法理解.
我有以下枚举:
package ir.raysis.tcs.rule.days;
public enum Days {
SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
THURSDAY, FRIDAY, SATURDAY;
}
我尝试将其映射Set<Days>为如下日期:
@ElementCollection(targetClass = Days.class)
@JoinTable(name = "days",joinColumns = @JoinColumn(name = "rule_id"))
@Column(name ="daysOfWeek", nullable = false) @Enumerated(EnumType.STRING)
private Set<Days> days = new HashSet<>();
但是,它会引发以下异常:
Initial SessionFactory creation failed.org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: rule, for columns: [org.hibernate.mapping.Column(days)]
Apr 14, 2013 4:15:17 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/ptcs] threw exception [javax.servlet.ServletException: java.lang.ExceptionInInitializerError] with root …我正在使用eclipse开发一个Web应用程序,当我试图在eclipse中运行我的应用程序时,我遇到了一个问题.
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007f41e4e610b0, pid=3463, tid=139924549404416
#
# JRE version: 7.0_09-b05
# Java VM: Java HotSpot(TM) 64-Bit Server VM (23.5-b02 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# C [libwebkitgtk-1.0.so.0+0x11670b0] void WTF::freeOwnedGPtr<_GdkEvent>(_GdkEvent*)+0x15e00
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# If you would like to …基本上这是我的问题: 如何用"喜欢"查询MongoDB？
但是我想这里的所有答案都适用于你使用mongodb shell命令行的时候,那么db.users.find({"name": /.*m.*/})当我们使用java时,它们是等价的.
这是我想要做的
Run Code Online (Sandbox Code Playgroud)DBCollection coll = MongoDBUtil.getDB().getCollection("post_details"); BasicDBObject query = new BasicDBObject(); query.put("price", new BasicDBObject("$gt", 5).append("$lt", 8));
/*what should i write instead of this line*/
query.put("title", "/.*m.*/");
DBCursor cur = coll.find(query);
我试图从bash脚本运行此命令:
mongo 192.168.10.20:27000 --eval "use admin && db.shutdownServer() && quit()"
但我得到这个错误:
[rs.initiate() && use admin && db.shutdownServer() && quit()] doesn't exist
如何在不使用js文件的情况下执行此操作？
我已经研究了这篇关于蓝/绿部署的文章,然后一些谷歌搜索引入了我关于Canary Release的这篇文章.我有这种含糊之处:数据库会发生什么？我们应该如何使它们同步？我有两种可能的情况:
可能存在第三种情况,对主蓝/绿部署中的数据库实施蓝/绿部署.
您认为更好的解决方案是什么？为什么？你建议任何其他练习或众所周知的模式吗？
谢谢
我已经转换为字节数组但我不断收到此错误:
ERROR 2015-02-25 11:12:30,517 [[ESR].HTTP_Request_Listener.worker.01] org.mule.exception.DefaultMessagingExceptionStrategy:
********************************************************************************
Message : Response code 400 mapped as failure. Message payload is of type: BufferInputStream
Code : MULE_ERROR--2
--------------------------------------------------------------------------------
Exception stack is:
1. Response code 400 mapped as failure. Message payload is of type: BufferInputStream (org.mule.module.http.internal.request.ResponseValidatorException)
org.mule.module.http.internal.request.SuccessStatusCodeValidator:37 (http://www.mulesoft.org/docs/site/current3/apidocs/org/mule/module/http/internal/request/ResponseValidatorException.html)
--------------------------------------------------------------------------------
Root Exception stack trace:
org.mule.module.http.internal.request.ResponseValidatorException: Response code 400 mapped as failure. Message payload is of type: BufferInputStream
at org.mule.module.http.internal.request.SuccessStatusCodeValidator.validate(SuccessStatusCodeValidator.java:37)
at org.mule.module.http.internal.request.DefaultHttpRequester.innerProcess(DefaultHttpRequester.java:202)
at org.mule.module.http.internal.request.DefaultHttpRequester.process(DefaultHttpRequester.java:166)
+ 3 more (set debug level logging or '-Dmule.verbose.exceptions=true' for everything)
******************************************************************************** …有什么方法可以从 Java 应用程序更改 postgreSQL 当前数据库？或者有什么等价物\connect report吗？我知道我可以通过更改 JDBC 连接字符串来做到这一点，但有没有更好的选择？
这就是我在做的事情:
List scores = Stream.concat(oldEntries.stream(), newEntries.stream())
.sorted()
.distinct()
.limit(maxSize)
.collect(Collectors.toList());
我期待一个没有任何重复的排序列表,但有时候列表中有重复.
我已经覆盖了hashCode和equals方法,我还观察到这些方法每次都返回正确的值.任何人都可以看到我的流有什么问题吗？
这是我的equals()和hashCode()它们由IDEA自动生成:
..
private int userId;
private int levelId;
private int score;
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Score score = (Score) o;
if (userId != score.userId) return false;
return levelId == score.levelId;
}
@Override
public int hashCode() {
int result = userId;
result = 31 * result + levelId;
return result;
} …