spring3 2 min read 6 comments

Spring expression language (SpEL) allow developer uses expression to execute method and inject the method returned value into property, or so called “SpEL method invocation“. Spring EL in Annotation See how to do Spring EL method invocation with @Value annotation. package com.mkyong.core; import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; @Component("customerBean") public class Customer { @Value("#{‘mkyong’.toUpperCase()}") private String name; […]

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spring3 2 min read 3 comments

Spring expression language (SpEL) supports many functionality, and you can test those expression features with this special “ExpressionParser” interface. Here’s two code snippets, show the basic usage of using Spring EL. SpEL to evaluate the literal string expression. ExpressionParser parser = new SpelExpressionParser(); Expression exp = parser.parseExpression("’put spel expression here’"); String msg = exp.getValue(String.class); SpEL […]

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spring 2 min read 18 comments

In Spring, @Qualifier means, which bean is qualify to autowired on a field. See following scenario : Autowiring Example See below example, it will autowired a “person” bean into customer’s person property. package com.mkyong.common; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; public class Customer { @Autowired private Person person; //… } But, two similar beans “com.mkyong.common.Person” are declared […]

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spring 2 min read 5 comments

In Spring, “Autowiring by AutoDetect“, means chooses “autowire by constructor” if default constructor (argument with any data type), otherwise uses “autowire by type“. See an example of Spring “auto wiring by autodetect”. Auto wiring the “kungfu” bean into “panda”, via constructor or type (base on the implementation of panda bean). <bean id="panda" class="com.mkyong.common.Panda" autowire="autodetect" /> […]

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spring 2 min read 7 comments

Uses Spring to dependency inject a bean via constructor. 1. IOutputGenerator An interface and implementation class of it. package com.mkyong.output; public interface IOutputGenerator { public void generateOutput(); } package com.mkyong.output.impl; import com.mkyong.output.IOutputGenerator; public class JsonOutputGenerator implements IOutputGenerator { public void generateOutput(){ System.out.println("This is Json Output Generator"); } } 2. Helper class A helper class, later […]

Read more Spring DI via constructor
spring 2 min read 3 comments

A simple Spring example to show you how to dependency inject a bean via setter method, the most common used DI method. 1. IOutputGenerator An interface and implemntation class of it. package com.mkyong.output; public interface IOutputGenerator { public void generateOutput(); } package com.mkyong.output.impl; import com.mkyong.output.IOutputGenerator; public class CsvOutputGenerator implements IOutputGenerator { public void generateOutput() { […]

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mongodb 3 min read 26 comments

This guide shows you how to install MongoDB on Ubuntu. Ubuntu 12.10 MongoDB 2.2.3 1. Add 10gen package to source.list.d Ubuntu 12 comes with a “mongo” package, but not the latest version. $ sudo apt-cache search mongodb mongodb mongodb-clients mongodb-dev mongodb-server It’s recommended to add 10gen package to /etc/apt/sources.list.d, as it contains the latest stable […]

Read more How to install mongoDB on Ubuntu
mongodb 1 min read 4 comments

In Spring data for MongoDB, you can use remove() and findAndRemove() to delete documents from MongoDB. remove() – delete single or multiple documents. findAndRemove() – delete single document, and returns the deleted document. Common Mistake Don’t use findAndRemove() to perform a batch delete (remove multiple documents), only the first document that matches the query will […]

Read more Spring Data MongoDB : Delete document
mongodb 4 min read 10 comments

In Spring data MongoDB, you can use save(), insert() to save a or a list of objects into mongoDB database. User user = new User("…"); //save user object into "user" collection / table //class name will be used as collection name mongoOperation.save(user); //save user object into "tableA" collection mongoOperation.save(user,"tableA"); //insert user object into "user" collection […]

Read more Spring Data MongoDB : Insert document
mongodb 5 min read 52 comments

In this tutorial, we show you how to use “SpringData for MongoDB” framework, to perform CRUD operations in MongoDB, via Spring’s annotation and XML schema. Updated on 1/04/2013 Article is updated to use latest SpringData v 1.2.0.RELEASE, it was v1.0.0.M2. Tools and technologies used : Spring Data MongoDB – 1.2.0.RELEASE Spring Core – 3.2.2.RELEASE Java […]

Read more Spring Data MongoDB hello world example
mongodb 1 min read 18 comments

MongoDB comes with “com.mongodb.util.JSON” class to convert JSON data directly to a DBObject. For example, data represent in JSON format : { ‘name’ : ‘mkyong’, ‘age’ : 30 } To convert it to DBObject, you can code like this : DBObject dbObject = (DBObject) JSON.parse("{‘name’:’mkyong’, ‘age’:30}"); Example See a full example to convert above JSON […]

Read more Java MongoDB : Convert JSON data to DBObject
mongodb 1 min read 5 comments

In Java, you can use db.getCollection(“your collection name”) to get a single collection to use. DBCollection collection = db.getCollection("yourCollection"); If you do not know the collection name, use db.getCollectionNames() to get the entire list of collection names from a selected database. DB db = mongo.getDB("yourdb"); Set<String> collections = db.getCollectionNames(); for (String collectionName : collections) { […]

Read more Java MongoDB : Get collection from database
mongodb 1 min read 6 comments

When Staring the mongoDB server, it hits below errors, and the mongoDB server is unable to start. ************** old lock file: \data\db\mongod.lock. probably means unclean shutdown recommend removing file and running –repair see: http://dochub.mongodb.org/core/repair for more information ************* Mon May 09 12:37:43 [initandlisten] exception in initAndListen std::exception: old lock file, terminating Mon May 09 12:37:43 […]

Read more old lock file: \data\db\mongod.lock, probably means unclean shutdown
java 1 min read 2 comments

In Java, we can use String.valueOf() to convert a char array to a String. JavaSample1.java package com.mkyong.markdown; public class JavaSample1 { public static void main(String[] args) { char[] charArrays = new char[]{‘1’, ‘2’, ‘3’, ‘A’, ‘B’, ‘C’}; String str = new String(charArrays); System.out.println(str); // 123ABC String str2 = String.valueOf(charArrays); System.out.println(str2); // 123ABC } } Output […]

Read more Java – How to convert Char[] to String
java 2 min read 8 comments

In Java, you can use String.toCharArray() to convert a String into a char array. StringToCharArray.java package com.mkyong.utils; public class StringToCharArray { public static void main(String[] args) { String password = "password123"; char[] passwordInCharArray = password.toCharArray(); for (char temp : passwordInCharArray) { System.out.println(temp); } } } Output p a s s w o r d 1 […]

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mongodb 1 min read 4 comments

This Article is outdated! Please refer to this latest guide to install MongoDB as Windows Service. A guide to show you how to installed MongoDB on Windows. 1. mongod –help Get to know all the Windows service related commands by typing “mongod –help“. C:\MongoDB\bin>mongod –help Windows Service Control Manager options: –install install mongodb service –remove […]

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hibernate 3 min read 9 comments

Hibernate component represents as a group of values or properties, not entity (table). See following tutorial to understand how component works in Hibernate. 1. Customer Table See below customer table. Customer table, SQL script in MySQL database. CREATE TABLE `customer` ( `CUST_ID` int(10) unsigned NOT NULL AUTO_INCREMENT, `CUST_NAME` varchar(10) NOT NULL, `AGE` int(10) unsigned NOT […]

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hibernate 7 min read 146 comments

In this tutorial, we show you how to use Hibernate to implements “many-to-many table relationship, with extra column in the join table“. Note For many to many relationship with NO extra column in the join table, please refer to this @many-to-many tutorial 1. Many-to-many table + extra columns in join table The STOCK and CATEGORY […]

Read more Hibernate – Many-to-Many example – join table + extra column (Annotation)
hibernate 4 min read 42 comments

In this tutorial, it will reuse the entire infrastructure of the previous “Hibernate many to many example – XML mapping” tutorial, enhance it to support Hibernare / JPA annotation. Note For many to many with extra columns in join table, please refer to this tutorial. Project Structure Review the new project structure of this tutorial. […]

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hibernate 1 min read 3 comments

Problem A table named “category” in MySQL database, contains a “DESC” keyword as column name. CREATE TABLE `category` ( `CATEGORY_ID` int(10) unsigned NOT NULL AUTO_INCREMENT, `NAME` varchar(10) NOT NULL, `DESC` varchar(255) NOT NULL, PRIMARY KEY (`CATEGORY_ID`) USING BTREE ); Hibernate XML mapping file <hibernate-mapping> <class name="com.mkyong.stock.Category" table="category" catalog="mkyongdb"> … <property name="desc" type="string"> <column name="DESC" not-null="true" […]

Read more Hibernate – Unable to insert if column named is keyword, such as DESC
hibernate 4 min read 50 comments

In this tutorial, it will reuse the entire infrastructure of the previous “Hibernate one to many relationship example – XML mapping” tutorial, enhance it to support Hibernate / JPA annotation. Project Structure Review the new project structure of this tutorial. Note Since Hibernate 3.6, annotation codes are merged into the Hibernate core module, so, the […]

Read more Hibernate – One-to-Many example (Annotation)
hibernate 3 min read 29 comments

In this tutorial, it will reuse the entire infrastructure of the previous “Hibernate one to one relationship example – XML mapping” tutorial, enhance it to support Hibernate / JPA annotation. Project Structure See the final project structure of this tutorial. Note Since Hibernate 3.6, annotation codes are merged into the Hibernate core module, so, the

Read more Hibernate – One-to-One example (Annotation)