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使用 Singleton Object Employee、Crunchify Java POJO 和详细的 TestCase 完成端到端 Java 教程

已发表: 2014-11-06

Crunchify Singleton Pattern - 完整的端到端教程

在本 Java 教程中，我们将介绍在企业项目中使用Singleton pattern所需的所有详细步骤。 我们使用 Singleton 对象在运行时推送所需的数据，并使用相同的 Singleton 对象在运行时检索数据。 您可以从任何地方访问 Singleton 对象。 如果您想了解有关单例模式的更多信息，请遵循此单例教程。

让我们开始吧

第1步

创建简单的 Crunchify Object POJO： CrunchifyObject.java

CrunchifyObject 和 Employee Java POJO

第2步

创建所有的 setter 和 getter。

第三步

创建单例类： CrunchifySingleton.java

第四步

将所有实用程序方法写入 Singleton 类

第 5 步

最后创建测试类： CrunchifyObjectTest.java

您需要以下 JSON 依赖项：

pom.xml - JSON Dependency
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< dependency >
< groupId > org . json < / groupId >
< artifactId > json < / artifactId >
< version > 20151123 < / version >
< / dependency >

CrunchifyObject.java

CrunchifyObject.java
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package crunchify . com . tutorial ;
 
import java . util . List ;
 
/**
* @author Crunchify.com
* This is simple CrunchifyObject POJO contains another class "Employee" as a field
*/
 
public class CrunchifyObject {
public String name ;
public String address ;
public List <Employee> employees ;
 
public String getName ( ) {
return name ;
}
 
public void setName ( String name ) {
this . name = name ;
}
 
public String getAddress ( ) {
return address ;
}
 
public void setAddress ( String address ) {
this . address = address ;
}
 
public List <Employee> getEmployees ( ) {
return employees ;
}
 
public void setEmployees ( List <Employee> employees ) {
this . employees = employees ;
}
 
// Class Employee
public class Employee {
public String firstName ;
public String lastName ;
public int phoneNumber ;
 
public String getFirstName ( ) {
return firstName ;
}
 
public void setFirstName ( String firstName ) {
this . firstName = firstName ;
}
 
public String getLastName ( ) {
return lastName ;
}
 
public void setLastName ( String lastName ) {
this . lastName = lastName ;
}
 
public int getPhoneNumber ( ) {
return phoneNumber ;
}
 
public void setPhoneNumber ( int phoneNumber ) {
this . phoneNumber = phoneNumber ;
}
}
}

CrunchifySingleton.java

CrunchifySingleton.java
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package crunchify . com . tutorial ;
 
import java . util . ArrayList ;
import java . util . HashMap ;
import java . util . List ;
import java . util . Map ;
 
import org . json . JSONArray ;
import org . json . JSONObject ;
 
import crunchify . com . tutorial . CrunchifyObject . Employee ;
 
/**
* @author Crunchify.com
* This is Singleton class used to access from any where from your project. Here we are using it
*         from CrunchifyObjectTest.java
*
*/
public class CrunchifySingleton {
 
private List <Employee> employees = new ArrayList <Employee> ( ) ;
private static CrunchifySingleton singletonInstance = null ;
private CrunchifyObject crunchify = new CrunchifyObject ( ) ;
 
public static CrunchifySingleton getCrunchifySingletonInstance ( ) {
if ( singletonInstance == null ) {
singletonInstance = new CrunchifySingleton ( ) ;
}
return singletonInstance ;
}
 
public void addEmployee ( Employee employee ) {
synchronized ( employees ) {
employees . add ( employee ) ;
}
}
 
public List <Employee> getEmployee ( ) {
return employees ;
}
 
public void addCrunchify ( CrunchifyObject crunchify ) {
synchronized ( crunchify ) {
this . crunchify = crunchify ;
}
}
 
public String getCrunchifyObject ( ) {
JSONObject obj = new JSONObject ( ) ;
obj . put ( "name" , crunchify . getName ( ) ) ;
obj . put ( "address" , crunchify . getAddress ( ) ) ;
 
JSONArray employeeJson = new JSONArray ( ) ;
for ( Employee emp : employees ) {
 
Map < String , String > employeeData = new HashMap < String , String > ( ) ;
employeeData . put ( "firstName" , emp . getFirstName ( ) ) ;
employeeData . put ( "lastName" , emp . getLastName ( ) ) ;
employeeData . put ( "phoneNumber" , emp . getPhoneNumber ( ) + "" ) ;
 
employeeJson . put ( employeeData ) ;
}
obj . put ( "employees" , employeeJson ) ;
return obj . toString ( ) ;
}
}

CrunchifyObjectTest.java

CrunchifyObjectTest.java
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package crunchify . com . tutorial ;
 
import crunchify . com . tutorial . CrunchifyObject . Employee ;
 
/**
* @author Crunchify.com
* This is test class used to create all required objects and use Singleton object to push and
*         retrieve value at runtime. You could use the same singleton object from anywhere in your enterprise project
*/
 
public class CrunchifyObjectTest {
 
static CrunchifySingleton instance = CrunchifySingleton . getCrunchifySingletonInstance ( ) ;
 
public static void main ( String [ ] args ) {
populateAndSaveDataFromSingletonObject ( ) ;
retrieveDataFromSingletonObject ( ) ;
}
 
private static void retrieveDataFromSingletonObject ( ) {
String result = instance . getCrunchifyObject ( ) ;
System . out . println ( result ) ;
}
 
private static void populateAndSaveDataFromSingletonObject ( ) {
 
// Create CrunchifyObject
CrunchifyObject crunchifyObj = new CrunchifyObject ( ) ;
crunchifyObj . setName ( "Crunchify.com" ) ;
crunchifyObj . setAddress ( "NYC - US" ) ;
 
// Create Employee1
Employee emp1 = crunchifyObj . new Employee ( ) ;
emp1 . setFirstName ( "Mike" ) ;
emp1 . setLastName ( "Rose" ) ;
emp1 . setPhoneNumber ( 1222222222 ) ;
 
// Create Employee2
Employee emp2 = crunchifyObj . new Employee ( ) ;
emp2 . setFirstName ( "app" ) ;
emp2 . setLastName ( "shah" ) ;
emp2 . setPhoneNumber ( 1333333333 ) ;
 
// Create Employee3
Employee emp3 = crunchifyObj . new Employee ( ) ;
emp3 . setFirstName ( "Dexter" ) ;
emp3 . setLastName ( "My" ) ;
emp3 . setPhoneNumber ( 1444444444 ) ;
 
// Add all Employee Object to CrunchifySingleton object
instance . addEmployee ( emp1 ) ;
instance . addEmployee ( emp2 ) ;
instance . addEmployee ( emp3 ) ;
 
// Add Employees to CrunchifyObject
crunchifyObj . setEmployees ( instance . getEmployee ( ) ) ;
 
// Now finally add CrunchifyObject to same CrunchifySingleton object which will use to retrieve all data
instance . addCrunchify ( crunchifyObj ) ;
}
 
}

结果：

Singleton Object Result
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{
     "address" : "NYC - US" ,
     "name" : "Crunchify.com" ,
     "employees" : [
         {
             "lastName" : "Rose" ,
             "phoneNumber" : "1222222222" ,
             "firstName" : "Mike"
         } ,
         {
             "lastName" : "Shah" ,
             "phoneNumber" : "1333333333" ,
             "firstName" : "app"
         } ,
         {
             "lastName" : "My" ,
             "phoneNumber" : "1444444444" ,
             "firstName" : "Dexter"
         }
     ]
}