在SAP接口编程之 NCo3.0系列(06) : 会话管理 这篇文章中，对会话管理的相关知识点已经说得很详细了，请参考。现在用JCo3.0来实现。
1. JCoContext
如果SAP中多个函数需要在一个session中运行，需要JCoContext来提供保证。如果在同一个线程中，大体模式这样：
JCoContext.begin(sapDestination);
fm1.execute(sapDestination);
fm2.execute(sapDestination);
JCoContext.end(destination);
begin()和end()之间的函数execute之后，SAP不会释放连接，确保同一个session之中。
第二种情况：如果不同的函数不在同一个线程中，需要由开发人员实现SessionReferenceProvider接口，在类中提供session id。逻辑跟nco3.0也是一样的。JCo3.0提供了一个示例代码，但是搞的太复杂，我弄了一个简单的，方便理解。
2. SAP函数
我们要使用的函数是从标准系统函数INCREMENT_COUNTER
，GET_COUNTER拷贝而来的。在SAP系统中INCREMENT_COUNTER
，GET_COUNTER在同一个function group中，共享一个变量count（计数器），每次运行INCREMENT_COUNTER
, count就会加一，GET_COUNTER函数
可以获得这个count。因为这两个函数不能被远程调用，所以我们将这两个函数拷贝出另外两个函数ZINCREMENT_COUNTER和ZGET_COUNTER。
3. 同一线程中执行函数
首先我们把两个函数定义在一个类RfcFunctions中：
package jco3.demo6;
import com.sap.conn.jco.JCoDestination;
import com.sap.conn.jco.JCoException;
import com.sap.conn.jco.JCoFunction;
public class RfcFunctions
{
public static int runGetCounter(JCoDestination dest) throws JCoException
{
JCoFunction counterFM = dest.getRepository().getFunction("ZGET_COUNTER");
counterFM.execute(dest);
int counter = (int) counterFM.getExportParameterList().getValue("GET_VALUE");
return counter;
}
public static void runIncrement(JCoDestination dest) throws JCoException
{
JCoFunction increment = dest.getRepository().getFunction("ZINCREMENT_COUNTER");
increment.execute(dest);
}
}
然后编写测试类进行测试：
package jco3.demo6;
import com.sap.conn.jco.JCoContext;
import com.sap.conn.jco.JCoDestination;
import com.sap.conn.jco.JCoDestinationManager;
import com.sap.conn.jco.JCoException;
public class TestSessionSameThread
{
public static void main(String[] args) throws JCoException, InterruptedException
{
// get JCoDestination object instance
JCoDestination destination = JCoDestinationManager.getDestination("ECC");
// make sure the two functions will be executed in the same session
JCoContext.begin(destination);
// Before increment
System.out.println("Before execution of ZINCREMENT_COUNTER:");
System.out.println("Counter:" + RfcFunctions.runGetCounter(destination));
// Run incrementCounter five times
for(int i = 0; i < 5; i++){
RfcFunctions.runIncrement(destination);
System.out.println("Add:" + (i + 1));
}
// After increment
System.out.println("After execution of ZINCREMENT_COUNTER:");
System.out.println("Counter:" + RfcFunctions.runGetCounter(destination));
// release the connection
JCoContext.end(destination);
}
}
代码很直观，就不多说了。函数执行前，counter的值为0，运行函数5次之后，counter的值为5。如果我们注释掉JCoContext.begin(destination);和JCoContext.end(destination);，可以对比出不同的效果。
4. 不同线程中执行函数
如果在不同的线程中执行不同的函数，需要开发者提供session id。我准备将两个函数放在不同的线程中：
- 在JVM的主线程中调用
ZGET_COUNTER，查看counter的结果。 - 在另外一个线程中运行
ZINCREMENT_COUNTER，两个线程通过JCoContext，保持在同一个session ID下。
4.1 实现JCoSessionReference接口
JCoSessionRefence实现类的主要作用是提供session ID:
package jco3.session;
import java.util.concurrent.atomic.AtomicInteger;
import com.sap.conn.jco.ext.JCoSessionReference;
public class JCoSessionRefenceImpl implements JCoSessionReference
{
private AtomicInteger atomInt = new AtomicInteger(0);
private String id = "session"+String.valueOf(atomInt.addAndGet(1));
public void contextFinished()
{
}
public void contextStarted()
{
}
@Override
public String getID()
{
/**
* We need to override getID() method
*/
return id;
}
}
4.2 实现SessionReferenceProvider接口
在SessionReferenceProvider接口的实现类中，改写getCurrentSessionReference()方法，获取上面定义的JCoSessionRefence，从而获得session ID。其他方法保持不动。
package jco3.session;
import com.sap.conn.jco.ext.JCoSessionReference;
import com.sap.conn.jco.ext.SessionException;
import com.sap.conn.jco.ext.SessionReferenceProvider;
public class SessionReferencProviderImpl implements SessionReferenceProvider
{
@Override
public JCoSessionReference getCurrentSessionReference(String scopeType)
{
/**
* We need to override getCurrentSessionReference() method
*/
JCoSessionRefenceImpl sessionRef = new JCoSessionRefenceImpl();
return sessionRef;
}
@Override
public boolean isSessionAlive(String sessionID)
{
return false;
}
public void jcoServerSessionContinued(String sessionID) throws SessionException
{
}
public void jcoServerSessionFinished(String sessionID)
{
}
public void jcoServerSessionPassivated(String sessionID) throws SessionException
{
}
public JCoSessionReference jcoServerSessionStarted() throws SessionException
{
return null;
}
}
4.3 注册 SessionReferenceProvider接口
注册SessionReferenceProvider接口的实现类，这样JCoDestination就有状态管理功能了。
package jco3.session;
import com.sap.conn.jco.JCoDestination;
import com.sap.conn.jco.JCoDestinationManager;
import com.sap.conn.jco.JCoException;
import com.sap.conn.jco.ext.Environment;
import com.sap.conn.jco.ext.SessionReferenceProvider;
public class DestinationProvider
{
public static JCoDestination getDestination() throws JCoException
{
// create an instance of SessionReferenceProvider
// and register in environment
SessionReferenceProvider provider = new SessionReferencProviderImpl();
Environment.registerSessionReferenceProvider(provider);
JCoDestination destination = JCoDestinationManager.getDestination("ECC");
return destination;
}
}
4.4 在单独线程中执行ZINCREMENT_COUNTER
定义WorkingThread, 从Thread类继承，在这个线程中执行函数ZINCREMENT_COUNTER 5次。
package jco3.demo6;
import com.sap.conn.jco.JCoDestination;
import com.sap.conn.jco.JCoException;
public class WorkingThread extends Thread
{
private boolean doneSignal;
private JCoDestination destination;
// constructor
public WorkingThread(JCoDestination destination, boolean doneSignal)
{
this.destination = destination;
this.doneSignal = doneSignal;
}
public boolean hasDone()
{
return doneSignal;
}
@Override
public void run()
{
/**
* run method of runIncrement() for five times
*/
for (int i = 0; i < 5; i++){
try {
RfcFunctions.runIncrement(this.destination);
System.out.println("Run " + (i+1) + " times.");
} catch (JCoException e) {
e.printStackTrace();
}
}
this.doneSignal = true;
}
}
doneSignal用于标识该线程是否结束。线程本身结束，是run()方法运行完毕。
4.5 测试多线程函数调用
好了，最后来测试在多线程中函数调用：
package jco3.demo6;
import com.sap.conn.jco.JCoContext;
import com.sap.conn.jco.JCoDestination;
import com.sap.conn.jco.JCoException;
import jco3.session.DestinationProvider;
public class TestSAPSessionMultiThread
{
public static void main(String[] args) throws JCoException, InterruptedException
{
/**
* Run ZINCREMENT_COUNTER & ZGET_COUNTER functions in
* different threads in a stateful way.
*
* The SAP will keep a session id which was created in
* JCoSessionReferenceImpl class
* and used in SessionReferenceProviderImpl class.
*
* Before using, SessionReferenceProviderImpl class should be
* registered using Environment.registerSessionReferenceProvider() method.
*/
// get JCoDestination object instance
JCoDestination destination = DestinationProvider.getDestination();
// make sure the two functions will be executed in the same session
JCoContext.begin(destination);
// Before increment
System.out.println("Before execution of ZINCREMENT_COUNTER:");
System.out.println("Counter:" + RfcFunctions.runGetCounter(destination));
// start a new Thread in which function ZINCREMENT_COUNTER
// will be executed for five times
WorkingThread workingThread = new WorkingThread(destination, false);
workingThread.start();
// wait and switch thread
Thread.sleep(1000);
// After increment
if (workingThread.hasDone() == true){
System.out.println("After execution of ZINCREMENT_COUNTER:");
System.out.println("Counter:" + RfcFunctions.runGetCounter(destination));
}
// release the connection
JCoContext.end(destination);
}
}
与前面同一个线程中代码的主要区别是：
定义一个WorkingThread类的实例，然后启动线程：
WorkingThread workingThread = new WorkingThread(destination, false);
workingThread.start();
然后通过Thread.sleep(), 将线程切换到workingThread中执行，执行完毕再回到主线程显示结果。
