Java ELProcessor类代码示例

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testEnvironmentResolver(){
    EnvironmentImpl environment = new EnvironmentImpl();
    environment.setAttribute( "testAtr1", true );
    environment.setAttribute( "testAtr2", "33" );
    environment.setAttribute( "testAtr3", null );

    ELProcessor processor = ElUtil.initNewELProcessor( environment, null );

    boolean result = (boolean)processor.eval( "empty testAtr3 && testAtr1" );

    // this again fails: "ELResolver cannot handle a null base Object with identifier 'unknownAtr'"
    //boolean result = (boolean)processor.eval( "empty testAtr3 && testAtr1 && empty unknownAtr" );

    Assert.assertTrue( result );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testEnvironmentResolverDate(){
    Date start = new Date();

    EnvironmentImpl environment = new EnvironmentImpl();
    environment.setAttribute( "currentMillis", System.currentTimeMillis() );

    try{
        Thread.sleep( 30 );
    }
    catch( InterruptedException e ){
    }

    ELProcessor processor = ElUtil.initNewELProcessor( environment, null );

    boolean result = (boolean)processor.eval( "NOW.time > currentMillis" );
    Assert.assertTrue( result );

    Date now = (Date)processor.eval( "NOW" );
    Assert.assertTrue( now.after( start ) );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testElExpressionGettingMessagesByCaegory() {
	messages.add(new SimpleMessage("client.id", "will generated", Severity.INFO));
	messages.add(new SimpleMessage("client.name", "not null"));
	messages.add(new SimpleMessage("client.name", "not empty"));

	ELProcessor el = new ELProcessor();
	el.defineBean("messages", messages);

	String result = el.eval("messages.errors.from('client.name')").toString();
	assertThat(result, is("not null, not empty"));

	result = el.eval("messages.errors.from('client.name').join(' - ')").toString();
	assertThat(result, is("not null - not empty"));

	result = el.eval("messages.errors.from('client.id')").toString();
	assertThat(result, isEmptyString());

	result = el.eval("messages.info.from('client.id')").toString();
	assertThat(result, is("will generated"));
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
/**
 * Creates and prepares a new ELProcessor instance with workflow engine configuration to evaluate expressions on
 * workflow instance environment together with some additional features (NOW variable, WORKFLOW_INSTANCE_ID variable).
 * 
 * The ELProcessor instance is meant to be used "quickly" only for current task execution/evaluation and should be discarded after that.
 */
public static ELProcessor initNewELProcessor( Environment environment, Long externalInstanceId ){
    ELProcessor processor = new ELProcessor();
    processor.getELManager().addBeanNameResolver( new EnvironmentBeanNameResolver( environment ) );
    processor.setValue( ReservedVariables.NOW, new Date() );
    processor.setValue( ReservedVariables.WORKFLOW_INSTANCE_ID, externalInstanceId );
    return processor;
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Override
public boolean evaluate( GraphInstance instance ){
    boolean result = false;
    if( StringUtils.isNotBlank( condition ) ){
        ELProcessor processor = ElUtil.initNewELProcessor( instance.getEnvironment(), instance.getExternalId() );
        result = (boolean)processor.eval( condition );
    }
    return result;
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Override
public void execute( GraphEngine engine, Token token ){
    GraphInstance instance = token.getInstance();
    Environment environment = instance.getEnvironment();

    if( !environment.containsAttribute( attribute ) ){
        if( isRequired ){
            // Throw exception
            throw new WorkflowException( "Missing required attribute '" + attribute + "'" );
        }
        else{
            // Use default value
            if( defaultValue instanceof String && ElUtil.hasBrackets( (String)defaultValue ) ){
                ELProcessor processor = ElUtil.initNewELProcessor( environment, instance.getExternalId() );
                Object expressionResult = processor.eval( ElUtil.removeBrackets( (String)defaultValue ) );
                environment.setAttribute( attribute, expressionResult );
            }
            else{
                environment.setAttribute( attribute, defaultValue );
            }
        }
    }

    // Validate type of value
    Object value = environment.getAttribute( attribute );
    if( value != null && !type.isAssignableFrom( value.getClass() ) ){
        throw new WorkflowException( "The value of attribute '" + attribute
                + "' is of type " + value.getClass().getCanonicalName()
                + " whis is not assignable to the expected type " + type.getCanonicalName() );
    }

    engine.complete( token, null );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Override
public void execute( GraphEngine engine, Token token ){
    GraphInstance instance = token.getInstance();
    Environment environment = instance.getEnvironment();
    if( value instanceof String && ElUtil.hasBrackets( (String)value ) ){
        ELProcessor processor = ElUtil.initNewELProcessor( environment, instance.getExternalId() );
        Object expressionResult = processor.eval( ElUtil.removeBrackets( (String)value ) );
        environment.setAttribute( attribute, expressionResult );
    }
    else{
        environment.setAttribute( attribute, value );
    }
    engine.complete( token, null );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Override
@SuppressWarnings("unchecked")
public T evaluate( GraphInstance instance ){
    if( StringUtils.isNotBlank( expression ) ){
        ELProcessor processor = ElUtil.initNewELProcessor( instance.getEnvironment(), instance.getExternalId() );
        Object expressionResult = processor.eval( ElUtil.removeBrackets( expression ) );
        return (T)expressionResult;
    }
    return null;
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testBean(){
    ELProcessor processor = ElUtil.initNewELProcessor( new EnvironmentImpl(), null );

    processor.defineBean( "client", new Client( 1, "Heli Kopter" ) );
    String name = (String)processor.eval( "client.name" );

    Assert.assertEquals( name, "Heli Kopter" );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testConditions(){
    ELProcessor processor = ElUtil.initNewELProcessor( new EnvironmentImpl(), null );

    processor.defineBean( "client", new Client( 1, "Heli Kopter" ) );
    boolean result = (boolean)processor.eval( "not empty client.name and client.id > 0" );

    Assert.assertTrue( result );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testValue(){
    ELProcessor processor = ElUtil.initNewELProcessor( new EnvironmentImpl(), null );

    processor.setValue( "throwException", false );
    boolean success = (boolean)processor.eval( "not throwException" );

    Assert.assertTrue( success );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testEnvironmentBean(){
    EnvironmentImpl environment = new EnvironmentImpl();
    environment.setAttribute( "testAtr1", true );
    environment.setAttribute( "testAtr2", "33" );
    environment.setAttribute( "testAtr3", null );

    ELProcessor processor = ElUtil.initNewELProcessor( environment, null );
    // this way all the parameters must be prefixed with "env.", but we will at least be able to check unmapped attributes without an exception
    processor.defineBean( "env", environment.getAttributes() );

    boolean result = (boolean)processor.eval( "empty env.testAtr3 && env.testAtr1 && empty env.unknownAtr" );

    Assert.assertTrue( result );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testEnvironmentResolverNull(){
    EnvironmentImpl environment = new EnvironmentImpl();
    environment.setAttribute( "testDate1", null );

    ELProcessor processor = ElUtil.initNewELProcessor( environment, null );

    // in EL, null.fieldName does not throw a nullpointer, and null in conditions always returns false
    boolean result = (boolean)processor.eval( "testDate1.time < System.currentTimeMillis()" );
    Assert.assertFalse( result );
    result = (boolean)processor.eval( "testDate1.whatever > System.currentTimeMillis()" );
    Assert.assertFalse( result );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testEnvironmentResolverInstanceIdNull(){
    EnvironmentImpl environment = new EnvironmentImpl();

    ELProcessor processor = ElUtil.initNewELProcessor( environment, null );

    Long instanceId = (Long)processor.eval( "WORKFLOW_INSTANCE_ID" );
    Assert.assertEquals( null, instanceId );
}
 

import javax.el.ELProcessor; //导入依赖的package包/类
@Test
public void testEnvironmentResolverInstanceId(){
    EnvironmentImpl environment = new EnvironmentImpl();

    ELProcessor processor = ElUtil.initNewELProcessor( environment, 55L );

    long instanceId = (long)processor.eval( "WORKFLOW_INSTANCE_ID" );
    Assert.assertEquals( 55, instanceId );
}