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DataBindingPropertyAccessor with factory methods (forReadOnlyAccess etc)

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Includes configurable write support at ReflectivePropertyAccessor level.

Issue: SPR-16588
This commit is contained in:
Juergen Hoeller
2018-03-22 00:03:06 +01:00
parent 94c525cdc8
commit b5511645b8
3 changed files with 66 additions and 51 deletions
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59
spring-expression/src/main/java/org/springframework/expression/spel/support/SimplePropertyAccessor.java → spring-expression/src/main/java/org/springframework/expression/spel/support/DataBindingPropertyAccessor.java
View File

@@ -18,13 +18,9 @@ package org.springframework.expression.spel.support;
import java.lang.reflect.Method;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.lang.Nullable;
/**
* A simple {@link org.springframework.expression.PropertyAccessor} variant that
* uses reflection to access properties for reading and possibly also writing.
* A {@link org.springframework.expression.PropertyAccessor} variant for data binding
* purposes, using reflection to access properties for reading and possibly writing.
*
* <p>A property can be accessed through a public getter method (when being read)
* or a public setter method (when being written), and also as a public field.
@@ -35,47 +31,21 @@ import org.springframework.lang.Nullable;
*
* @author Juergen Hoeller
* @since 4.3.15
* @see #forReadOnlyAccess()
* @see #forReadWriteAccess()
* @see SimpleEvaluationContext
* @see StandardEvaluationContext
* @see ReflectivePropertyAccessor
*/
public class SimplePropertyAccessor extends ReflectivePropertyAccessor {
private final boolean allowWrite;
/**
* Create a new property accessor for reading as well writing.
* @see #SimplePropertyAccessor(boolean)
*/
public SimplePropertyAccessor() {
this.allowWrite = true;
}
public class DataBindingPropertyAccessor extends ReflectivePropertyAccessor {
/**
* Create a new property accessor for reading and possibly also writing.
* @param allowWrite whether to also allow for write operations
* @see #canWrite
*/
public SimplePropertyAccessor(boolean allowWrite) {
this.allowWrite = allowWrite;
}
@Override
public boolean canWrite(EvaluationContext context, @Nullable Object target, String name) throws AccessException {
return (this.allowWrite && super.canWrite(context, target, name));
}
@Override
public void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object newValue)
throws AccessException {
if (!this.allowWrite) {
throw new AccessException("PropertyAccessor for property '" + name +
"' on target [" + target + "] does not allow write operations");
}
super.write(context, target, name, newValue);
private DataBindingPropertyAccessor(boolean allowWrite) {
super(allowWrite);
}
@Override
@@ -83,4 +53,19 @@ public class SimplePropertyAccessor extends ReflectivePropertyAccessor {
return (method.getDeclaringClass() != Object.class);
}
/**
* Create a new data-binding property accessor for read-only access.
*/
public static DataBindingPropertyAccessor forReadOnlyAccess() {
return new DataBindingPropertyAccessor(false);
}
/**
* Create a new data-binding property accessor for read-write access.
*/
public static DataBindingPropertyAccessor forReadWriteAccess() {
return new DataBindingPropertyAccessor(true);
}
}

50
spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectivePropertyAccessor.java
View File

@@ -46,7 +46,7 @@ import org.springframework.util.StringUtils;
/**
* A powerful {@link PropertyAccessor} that uses reflection to access properties
* for reading and writing.
* for reading and possibly also for writing.
*
* <p>A property can be accessed through a public getter method (when being read)
* or a public setter method (when being written), and also as a public field.
@@ -57,7 +57,7 @@ import org.springframework.util.StringUtils;
* @since 3.0
* @see StandardEvaluationContext
* @see SimpleEvaluationContext
* @see SimplePropertyAccessor
* @see DataBindingPropertyAccessor
*/
public class ReflectivePropertyAccessor implements PropertyAccessor {
@@ -73,6 +73,8 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
}
private final boolean allowWrite;
private final Map<PropertyCacheKey, InvokerPair> readerCache = new ConcurrentHashMap<>(64);
private final Map<PropertyCacheKey, Member> writerCache = new ConcurrentHashMap<>(64);
@@ -83,6 +85,25 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
private volatile InvokerPair lastReadInvokerPair;
/**
* Create a new property accessor for reading as well writing.
* @see #ReflectivePropertyAccessor(boolean)
*/
public ReflectivePropertyAccessor() {
this.allowWrite = true;
}
/**
* Create a new property accessor for reading and possibly writing.
* @param allowWrite whether to also allow for write operations
* @since 4.3.15
* @see #canWrite
*/
public ReflectivePropertyAccessor(boolean allowWrite) {
this.allowWrite = allowWrite;
}
/**
* Returns {@code null} which means this is a general purpose accessor.
*/
@@ -200,7 +221,7 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
@Override
public boolean canWrite(EvaluationContext context, @Nullable Object target, String name) throws AccessException {
if (target == null) {
if (!this.allowWrite || target == null) {
return false;
}
@@ -235,6 +256,11 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
public void write(EvaluationContext context, @Nullable Object target, String name, @Nullable Object newValue)
throws AccessException {
if (!this.allowWrite) {
throw new AccessException("PropertyAccessor for property '" + name +
"' on target [" + target + "] does not allow write operations");
}
Assert.state(target != null, "Target must not be null");
Class<?> type = (target instanceof Class ? (Class<?>) target : target.getClass());
@@ -477,14 +503,18 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
}
/**
* Attempt to create an optimized property accessor tailored for a property of a particular name on
* a particular class. The general ReflectivePropertyAccessor will always work but is not optimal
* due to the need to lookup which reflective member (method/field) to use each time read() is called.
* This method will just return the ReflectivePropertyAccessor instance if it is unable to build
* something more optimal.
* Attempt to create an optimized property accessor tailored for a property of a
* particular name on a particular class. The general ReflectivePropertyAccessor
* will always work but is not optimal due to the need to lookup which reflective
* member (method/field) to use each time read() is called. This method will just
* return the ReflectivePropertyAccessor instance if it is unable to build a more
* optimal accessor.
* <p>Note: An optimal accessor is currently only usable for read attempts.
* Do not call this method if you need a read-write accessor.
* @see OptimalPropertyAccessor
*/
public PropertyAccessor createOptimalAccessor(EvaluationContext context, @Nullable Object target, String name) {
// Don't be clever for arrays or null target
// Don't be clever for arrays or a null target...
if (target == null) {
return this;
}
@@ -506,7 +536,7 @@ public class ReflectivePropertyAccessor implements PropertyAccessor {
this.readerCache.put(cacheKey, invocationTarget);
}
}
if (method != null) {
if (method != null && isCandidateForProperty(method)) {
return new OptimalPropertyAccessor(invocationTarget);
}
}

8
spring-expression/src/test/java/org/springframework/expression/spel/PropertyAccessTests.java
View File

@@ -32,7 +32,7 @@ import org.springframework.expression.PropertyAccessor;
import org.springframework.expression.TypedValue;
import org.springframework.expression.spel.standard.SpelExpression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.SimplePropertyAccessor;
import org.springframework.expression.spel.support.DataBindingPropertyAccessor;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.expression.spel.testresources.Person;
@@ -194,14 +194,14 @@ public class PropertyAccessTests extends AbstractExpressionTests {
public void noGetClassAccess() {
Expression expr = parser.parseExpression("'a'.class.getName()");
StandardEvaluationContext context = new StandardEvaluationContext();
context.setPropertyAccessors(Collections.singletonList(new SimplePropertyAccessor()));
context.setPropertyAccessors(Collections.singletonList(DataBindingPropertyAccessor.forReadWriteAccess()));
expr.getValue(context);
}
@Test
public void propertyReadWrite() {
StandardEvaluationContext context = new StandardEvaluationContext();
context.setPropertyAccessors(Collections.singletonList(new SimplePropertyAccessor()));
context.setPropertyAccessors(Collections.singletonList(DataBindingPropertyAccessor.forReadWriteAccess()));
Expression expr = parser.parseExpression("name");
Person target = new Person("p1");
@@ -216,7 +216,7 @@ public class PropertyAccessTests extends AbstractExpressionTests {
@Test(expected = SpelEvaluationException.class)
public void propertyReadOnly() {
StandardEvaluationContext context = new StandardEvaluationContext();
context.setPropertyAccessors(Collections.singletonList(new SimplePropertyAccessor(false)));
context.setPropertyAccessors(Collections.singletonList(DataBindingPropertyAccessor.forReadOnlyAccess()));
Expression expr = parser.parseExpression("name");
Person target = new Person("p1");