Package org.springframework.context.expression

Class MapAccessor

java.lang.Object

org.springframework.context.expression.MapAccessor

All Implemented Interfaces:

Opcodes, PropertyAccessor, CompilablePropertyAccessor, TargetedAccessor

public class MapAccessor
extends Object
implements CompilablePropertyAccessor

EL property accessor that knows how to traverse the keys of a standard Map.

Since:

3.0

Author:

Juergen Hoeller, Andy Clement

Field Summary

Fields inherited from interface org.springframework.asm.Opcodes

AALOAD, AASTORE, ACC_ABSTRACT, ACC_ANNOTATION, ACC_BRIDGE, ACC_DEPRECATED, ACC_ENUM, ACC_FINAL, ACC_INTERFACE, ACC_MANDATED, ACC_MODULE, ACC_NATIVE, ACC_OPEN, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_RECORD, ACC_STATIC, ACC_STATIC_PHASE, ACC_STRICT, ACC_SUPER, ACC_SYNCHRONIZED, ACC_SYNTHETIC, ACC_TRANSIENT, ACC_TRANSITIVE, ACC_VARARGS, ACC_VOLATILE, ACONST_NULL, ALOAD, ANEWARRAY, ARETURN, ARRAYLENGTH, ASM10_EXPERIMENTAL, ASM4, ASM5, ASM6, ASM7, ASM8, ASM9, ASTORE, ATHROW, BALOAD, BASTORE, BIPUSH, CALOAD, CASTORE, CHECKCAST, D2F, D2I, D2L, DADD, DALOAD, DASTORE, DCMPG, DCMPL, DCONST_0, DCONST_1, DDIV, DLOAD, DMUL, DNEG, DOUBLE, DREM, DRETURN, DSTORE, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, F_APPEND, F_CHOP, F_FULL, F_NEW, F_SAME, F_SAME1, F2D, F2I, F2L, FADD, FALOAD, FASTORE, FCMPG, FCMPL, FCONST_0, FCONST_1, FCONST_2, FDIV, FLOAD, FLOAT, FMUL, FNEG, FREM, FRETURN, FSTORE, FSUB, GETFIELD, GETSTATIC, GOTO, H_GETFIELD, H_GETSTATIC, H_INVOKEINTERFACE, H_INVOKESPECIAL, H_INVOKESTATIC, H_INVOKEVIRTUAL, H_NEWINVOKESPECIAL, H_PUTFIELD, H_PUTSTATIC, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IALOAD, IAND, IASTORE, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, ICONST_M1, IDIV, IF_ACMPEQ, IF_ACMPNE, IF_ICMPEQ, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ICMPLT, IF_ICMPNE, IFEQ, IFGE, IFGT, IFLE, IFLT, IFNE, IFNONNULL, IFNULL, IINC, ILOAD, IMUL, INEG, INSTANCEOF, INTEGER, INVOKEDYNAMIC, INVOKEINTERFACE, INVOKESPECIAL, INVOKESTATIC, INVOKEVIRTUAL, IOR, IREM, IRETURN, ISHL, ISHR, ISTORE, ISUB, IUSHR, IXOR, JSR, L2D, L2F, L2I, LADD, LALOAD, LAND, LASTORE, LCMP, LCONST_0, LCONST_1, LDC, LDIV, LLOAD, LMUL, LNEG, LONG, LOOKUPSWITCH, LOR, LREM, LRETURN, LSHL, LSHR, LSTORE, LSUB, LUSHR, LXOR, MONITORENTER, MONITOREXIT, MULTIANEWARRAY, NEW, NEWARRAY, NOP, NULL, POP, POP2, PUTFIELD, PUTSTATIC, RET, RETURN, SALOAD, SASTORE, SIPUSH, SOURCE_DEPRECATED, SOURCE_MASK, SWAP, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_SHORT, TABLESWITCH, TOP, UNINITIALIZED_THIS, V_PREVIEW, V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V10, V11, V12, V13, V14, V15, V16, V17, V18, V19, V20, V21, V22, V23, V9

Constructor Summary

Constructors

Constructor	Description
MapAccessor()	Create a new map accessor for reading as well as writing.
MapAccessor(boolean allowWrite)	Create a new map accessor for reading and possibly also writing.

Method Summary

Modifier and Type	Method	Description
boolean	canRead(EvaluationContext context, Object target, String name)	Called to determine if this property accessor is able to read a specified property on a specified target object.
boolean	canWrite(EvaluationContext context, Object target, String name)	Called to determine if this property accessor is able to write to a specified property on a specified target object.
void	generateCode(String propertyName, MethodVisitor mv, CodeFlow cf)	Generate the bytecode that performs the access operation into the specified MethodVisitor using context information from the CodeFlow where necessary.
Class<?>	getPropertyType()	Return the type of the accessed property - may only be known once an access has occurred.
Class<?>[]	getSpecificTargetClasses()	Get the set of classes for which this accessor should be called.
boolean	isCompilable()	Return true if this property accessor is currently suitable for compilation.
TypedValue	read(EvaluationContext context, Object target, String name)	Called to read a property from a specified target object.
void	write(EvaluationContext context, Object target, String name, Object newValue)	Called to write to a property on a specified target object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

MapAccessor

public MapAccessor()

Create a new map accessor for reading as well as writing.

Since:

6.2

See Also:

• MapAccessor(boolean)

MapAccessor

public MapAccessor(boolean allowWrite)

Create a new map accessor for reading and possibly also writing.

Parameters:

allowWrite - whether to allow write operations on a target instance

Since:

6.2

See Also:

• canWrite(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String)

Method Details

getSpecificTargetClasses

public Class<?>[] getSpecificTargetClasses()

Description copied from interface: TargetedAccessor

Get the set of classes for which this accessor should be called.

Returning null or an empty array indicates this is a generic accessor that can be called in an attempt to access an element on any type.

Specified by:

getSpecificTargetClasses in interface TargetedAccessor

Returns:

an array of classes that this accessor is suitable for (or null or an empty array if a generic accessor)

canRead

public boolean canRead(EvaluationContext context,
 @Nullable
 Object target,
 String name)
                throws AccessException

Description copied from interface: PropertyAccessor

Called to determine if this property accessor is able to read a specified property on a specified target object.

Specified by:

canRead in interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - the name of the property being accessed

Returns:

true if this property accessor is able to read the property

Throws:

AccessException - if there is any problem determining whether the property can be read

read

public TypedValue read(EvaluationContext context,
 @Nullable
 Object target,
 String name)
                throws AccessException

Description copied from interface: PropertyAccessor

Called to read a property from a specified target object.

Should only succeed if PropertyAccessor.canRead(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String) also returns true.

Specified by:

read in interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - the name of the property being accessed

Returns:

a TypedValue object wrapping the property value read and a type descriptor for it

Throws:

AccessException - if there is any problem reading the property value

canWrite

public boolean canWrite(EvaluationContext context,
 @Nullable
 Object target,
 String name)
                 throws AccessException

Description copied from interface: PropertyAccessor

Called to determine if this property accessor is able to write to a specified property on a specified target object.

Specified by:

canWrite in interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - the name of the property being accessed

Returns:

true if this property accessor is able to write to the property

Throws:

AccessException - if there is any problem determining whether the property can be written to

write

public void write(EvaluationContext context,
 @Nullable
 Object target,
 String name,
 @Nullable
 Object newValue)
           throws AccessException

Description copied from interface: PropertyAccessor

Called to write to a property on a specified target object.

Should only succeed if PropertyAccessor.canWrite(org.springframework.expression.EvaluationContext, java.lang.Object, java.lang.String) also returns true.

Specified by:

write in interface PropertyAccessor

Parameters:

context - the evaluation context in which the access is being attempted

target - the target object upon which the property is being accessed

name - the name of the property being accessed

newValue - the new value for the property

Throws:

AccessException - if there is any problem writing to the property value

isCompilable

public boolean isCompilable()

Description copied from interface: CompilablePropertyAccessor

Return true if this property accessor is currently suitable for compilation.

Specified by:

isCompilable in interface CompilablePropertyAccessor

getPropertyType

public Class<?> getPropertyType()

Description copied from interface: CompilablePropertyAccessor

Return the type of the accessed property - may only be known once an access has occurred.

Specified by:

getPropertyType in interface CompilablePropertyAccessor

generateCode

public void generateCode(String propertyName,
 MethodVisitor mv,
 CodeFlow cf)

Description copied from interface: CompilablePropertyAccessor

Generate the bytecode that performs the access operation into the specified MethodVisitor using context information from the CodeFlow where necessary.

Specified by:

generateCode in interface CompilablePropertyAccessor

Parameters:

propertyName - the name of the property

mv - the ASM method visitor into which code should be generated

cf - the current state of the expression compiler