@Around advice for full control in Spring Boot - Step-by-Step Execution

Concept Flow - @Around advice for full control

Method call intercepted

↓

@Around advice starts

↓

Pre-processing logic

↓

Proceed with original method?

No→Skip method execution

Yes↓

Call original method

↓

Post-processing logic

↓

Return result or modify

↓

Method call completes

The @Around advice intercepts a method call, runs code before and after the method, and can decide to run or skip the original method, controlling the final result.

Execution Sample

Spring Boot

@Around("execution(* com.example.service.*.*(..))")
public Object aroundAdvice(ProceedingJoinPoint pjp) throws Throwable {
  System.out.println("Before method");
  Object result = pjp.proceed();
  System.out.println("After method");
  return result;
}

This advice prints messages before and after the original method runs, then returns the method's result.

Execution Table

Step	Action	Evaluation	Result
1	Method call intercepted	Method in target package called	Proceed to advice
2	Print 'Before method'	Runs before original method	Message shown
3	Call pjp.proceed()	Original method executes	Original method result obtained
4	Print 'After method'	Runs after original method	Message shown
5	Return result	Return value from advice	Original method result returned
6	Method call completes	Caller receives result	Execution ends

💡 Method call completes after advice returns the original method's result

Variable Tracker

Variable	Start	After Step 3	Final
result	null	original method's return value	original method's return value

Key Moments - 3 Insights

Why do we call pjp.proceed() inside @Around advice?

Calling pjp.proceed() runs the original method. Without it, the original method is skipped (see execution_table step 3).

Can @Around advice modify the method's return value?

Yes, by changing the 'result' variable before returning it (see execution_table step 5).

What happens if pjp.proceed() is not called?

The original method does not run, and the advice can return a custom value or skip execution (not shown in this example but implied).

Visual Quiz - 3 Questions

Look at the execution table, what happens at step 3?

A The method call is intercepted

B The advice prints 'After method'

C The original method is executed

D The advice returns the result

💡 Hint

Check the 'Action' and 'Result' columns at step 3 in the execution_table

At which step does the advice print 'Before method'?

A Step 2

B Step 4

C Step 1

D Step 5

💡 Hint

Look for the print action before the original method call in the execution_table

If pjp.proceed() is not called, what changes in the execution flow?

A The advice prints 'After method' twice

B The original method is skipped

C The method call is never intercepted

D The advice cannot return a result

💡 Hint

Refer to the key_moments section about skipping the original method

Concept Snapshot

@Around advice intercepts method calls
Runs code before and after method
Calls pjp.proceed() to run original method
Can skip or modify method execution
Returns final result to caller

Full Transcript

The @Around advice in Spring Boot intercepts method calls matching a pointcut. When a method is called, the advice runs first, allowing code before the method. Calling pjp.proceed() runs the original method and captures its result. After that, the advice can run more code and modify or return the result. If pjp.proceed() is not called, the original method is skipped. This gives full control over method execution flow.

Practice

1. What is the main purpose of using @Around advice in Spring AOP?

easy

A. To run code before and after a method, controlling its execution fully

B. To only run code after a method finishes

C. To replace the method with a new implementation without calling the original

D. To log method parameters without affecting execution

Solution

1. Step 1: Understand the role of @Around advice

   @Around advice wraps a method, allowing code to run before and after the method execution.

2. Step 2: Compare options with this behavior

   Only To run code before and after a method, controlling its execution fully describes full control before and after the method, matching @Around's purpose.

3. Final Answer:

   To run code before and after a method, controlling its execution fully -> Option A

4. Quick Check:

   @Around advice = full control before and after method [OK]

Hint: Remember @Around wraps method execution fully [OK]

Common Mistakes:

• Thinking @Around only runs after method
• Confusing @Around with @After or @Before
• Forgetting @Around can modify inputs and outputs

2. Which of the following is the correct way to proceed with the original method inside an @Around advice method?

easy

A. return joinPoint.proceed();

B. joinPoint.execute();

C. proceed(joinPoint);

D. joinPoint.run();

Solution

1. Step 1: Recall the method to call original execution

   In @Around advice, the original method is executed by calling joinPoint.proceed().

2. Step 2: Match the correct syntax

   Only return joinPoint.proceed(); uses the correct method name and syntax to proceed.

3. Final Answer:

   return joinPoint.proceed(); -> Option A

4. Quick Check:

   Call original method with joinPoint.proceed() [OK]

Hint: Use joinPoint.proceed() to run original method [OK]

Common Mistakes:

• Using incorrect method names like execute() or run()
• Forgetting to return the result of proceed()
• Calling proceed() without parentheses

3. Given the following @Around advice code, what will be printed when someMethod() returns "Hello"?

@Around("execution(* someMethod())")
public Object aroundAdvice(ProceedingJoinPoint joinPoint) throws Throwable {
    System.out.println("Before");
    Object result = joinPoint.proceed();
    System.out.println("After");
    return result + " World";
}

medium

A. Before
Hello
After
World

B. Hello
Before
After
World

C. Before
After
Hello

D. Before
After
Hello World

Solution

1. Step 1: Trace the advice execution order

   The advice prints "Before", then calls the original method which returns "Hello", then prints "After".

2. Step 2: Understand the returned value

   The advice returns the original result plus " World", so the final returned string is "Hello World".

3. Final Answer:

   Before After Hello World -> Option D

4. Quick Check:

   Prints before and after, returns modified result [OK]

Hint: Remember @Around runs code before and after proceed() [OK]

Common Mistakes:

• Assuming original method output is unchanged
• Mixing print order with return value
• Forgetting to add " World" to result

4. Identify the error in this @Around advice method:

@Around("execution(* someMethod())")
public Object aroundAdvice(ProceedingJoinPoint joinPoint) {
    System.out.println("Start");
    Object result = joinPoint.proceed();
    System.out.println("End");
    return result;
}

medium

A. Incorrect annotation syntax

B. Missing throws Throwable declaration in method signature

C. Should call joinPoint.execute() instead of proceed()

D. Cannot return Object type from advice

Solution

1. Step 1: Check method signature requirements

   joinPoint.proceed() throws Throwable, so the advice method must declare throws Throwable or handle it.

2. Step 2: Identify missing throws declaration

   The method lacks "throws Throwable", causing a compile error.

3. Final Answer:

   Missing throws Throwable declaration in method signature -> Option B

4. Quick Check:

   proceed() throws Throwable, must declare it [OK]

Hint: Add throws Throwable when calling joinPoint.proceed() [OK]

Common Mistakes:

• Ignoring checked exceptions from proceed()
• Using wrong method name instead of proceed()
• Not matching annotation syntax

5. You want to create an @Around advice that modifies the input argument of a method before execution and changes the returned result after execution. Which approach correctly achieves this?

hard

A. Modify the method parameters directly without using proceed, then return null

B. Call joinPoint.proceed() without arguments, then ignore the result and return a new value

C. Modify the argument array via joinPoint.getArgs(), then call joinPoint.proceed(modifiedArgs), and finally modify the returned result before returning

D. Use joinPoint.proceed() and modify the result, but cannot change input arguments

Solution

1. Step 1: Understand argument modification in @Around advice

   You can get and modify method arguments using joinPoint.getArgs() and pass them to proceed() to change inputs.

2. Step 2: Modify the returned result after proceed()

   After calling proceed with modified arguments, you can change the returned value before returning it.

3. Final Answer:

   Modify the argument array via joinPoint.getArgs(), then call joinPoint.proceed(modifiedArgs), and finally modify the returned result before returning -> Option C

4. Quick Check:

   Change inputs with proceed(args), then modify output [OK]

Hint: Use proceed(modifiedArgs) to change inputs, then modify output [OK]

Common Mistakes:

• Calling proceed() without modified arguments when inputs need change
• Trying to change parameters directly without proceed()
• Ignoring returned result modification