How to Test Classes with Embedded `new()` Calls Using Mockito Spies?

To correctly handle JDBC transactions, you must first turn off the automatic commit mode, then perform multiple operations, and finally commit or rollback according to the results; 1. Call conn.setAutoCommit(false) to start the transaction; 2. Execute multiple SQL operations, such as INSERT and UPDATE; 3. Call conn.commit() if all operations are successful, and call conn.rollback() if an exception occurs to ensure data consistency; at the same time, try-with-resources should be used to manage resources, properly handle exceptions and close connections to avoid connection leakage; in addition, it is recommended to use connection pools and set save points to achieve partial rollback, and keep transactions as short as possible to improve performance.

Virtual threads have significant performance advantages in highly concurrency and IO-intensive scenarios, but attention should be paid to the test methods and applicable scenarios. 1. Correct tests should simulate real business, especially IO blocking scenarios, and use tools such as JMH or Gatling to compare platform threads; 2. The throughput gap is obvious, and it can be several times to ten times higher than 100,000 concurrent requests, because it is lighter and efficient in scheduling; 3. During the test, it is necessary to avoid blindly pursuing high concurrency numbers, adapting to non-blocking IO models, and paying attention to monitoring indicators such as latency and GC; 4. In actual applications, it is suitable for web backend, asynchronous task processing and a large number of concurrent IO scenarios, while CPU-intensive tasks are still suitable for platform threads or ForkJoinPool.

TosetJAVA_HOMEonWindows,firstlocatetheJDKinstallationpath(e.g.,C:\ProgramFiles\Java\jdk-17),thencreateasystemenvironmentvariablenamedJAVA_HOMEwiththatpath.Next,updatethePATHvariablebyadding%JAVA\_HOME%\bin,andverifythesetupusingjava-versionandjavac-v

ServiceMesh is an inevitable choice for the evolution of Java microservice architecture, and its core lies in decoupling network logic and business code. 1. ServiceMesh handles load balancing, fuse, monitoring and other functions through Sidecar agents to focus on business; 2. Istio Envoy is suitable for medium and large projects, and Linkerd is lighter and suitable for small-scale trials; 3. Java microservices should close Feign, Ribbon and other components and hand them over to Istiod for discovery and communication; 4. Ensure automatic injection of Sidecar during deployment, pay attention to traffic rules configuration, protocol compatibility, and log tracking system construction, and adopt incremental migration and pre-control monitoring planning.

The key to implementing a linked list is to define node classes and implement basic operations. ①First create the Node class, including data and references to the next node; ② Then create the LinkedList class, implementing the insertion, deletion and printing functions; ③ Append method is used to add nodes at the tail; ④ printList method is used to output the content of the linked list; ⑤ deleteWithValue method is used to delete nodes with specified values and handle different situations of the head node and the intermediate node.

Preventing server-side template injection (SSTI) requires four aspects: 1. Use security configurations, such as disabling method calls and restricting class loading; 2. Avoid user input as template content, only variable replacement and strictly verify input; 3. Adopt sandbox environments, such as Pebble, Mustache or isolating rendering context; 4. Regularly update the dependent version and review the code logic to ensure that the template engine is configured reasonably and prevent the system from being attacked due to user-controllable templates.

To improve the performance of Java collection framework, we can optimize from the following four points: 1. Choose the appropriate type according to the scenario, such as frequent random access to ArrayList, quick search to HashSet, and concurrentHashMap for concurrent environments; 2. Set capacity and load factors reasonably during initialization to reduce capacity expansion overhead, but avoid memory waste; 3. Use immutable sets (such as List.of()) to improve security and performance, suitable for constant or read-only data; 4. Prevent memory leaks, and use weak references or professional cache libraries to manage long-term survival sets. These details significantly affect program stability and efficiency.

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