java - 如何在 Java 中处理 PSQLException？

Question

我对我的一个实体有一个唯一的约束，每当我收到一个 PSQLException，只要违反该约束就会发生，我想用一个错误的请求来响应。

这是我尝试实现的异常处理程序:

@ControllerAdvice
public class DatabaseExceptionHandler {
    @ExceptionHandler(value = PSQLException.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public void handleDatabaseExceptions(PSQLException e) {
        // i want to respond with a bad request only when this condition is satisfied
//
//        if (e.getSQLState().equals("23505")) {
//
//        }
    }

}

这是模型在数据库中的保存位置:

 public DepartmentForHoliday setDepartment(DepartmentForHoliday department) {
        if (department.getDepartmentId() == null) {
            Department savedDepartment = new Department();
            savedDepartment.setName(department.getName());
            try {
                departmentRepository.save(savedDepartment);
            } catch (PSQLException e) {
              /*here i have a compiler error which says that this exception is never thrown in the corresponding try block, but where ?*/
            }
}

这是我添加重复条目时抛出的异常:

org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "uk_1t68827l97cwyxo9r1u6t4p7d"
  Detail: Key (name)=(Tech) already exists.
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2458) ~[postgresql-9.4.1211.jre7.jar:9.4.1211.jre7]

如何处理 PSQLExceptions？我应该将自己的异常作为包装器还是如何解决这个问题？

Answer 1

关键问题是 PSQLException 被包装到一些 Spring 异常中(我从你的代码中假设)；你必须打开它(例如使用 Guava 的 Throwables ):

public DepartmentForHoliday setDepartment(DepartmentForHoliday department) {
    if (department.getDepartmentId() == null) {
        Department savedDepartment = new Department();
        savedDepartment.setName(department.getName());
        try {
            departmentRepository.save(savedDepartment);
        } catch (RuntimeException e) {
            Throwable rootCause = com.google.common.base.Throwables.getRootCause(e);
            if (rootCause instanceof SQLException) {
                if ("23505".equals(((SQLException) rootCause).getSQLState())) {
                    // do smth interesting :)
                }
            }
        }
    }
}

完成后，您可以抛出自定义异常并在 DatabaseExceptionHandler 中处理它