System.out.println("unescape: " + EscapeUtil.unescape(escape));替换系统的这种使用。出去或系统。用记录器犯错。
时间: 2024-03-21 16:43:12 浏览: 21
使用记录器来替换System.out.println(),可以使用Java自带的日志框架java.util.logging,代码示例如下:
```
import java.util.logging.Logger;
public class MyClass {
private static final Logger LOGGER = Logger.getLogger(MyClass.class.getName());
public static void main(String[] args) {
String escape = "test%20string";
LOGGER.info("unescape: " + EscapeUtil.unescape(escape));
}
}
```
这里使用Logger.getLogger()方法获取Logger实例,参数传入当前类的类名,这样可以将日志输出到控制台。然后使用Logger.info()方法输出信息,这样可以将错误信息、调试信息等按照不同级别进行分类输出,便于后续查找问题。
相关问题
解释一下这段代码 try { ("SELECT * FROM users WHERE username='xx"); while (rs.next()) { System.out.println("Username: " + rs.getString("username")); System.out.println(": " + rs.getString("")); System.out.println(": " + rs.getString("")); System.out.println(": " + rs.getString("")); } con.close(); } catch (SQLException e) { e.printStackTrace(); } }
这段代码是一个Java程序使用JDBC连接数据库,并查询用户信息的示例。具体解释如下:
1. `try { ... } catch (SQLException e) { ... }`: 这是一个try-catch语句块,用于捕获可能出现的SQL异常并进行处理。
2. `("SELECT * FROM users WHERE username='xx")`: 这是一个SQL语句,用于查询名为"xx"的用户的所有信息。实际应用中应该使用参数化查询来避免SQL注入攻击。
3. `while (rs.next()) { ... }`: 这是一个循环语句,用于遍历查询结果集中的每一行数据。
4. `System.out.println("Username: " + rs.getString("username"));`: 这行代码用于输出用户名。
5. `System.out.println(": " + rs.getString(""));`: 这行代码用于输出某个字段的值,但是由于没有指定字段名,所以代码有误。
6. `System.out.println(": " + rs.getString(""));`: 这行代码同样用于输出某个字段的值,但是由于没有指定字段名,所以代码有误。
7. `System.out.println(": " + rs.getString(""));`: 这行代码同样用于输出某个字段的值,但是由于没有指定字段名,所以代码有误。
8. `con.close();`: 这行代码用于关闭数据库连接,释放资源。
总的来说,这段代码存在一些问题,例如没有指定查询结果集中需要输出的字段名,可能会导致输出错误的数据,还有就是SQL注入问题。在实际应用中,需要注意这些问题并做出相应的处理。
将package shiyan3; public class Test { public static void main(String[] args) { try { Student student = new Student("Alice", "123456", "Computer Science"); System.out.println("Student name: " + student.getUsername()); System.out.println("Student password: " + student.getPassword()); System.out.println("Student major: " + student.getMajor()); Teacher teacher = new Teacher("Bob", "123456", "Mathematics"); System.out.println("Teacher name: " + teacher.getUsername()); System.out.println("Teacher password: " + teacher.getPassword()); System.out.println("Teacher department: " + teacher.getDepartment()); Admin admin = new Admin("Charlie", "123456", "Director"); System.out.println("Admin name: " + admin.getUsername()); System.out.println("Admin password: " + admin.getPassword()); System.out.println("Admin position: " + admin.getPosition()); } catch (Exception e) { System.out.println("An error occurred: " + e.getMessage()); } } }修改这段代码,使他有键盘输入的值
以下是修改后的代码,使用了Scanner类来获取键盘输入的值:
```java
package shiyan3;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
try {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter student name: ");
String studentName = scanner.nextLine();
System.out.print("Enter student password: ");
String studentPassword = scanner.nextLine();
System.out.print("Enter student major: ");
String studentMajor = scanner.nextLine();
Student student = new Student(studentName, studentPassword, studentMajor);
System.out.println("Student name: " + student.getUsername());
System.out.println("Student password: " + student.getPassword());
System.out.println("Student major: " + student.getMajor());
System.out.print("\nEnter teacher name: ");
String teacherName = scanner.nextLine();
System.out.print("Enter teacher password: ");
String teacherPassword = scanner.nextLine();
System.out.print("Enter teacher department: ");
String teacherDepartment = scanner.nextLine();
Teacher teacher = new Teacher(teacherName, teacherPassword, teacherDepartment);
System.out.println("Teacher name: " + teacher.getUsername());
System.out.println("Teacher password: " + teacher.getPassword());
System.out.println("Teacher department: " + teacher.getDepartment());
System.out.print("\nEnter admin name: ");
String adminName = scanner.nextLine();
System.out.print("Enter admin password: ");
String adminPassword = scanner.nextLine();
System.out.print("Enter admin position: ");
String adminPosition = scanner.nextLine();
Admin admin = new Admin(adminName, adminPassword, adminPosition);
System.out.println("Admin name: " + admin.getUsername());
System.out.println("Admin password: " + admin.getPassword());
System.out.println("Admin position: " + admin.getPosition());
scanner.close();
} catch (Exception e) {
System.out.println("An error occurred: " + e.getMessage());
}
}
}
```