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![新增权限分类]()
新增权限分类 @Override public R insert(Role role) { if (role.getRoleName() == null || role.getRoleName().isEmpty()) { return R.failure().message("缺少必要的参数"); } // 查询 role_id 的最大值 QueryWrapper<Role> queryWrapper = new QueryWrapper<>(); queryWrapper.select("max(role_id) as role_id"); try { Role maxRole = roleMapper.selectOne(queryWrapper); // 得到最 role_id + 1, 将其作为新的 role_id 并添加到数据中 Integer newRoleId = maxRole.getRoleId() + 1; // 校验提交的新的权限名称是否已经存在 UpdateWrapper<Role> wapper = new UpdateWrapper<>(); wapper.eq("role_name", role.getRoleName()); List<Role> list = roleMapper.selectList(wapper); // 不存在则开始增加 if (list == null) { role.setRoleId(newRoleId); role.setRoleName(role.getRoleName()); // 执行新增操作 int i = roleMapper.insert(role); if (i > 0) { return R.success().message("添加成功"); } return R.failure().message("未知错误"); } return R.failure().message("错误，此权限已存在"); } catch (Exception e) { return R.failure().message("发生意料之外的错误，err: " + e); } } -
![修改信息，只允许部分参数，其余参数屏蔽]()
修改信息，只允许部分参数，其余参数屏蔽 @Override public R update(OrderHeader orderHeader) { // 检查 id 是否存在，检查其余的参数是空或 null // 使用完全导入以避免 StringUtils 冲突 com.mysql.jdbc.StringUtils if (org.apache.commons.lang3.StringUtils.isAnyEmpty(orderHeader.getClient(), orderHeader.getWhichDay(), orderHeader.getSignedAt()) || orderHeader.getId() == null || orderHeader.getId().isEmpty()) { return R.failure().message("缺少必要的参数"); } // 查询原始数据 OrderHeader originalOrderHeader = orderHeaderMapper.selectById(orderHeader.getId()); if (originalOrderHeader == null) { return R.failure().message("找不到要更新的数据"); } // 要修改的 originalOrderHeader.setClient(orderHeader.getClient()); originalOrderHeader.setWhichDay(orderHeader.getWhichDay()); originalOrderHeader.setSignedAt(orderHeader.getSignedAt()); // 不允许修改的 originalOrderHeader.setSumHowMuch(null); originalOrderHeader.setSumHowMoneyTheoretical(null); originalOrderHeader.setIsDelete(null); originalOrderHeader.setIsLock(null); // 执行 try { int result = orderHeaderMapper.updateById(originalOrderHeader); if (result < 1) { return R.failure().message("更新信息失败"); } return R.success().message("息更新成功"); } catch (Exception e) { return R.failure().message("发生意料之外的错误，err: " + e); } } -
![java - 日历打印]()
java - 日历打印 {card-default label="Work2_1.java" width=""}import java.text.ParseException; import java.util.Calendar; import java.util.Scanner; public class Work2_1 { public static class TestCalender { public static void main(String[] args) throws ParseException { Scanner scanner = new Scanner(System.in); System.out.println("请输入年份:"); int year = scanner.nextInt(); Calendar date = Calendar.getInstance(); year = date.get(Calendar.YEAR); int m = 1; while (m < 13) { int month = m; Calendar cal = Calendar.getInstance(); cal.clear(); cal.set(Calendar.YEAR, year); cal.set(Calendar.MONTH, month - 1); int count = cal.getActualMaximum(Calendar.DAY_OF_MONTH); int week = cal.get(Calendar.DAY_OF_WEEK); System.out.printf("\t\t%d年%d月\n", year, month); System.out.print("日\t一\t二\t三\t四\t五\t六\n"); int i; for (i = 0; i < week - 1; i++) { System.out.print("\t"); } for (int j = 1; j <= count; j++) { System.out.print(j + "\t"); if ((i + j) % 7 == 0) { System.out.println(); } } System.out.println(); m++; } } } }{/card-default}{card-describe title="运行结果"}略{/card-describe} -
![java - 简单运算（加减乘除）]()
java - 简单运算（加减乘除） {card-default label="Work1_2.java" width=""}import java.util.Scanner; public class Work1_2 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("请输入第一个数："); double num1 = scanner.nextDouble(); System.out.println("请输入第二个数："); double num2 = scanner.nextDouble(); System.out.println("请输入要进行的运算的编号 1：加 2：减 3：乘 4：除"); int num3 = scanner.nextInt(); switch (num3) { case 1: double num4 = num1 + num2; System.out.println(num1 + "+" + num2 + "=" + num4); break; case 2: double num5 = num1 - num2; System.out.println(num1 + "-" + num2 + "=" + num5); break; case 3: double num6 = num1 * num2; System.out.println(num1 + "*" + num2 + "=" + num6); break; case 4: double num7 = num1 / num2; System.out.println(num1 + "/" + num2 + "=" + num7); break; } } }{/card-default}{card-describe title="运行结果"}请输入第一个数：12请输入第二个数：4请输入要进行的运算的编号 1：加 2：减 3：乘 4：除412.0/4.0=3.0{/card-describe} -
![方法重载 - OverloadDemo - 4.3.3]()
方法重载 - OverloadDemo - 4.3.3 {card-default label="OverloadDemo.java" width=""}public class OverloadDemo { public void display(int a) { System.out.println("a = " + a); }// 如果没有本段int a，则在结尾的obj.display中，输出的结果自动转化为double类型 public void display(double d) { System.out.println("d = " + d); } public void display() { System.out.println("无参数构造法");// 本句在被注释或删除后，将变为无参数构造法 } public void display(int a, int b) { System.out.println("a = " + a + " ,b =" + b); } // 测试方法重载的使用 public static void main(String[] args) { OverloadDemo obj = new OverloadDemo(); obj.display(); obj.display(10);// 取决于是否有int，无int则会被转化为double类型 obj.display(20,30); obj.display(0.2); } }{/card-default}{card-describe title="运行结果"}无参数构造法a = 10a = 20 ,b =30d = 0.2{/card-describe} -
![类和对象 - NULL - EmployeeDemo - DEMO3 - 4.1 - 4.2]()
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![java - ContinueDemo - ContinueStartDemo - 3.2.5.3 - 3.2.5.4]()
