Question

我需要你帮助从List中获取值并将它们附加到insert语句中。我有一个名为Employee的课程：

public class Employee {
    private Integer id; //Getter and Setter
    private String name;//Getter and Setter
    private String remarks;//Getter and Setter
    private boolean disable;//Getter and Setter

public Employee(Integer id, String name,  String remarks, boolean disable){
            this.id = id;
            this.name = name;
            this.remarks=remarks;
            this.disable=disable;
    }

在bean中，我为employeeList生成随机数：

private List<Employee> employeeList;

private List<Employee> selectedEmployees;

public test() {
        super();
        employeeList = new ArrayList<Employee>();

    for (int i = 1; i <= 10; i++) {
        employeeList.add(new Employee(i, "Name " + i, "Remarks " + i, true));
    }

}

所选值将存储在列表selectedEmployees中。现在我想编写一个新方法来打印获取的值，然后将它们附加到insert语句以将选定的值插入表中。

public void updateRecords() {
    System.out.println("Size =" + selectedEmployees.size());
    //Here I need help to print the values of the list and then to append them to an insert statement to the table employees

insert into employees (id,name,remarks) values ();
}

Answer 1

您可以使用for each语句来达到此目的，但是因为您已声明了您的成员变量private而无法阅读它们，因此您应该声明您的班级成员public或声明getter读取成员数据

Connection connection = DriverManager.getConnection(...);
for(Employee e:selectedEmployees)
{
   System.out.println("Employee id: "+e.id+" name: " + e.name+ " remarks: " + e.remarks);
   String sql = "INSERT INTO employees (id,name,remarks) VALUES(?,?,?);";
   PreparedStatement statement = connection.prepareStatement(sql);
   statement.setInt(1, e.id);
   statement.setString(2, e.name);
   statement.setString(3, e.remarks);
   statement.executeUpdate();
}

Answer 2

对于arraylist，您将使用此语法。 X是列表中该员工的编号，那么您必须为变量创建getter和setter。

 Employees.get(x).getName ();

然后，您将创建一个雇用对象，然后像这样插入。

  Employee dude = new employee(1, name, remarks,   disable); 

  Employees.add(dude);

Answer 3

PreparedStatement#executeBatch是解决问题的最佳人选。

您可以像这样实现：

public void updateRecords(List<Employee> employees) {
    System.out.println("Size =" + selectedEmployees.size());
    //Here I need help to print the values of the list and then to append them   to an insert statement to the table employees

  String query = "insert into employees (id,name,remarks) values (?,?,?)";

  Connection con = ... // establish DB connection
  PreparedStatement ps = con.prepareStatement(query);
  for(Employee emp : employees) {
      ps.setNumber(1, emp.getId());
      ps.setString(2, emp.getName());
      ps.setString(3, emp.getRemarks());          
      ps.addBatch();
  }

  ps.executeBatch();

}

上面的代码只是一个示例，您需要将其编译为可编辑的，并且还需要进行适当的异常处理。

希望这有帮助。

如何从java List中获取值

3 个答案: