Question

我的地图将字符串存储为键，将对象的LinkedList存储为值。现在，我需要将此数据存储在数据库表中。我的地图数据类似于-

键：值

id : [2, 3, 4, 5]

name : [Rohit, Iravati, Uttam, Sushil]

jobrole : [Software Engineer, Software Engineer, Manager, Director]

salary : [100, 100, 100, 100]

我的表结构是-

[ID，名称，JOBROLE，薪水]

我没有得到应该如何从地图中读取数据以在给定查询下创建以将此地图数据存储在表中的方法-

insert into DBROLTA.Employee(id, name, jobrole, salary) values(2, 'Rohit', 'Software Engineer','100');
insert into DBROLTA.Employee(id, name, jobrole, salary) values(3, 'Iravati', 'Software Engineer','100');
insert into DBROLTA.Employee(id, name, jobrole, salary) values(4, 'Uttam', 'Manager','100');

任何人都可以帮助我。

Answer 1

要在地图中存储键和相应的值数组，请将键存储为id，将自定义对象存储为值。

其中自定义对象是具有id，name，jobrole和Salary属性的对象。

创建Map并将自定义对象存储到ID。因此，您可以轻松地检索对象并创建sql语句并执行它们。

 Map<Interger, CustomObject> = new HashMap<Integer, CustomObject>

对于多个插入式查询执行，请使用批处理插入和批处理执行方法，这是为了避免多个数据库命中。

请参考：How to execute multiple SQL statements from java进行批量更新操作。

Answer 2

您可以使用for循环遍历所有数据并一次构建一个查询字符串

也许是这样

for(int j = 0; j < mapOfData.get("ID").length(); j++){
     strID = mapOfData.get("ID").get(j);
     strName = mapOfData.get("Name").get(j);

     query = "INSERT INTO TABLE VALUES (" + strID + ", " + strName + ")";
}

您遍历整个地图（假设地图中没有丢失数据），访问每个链表，并从中获取值。

Answer 3

public static void main(String[] args) {
    Map<String, LinkedList<Object>> map = new HashMap<>();
    LinkedList<Object> data = new LinkedList<>();
    data.add(2);
    data.add(3);
    map.put("id", data);

    data = new LinkedList<>();
    data.add("Rohit");
    data.add("Iravati");
    map.put("name", data);

    data = new LinkedList<>();
    data.add("SE");
    data.add("SSE");
    map.put("jobrole", data);

    data = new LinkedList<>();
    data.add(100);
    data.add(200);
    map.put("salary", data);

    for (int i = 0; i < map.get("id").size(); i++) {
        Object id = map.get("id").get(i);
        Object name = map.get("name").get(i);
        Object jobrole = map.get("jobrole").get(i);
        Object salary = map.get("salary").get(i);
        // TODO Use above values to create your query.
        System.out.println(id + "-" + name + "-" + jobrole + "-" + salary);
    }

}

Answer 4

这是一种不好的方法，但是您当前的数据结构并没有给我太多选择。

public static void main(String[] args) {

    //GIVEN
    Map<String, LinkedList<Object>> data = new HashMap<>();
    data.put("id", Stream.of(1, 2, 3)
            .collect(Collectors.toCollection(LinkedList::new)));
    data.put("name", Stream.of("a", "b", "c")
            .collect(Collectors.toCollection(LinkedList::new)));
    data.put("jobrole", Stream.of("x", "y", "z")
            .collect(Collectors.toCollection(LinkedList::new)));
    data.put("salary", Stream.of(10.0, 20.0, 30.0)
            .collect(Collectors.toCollection(LinkedList::new)));

    //Let's fix your data structure first
    Employee[] employeesArr = null;
    for (Map.Entry<String, LinkedList<Object>> entry : data.entrySet()) {
        int count = 0;
        if (employeesArr == null) {
            employeesArr = new Employee[entry.getValue().size()];
            for (int i = 0; i < employeesArr.length; i++) {
                employeesArr[i] = new Employee();
            }
        }
        switch (entry.getKey()) {
            case "id":
                for (Object o : entry.getValue()) {
                    employeesArr[count++].setId((Integer) o);
                }
                break;
            case "name":
                for (Object o : entry.getValue()) {
                    employeesArr[count++].setName((String) o);
                }
                break;
            case "jobrole":
                for (Object o : entry.getValue()) {
                    employeesArr[count++].setRole((String) o);
                }
                break;
            case "salary":
                for (Object o : entry.getValue()) {
                    employeesArr[count++].setSalary((Double) o);
                }
                break;
        }
    }

    //employeesArr is a much better data structure
    for (int i = 0; i < employeesArr.length; i++) {
        //use PreparedStatement or an ORM
        System.out.println("insert into DBROLTA.Employee(id, name, jobrole, salary) values ("
                + employeesArr[i].getId() + ", '"
                + employeesArr[i].getName() + "', '"
                + employeesArr[i].getRole() + "', "
                + employeesArr[i].getSalary()
                + ");");
    }

}

Employee.java

public class Employee {
    private int id;
    private String name;
    private String role;
    private double salary;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    //other getters/setters
}

如何将Map <string，linkedlist <object =“” >>数据存储到数据库表中？

4 个答案: