Java代码实现行转列

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
public class Row2Line {

    public static void main(String[] args) throws IntrospectionException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {  
        //你提供的对象列表，需要转换的原数据 
        List<StudentGrand> StudentGrandList = getStudentGrandList();  
        //实现行转列的算法
        List<List<String>> convertedTable = convert(StudentGrandList);
        //打印转换后的集合，查看结果
        print(convertedTable);  
        //剩下的可以根据实际需求，将转换好的集合传给前端、或随意处理
    }  
  
    private static List<List<String>> convert(List<StudentGrand> StudentGrandList)  
            throws IntrospectionException, IllegalAccessException, InvocationTargetException {//取得StudentGrand的属性，当然你也可以用list = {"id", "name", ...}  
        Field[] declaredFields = StudentGrand.class.getDeclaredFields();
          
        List<List<String>> convertedTable = new ArrayList<List<String>>();  
          
        //多少个属性表示多少行，遍历行  
        for (Field field : declaredFields) {
            field.setAccessible(true);  
            ArrayList<String> rowLine = new ArrayList<String>();
            //list<T>多少个StudentGrand实体类表示有多少列，遍历列
            for (int i = 0, size = StudentGrandList.size(); i < size; i++) {
                //每一行的第一列对应StudentGrand字段名  
                //所以新table的第一列要设置为字段名
                if(i == 0){  
                    rowLine.add(field.getName());  
                }  
                //新table从第二列开始，某一列的某个值对应旧table第一列的某个字段
                else{  
                    StudentGrand StudentGrand = StudentGrandList.get(i);  
                    String val = (String) field.get(StudentGrand);//grand为int会报错
                    System.out.println(val);
                    rowLine.add(val);  
                }  
            }  
            convertedTable.add(rowLine);  
        }  
        return convertedTable;  
    }
    //测试用数据，实际应该从数据库查询，传过来的
    private static List<StudentGrand> getStudentGrandList () {  
        List<StudentGrand> list = new ArrayList<StudentGrand>();
        list.add(new StudentGrand("001", "toni", "语文", "98"));
        list.add(new StudentGrand("001", "toni", "数学", "98"));
        list.add(new StudentGrand("001", "toni", "外语", "98"));
        list.add(new StudentGrand("001", "toni", "体育", "98"));
        list.add(new StudentGrand("006", "amy", "语文", "98"));
        list.add(new StudentGrand("006", "amy", "数学", "98"));
        list.add(new StudentGrand("006", "amy", "外语", "98"));
        list.add(new StudentGrand("006", "amy", "体育", "98"));
        list.add(new StudentGrand("003", "安东尼", "语文", "98"));
        list.add(new StudentGrand("003", "安东尼", "数学", "98"));
        list.add(new StudentGrand("003", "安东尼", "外语", "98"));
        list.add(new StudentGrand("003", "安东尼", "体育", "98"));
        return list;  
    }  
    //打印查看结果
    private static void print(List<List<String>> convertedTable) {
        //String json = JSONArray.formObject(convertedTable).toString();
        for (List<String> list : convertedTable) { 
            for (String string : list) {
                System.out.print(string+"  ");  
            }  
            System.out.println();  
        }  
    }  
}