利用反射生成 MyBatisPlus中QueryWrapper动态条件

问题

在MyBatisPlus中经常会用到如下所示的代码来构造查询条件：

QueryWrapper queryWrapper = new QueryWrapper();

if (userQuery.getId() != null) {
    queryWrapper.eq("id", userQuery.getId());
}
if (userQuery.getName() != null) {
    queryWrapper.like("name", userQuery.getName());
}
if (userQuery.getNickname() != null) {
    queryWrapper.like("nickname", userQuery.getNickname());
}
if (userQuery.getAccount() != null) {
    queryWrapper.eq("account", userQuery.getAccount());
}
if (userQuery.getGender() != null) {
    queryWrapper.eq("gender", userQuery.getGender());
}
if (userQuery.getBirth1() != null) {
    queryWrapper.ge("birth", userQuery.getBirth1());
}
if (userQuery.getBirth2() != null) {
    queryWrapper.le("birth", userQuery.getBirth2());
}
if (userQuery.getTel() != null) {
    queryWrapper.eq("tel", userQuery.getTel());
}
if (userQuery.getEmail() != null) {
    queryWrapper.eq("email", userQuery.getEmail());
}
if (userQuery.getQq() != null) {
    queryWrapper.eq("qq", userQuery.getQq());
}
if (userQuery.getWechat() != null) {
    queryWrapper.eq("wechat", userQuery.getWechat());
}
if (userQuery.getHomePage() != null) {
    queryWrapper.eq("home_page", userQuery.getHomePage());
}
//.........
baseMapper.selectPage(page, queryWrapper);

大量这样的代码，可以通过如下所示的反射技术生成，从而一劳永安逸：

优化方案

public class APP{

    public static void main(String[] args) throws Exception {
        QueryWrapper queryWrapper = new QueryWrapper();
        Dept dept = Dept.builder()
                .deptno(1234)
//                .dname("sales")
                .loc("NEWYORK")
                .build();

        Method[] methods = Dept.class.getDeclaredMethods();
        for (Method method : methods) {
            String methodName = method.getName();
            if (methodName.contains("get")) {
                Object res = method.invoke(dept, null);
                if(res != null){
                    String columnName = getColumnName(methodName);
                    queryWrapper.eq(columnName,res);
                }
            }
        }

        System.out.println(queryWrapper);//在此处设置断点，可以查看保存到QueryWrapper中的值
    }

    // 根据getter方法名得到对应表的字段名
    public static String getColumnName(String name) {
        StringBuffer sb = new StringBuffer();
        name = name.substring(3, name.length()); //去掉get前缀
        char[] chars = name.toCharArray();
        for (int i = 0; i  65 && item