服务器遇到一个意外的情况，阻止它完成请求。

Question

服务器遇到一个意外的情况，阻止它完成请求。
用java写管理系统运行代码时报错了，这该怎么解决？

Answer 1

student中的有个字段无法转换，建议使用jdk内置的Date接收，或者直接使用string接收

Answer 2

请问具体解决方式是什么？

Answer 3

你贴下你的student类代码，现在也看不出来你是哪个字段报的错

Answer 4

package com.tom.demo.dao.impl;

import com.sun.xml.internal.messaging.saaj.util.SAAJUtil;
import com.tom.demo.dao.IStudentDao;
import com.tom.demo.domain.Pagination;
import com.tom.demo.domain.Student;
import com.tom.demo.utils.JdbcUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.*;


public class StudentDaoImpl implements IStudentDao {
    private JdbcTemplate jt = new JdbcTemplate(JdbcUtils.getDataSource());

    @Override
    public List<Student> findAll() {
        String sql = "select * from student";
        return jt.query(sql, new BeanPropertyRowMapper<>(Student.class));
    }

    @Override
    public boolean deleteStu(int id) {
        String sql = "delete from student where id = ?";
        int count = jt.update(sql, id);
        return count == 1;
    }

    @Override
    public Student findStuById(int id) {
        String sql = "select * from student where id = ?";
        List<Student> studentList = jt.query(sql, new BeanPropertyRowMapper<>(Student.class), id);
        return studentList.size() == 0 ? null : studentList.get(0);
    }

    @Override
    public boolean updateStuById(Student student) {
        String sql = "update student set username = ?, age = ?, gender = ?, " +
                "qq = ?, email =  ? where id = ?";
        int count = jt.update(sql, student.getUsername(),
                student.getAge(), student.getGender(),
                student.getQq(), student.getEmail(), student.getId());
        return count == 1;
    }

    @Override
    public boolean addStudent(Student student) {
        String sql = "insert into student(number,username,age, gender, qq, email)" +
                "values(?, ?, ?,?, ?,?)";

        int count = jt.update(sql, student.getNumber(), student.getUsername(), student.getAge(),
                student.getGender(), student.getQq(), student.getEmail());
        return count == 1;
    }

    @Override
    public boolean batchDeleteStu(List<Object[]> stuList) {
        String sql = "delete from student where id = ?";
        int[] updateCounts = jt.batchUpdate(sql, stuList);
        System.out.println("删除了: " + Arrays.toString(updateCounts));
        return updateCounts.length != 0;
    }

    @Override
    public long counts() {
        String sql = "select count(id) from student";
        Long counts = jt.queryForObject(sql, Long.class);
        return counts;
    }

    @Override
    public Pagination<Student> findStu(int curPageIndex, int pageNumbers) {
        Pagination<Student> pagination = new Pagination<>();
        // 获取数据库的总条数
        long counts = this.counts();
        System.out.println("一共有: " + counts);
        //    1. 数据条数, 查询数据库去;
        // a. 把总条数设置到分页对象当中去;
        pagination.setTotal(counts);
        // b. 计算总页码数
        int totalPages = (int) (counts % pageNumbers == 0 ? counts / pageNumbers : (counts / pageNumbers) + 1);
        System.out.println("计算出来的总页数是: " + totalPages);
        // 设置到页对象当中去
        pagination.setTotalPages(totalPages);
        pagination.setCurPageIndex(curPageIndex);
        pagination.setPageNumbers(pageNumbers);

        // 封装分页对象中的list集合, 这里装的是Student对象;
        int curIndex = (curPageIndex -1) * pageNumbers;
        String sql = "select * from student limit ?,?";
        List<Student> studentList = jt.query(sql, new BeanPropertyRowMapper<>(Student.class), curIndex, pageNumbers);
        System.out.println("得到的学生对象列表是: " + studentList);
        pagination.setList(studentList);
        return pagination;
    }

    @Override
    public Pagination conditionQuery(Map<String, String[]> condition) {
        Pagination<Student> pagination = new Pagination<>();
        // where 1 = 1
        Set<String> keySet = condition.keySet();
        StringBuffer sb = new StringBuffer();
        // 拼接动态sql
        // 这个sql语句后边的where 1 = 1, 不影响查询操作; 返回结果
        // 最终是`select * from student`. where 1 = 1是为了拼接后边的sql, 直接and 不报错. 如果不 1= 1,则
        // where and 这个sql语句不合法;
        sb.append("select * from student where 1 = 1");

        // String sql = "select * from student where 1 = 1 and username like "%王%" and gender = "女"
        // key: username
        //      gender
        //      email
        for (String key1 : keySet) {
            String key = key1.trim();
            String value = condition.get(key1)[0].trim();
            if(!value.equals("")) {
                sb.append(" and ").
                        append(key).
                        append(" like ").
                        append("\"").
                        append("%").
                        append(value).
                        append("%").
                        append("\"");
            }
        }

        // 拼接动态sql的注意事项:
        // 1. 注意语法规范;
        // 2. 空格注意一下;
        String sql = sb.toString() + " limit 0,20" ;
        System.out.println(sql);
        // 拿到了动态的sql语句; 下边根据sql语句进行查询操作. 然后封装对象;
        List<Student> studentList = jt.query(sql, new BeanPropertyRowMapper<>(Student.class));

        // 查询出来的总条数, 也就是分页实体类当中的总条数.
        int counts = 0;
        int totalPage = 0;
        int curPageIndex = 1;
        int pageNumbers = 20;
        if(studentList.size() != 0){
            counts = studentList.size();
            //直接写死了. 不太好. 先暂时这样
            totalPage = counts % pageNumbers == 0 ? counts / pageNumbers : counts / pageNumbers + 1;
        }

        pagination.setList(studentList);
        pagination.setTotal(counts);
        pagination.setTotalPages(totalPage);
        pagination.setCurPageIndex(curPageIndex);
        pagination.setPageNumbers(pageNumbers);

        return pagination;
    }


}