mybatis的学习和使用--TypeHandler的使用--使用自定义的handler(6)

在mybatis的学习和使用--TypeHandler的使用--使用自定义的handler(5)中实现了自定义的java.util.Date和varchar的转换。

本文章再介绍下如何实现java.util.List和varchar的转换，其实也比较简单。

代码示例：https://github.com/wangjiuong/MybatisDemo/tree/master/MyBatisListTypeHandler

建表语句如下：

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for `t_user_list_handler`
-- ----------------------------
DROP TABLE IF EXISTS `t_user_list_handler`;
CREATE TABLE `t_user_list_handler` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) DEFAULT NULL,
  `password` varchar(255) DEFAULT NULL,
  `hobies` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=21 DEFAULT CHARSET=utf8;

bean对象设计如下：

package com.wang.MyBatis.model;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;

public class UserBean implements Serializable {
    private Integer id;
    private String username;
    private String password;
    private List<String> hobies;

    public UserBean() {

    }

    public UserBean(String username, String password, ArrayList<String> hobies) {
        this.username = username;
        this.password = password;
        this.hobies = hobies;

    }

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public List<String> getHobies() {
        return hobies;
    }

    public void setHobies(List<String> hobies) {
        this.hobies = hobies;
    }

    public String toString() {
        return new Gson().toJson(this);
    }
}

其中用到的gson实现了序列化。

 

MyListTypeHandler的实现如下：

package com.wang.MyBatis.typeHandler;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;

@MappedJdbcTypes({ JdbcType.VARCHAR })
@MappedTypes({ List.class })
public class MyListTypeHandler extends BaseTypeHandler<List<String>> {

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, List<String> parameter, JdbcType jdbcType)
            throws SQLException {
        System.out.println("1");
        ps.setString(i, parameter.toString());
    }

    @Override
    public List<String> getNullableResult(ResultSet rs, String columnName) throws SQLException {
        // TODO Auto-generated method stub
        String columnConetnt = rs.getString(columnName);
        List<String> result = new ArrayList<String>();
        if (null != columnName) {
            String subString = columnConetnt.substring(1, columnConetnt.length() - 1);
            if (null != subString) {
                String[] hobies = subString.split(",");
                for (String hoby : hobies) {
                    result.add(hoby);
                }
            }
        }
        return result;
    }

    @Override
    public List<String> getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        // TODO Auto-generated method stub
        System.out.println("3" + rs.getString(columnIndex));
        return null;
    }

    @Override
    public List<String> getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        // TODO Auto-generated method stub
        System.out.println("4" + cs.getString(columnIndex));
        return null;
    }
}

代码执行结果如下：

数据库中信息如下：

console中输出如下：