Question

我正在尝试为ArrayList编写类型处理程序，但这给了我任何一个帮助我的错误。

我想将ArrayList作为VARCHAR存储在DB中，并将其作为ArrayList检索。

package com.someweb.typehandlers;

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

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;
//@MappedTypes(java.util.ArrayList.class)

//@MappedJdbcTypes(JdbcType.VARCHAR)
public class StringArrayListTypeHandler extends BaseTypeHandler<ArrayList<String>> 
{
@Override
public void setNonNullParameter(PreparedStatement ps, int i, ArrayList<String> parameter, JdbcType jdbcType)
        throws SQLException {
    // TODO Auto-generated method stub
    StringBuilder str=new StringBuilder(parameter.toString());
    ps.setString(i,str.substring(1,str.length()-1));

}

@Override
public ArrayList<String> getNullableResult(ResultSet rs, String columnName) throws SQLException {
    // TODO Auto-generated method stub

    String str=rs.getString(columnName);

    ArrayList<String> roles=new ArrayList<String>();
    String[] rolesarray=str.split(",");
    for(String s:rolesarray)
    roles.add(s);

    return roles;
}

@Override
public ArrayList<String> getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
    // TODO Auto-generated method stub
    String str=rs.getString(columnIndex);

    ArrayList<String> roles=new ArrayList<String>();
    String[] rolesarray=str.split(",");
    for(String s:rolesarray)
    roles.add(s);

    return roles;   }

@Override
public ArrayList<String> getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
    // TODO Auto-generated method stub
    String str=cs.getString(columnIndex);

    ArrayList<String> roles=new ArrayList<String>();
    String[] rolesarray=str.split(",");
    for(String s:rolesarray)
    roles.add(s);

    return roles;   }

}

我是myBatis的新手。所以有人帮助我，我无法弄清楚如何实现这一目标

我的dto课程看起来像这样

package com.someweb.dto;

import java.security.Principal;
import java.sql.Array;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

public class UserDTO implements Principal {

private int id;
private String username;

private String name;
private String password;
private String token;
private String email;
private boolean isAuthenticated;
private boolean is_active;

private List<String> role;
private String phone;
public String getToken() {
    return token;
}

public void setToken(String token) {
    this.token = token;
}

public String getUsername() {
    return username;
}

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

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public boolean isAuthenticated() {
    return isAuthenticated;
}

public void setAuthenticated(boolean isAuthenticated) {
    this.isAuthenticated = isAuthenticated;
}

public List<String> getRole() {
    return role;
}



public void setRole(List<String> role) {
    this.role = role;
}
public void setRole(String role) {
     this.role.add(role);
}
 public void addRole(String role)
 {
     if(role==null) this.role=new ArrayList<String>();
     this.role.add(role);

 }

public int getId() {
    return id;
}

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

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getPassword() {
    return password;
}

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

public boolean isIs_active() {
    return is_active;
}

public void setIs_active(boolean is_active) {
    this.is_active = is_active;
}

public String getPhone() {
    return phone;
}

public void setPhone(String phone) {
    this.phone = phone;
}
}

我的mapper文件代码是这样的

    <resultMap id="userResultMap" type="com.someweb.dto.UserDTO">
  <id property="id" column="id" />
  <result property="username" column="username"/>
  <result property="password" column="password"/>
  <result property="email" column="email"/>
 <result property="phone" column="phone"/>
 <result property="is_active" column="is_active"/>
  <collection property="role" ofType="java.lang.String" >
        <result column="role" />
    </collection>

</resultMap>
<insert id="insertUser" useGeneratedKeys="true"
    keyProperty="id">
  insert into tblusers(username,password,email,phone,role,is_active) 
  values(#{username},#{password},#{email},#{phone},#{role,typeHandler=com.someweb.typehandlers.StringArrayListTypeHandler},#{is_active})
</insert>

现在插入执行。但是，当将数据检索到DTO时，整个角色字段已作为ArrayList中的单个字符串获取。

如果删除typeHandler属性，我会收到错误

Cause: org.postgresql.util.PSQLException: Can't infer the SQL type to use for an instance of java.util.ArrayList. Use setObject() with an explicit Types value to specify the type to use.

Answer 1

我找到了解决方案

Collection用于获取一对多关系的许多方面因此它总是返回多个记录中的对象集合

在我的情况下，我需要来自记录的单个单元格的ArrayList。我必须删除<collection>标记并且只需使用<result>标记，如下所示代码工作

<result property="role" column="role" javaType="java.util.ArrayList"
        jdbcType="VARCHAR" typeHandler="com.greenflight.typehandlers.StringArrayListTypeHandler" />

在myBatis

1 个答案: