我正在尝试为 ArrayList 编写类型处理程序，但这给了我错误任何人都可以帮助我。
我想将 ArrayList 作为 VARCHAR 存储在数据库中并将其作为 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点
我的 dto 类看起来像这样
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;
}
}
我的映射器文件代码是这样的
<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>
现在执行插入。但是，当将数据检索到 DTO 时，整个角色字段将作为 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.
