pojo类

package com.sg.bean;public class User {    /**     * 用户ID     */    private String userID;        /**     * 用户名      */    private String userName;        /**     * 用户状态     * @see com.sg.bean.EnumStatus     */    private EnumStatus status;        public String getUserID() {        return userID;    }    public void setUserID(String userID) {        this.userID = userID;    }    public String getUserName() {        return userName;    }    public void setUserName(String userName) {        this.userName = userName;    }    public EnumStatus getStatus() {        return status;    }    public void setStatus(EnumStatus status) {        this.status = status;    }}

枚举类

package com.sg.bean;public enum EnumStatus {    NORMAL("1", "正常"),    DELETE("2", "删除"),    LOGICDEL("3", "注销");        private EnumStatus(String code, String description) {        this.code = code;        this.description = description;    }    private String code;        private String description;    public String getCode() {        return code;    }    public void setCode(String code) {        this.code = code;    }    public String getDescription() {        return description;    }    public void setDescription(String description) {        this.description = description;    }}

重点来了——ibatis类型转换接口实现

先看一下源码中的注释

com.ultrapower.common.ibatis.sqlmap.client.extensions.TypeHandlerCallbackA simple interface for implementing custom type handlers. Using this interface, you can implement a type handler that will perform customized processing before parameters are set on a PreparedStatement and after values are retrieved from a ResultSet. Using a custom type handler you can extend the framework to handle types that are not supported, or handle supported types in a different way. For example, you might use a custom type handler to implement proprietary BLOB support (e.g. Oracle), or you might use it to handle booleans using "Y" and "N" instead of the more typical 0/1. EXAMPLE Here's a simple example of a boolean handler that uses "Yes" and "No".  public class YesNoBoolTypeHandlerCallback implements TypeHandlerCallback { 
   private static final String YES = "Yes";   private static final String NO = "No"; 
   public Object getResult(ResultGetter getter) throws SQLException {     String s = getter.getString();     if (YES.equalsIgnoreCase(s)) {       return new Boolean (true);     } else if (NO.equalsIgnoreCase(s)) {       return new Boolean (false);     } else {       throw new SQLException ("Unexpected value " + s + " found where "+YES+" or "+NO+" was expected.");     }   } 
   public void setParameter(ParameterSetter setter, Object parameter) throws SQLException {     boolean b = ((Boolean)parameter).booleanValue();     if (b) {       setter.setString(YES);     } else {       setter.setString(NO);     }   } 
   public Object valueOf(String s) {     if (YES.equalsIgnoreCase(s)) {       return new Boolean (true);     } else if (NO.equalsIgnoreCase(s)) {       return new Boolean (false);     } else {       throw new SQLException ("Unexpected value " + s + " found where "+YES+" or "+NO+" was expected.");     }   } 
 }

针对User对象中的EnumStatus，他的转换类如下

package com.sg.util;import java.sql.SQLException;import java.sql.Types;import com.ibatis.sqlmap.client.extensions.ParameterSetter;import com.ibatis.sqlmap.client.extensions.ResultGetter;import com.ibatis.sqlmap.client.extensions.TypeHandlerCallback;import com.sg.bean.EnumStatus;public class EnumStatusHandler implements TypeHandlerCallback {    public Object getResult(ResultGetter getter) throws SQLException {        EnumStatus result = null;        if(!getter.wasNull() && getter.getObject()!= null) {            for(EnumStatus status : EnumStatus.values()) {                if(status.getCode().equals(getter.getObject())) {                    result = status;                    break;                }            }        }        return result;    }    public void setParameter(ParameterSetter setter, Object obj)            throws SQLException {        if(obj == null) {            setter.setInt(Types.INTEGER);        }else {            EnumStatus status = (EnumStatus)obj;            setter.setString(status.getCode());        }    }    public Object valueOf(String s) {        return s;    }}

ibatis配置文件声明

1. 没有破坏pojo的纯净，pojo对象的扩展和可维护性更高；
2. 枚举类加强了User对象对属性类型的把控，开发这不用担心其他人在status属性中放错值了；
3. pojo的扩展性增强，比如现在前台展示需要展示名称，开发者只需对枚举进行简单的读取就可以将数据库中的0、1转为自然语言；
4. 脱离实体的限制，比如前台需要展示status的可选值，枚举类便可以首当其冲。