（六）加密的字段类型入库

在中处理了加密字段，但如果要把这个加密字段使用mybatis入库，则会报以下错误：

caused by: java.lang.illegalstateexception: type handler was null on parameter mapping for property 'secret'. it was either not specified and/or could not be found for the javatype (github.zhangq.secretstringtest.config.secretstring) : jdbctype (null) combination.
    at org.apache.ibatis.mapping.parametermapping$builder.validate(parametermapping.java:119)
    at org.apache.ibatis.mapping.parametermapping$builder.build(parametermapping.java:104)
    at org.apache.ibatis.builder.sqlsourcebuilder$parametermappingtokenhandler.buildparametermapping(sqlsourcebuilder.java:123)
    at org.apache.ibatis.builder.sqlsourcebuilder$parametermappingtokenhandler.handletoken(sqlsourcebuilder.java:67)
    at org.apache.ibatis.parsing.generictokenparser.parse(generictokenparser.java:78)
    at org.apache.ibatis.builder.sqlsourcebuilder.parse(sqlsourcebuilder.java:45)
    at org.apache.ibatis.scripting.defaults.rawsqlsource.<init>(rawsqlsource.java:46)
    at org.apache.ibatis.scripting.defaults.rawsqlsource.<init>(rawsqlsource.java:40)
    at org.apache.ibatis.scripting.xmltags.xmlscriptbuilder.parsescriptnode(xmlscriptbuilder.java:72)
    at org.apache.ibatis.scripting.xmltags.xmllanguagedriver.createsqlsource(xmllanguagedriver.java:44)
    at org.apache.ibatis.builder.xml.xmlstatementbuilder.parsestatementnode(xmlstatementbuilder.java:94)
    at org.apache.ibatis.builder.xml.xmlmapperbuilder.buildstatementfromcontext(xmlmapperbuilder.java:135)
    at org.apache.ibatis.builder.xml.xmlmapperbuilder.buildstatementfromcontext(xmlmapperbuilder.java:128)
    at org.apache.ibatis.builder.xml.xmlmapperbuilder.configurationelement(xmlmapperbuilder.java:118)
    ... 82 more

简单看就是自定义的类型识别不了，这个时候我们就可以用到mybatis的typehandler了，typehandler有4个参数：

public interface typehandler<t> {

  void setparameter(preparedstatement ps, int i, t parameter, jdbctype jdbctype) throws sqlexception;

  t getresult(resultset rs, string columnname) throws sqlexception;

  t getresult(resultset rs, int columnindex) throws sqlexception;

  t getresult(callablestatement cs, int columnindex) throws sqlexception;

}

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看参数命名，可以很简单的理解到方法的意思，那么我们定义一个typehandler，分别实现这4个方法，如下：

/**
 * @author zhangqiuyang
 * created on 2018/8/17.
 */

@mappedtypes(value = {secretstring.class})
public class secretstringtypehandler implements typehandler<secretstring> {

    /**
     * @param rs
     * @param columnname
     * @return
     * @throws sqlexception
     */
    @override
    public secretstring getresult(resultset rs, string columnname) throws sqlexception {
        string value = rs.getstring(columnname);
        if (value != null) {
            return new secretstring(value);
        }
        return null;
    }

    /**
     * @param rs
     * @param columnindex
     * @return
     * @throws sqlexception
     */
    @override
    public secretstring getresult(resultset rs, int columnindex) throws sqlexception {
        string value = rs.getstring(columnindex);
        if (value != null) {
            return new secretstring(value);
        }
        return null;
    }

    /**
     * @param cs
     * @param columnindex
     * @return
     * @throws sqlexception
     */
    @override
    public secretstring getresult(callablestatement cs, int columnindex) throws sqlexception {
        string value = cs.getstring(columnindex);
        if (value != null) {
            return new secretstring(value);
        }
        return null;
    }

    /**
     * @param ps
     * @param i
     * @param parameter
     * @param arg3
     * @throws sqlexception
     */
    @override
    public void setparameter(preparedstatement ps, int i, secretstring parameter, jdbctype arg3) throws sqlexception {
        string value = "";
        if (parameter != null) {
            value = parameter.tostring();
        }
        ps.setstring(i, value);
    }
}

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实现完成后，需要指定下配置，让mybatis扫描到这个typehandler，在application.yml增加mybatis.type-handlers-package：typehandler所在的包名。如果想从代码中注入配置，则需要在注入sqlsessionfactory的时候setvfs。

 @bean(name = "sqlsessionfactory")
 @primary
 public sqlsessionfactory sqlsessionfactory(@qualifier("datasource") datasource datasource,
                                                   @qualifier("configuration") org.apache.ibatis.session.configuration configuration) throws exception {
     sqlsessionfactorybean bean = new sqlsessionfactorybean();
     bean.setvfs(springbootvfs.class);
     bean.settypehandlerspackage("xxxxxx");
     bean.setdatasource(datasource);
     bean.setmapperlocations(new pathmatchingresourcepatternresolver().getresources("classpath:mapping/*.xml"));
     bean.setconfiguration(configuration);return bean.getobject();
 }

 github：https://github.com/zqyx5201/secretstringtest