去掉mybatis plus插件生成的mapper.xml文件

前言：使用mybatis自动生成mapper.xml文件，同时自己写的sql放在mapperExt.xml中，随着表的增加，启动越来越慢，为减少加载xml的时间，去掉生成的mapper.xml文件，步骤如下

1.重写AutoSqlInjector的inject(...)方法

	/**
	 * 自定义方法，注入点（子类需重写该方法）
	 */
	public void inject(Configuration configuration, MapperBuilderAssistant builderAssistant, Class mapperClass,
			Class modelClass, TableInfo table) {
		// to do nothing
	}

重写后如下：

public class CustomAutoSqlInjector {

    /**
     * 自定义方法，注入点（子类需重写该方法）
     */
    @Override
    public void inject(Configuration configuration, MapperBuilderAssistant builderAssistant, Class mapperClass, Class modelClass, TableInfo table) {
        injectSelectRecordsSql(configuration, builderAssistant, mapperClass, modelClass, table);
        injectSelectRecordsByConditionSql(configuration, builderAssistant, mapperClass, modelClass, table);
        injectSelectIdPageSql(configuration, builderAssistant, mapperClass, modelClass, table);
    }

    protected void injectSelectRecordsSql(Configuration configuration, MapperBuilderAssistant builderAssistant, Class mapperClass, Class modelClass, TableInfo table) {
        String method = "selectRecords";
        String sql = selectRecordsSql(table);
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        this.addSelectMappedStatement(mapperClass, method, sqlSource, modelClass, table);
    }

    protected void injectSelectRecordsByConditionSql(Configuration configuration, MapperBuilderAssistant builderAssistant, Class mapperClass, Class modelClass, TableInfo table) {
        String method = "selectRecordsByCondition";
        String sql = selectRecordsByCondition(table);
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        this.addSelectMappedStatement(mapperClass, method, sqlSource, modelClass, table);
    }

    protected void injectSelectIdPageSql(Configuration configuration, MapperBuilderAssistant builderAssistant, Class mapperClass, Class modelClass, TableInfo table) {
        String method = "selectIdPage";
        String sql = selectIdPageSql(table);
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        this.addSelectMappedStatement(mapperClass, method, sqlSource, modelClass, table);
    }

    protected String selectRecordsSql(TableInfo tableInfo) {
        StringBuilder sql = new StringBuilder();
        sql.append("");
        return sql.toString();
    }

    protected String selectRecordsByCondition(TableInfo tableInfo) {
        StringBuilder sql = new StringBuilder();
        sql.append("");
        return sql.toString();
    }

    protected String selectIdPageSql(TableInfo tableInfo){
        StringBuilder sql = new StringBuilder();
        sql.append("");
        return sql.toString();
    }
}

2.修改mybatis-plus配置文件（application.yml）指定刚刚自定义的注入器位置

mybatis-plus:
    type-aliases-package: com.xxx.dal.model
    mapper-locations: classpath*:com/xxx/dal/mapper/**/*.xml
    configuration:
        map-underscore-to-camel-case: true
        default-fetch-size: 100
        default-statement-timeout: 30
    global-config:
      sql-injector: com.xxx.dal.config.CustomAutoSqlInjector

可以删除自动生产mapper.xml文件，只保留maperExt.xml即可

另：也可以重写update语句中的set部分,支持update空字符串

 /**
     * SQL 更新 set 语句
     *
     * @param table  表
     * @param prefix 前缀
     */
    @Override
    protected String sqlSet(TableInfo table, String prefix) {
        StringBuilder set = new StringBuilder();
        set.append("");
        List fieldList = table.getFieldList();
        for (TableFieldInfo fieldInfo : fieldList) {
            set.append(convertIfTagForUpdate(true, fieldInfo, prefix, false));
            set.append(fieldInfo.getColumn()).append("=#{");
            if (null != prefix) {
                set.append(prefix);
            }
            set.append(fieldInfo.getEl()).append("},");
            set.append(convertIfTagForUpdate(true, fieldInfo, null, true));
        }
        set.append("\n");
        return set.toString();
    }

    /**
     * IF 条件转换方法
     *
     * @param ignored   允许忽略
     * @param fieldInfo 字段信息
     * @param prefix    条件前缀
     * @param colse     是否闭合标签
     */
    protected String convertIfTagForUpdate(boolean ignored, TableFieldInfo fieldInfo, String prefix, boolean colse) {
        /* 忽略策略 */
        FieldStrategy fieldStrategy = fieldInfo.getFieldStrategy();
        if (fieldStrategy == FieldStrategy.IGNORED) {
            if (ignored) {
                return "";
            }
            // 查询策略，使用全局策略
            GlobalConfiguration.getGlobalConfig(configuration).getFieldStrategy();
        }
        // 关闭标签
        if (colse) {
            return "";
        }
        // 前缀处理
        String property = fieldInfo.getProperty();
        if (null != prefix) {
            property = prefix + property;
        }
        return String.format("\n\t", property);
    }