mybatis test把空字符串解析为0-蒲公英云

mybatis test把空字符串解析为0

直接入主题：

一个mybatis的Mapper文件

xxxxMapper(Mapparams);

相关xml代码片段：

  <if test="packageType!= null and packageType!= '' or packageType == 0">  
    and package\_type = \#\{packageType,jdbcType=TINYINT\}  
  </if>

service端部分代码：

Mapparams = new HashMap<>();

params.put(“packageType”,””);

最初的设想，前端页面传入packageType条件为空字符串时，不把packageType作为过滤条件，但是上面的代码却达不到效果，下面从源码入手分析下为什么产生上述效果：

SimpleNode::getValue —>SimpleNode::evaluateGetValueBody—>ASTEq::getValueBody—>OgnlOps::equal—>OgnlOps::compareWithConversion

protected Object evaluateGetValueBody(OgnlContext context, Object source)  
        throws OgnlException  
\{  
    context.setCurrentObject(source);  
    context.setCurrentNode(this);
    if (!\_constantValueCalculated)  
    \{  
        \_constantValueCalculated = true;  
        boolean constant = isConstant(context);
        if (constant)  
        \{  
            \_constantValue = getValueBody(context, source);  
        \}
        \_hasConstantValue = constant;  
    \}
    return \_hasConstantValue ? \_constantValue : getValueBody(context, source);  
\}

要找到原因不耐烦的话可以直接跳转到OgnlOps::compareWithConversion方法

public static int compareWithConversion(Object v1, Object v2)  
\{  
    int result;
    if (v1 == v2) \{  
        result = 0;  
    \} else \{  
        int t1 = getNumericType(v1), t2 = getNumericType(v2), type = getNumericType(t1, t2, true);
        switch(type) \{  
        case BIGINT:  
            result = bigIntValue(v1).compareTo(bigIntValue(v2));  
            break;
        case BIGDEC:  
            result = bigDecValue(v1).compareTo(bigDecValue(v2));  
            break;
        case NONNUMERIC:  
            if ((t1 == NONNUMERIC) && (t2 == NONNUMERIC)) \{  
                if ((v1 instanceof Comparable) && v1.getClass().isAssignableFrom(v2.getClass())) \{  
                    result = ((Comparable) v1).compareTo(v2);  
                    break;  
                \} else \{  
                    throw new IllegalArgumentException("invalid comparison: " + v1.getClass().getName() + " and "  
                            + v2.getClass().getName());  
                \}  
            \}  
            // else fall through  
        case FLOAT:  
        case DOUBLE:

double dv1 = doubleValue(v1),
dv2 = doubleValue(v2);

return (dv1 == dv2) ? 0 : ((dv1 < dv2) ? -1 : 1);

        default:  
            long lv1 = longValue(v1),  
            lv2 = longValue(v2);
            return (lv1 == lv2) ? 0 : ((lv1 < lv2) ? -1 : 1);  
        \}  
    \}  
    return result;  
\}

最终会走到上面标红部分代码，而空字符串也会被转换成double的0.0，此时当空字符串时packageType!= null and packageType!= ‘’ or packageType == 0这个判断就会返回true，下面给出解决方案：

  <if test="packageType!= null and packageType!= '' or packageType == '0'.toString()">  
    and package\_type = \#\{packageType,jdbcType=TINYINT\}  
  </if>