java.lang.Math.exp(1.0) has different result between jdk versions. so do not use createQueryTest, write a separate test for it.
```
jdk version   	result
1.7.0_11		2.7182818284590455
1.7.0_05        2.7182818284590455
1.7.0_71		2.718281828459045
```

Author: scwf <wangfei1@huawei.com>

Closes #6274 from scwf/java_method and squashes the following commits:

3dd2516 [scwf] address comments
5fa1459 [scwf] style
df46445 [scwf] fix test error
fcb6d22 [scwf] fix udf_java_method