ExtractByUrl (webmagic 1.0.0-SNAPSHOT API)

```
@Retention(RUNTIME)
@Target(FIELD)
public @interface ExtractByUrl
```
Define a extractor to extract data in url of current page. Only regex can be used.

Since:

0.2.0

Author:

code4crafter@gmail.com

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element	Description
`boolean`	`multi`	Deprecated. since 0.4.2
`boolean`	`notNull`	Define whether the field can be null. If set to 'true' and the extractor get no result, the entire class will be discarded.
`java.lang.String`	`value`	Extractor expression, only regex can be used

- Element Detail
  - value
```
java.lang.String value
```
    Extractor expression, only regex can be used
    
    Returns:
    
    extractor expression
    
    Default:
    
    ""
- - notNull
```
boolean notNull
```
    Define whether the field can be null.
    If set to 'true' and the extractor get no result, the entire class will be discarded.
    
    Returns:
    
    whether the field can be null
    
    Default:
    
    false
- - multi
```
boolean multi
```
    Deprecated.
    since 0.4.2
    
    Define whether the extractor return more than one result. When set to 'true', the extractor return a list of string (so you should define the field as List).
    Deprecated since 0.4.2. This option is determined automatically by the class of field.
    
    Returns:
    
    whether the extractor return more than one result
    
    Default:
    
    false