在Struts中对用户输入信息的校验方法对比:validate 和validator

在Struts中对用户输入信息的校验一般在FromBean中进行（除非需要访问数据库进行诸如登录信息的校验，因为这是Action的工作），本文将阐述如何在Struts中实现可配置的信息校验。

一、在FormBean中手工实现

最简单的方法是直接在FormBean中重写ActionForm类的validate方法，validate方法签名如下：


public ActionErrors validate(ActionMapping mapping, HttpServletRequest req)

比如需要校验age字段必须填写数字：

1



public ActionErrors validate(ActionMapping mapping, HttpServletRequest req)

{
2

ActionErrors errors = new ActionErrors();
3


4

String age = this.getAge();
5



if(!this.isNumber(age))

{ // isNumber() is not implemented
6

errors.add(

,

);
7

}
8


9

return errors;
10

}
在form提交后，容器会调用validate方法对表单数据进行校验，如果返回的ActionErrors为空（即校验通过），则将FormBean提交Action，否则重定向到提交form的页面。
这种方法实现简单，直观，容易测试、调试，但不可避免地存在以下缺点：

1、很难重用，导致重复开发
有很多校验逻辑在整个网站中是相同的，比如上述的数字校验，还有email校验、长度校验等等，而通过覆盖validate方法很难对这些校验过程进行重用，除非定义一些helper类封装校验方法（比如上述的isNumber()）。而当需要为另一个FormBean加入相同的校验逻辑时必须重复地覆盖validate方法

2、难于扩展
当要对一个表单增、删、改校验逻辑时必须修改validate方法，重新打包、部署

3、不可配置
因为校验逻辑硬编码于class文件中，运行时不可能做到灵活地配置校验逻辑

因此，Struts中加入了另一种更灵活的校验机制：

二、使用Validator

Validator提供了一种基于xml配置文件的校验模型，要使用这一模型必须做如下实现：

1、FormBean继承org.apache.struts.validator.ValidatorForm而不是ActionForm

2、不覆盖validate方法

3、创建validator-rules.xml及validation.xml文件
validator-rules.xml定义了可用来配置的校验逻辑，如：

1

<form-validation>
2

<global>
3

<validator name="required"
4

classname="org.apache.struts.validator.FieldChecks"
5

method="validateRequired"
6

methodParams="java.lang.Object,
7

org.apache.commons.validator.ValidatorAction,
8

org.apache.commons.validator.Field,
9

org.apache.struts.action.ActionMessages,
10

org.apache.commons.validator.Validator,
11

javax.servlet.http.HttpServletRequest"
12

msg="errors.required"/>
13

<validator name="requiredif"
14

classname="org.apache.struts.validator.FieldChecks"
15

method="validateRequiredIf"
16

methodParams="java.lang.Object,
17

org.apache.commons.validator.ValidatorAction,
18

org.apache.commons.validator.Field,
19

org.apache.struts.action.ActionMessages,
20

org.apache.commons.validator.Validator,
21

javax.servlet.http.HttpServletRequest"
22

msg="errors.required"/>
23

<validator name="validwhen"
24

msg="errors.required"
25

classname="org.apache.struts.validator.validwhen.ValidWhen"
26

method="validateValidWhen"
27

methodParams="java.lang.Object,
28

org.apache.commons.validator.ValidatorAction,
29

org.apache.commons.validator.Field,
30

org.apache.struts.action.ActionMessages,
31

org.apache.commons.validator.Validator,
32

javax.servlet.http.HttpServletRequest"/>
33

<validator name="minlength"
34

classname="org.apache.struts.validator.FieldChecks"
35

method="validateMinLength"
36

methodParams="java.lang.Object,
37

org.apache.commons.validator.ValidatorAction,
38

org.apache.commons.validator.Field,
39

org.apache.struts.action.ActionMessages,
40

org.apache.commons.validator.Validator,
41

javax.servlet.http.HttpServletRequest"
42

depends=""
43

msg="errors.minlength"
44

jsFunction="org.apache.commons.validator.javascript.validateMinLength"/>
45

<validator name="maxlength"
46

classname="org.apache.struts.validator.FieldChecks"
47

method="validateMaxLength"
48

methodParams="java.lang.Object,
49

org.apache.commons.validator.ValidatorAction,
50

org.apache.commons.validator.Field,
51

org.apache.struts.action.ActionMessages,
52

org.apache.commons.validator.Validator,
53

javax.servlet.http.HttpServletRequest"
54

depends=""
55

msg="errors.maxlength"
56

jsFunction="org.apache.commons.validator.javascript.validateMaxLength"/>
57

<validator name="mask"
58

classname="org.apache.struts.validator.FieldChecks"
59

method="validateMask"
60

methodParams="java.lang.Object,
61

org.apache.commons.validator.ValidatorAction,
62

org.apache.commons.validator.Field,
63

org.apache.struts.action.ActionMessages,
64

org.apache.commons.validator.Validator,
65

javax.servlet.http.HttpServletRequest"
66

depends=""
67

msg="errors.invalid"/>
68

<validator name="byte"
69

classname="org.apache.struts.validator.FieldChecks"
70

method="validateByte"
71

methodParams="java.lang.Object,
72

org.apache.commons.validator.ValidatorAction,
73

org.apache.commons.validator.Field,
74

org.apache.struts.action.ActionMessages,
75

org.apache.commons.validator.Validator,
76

javax.servlet.http.HttpServletRequest"
77

depends=""
78

msg="errors.byte"
79

jsFunctionName="ByteValidations"/>
80

<validator name="short"
81

classname="org.apache.struts.validator.FieldChecks"
82

method="validateShort"
83

methodParams="java.lang.Object,
84

org.apache.commons.validator.ValidatorAction,
85

org.apache.commons.validator.Field,
86

org.apache.struts.action.ActionMessages,
87

org.apache.commons.validator.Validator,
88

javax.servlet.http.HttpServletRequest"
89

depends=""
90

msg="errors.short"
91

jsFunctionName="ShortValidations"/>
92

<validator name="integer"
93

classname="org.apache.struts.validator.FieldChecks"
94

method="validateInteger"
95

methodParams="java.lang.Object,
96

org.apache.commons.validator.ValidatorAction,
97

org.apache.commons.validator.Field,
98

org.apache.struts.action.ActionMessages,
99

org.apache.commons.validator.Validator,
100

javax.servlet.http.HttpServletRequest"
101

depends=""
102

msg="errors.integer"
103

jsFunctionName="IntegerValidations"/>
104

<validator name="long"
105

classname="org.apache.struts.validator.FieldChecks"
106

method="validateLong"
107

methodParams="java.lang.Object,
108

org.apache.commons.validator.ValidatorAction,
109

org.apache.commons.validator.Field,
110

org.apache.struts.action.ActionMessages,
111

org.apache.commons.validator.Validator,
112

javax.servlet.http.HttpServletRequest"
113

depends=""
114

msg="errors.long"/>
115

<validator name="float"
116

classname="org.apache.struts.validator.FieldChecks"
117

method="validateFloat"
118

methodParams="java.lang.Object,
119

org.apache.commons.validator.ValidatorAction,
120

org.apache.commons.validator.Field,
121

org.apache.struts.action.ActionMessages,
122

org.apache.commons.validator.Validator,
123

javax.servlet.http.HttpServletRequest"
124

depends=""
125

msg="errors.float"
126

jsFunctionName="FloatValidations"/>
127

<validator name="double"
128

classname="org.apache.struts.validator.FieldChecks"
129

method="validateDouble"
130

methodParams="java.lang.Object,
131

org.apache.commons.validator.ValidatorAction,
132

org.apache.commons.validator.Field,
133

org.apache.struts.action.ActionMessages,
134

org.apache.commons.validator.Validator,
135

javax.servlet.http.HttpServletRequest"
136

depends=""
137

msg="errors.double"/>
138

<validator name="date"
139

classname="org.apache.struts.validator.FieldChecks"
140

method="validateDate"
141

methodParams="java.lang.Object,
142

org.apache.commons.validator.ValidatorAction,
143

org.apache.commons.validator.Field,
144

org.apache.struts.action.ActionMessages,
145

org.apache.commons.validator.Validator,
146

javax.servlet.http.HttpServletRequest"
147

depends=""
148

msg="errors.date"
149

jsFunctionName="DateValidations"/>
150

<validator name="intRange"
151

classname="org.apache.struts.validator.FieldChecks"
152

method="validateIntRange"
153

methodParams="java.lang.Object,
154

org.apache.commons.validator.ValidatorAction,
155

org.apache.commons.validator.Field,
156

org.apache.struts.action.ActionMessages,
157

org.apache.commons.validator.Validator,
158

javax.servlet.http.HttpServletRequest"
159

depends="integer"
160

msg="errors.range"/>
161

<validator name="floatRange"
162

classname="org.apache.struts.validator.FieldChecks"
163

method="validateFloatRange"
164

methodParams="java.lang.Object,
165

org.apache.commons.validator.ValidatorAction,
166

org.apache.commons.validator.Field,
167

org.apache.struts.action.ActionMessages,
168

org.apache.commons.validator.Validator,
169

javax.servlet.http.HttpServletRequest"
170

depends="float"
171

msg="errors.range"/>
172

<validator name="doubleRange"
173

classname="org.apache.struts.validator.FieldChecks"
174

method="validateDoubleRange"
175

methodParams="java.lang.Object,
176

org.apache.commons.validator.ValidatorAction,
177

org.apache.commons.validator.Field,
178

org.apache.struts.action.ActionMessages,
179

org.apache.commons.validator.Validator,
180

javax.servlet.http.HttpServletRequest"
181

depends="double"
182

msg="errors.range"/>
183

<validator name="creditCard"
184

classname="org.apache.struts.validator.FieldChecks"
185

method="validateCreditCard"
186

methodParams="java.lang.Object,
187

org.apache.commons.validator.ValidatorAction,
188

org.apache.commons.validator.Field,
189

org.apache.struts.action.ActionMessages,
190

org.apache.commons.validator.Validator,
191

javax.servlet.http.HttpServletRequest"
192

depends=""
193

msg="errors.creditcard"/>
194

<validator name="email"
195

classname="org.apache.struts.validator.FieldChecks"
196

method="validateEmail"
197

methodParams="java.lang.Object,
198

org.apache.commons.validator.ValidatorAction,
199

org.apache.commons.validator.Field,
200

org.apache.struts.action.ActionMessages,
201

org.apache.commons.validator.Validator,
202

javax.servlet.http.HttpServletRequest"
203

depends=""
204

msg="errors.email"/>
205

<validator name="url"
206

classname="org.apache.struts.validator.FieldChecks"
207

method="validateUrl"
208

methodParams="java.lang.Object,
209

org.apache.commons.validator.ValidatorAction,
210

org.apache.commons.validator.Field,
211

org.apache.struts.action.ActionMessages,
212

org.apache.commons.validator.Validator,
213

javax.servlet.http.HttpServletRequest"
214

depends=""
215

msg="errors.url"/>
216

<!--
217

This simply allows struts to include the validateUtilities into a page, it should
218

not be used as a validation rule.
219

-->
220

<validator name="includeJavaScriptUtilities"
221

classname=""
222

method=""
223

methodParams=""
224

depends=""
225

msg=""
226

jsFunction="org.apache.commons.validator.javascript.validateUtilities"/>
227

<validator name="codeinput"
228

classname="consultII.web.utils.MyValidator"
229

method="validateCodeInput"
230

methodParams="java.lang.Object,
231

org.apache.commons.validator.ValidatorAction,
232

org.apache.commons.validator.Field,
233

org.apache.struts.action.ActionMessages,
234

javax.servlet.http.HttpServletRequest"
235

msg="errors.code"/>
236

<validator name="userinfo"
237

classname="consultII.web.utils.MyValidator"
238

method="validateUserInfo"
239

methodParams="java.lang.Object,
240

org.apache.commons.validator.ValidatorAction,
241

org.apache.commons.validator.Field,
242

org.apache.struts.action.ActionMessages,
243

javax.servlet.http.HttpServletRequest"
244

msg="errors.info"/>
245

</global>
246

</form-validation>

该配置文件的具体格式请查阅Struts的官方文档。可以看出其中对很多常用的校验逻辑进行了封装，比如数字校验（92行到103行），长度校验（33行到56行）等。

而validation.xml则是Validator的核心，其中可对各个FormBean中需要校验字段及校验逻辑进行灵活的配置：

1

<form-validation>
2

<formset>
3

<form name="login">
4

<field property="username" depends="required"/>
5

<field property="password" depends="required"/>
6

<field property="input" depends="required,codeinput"/>
7

</form>
8

<form name="search">
9

<field property="keyword" depends="required"/>
10

</form>
11

<form name="signin">
12

<field property="username" depends="required"/>
13

<field property="password" depends="required"/>
14

<field property="passagain" depends="required"/>
15

<field property="question" depends="required,userinfo"/>
16

<field property="answer" depends="required,userinfo"/>
17

<field property="age" depends="required,integer"/>
18

<field property="input" depends="required,codeinput"/>
19

<field property="email" depends="email"/>
20

</form>
21

<form name="ask">
22

<field property="content" depends="required"/>
23

</form>
24

</formset>
25

</form-validation>
26


具体格式可查阅官方文档，如上例，3到5行定义了需要对名为“loging”的FormBean的“username”、“password”分别进行“required”校验（即必填字段）。校验逻辑之间可以组合，如第6行的“required,codeinput”，定义了先进行required校验，通过了再进行codeinput校验。

与在validate方法内进行校验相比，使用Validator的优势就很明显了，可重用（从上述xml文件可以看出对很多字段都进行了required校验）；可灵活配置、扩展，只需修改validation.xml文件就可以改变校验逻辑。