在Struts中对用户输入信息的校验方法对比:validate 和validator-阿里云开发者社区

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：

public ActionErrors validate(ActionMapping mapping, HttpServletRequest req) {
2

ActionErrors errors = new ActionErrors();
3

String age = this.getAge();
5

if(!this.isNumber(age)){ // isNumber() is not implemented
6

errors.add(

);
7

}
8

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：

< 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,
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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"
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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：

< 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。

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

一、在FormBean中手工实现

二、使用Validator

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