Java注解Annotation用起來很方便，也越來越流行，由于其簡單、簡練且易于使用等特點，很多開發工具都提供了注解功能，不好的地方就是代碼入侵比較嚴重，所以使用的時候要有一定的選擇性。

這篇文章將利用注解，來做一個Bean的數據校驗。

下載

http://download.csdn.net/download/hanghangaidoudou/10139375

項目結構?

定義注解

該注解可以驗證成員屬性是否為空，長度，提供了幾種常見的正則匹配，也可以使用自定義的正則去判斷屬性是否合法，同時可以為該成員提供描述信息。

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package?org.xdemo.validation.annotation; import?java.lang.annotation.ElementType; import?java.lang.annotation.Retention; import?java.lang.annotation.RetentionPolicy; import?java.lang.annotation.Target; import?org.xdemo.validation.RegexType; /** ?*?數據驗證 ?*?@author?Goofy ?*/ @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.FIELD,ElementType.PARAMETER}) public?@interface?DV?{ ????? ????//是否可以為空 ????boolean?nullable()?default?false; ????? ????//最大長度 ????int?maxLength()?default?0; ????? ????//最小長度 ????int?minLength()?default?0; ????? ????//提供幾種常用的正則驗證 ????RegexType?regexType()?default?RegexType.NONE; ????? ????//自定義正則驗證 ????String?regexExpression()?default?""; ????? ????//參數或者字段描述,這樣能夠顯示友好的異常信息 ????String?description()?default?""; }

注解的解析

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package?org.xdemo.validation.annotation.support; import?java.lang.reflect.Field; import?org.xdemo.validation.RegexType; import?org.xdemo.validation.annotation.DV; import?org.xdemo.validation.utils.RegexUtils; import?org.xdemo.validation.utils.StringUtils; /** ?*?注解解析 ?*?@author?Goofy ?*/ public?class?ValidateService?{ ????? ????private?static?DV?dv; ????? ????public?ValidateService()?{ ????????super(); ????} ????? ????//解析的入口 ????public?static?void?valid(Object?object)?throws?Exception{ ????????//獲取object的類型 ????????Class<??extends?Object>?clazz=object.getClass(); ????????//獲取該類型聲明的成員 ????????Field[]?fields=clazz.getDeclaredFields(); ????????//遍歷屬性 ????????for(Field?field:fields){ ????????????//對于private私有化的成員變量，通過setAccessible來修改器訪問權限 ????????????field.setAccessible(true); ????????????validate(field,object); ????????????//重新設置會私有權限 ????????????field.setAccessible(false); ????????} ????} ????? ????? ????public?static?void?validate(Field?field,Object?object)?throws?Exception{ ????????String?description; ????????Object?value; ????????//獲取對象的成員的注解信息 ????????dv=field.getAnnotation(DV.class); ????????value=field.get(object); ????????? ????????if(dv==null)return; ????????? ????????description=dv.description().equals("")?field.getName():dv.description(); ????????? ????????/*************注解解析工作開始******************/ ????????if(!dv.nullable()){ ????????????if(value==null||StringUtils.isBlank(value.toString())){ ????????????????throw?new?Exception(description+"不能為空"); ????????????} ????????} ????????? ????????if(value.toString().length()>dv.maxLength()&&dv.maxLength()!=0){ ????????????throw?new?Exception(description+"長度不能超過"+dv.maxLength()); ????????} ????????? ????????if(value.toString().length()<dv.minLength()&&dv.minLength()!=0){ ????????????throw?new?Exception(description+"長度不能小于"+dv.minLength()); ????????} ????????? ????????if(dv.regexType()!=RegexType.NONE){ ????????????switch?(dv.regexType())?{ ????????????????case?NONE: ????????????????????break; ????????????????case?SPECIALCHAR: ????????????????????if(RegexUtils.hasSpecialChar(value.toString())){ ????????????????????????throw?new?Exception(description+"不能含有特殊字符"); ????????????????????} ????????????????????break; ????????????????case?CHINESE: ????????????????????if(RegexUtils.isChinese2(value.toString())){ ????????????????????????throw?new?Exception(description+"不能含有中文字符"); ????????????????????} ????????????????????break; ????????????????case?EMAIL: ????????????????????if(!RegexUtils.isEmail(value.toString())){ ????????????????????????throw?new?Exception(description+"地址格式不正確"); ????????????????????} ????????????????????break; ????????????????case?IP: ????????????????????if(!RegexUtils.isIp(value.toString())){ ????????????????????????throw?new?Exception(description+"地址格式不正確"); ????????????????????} ????????????????????break; ????????????????case?NUMBER: ????????????????????if(!RegexUtils.isNumber(value.toString())){ ????????????????????????throw?new?Exception(description+"不是數字"); ????????????????????} ????????????????????break; ????????????????case?PHONENUMBER: ????????????????????if(!RegexUtils.isPhoneNumber(value.toString())){ ????????????????????????throw?new?Exception(description+"不是數字"); ????????????????????} ????????????????????break; ????????????????default: ????????????????????break; ????????????} ????????} ????????? ????????if(!dv.regexExpression().equals("")){ ????????????if(value.toString().matches(dv.regexExpression())){ ????????????????throw?new?Exception(description+"格式不正確"); ????????????} ????????} ????????/*************注解解析工作結束******************/ ????} }

用到的幾個類

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package?org.xdemo.validation; /** ?*?常用的數據類型枚舉 ?*?@author?Goofy ?* ?*/ public?enum?RegexType?{ ????? ????NONE, ????SPECIALCHAR, ????CHINESE, ????EMAIL, ????IP,? ????NUMBER, ????PHONENUMBER; ????? }

其中正則驗證類和字符串工具類請參考以下鏈接：

SuperUtil之RegexUtils

SuperUtil之StringUtils

使用方法

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package?org.xdemo.validation.test; import?org.xdemo.validation.RegexType; import?org.xdemo.validation.annotation.DV; public?class?User?{ ????? ????@DV(description="用戶名",minLength=6,maxLength=32,nullable=false) ????private?String?userName; ????? ????private?String?password; ????? ????@DV(description="郵件地址",nullable=false,regexType=RegexType.EMAIL) ????private?String?email; ????? ????? ????public?User(){} ????? ????public?User(String?userName,?String?password,?String?email)?{ ????????super(); ????????this.userName?=?userName; ????????this.password?=?password; ????????this.email?=?email; ????} ????? ????? ????? ????public?String?getUserName()?{ ????????return?userName; ????} ????public?void?setUserName(String?userName)?{ ????????this.userName?=?userName; ????} ????public?String?getPassword()?{ ????????return?password; ????} ????public?void?setPassword(String?password)?{ ????????this.password?=?password; ????} ????public?String?getEmail()?{ ????????return?email; ????} ????public?void?setEmail(String?email)?{ ????????this.email?=?email; ????} }

測試代碼

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package?org.xdemo.validation.test; import?org.xdemo.validation.annotation.support.ValidateService; /** ?*?@author?Goofy ?*/ public?class?Test?{ ????public?static?void?main(String[]?args){ ????????User?user=new?User("張三",?"xdemo.org",?"252878950@qq.com"); ????????try?{ ????????????ValidateService.valid(user); ????????}?catch?(Exception?e)?{ ????????????e.printStackTrace(); ????????} ????????user=new?User("zhangsan","xdemo.org","xxx@"); ????????try?{ ????????????ValidateService.valid(user); ????????}?catch?(Exception?e)?{ ????????????e.printStackTrace(); ????????} ????????user=new?User("zhangsan","xdemo.org",""); ????????try?{ ????????????ValidateService.valid(user); ????????}?catch?(Exception?e)?{ ????????????e.printStackTrace(); ????????} ????} }

運行效果

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