Java正则表达式匹配字符串并提取中间的值

本是古典何须时尚 2021-12-18 14:41 577阅读 0赞

## 前言 ##

有时候正则表达式不只是匹配一下什么数字/邮箱/身份证/日期等等,还需要匹配某一段文字,并按照既定格式提取其中的某些值.

## 场景一:提取SAML2报文 ##

`SAML2报文`内容如下,从中提取对应的attribute `name`和`value`.

<saml:AttributeStatement>
    	<saml:Attribute Name="mail">
    		<saml:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xs:string">zhengkai.blog.csdn.net</saml:AttributeValue>
    	</saml:Attribute>
    	<saml:Attribute Name="cn">
    		<saml:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xs:string">amAdmin</saml:AttributeValue>
    	</saml:Attribute>
    </saml:AttributeStatement>

show time

public static void main(String[] args) { 
    		String content = "";
    		content = "<saml:AttributeStatement>";
    		content += " <saml:Attribute Name=\"mail\">";
    		content += " <saml:AttributeValue xmlns:xs=\"http://www.w3.org/2001/XMLSchema\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:type=\"xs:string\">zhengkai.blog.csdn.net</saml:AttributeValue>";
    		content += " </saml:Attribute>";
    		content += " <saml:Attribute Name=\"cn\">";
    		content += " <saml:AttributeValue xmlns:xs=\"http://www.w3.org/2001/XMLSchema\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:type=\"xs:string\">amAdmin</saml:AttributeValue>";
    		content += " </saml:Attribute>";
    		content += "</saml:AttributeStatement>";
    		String pattern = "\\<saml\\:Attribute Name=\\\"(?<scope>.*?)\\\"\\>[\\s\\S]*?\\<saml\\:AttributeValue[\\s\\S]*?\\>(?<value>.*?)\\<\\/saml\\:AttributeValue\\>[\\s\\S]*?\\<\\/saml\\:Attribute\\>";
    		Pattern r = Pattern.compile(pattern);
    		Matcher matcher = r.matcher(saml2attributeString);
    		while (matcher.find()){ 
    			String attributeName = matcher.group("scope");
    			String attributeValue = matcher.group("value");
    			System.out.println("attributeName->"+attributeName +",attributeValue->"+attributeValue );
    		}
    	}

控制台输出

$ attributeName->mail,attributeValue->zhengkai.blog.csdn.net
    $ vattributeName->cn,attributeValue->amAdmin

## 解析 ##

\\<saml\\:Attribute Name=\\\"(?<scope>.*?)\\\"\\>[\\s\\S]*?\\<saml\\:AttributeValue[\\s\\S]*?\\>(?<value>.*?)\\<\\/saml\\:AttributeValue\\>[\\s\\S]*?\\<\\/saml\\:Attribute\\>

1.  `(?<scope>.*?)`是用于`标识`scope的方式，表示夹在中间的字符串都叫scope，可以通过`matcher.group("scope")`提取。
2.  所有`非`正则的符号都需要`转义`，所以你会看到很多`\\<`或者换`\\"`之类的`\\`
3.  `[\\s\\S]*?` 是用来匹配任意字符，表示在`前后有界定`的情况下（例如夹在`<xxx></xxx>`中间的字符串），可以`忽略`那些不规则字符串的匹配。

## 场景2:提取sql中的表名和字段 ##

来自github网友`@ydq` 给[`SpringBootCodeGenerator`贡献的正则表达式][SpringBootCodeGenerator],非常不错,值得深刻学习.

//匹配整个ddl，将ddl分为表名，列sql部分，表注释
        private static final Pattern DDL_PATTERN = Pattern.compile("\\s*create\\s+table\\s+(?<tableName>\\S+)[^\$]*\\((?<columnsSQL>[\\s\\S]+)\$[^\\)]+?(comment\\s*(=|on\\s+table)\\s*'(?<tableComment>.*?)'\\s*;?)?$", Pattern.CASE_INSENSITIVE);
        //匹配列sql部分，分别解析每一列的列名 类型 和列注释
        private static final Pattern COL_PATTERN = Pattern.compile("\\s*(?<fieldName>\\S+)\\s+(?<fieldType>\\w+)\\s*(?:\$[\\s\\d,]+\$)?((?!comment).)*(comment\\s*'(?<fieldComment>.*?)')?\\s*(,|$)", Pattern.CASE_INSENSITIVE);
    
        public static void parse(String sql){ 
            Matcher matcher = DDL_PATTERN.matcher(sql);
            if (matcher.find()){ 
                String tableName = matcher.group("tableName");
                String tableComment = matcher.group("tableComment");
                System.out.println(tableName + "\t\t" + tableComment);
                System.out.println("==========");
                String columnsSQL = matcher.group("columnsSQL");
                if (columnsSQL != null && columnsSQL.length() > 0){ 
                    Matcher colMatcher = COL_PATTERN.matcher(columnsSQL);
                    while (colMatcher.find()){ 
                        String fieldName = colMatcher.group("fieldName");
                        String fieldType = colMatcher.group("fieldType");
                        String fieldComment = colMatcher.group("fieldComment");
                        if (!"key".equalsIgnoreCase(fieldType)){ 
                            System.out.println(fieldName + "\t\t" + fieldType + "\t\t" + fieldComment);
                        }
                    }
                }
            }
        }
    
        public static void main(String[] args){ 
            System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
            parse("CREATE TABLE `userinfo` (\n" +
                    " `user_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '用户ID',\n" +
                    " `username` varchar(255) NOT NULL COMMENT '用户名',\n" +
                    " `addtime` datetime NOT NULL COMMENT '创建时间',\n" +
                    " PRIMARY KEY (`user_id`)\n" +
                    ") ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='用户信息'");
            System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
            parse("CREATE TABLE `USER` (\n" +
                    "`ID` varchar(32) PRIMARY KEY COMMENT '主键',\n" +
                    "`password` varchar(32) NOT NULL COMMENT '密码',\n" +
                    "`username` varchar(32) NOT NULL COMMENT '用户'\n" +
                    ") ENGINE=InnoDB DEFAULT CHARSET=utf8;");
            System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
            parse("CREATE TABLE `tb_amount` (\n" +
                    "`ID` int(10) NOT NULL AUTO_INCREMENT,\n" +
                    "`PRODUCT_CODE` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '产品代码',\n" +
                    "`GENDER` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '性别(male,female)',\n" +
                    "`MIN_INSURED_AGE` int(3) NULL DEFAULT NULL COMMENT '最小投保年龄',\n" +
                    "`MAX_INSURED_AGE` int(3) NULL DEFAULT NULL COMMENT '最大投保年龄',\n" +
                    "`AMOUNT` double(10, 2) NULL DEFAULT NULL COMMENT '基本保额',\n" +
                    "`PREMIUM_RATE` double(10, 2) NULL DEFAULT NULL COMMENT '基本保费',\n" +
                    "`YEAR_NUM` int(3) NULL DEFAULT NULL COMMENT '缴费年限',\n" +
                    "`PREMIUM_TYPE` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '费率类型',\n" +
                    "`INSURANCE_PERIOD` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '保险期间(30年，60年)',\n" +
                    "`INSURANCE_PERIOD_TYPE` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '保险期间类型(如定期年0,定期岁1,终身2,以后终身对应值：200)',\n" +
                    "`PAY_MODE` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '交费方式',\n" +
                    "PRIMARY KEY (`ID`) USING BTREE\n" +
                    ") ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;");
        }

控制台输出内容:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
    `userinfo`		用户信息
    ==========
    `user_id`		int		用户ID
    `username`		varchar		用户名
    `addtime`		datetime		创建时间
    >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
    `USER`		null
    ==========
    `ID`		varchar		主键
    `password`		varchar		密码
    `username`		varchar		用户
    >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
    `tb_amount`		null
    ==========
    `ID`		int		null
    `PRODUCT_CODE`		varchar		产品代码
    `GENDER`		varchar		性别(male,female)
    `MIN_INSURED_AGE`		int		最小投保年龄
    `MAX_INSURED_AGE`		int		最大投保年龄
    `AMOUNT`		double		基本保额
    `PREMIUM_RATE`		double		基本保费
    `YEAR_NUM`		int		缴费年限
    `PREMIUM_TYPE`		varchar		费率类型
    `INSURANCE_PERIOD`		varchar		保险期间(30年，60年)
    `INSURANCE_PERIOD_TYPE`		varchar		保险期间类型(如定期年0,定期岁1,终身2,以后终身对应值：200)
    `PAY_MODE`		varchar		交费方式

[SpringBootCodeGenerator]: https://github.com/moshowgame/SpringBootCodeGenerator/issues/22