jwt是json web token的缩写，常用于安全校验

jwt的组成

jwt有三部分组成，用.拼接

这三部分是

• Header(数据类型和加密算法类型)

  {
      'typ': 'JWT',
      'alg': 'HS256'
  }
  

• Payload (存放有效信息)

  {
      'sub': '1234567890',
      'name': 'john',
      'admin': true
  }
  

• signatrue 对前两个部分进行再编码

  var encodeString = base64UrlEncode(header) + '.' + 
  base64UrlEncode(payload)
  
  var signatrue = HMACSHA256(encodedString, 'secret')
  

依赖

        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>0.9.1</version>
        </dependency>
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-core</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>javax.activation</groupId>
            <artifactId>activation</artifactId>
            <version>1.1.1</version>
        </dependency>