添加jackson依赖：
// https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-core compile group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.8.2' // https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind compile group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.8.2' // https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-annotations compile group: 'com.fasterxml.jackson.core', name: 'jackson-annotations', version: '2.8.2'