JacksonExp.java

build.gradle

apply plugin: 'java'

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.fasterxml.jackson.core:jackson-core:2.6.7'
    compile 'com.fasterxml.jackson.core:jackson-databind:2.6.7'
    testCompile 'junit:junit:4.+'
}

sourceSets {
    main {
        java {
            srcDir '.'
            exclude 'Test*.java'
        }
    }
    test {
        java {
            srcDir '.'
            include 'Test*.java'
        }
    }
}

test {
    testLogging {
        events 'passed', 'skipped', 'failed', 'standardOut', 'standardError'
    }
}

task run(type:JavaExec) {
    main = project.hasProperty('main') ? project.getProperty('main') : 'JacksonExp'
    classpath = sourceSets.main.runtimeClasspath
}

JacksonExp.java

import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonExp {
    public static void main(String[] args) throws java.io.IOException {
        final String json = "{\"id\":12345e3}";
        final ObjectMapper mapper = new ObjectMapper();
        final SampleData data = mapper.readValue(json, SampleData.class);
        System.out.println(data.toString());
    }
}

class SampleData {
    public String toString() {
        return "SampleData [id=" + id + "]";
    }

    public int id;
}

SampleData [id=12345000]