Jackson 介紹

Jackson框架是基于Java平臺的一套數(shù)據(jù)處理工具，被稱為“最好的Java Json解析器”。
Jackson框架包含了3個核心庫：streaming,databind,annotations.Jackson還包含了其它數(shù)據(jù)處理類庫，此外不作說明。
Jackson版本： 1.x (目前版本從1.1~1.9)與2.x。1.x與2.x從包的命名上可以看出來，1.x的類庫中，包命名以：org.codehaus.jackson.xxx開頭，而2.x類庫中包命令：com.fastxml.jackson.xxx開頭

• Jackson Home Page：https://github.com/FasterXML/jackson
• Jackson Wiki：http://wiki.fasterxml.com/JacksonHome
• Jackson doc: https://github.com/FasterXML/jackson-docs
• Jackson Download Page：http://wiki.fasterxml.com/JacksonDownload

jackson核心類說明

• JsonGenerator：定義了寫JSON內(nèi)容的公共api基類，實例使用工廠方法創(chuàng)建；
• JsonFactory：jackson包最主要的工廠類，主要被用于配置和構(gòu)建reader(JsonParser)和writer(JsonGenerator)；
• ObjectMapper：ObjectMapper提供讀寫JSON、POJOs對象序列化成JSON和反序列化、JSON樹模型；ObjectMapper是json序列化與反序列化的核心，可以在ObjectMapper配置許多屬性。
• ConfigFeature——配置類接口
  • MapperFeature——Enumeration that defines simple on/off features to set for {@link ObjectMapper}
  • DeserializationFeature——Enumeration that defines simple on/off features that affect the way Java objects are deserialized from JSON
  • SerializationFeature——Enumeration that defines simple on/off features that affect the way Java objects are serialized

maven引入jackson包

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.8.5</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.8.5</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.8.5</version>
</dependency>

POJOs序列化為JSON以及JSON反序列化成POJOs

POJOs (Plain Old Java Objects)

public static class MyClass {
    private String name;
    private String passwd;
    private String address;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPasswd() {
        return passwd;
    }
    public void setPasswd(String passwd) {
        this.passwd = passwd;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    @Override
    public String toString() {
        return "MyClass{" +
                "name='" + name + '\'' +
                ", passwd='" + passwd + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

jackson序列化以及反序列化

@Test
public void test() throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    MyClass myClass = new MyClass();
    myClass.setName("daidai");
    myClass.setPasswd("123456");
    myClass.setAddress("beijing");
    File newFile = new File("my-class.json");
    System.out.println(mapper.canSerialize(Timestamp.class));
    System.out.println(mapper.canDeserialize(JsonUtil.constructParametricType(List.class, MyClass.class)));
    // json序列化
    // 序列化到文件
    mapper.writeValue(newFile, myClass);
    // 序列化成字符串
    String json = mapper.writeValueAsString(myClass);
    System.out.println(json);
    // json反序列化
    // 從文件反序列化
    MyClass older = mapper.readValue(new File("my-class.json"), MyClass.class);
    System.out.println(older);
    // 從json串反序列化
    MyClass older2 = mapper.readValue(json, MyClass.class);
    System.out.println(older2);
    // json Tree解析
    JsonNode root = mapper.readTree(newFile);
    System.out.println(root.at("/passwd"));
    System.out.println(root.at("/name"));
    System.out.println(root.at("/address"));
}

參考資料：http://blog.csdn.net/java_huashan/article/details/46375857