jackson笔记

使用版本为2.6.4

网上已经有挺多教程了来着，而后是用的之前的版本，这里作下新的版本的笔记。 关于jackson的优势主要参考 点我看优势哟！

jacksonjar介绍

• jackson-core(必须包含)，提供流模式
• jackson-databind数据绑定包，提供对象绑定与数模型
• jackson-annotations注解包，提供注解

使用maven下载jackson相关jar：

<!--jackson-->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.6.4</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.6.4</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.6.4</version>
        </dependency>

如下用demo的形式。介绍经常使用的功能；

demo之前初始化后续要用的各类变量，以及设置,Student类就不贴了；

ObjectMapper mapper; // can reuse, share globally
    JsonNodeFactory nodeFactory;
    JsonFactory jsonFactory;
    JsonGenerator generator;
    @Before
    public void mapper(){
        mapper = new ObjectMapper();
        /*设置输出显示为json格式*/
        mapper.configure(SerializationFeature.INDENT_OUTPUT, true);
        /*设置JSON按照name排序*/
        mapper.configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS, true);
        /*设置date样式*/
        SimpleDateFormat outputFormat = new SimpleDateFormat("dd-MM-yyyy");
        mapper.setDateFormat(outputFormat);
        /*设置忽略空的值*/
        mapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
        /*用tree model 模式构造json*/
        /*设置节点工厂，用于参数节点*/
        nodeFactory = new JsonNodeFactory(false);
        /*
        创造工厂将JSON节点生成为JSON字符串
        设置输出为System.out*/
        jsonFactory = new JsonFactory();
        try {
            generator = jsonFactory.createGenerator(out);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

demo1

/**
     * Bean to JSON
     * result:{"name":"jackson","age":25,"course":{"number":12}}
     */
    @Test
    public void demo1(){
        try {
            Student student = new Student();
            Course course = new Course();
            course.setNumber(12);
            student.setAge(25);
            student.setName("jackson");
            student.setCourse(course);
            System.out.print(mapper.writeValueAsString(student));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

demo2

/**
     * Map To JSON
     * result:{"name":"jackson","age":25}
     */
    @Test
    public void demo2(){
        try {
            Map<String,Object> map = new HashMap<String, Object>();
            map.put("name","jackson");
            map.put("age",25);
            System.out.print(mapper.writeValueAsString(map));

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

demo3

/**
     * List To JSON
     * Result:["jackson",25]
     */
    @Test
    public void demo3(){
        try{
            List<Object> list = new ArrayList<Object>();
            list.add("jackson");
            list.add(25);

            System.out.println(mapper.writeValueAsString(list));


        }catch (IOException e){

            e.printStackTrace();
        }
    }

demo4

/**
     * List Map To JSON
     * Result:{"name":"jackson","course":[{"math":98},{"english":100}],"age":25}
     */
    @Test
    public void demo4(){
        try {
            Map<String,Object> map = new HashMap<String, Object>();
            map.put("name","jackson");
            map.put("age",25);

            List<Object> list = new ArrayList<Object>();
            Map<String,Object> mapCourse1 = new HashMap<String, Object>();
            mapCourse1.put("math",98);
            Map<String,Object> mapCourse2 = new HashMap<String, Object>();
            mapCourse2.put("english",100);
            list.add(mapCourse1);
            list.add(mapCourse2);

            map.put("course",list);

            System.out.println(mapper.writeValueAsString(map));
        }catch (IOException e){
            e.printStackTrace();
        }
    }

demo5

/**
     * Date formate set
     * result:{"birthday" : "23-03-2012"}
     */
    @Test
    public void demo5(){

        Map<String,Date> map = new HashMap<String, Date>();
        SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy");

        try {
            map.put("birthday",format.parse("23-03-2012"));
        } catch (ParseException e) {
            e.printStackTrace();
        }

        try {
            out.println(mapper.writeValueAsString(map));
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }


    }

demo6

/**
     * Tree model 模式
     *
     * Tree model to Json
     *
     * result:{"name":"jackson","major":{"mathnum":12},"addr":[{"addr":"cq"}]}
     */
    @Test
    public void demo6(){

        ObjectNode teacher = nodeFactory.objectNode();
        teacher.put("name","jackson");

        ObjectNode course = teacher.putObject("major");
        course.put("mathnum",12);

        ArrayNode addr = teacher.putArray("addr");

        ObjectNode detailAddr = nodeFactory.objectNode();
        detailAddr.put("addr","cq");
        addr.add(detailAddr);

        try {
            mapper.writeTree(generator, teacher);
        } catch (IOException e) {
            e.printStackTrace();
        }


    }

demo7

/**
     * Tree model 模式
     *
     * Json to Tree model and tree model to json
     */
    @Test
    public void demo7(){

        String jsonString = "{\"name\":\"jackson\",\"major\":{\"mathnum\":12},\"addr\":[{\"addr\":\"cq\"}]}";

        ObjectNode teacher = null;
        try {
            teacher = (ObjectNode) mapper.readTree(jsonString);
        } catch (IOException e) {
            e.printStackTrace();
        }

        out.println("name:"+teacher.get("name").asText());

        ObjectNode major = (ObjectNode) teacher.get("major");
        out.println("mathnum:"+major.get("mathnum").asInt());

        ArrayNode addr = (ArrayNode) teacher.get("addr");
        ObjectNode addr1 = (ObjectNode) addr.get(0);
        out.println("addr:"+addr1.get("addr").asText());
    }

以上为基本与用法,更高端的能够参考：

• jackson教程1
• github主页