Fastjson API ParseProcess

1. Fastjson API ParseProcess简介

ParseProcess是编程扩展定制反序列化的接口。fastjson支持如下ParseProcess：

• ExtraProcessor 用于处理多余的字段
• ExtraTypeProvider 用于处理多余字段时提供类型信息

2. 使用ExtraProcessor 处理多余字段

public static class VO {
    private int id;
    private Map<String, Object> attributes = new HashMap<String, Object>();
    public int getId() { return id; }
    public void setId(int id) { this.id = id;}
    public Map<String, Object> getAttributes() { return attributes;}
}

ExtraProcessor processor = new ExtraProcessor() {
    public void processExtra(Object object, String key, Object value) {
        VO vo = (VO) object;
        vo.getAttributes().put(key, value);
    }
};

VO vo = JSON.parseObject("{\"id\":123,\"name\":\"abc\"}", VO.class, processor);
Assert.assertEquals(123, vo.getId());
Assert.assertEquals("abc", vo.getAttributes().get("name"));

3. 使用ExtraTypeProvider 为多余的字段提供类型

public static class VO {
    private int id;
    private Map<String, Object> attributes = new HashMap<String, Object>();
    public int getId() { return id; }
    public void setId(int id) { this.id = id;}
    public Map<String, Object> getAttributes() { return attributes;}
}

class MyExtraProcessor implements ExtraProcessor, ExtraTypeProvider {
    public void processExtra(Object object, String key, Object value) {
        VO vo = (VO) object;
        vo.getAttributes().put(key, value);
    }

    public Type getExtraType(Object object, String key) {
        if ("value".equals(key)) {
            return int.class;
        }
        return null;
    }
};
ExtraProcessor processor = new MyExtraProcessor();

VO vo = JSON.parseObject("{\"id\":123,\"value\":\"123456\"}", VO.class, processor);
Assert.assertEquals(123, vo.getId());
Assert.assertEquals(123456, vo.getAttributes().get("value")); // value本应该是字符串类型的，通过getExtraType的处理变成Integer类型了。