jackson学习----解析豆瓣的图书信息

 
异常一、
org.codehaus.jackson.map.JsonMappingException: No suitable constructor found for type [simple type, class com.douban.book.Book$Rating]: can not instantiate from JSON object (need to add/enable type information?)
 at [Source: java.io.StringReader@1cbfe9d; line: 1, column: 12] (through reference chain: com.douban.book.Book["rating"])
	at org.codehaus.jackson.map.JsonMappingException.from(JsonMappingException.java:163)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObjectUsingNonDefault(BeanDeserializer.java:740)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:683)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
	at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:299)
	at org.codehaus.jackson.map.deser.SettableBeanProperty$MethodProperty.deserializeAndSet(SettableBeanProperty.java:414)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:697)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
	at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2723)
	at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1854)
	at com.util.HttpIO.doPost(HttpIO.java:33)
	at com.douban.book.GetBookInfo.main(GetBookInfo.java:11)

在定义Rating内部类的时候没有使用static修饰

异常二、

org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "publisher" (Class com.douban.book.Book), not marked as ignorable
 at [Source: java.io.StringReader@1b8f864; line: 1, column: 852] (through reference chain: com.douban.book.Book["publisher"])
	at org.codehaus.jackson.map.exc.UnrecognizedPropertyException.from(UnrecognizedPropertyException.java:53)
	at org.codehaus.jackson.map.deser.StdDeserializationContext.unknownFieldException(StdDeserializationContext.java:267)
	at org.codehaus.jackson.map.deser.std.StdDeserializer.reportUnknownProperty(StdDeserializer.java:649)
	at org.codehaus.jackson.map.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:635)
	at org.codehaus.jackson.map.deser.BeanDeserializer.handleUnknownProperty(BeanDeserializer.java:1355)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:717)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
	at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2723)
	at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1854)
	at com.util.HttpIO.doPost(HttpIO.java:33)
	at com.douban.book.GetBookInfo.main(GetBookInfo.java:11)

publisher变量没有定义或者定义成private但是没有get set方法

异常三、

org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.lang.String out of START_ARRAY token
 at [Source: java.io.StringReader@1112783; line: 1, column: 75] (through reference chain: com.douban.book.Book["author"])
	at org.codehaus.jackson.map.JsonMappingException.from(JsonMappingException.java:163)
	at org.codehaus.jackson.map.deser.StdDeserializationContext.mappingException(StdDeserializationContext.java:219)
	at org.codehaus.jackson.map.deser.std.StringDeserializer.deserialize(StringDeserializer.java:44)
	at org.codehaus.jackson.map.deser.std.StringDeserializer.deserialize(StringDeserializer.java:13)
	at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:299)
	at org.codehaus.jackson.map.deser.SettableBeanProperty$MethodProperty.deserializeAndSet(SettableBeanProperty.java:414)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:697)
	at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:580)
	at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2723)
	at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1854)
	at com.util.HttpIO.doPost(HttpIO.java:33)
	at com.douban.book.GetBookInfo.main(GetBookInfo.java:11)

author应该是List<String>类型，定义成了String类型

---------------------------------分割线-------------------------------------------------

重要的几个类：

解析json方向

//解析器

org.codehaus.jackson.map.ObjectMapper;

//解析配置

org.codehaus.jackson.map.DeserializationConfig;

objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd"));

objectMapper.setDeserializationConfig(objectMapper.getDeserializationConfig().without(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES))

关于上面这个属性

关于jackson的DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES

-------------------------------------------------------------------------------------------------

注意使用Jackson解析json的一些方法和原则：

{}全部需要定义成类

[] 全部需要定义成List<>

内部类需要定义成static

所有的key都是value变量名对应

还有就是一些方法需要学习

http://itindex.net/detail/51074-java-%E5%88%A9%E7%94%A8-jackson

http://developers.douban.com/wiki/?title=guide

com.util.HttpIO类

package com.util;

import java.io.IOException;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.codehaus.jackson.map.ObjectMapper;

import com.douban.book.Book;

public class HttpIO
{
    public static void doPost(final String url, final String body)
    {

        HttpClient httpclient = new DefaultHttpClient();
        ObjectMapper mapper = new ObjectMapper();

        HttpPost post = new HttpPost(url);
        try
        {
            HttpResponse result = httpclient.execute(post);

            if (result.getStatusLine().getStatusCode() == 200)
            {
                String str = EntityUtils.toString(result.getEntity());
                System.out.println(str);

                Book book = mapper.readValue(str, Book.class);
                System.out.println(book);
            }
        }
        catch(ClientProtocolException e)
        {
            e.printStackTrace();
        }
        catch(IOException e)
        {
            e.printStackTrace();
        }
    }
}

　　

package com.douban.book;

import com.util.HttpIO;


//http://api.douban.com/v2/book/1220562
public class GetBookInfo
{
	public static void main(String[] args)
	{
		HttpIO.doPost("http://api.douban.com/v2/book/1220562",null);
	}
}

　　

package com.douban.book;

import java.util.List;

public class Book
{
    private String publisher;

    public String id;

    private String alt;

    private Rating rating;

    private List<String> author;

    private String alt_title;

    private Images images;

    private String title;

    private String mobile_link;

    private String summary;

    private Attrs attrs;

    private List<Tags> tags;

    private String subtitle;

    private String pubdate;

    private String isbn10;

    private String isbn13;

    private String url;

    private String author_intro;

    private String price;

    private String origin_title;

    private String binding;

    private String catalog;

    private String pages;

    private String image;

    private List<String> translator;
    
    

    public List<String> getTranslator()
    {
        return translator;
    }

    public void setTranslator(List<String> translator)
    {
        this.translator = translator;
    }

    public String getImage()
    {
        return image;
    }

    public void setImage(String image)
    {
        this.image = image;
    }

    public Images getImages()
    {
        return images;
    }

    public void setImages(Images images)
    {
        this.images = images;
    }

    public String getBinding()
    {
        return binding;
    }

    public void setBinding(String binding)
    {
        this.binding = binding;
    }

    public String getCatalog()
    {
        return catalog;
    }

    public void setCatalog(String catalog)
    {
        this.catalog = catalog;
    }

    public String getPages()
    {
        return pages;
    }

    public void setPages(String pages)
    {
        this.pages = pages;
    }

    static class Images
    {
        private String small;

        private String large;

        private String medium;

        public String getSmall()
        {
            return small;
        }

        public void setSmall(String small)
        {
            this.small = small;
        }

        public String getLarge()
        {
            return large;
        }

        public void setLarge(String large)
        {
            this.large = large;
        }

        public String getMedium()
        {
            return medium;
        }

        public void setMedium(String medium)
        {
            this.medium = medium;
        }

    }

    public String getOrigin_title()
    {
        return origin_title;
    }

    public void setOrigin_title(String origin_title)
    {
        this.origin_title = origin_title;
    }

    public Book()
    {

    }

    public Book(String str)
    {

    }

    public String getPubdate()
    {
        return pubdate;
    }

    public void setPubdate(String pubdate)
    {
        this.pubdate = pubdate;
    }

    public String getIsbn10()
    {
        return isbn10;
    }

    public void setIsbn10(String isbn10)
    {
        this.isbn10 = isbn10;
    }

    public String getIsbn13()
    {
        return isbn13;
    }

    public void setIsbn13(String isbn13)
    {
        this.isbn13 = isbn13;
    }

    public String getUrl()
    {
        return url;
    }

    public void setUrl(String url)
    {
        this.url = url;
    }

    public String getAuthor_intro()
    {
        return author_intro;
    }

    public void setAuthor_intro(String author_intro)
    {
        this.author_intro = author_intro;
    }

    public String getPrice()
    {
        return price;
    }

    public void setPrice(String price)
    {
        this.price = price;
    }

    public String getSubtitle()
    {
        return subtitle;
    }

    public void setSubtitle(String subtitle)
    {
        this.subtitle = subtitle;
    }

    public String getAlt()
    {
        return alt;
    }

    public void setAlt(String alt)
    {
        this.alt = alt;
    }

    public Rating getRating()
    {
        return rating;
    }

    public void setRating(Rating rating)
    {
        this.rating = rating;
    }

    public List<String> getAuthor()
    {
        return author;
    }

    public void setAuthor(List<String> author)
    {
        this.author = author;
    }

    public String getAlt_title()
    {
        return alt_title;
    }

    public void setAlt_title(String alt_title)
    {
        this.alt_title = alt_title;
    }

    public String getTitle()
    {
        return title;
    }

    public void setTitle(String title)
    {
        this.title = title;
    }

    public String getMobile_link()
    {
        return mobile_link;
    }

    public void setMobile_link(String mobile_link)
    {
        this.mobile_link = mobile_link;
    }

    public String getSummary()
    {
        return summary;
    }

    public void setSummary(String summary)
    {
        this.summary = summary;
    }

    public Attrs getAttrs()
    {
        return attrs;
    }

    public void setAttrs(Attrs attrs)
    {
        this.attrs = attrs;
    }

    public List<Tags> getTags()
    {
        return tags;
    }

    public void setTags(List<Tags> tags)
    {
        this.tags = tags;
    }

    static private class Tags
    {
        private String count;

        private String name;

        private String title;

        public String getTitle()
        {
            return title;
        }

        public void setTitle(String title)
        {
            this.title = title;
        }

        public String getCount()
        {
            return count;
        }

        public void setCount(String count)
        {
            this.count = count;
        }

        public String getName()
        {
            return name;
        }

        public void setName(String name)
        {
            this.name = name;
        }
    }

    static private class Attrs
    {
        private List<String> publiser;

        private List<String> pubdate;

        private List<String> author;

        private List<String> price;

        private List<String> title;

        private List<String> binding;

        private List<String> translator;

        private List<String> pages;

        public List<String> getPubliser()
        {
            return publiser;
        }

        public void setPubliser(List<String> publiser)
        {
            this.publiser = publiser;
        }

        public List<String> getPubdate()
        {
            return pubdate;
        }

        public void setPubdate(List<String> pubdate)
        {
            this.pubdate = pubdate;
        }

        public List<String> getAuthor()
        {
            return author;
        }

        public void setAuthor(List<String> author)
        {
            this.author = author;
        }

        public List<String> getPrice()
        {
            return price;
        }

        public void setPrice(List<String> price)
        {
            this.price = price;
        }

        public List<String> getTitle()
        {
            return title;
        }

        public void setTitle(List<String> title)
        {
            this.title = title;
        }

        public List<String> getBinding()
        {
            return binding;
        }

        public void setBinding(List<String> binding)
        {
            this.binding = binding;
        }

        public List<String> getTranslator()
        {
            return translator;
        }

        public void setTranslator(List<String> translator)
        {
            this.translator = translator;
        }

        public List<String> getPages()
        {
            return pages;
        }

        public void setPages(List<String> pages)
        {
            this.pages = pages;
        }
    }

    static class Rating
    {
        private int max;

        private String average;

        private int numRaters;

        private int min;

        public int getMax()
        {
            return max;
        }

        public void setMax(int max)
        {
            this.max = max;
        }

        public String getAverage()
        {
            return average;
        }

        public void setAverage(String average)
        {
            this.average = average;
        }

        public int getNumRaters()
        {
            return numRaters;
        }

        public void setNumRaters(int numRaters)
        {
            this.numRaters = numRaters;
        }

        public int getMin()
        {
            return min;
        }

        public void setMin(int min)
        {
            this.min = min;
        }

    }

    public String getPublisher()
    {
        return publisher;
    }

    public void setPublisher(String publisher)
    {
        this.publisher = publisher;
    }

}

{
    "rating": {
        "max": 10, 
        "numRaters": 345, 
        "average": "7.0", 
        "min": 0
    }, 
    "subtitle": "", 
    "author": [
        "[日] 片山恭一"
    ], 
    "pubdate": "2005-1", 
    "tags": [
        {
            "count": 133, 
            "name": "片山恭一", 
            "title": "片山恭一"
        }, 
        {
            "count": 62, 
            "name": "日本", 
            "title": "日本"
        }, 
        {
            "count": 60, 
            "name": "日本文学", 
            "title": "日本文学"
        }, 
        {
            "count": 38, 
            "name": "小说", 
            "title": "小说"
        }, 
        {
            "count": 32, 
            "name": "满月之夜白鲸现", 
            "title": "满月之夜白鲸现"
        }, 
        {
            "count": 15, 
            "name": "爱情", 
            "title": "爱情"
        }, 
        {
            "count": 8, 
            "name": "純愛", 
            "title": "純愛"
        }, 
        {
            "count": 8, 
            "name": "外国文学", 
            "title": "外国文学"
        }
    ], 
    "origin_title": "", 
    "image": "http://img3.douban.com/mpic/s1747553.jpg", 
    "binding": "平装", 
    "translator": [
        "豫人"
    ], 
    "catalog": "
      ", 
    "pages": "180", 
    "images": {
        "small": "http://img3.douban.com/spic/s1747553.jpg", 
        "large": "http://img3.douban.com/lpic/s1747553.jpg", 
        "medium": "http://img3.douban.com/mpic/s1747553.jpg"
    }, 
    "alt": "http://book.douban.com/subject/1220562/", 
    "id": "1220562", 
    "publisher": "青岛出版社", 
    "isbn10": "7543632608", 
    "isbn13": "9787543632608", 
    "title": "满月之夜白鲸现", 
    "url": "http://api.douban.com/v2/book/1220562", 
    "alt_title": "", 
    "author_intro": "", 
    "summary": "那一年，是听莫扎特、钓鲈鱼和家庭破裂的一年。说到家庭破裂，母亲怪自己当初没有找到好男人，父亲则认为当时是被狐狸精迷住了眼，失常的是母亲，但出问题的是父亲……。", 
    "price": "15.00元"
}

对于Book类当中的Bean变量 可以定义成private的 然后赋予get set方法，也可以直接定义成public的

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原文地址：https://www.cnblogs.com/wuxinliulei/p/4912824.html