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)
在定義Rating內部類的時候沒有使用static修飾java
異常2、apache
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變量沒有定義或者定義成private可是沒有get set方法json
異常3、api
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應該是List<String>類型,定義成了String類型app
---------------------------------分割線-------------------------------------------------ide
重要的幾個類:post
解析json方向學習
//解析器ui
org.codehaus.jackson.map.ObjectMapper;this
//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))
關於上面這個屬性
-------------------------------------------------------------------------------------------------
注意使用Jackson解析json的一些方法和原則:
{}所有須要定義成類
[] 所有須要定義成List<>
內部類須要定義成static
全部的key都是value變量名對應
還有就是一些方法須要學習
http://itindex.net/detail/51074-java-%E5%88%A9%E7%94%A8-jackson
http://developers.douban.com/wiki/?title=guide
com.util.HttpIO類
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": "日本文學", "title": "日本文學" }, {
"count": 38, "name": "小說", "title": "小說" }, {
"count": 32, "name": "滿月之夜白鯨現", "title": "滿月之夜白鯨現" }, {
"count": 15, "name": "愛情", "title": "愛情" }, {
"count": 8, "name": "純愛", "title": "純愛" }, {
"count": 8, "name": "外國文學", "title": "外國文學" } ], "origin_title": "", "image": "http://img3.douban.com/mpic/s1747553.jpg", "binding": "平裝", "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": "青島出版社", "isbn10": "7543632608", "isbn13": "9787543632608", "title": "滿月之夜白鯨現", "url": "http://api.douban.com/v2/book/1220562", "alt_title": "", "author_intro": "", "summary": "那一年,是聽莫扎特、釣鱸魚和家庭破裂的一年。說到家庭破裂,母親怪本身當初沒有找到好男人,父親則認爲當時是被狐狸精迷住了眼,失常的是母親,但出問題的是父親……。", "price": "15.00元" }
對於Book類當中的Bean變量 能夠定義成private的 而後賦予get set方法,也能夠直接定義成public的