Android数据解析-JSON解析
JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式,基于JavaScript(Standard ECMA-262 3rd Edition - December 1999)的一个子集。 JSON采用完全独立于语言的文本格式,web开发中这个哥们时常出现在你的程序中,你还不得不解析,一般说到JSON,都会不由自主的对比一下它的前辈XML,XML从设计之初到现在已经有十年的光景,在有些方面的作用已经超出其当时设计XML的初衷,WebService是XML的主要的战场,在网络应用场景中由于XML自身的标签形式和Dom形式的数据,解析相对来说会相对麻烦。这个时候JDouglas Crockford提出了JSON,不写不知道,才知道上次买的《JavaScript语言精粹》也是这货写的,⊙﹏⊙~说多了,进入正题吧:
JSON与XML
可读性:JSON和XML的可读性不相上下,JSON格式常用的符号是逗号,小括号,冒号,中括号,引号五种,比较简洁,XML规范的标签形式,都很易读易懂。
可扩展性:XML天生有很好的扩展性,JSON也有,没有什么是XML能扩展,而JSON却不能扩展。不过JSON在Javascript主场作战,可以存储Javascript复合对象,有着xml不可比拟的优势。
编码难度:XML有丰富的编码工具,比如Dom4j、JDom等,JSON也有提供的工具。无工具的情况下,写JSON会比XML稍微快一点(想对我而言),xml文档要多很多结构上的字符。
JSON数据格式:
键值对的形式:{"Name":"FlyElephant"}
数组是值(value)的有序集合。一个数组以“[”(左中括号)开始,“]”(右中括号)结束。值之间使用“,”(逗号)分隔,例如:[{"Name":"FlyElephant"},{"Name":"中山 郎"}]
值(value)可以是双引号括起来的字符串(string)、数值(number)、true、false、null、对象(object)或者数组(array)。这些结构可以嵌套.
JSON解析
Json的格式是固定的,就意味着大家可以按照规则自己解析,不过为了提高开发效率,有些工具提供了简单的功能供大家使用,比如说json-lib,GSON,既然是搞Android,就使用Gsonj解析,Gson下载地址https://code.google.com/p/google-gson/downloads/list?can=1&q=,下载最新的那个即可~之后添加到自己项目中~
不管是开发还是测试都离不开类对象,所以这个时候先建了一个Book类:
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public class Book {
public Book(String bookName, String author) {
super ();
BookName = bookName;
Author = author;
}
private String BookName;
private String Author;
public String getBookName() {
return BookName;
}
public void setBookName(String bookName) {
BookName = bookName;
}
public String getAuthor() {
return Author;
}
public void setAuthor(String author) {
Author = author;
}
} |
转换类对象:
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Book book= new Book( "明朝那些事" , "当年明月" );
Gson gson= new Gson();
//生成JSON调用toJSON
System.out.println( "Book: " + gson.toJson(book));
//解析JSON调用fromJSON
Book jsonBook=gson.fromJson(gson.toJson(book), Book. class );
System.out.println( "Name:" +jsonBook.getBookName()+ "--Author:" +jsonBook.getAuthor());
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结果如下:
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Book: { "BookName" : "明朝那些事" , "Author" : "当年明月" }
Name:明朝那些事--Author:当年明月 |
List<String>和类共同使用
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Gson gson = new Gson();
List<String> list = new ArrayList<String>();
list.add( "北京" );
list.add( "上海" );
list.add( "广州" );
list.add( "深圳" );
System.out.println( "IT城市:" + gson.toJson(list));
//注意这里的第二个参数 list = gson.fromJson(gson.toJson(list),
new TypeToken<List<String>>() {
}.getType());
for (String string : list) {
System.out.println(string);
}
Book book= new Book(gson.toJson(list), "当年明月" );
System.out.println( "Book: " + gson.toJson(book));
Book jsonBook=gson.fromJson(gson.toJson(book), Book. class );
System.out.println( "Name:" +jsonBook.getBookName()+ "--Author:" +jsonBook.getAuthor());
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结果如下:
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IT城市:[ "北京" , "上海" , "广州" , "深圳" ]
北京 上海 广州 深圳 Book: { "BookName" : "[\"北京\",\"上海\",\"广州\",\"深圳\"]" , "Author" : "当年明月" }
Name:[ "北京" , "上海" , "广州" , "深圳" ]--Author:当年明月
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List<Book>解析:
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Gson gson = new Gson();
List<Book> list = new ArrayList<Book>();
Book book1 = new Book( "明朝那些事" , "当年明月" );
Book book2 = new Book( "盗墓笔记" , "南派三叔" );
Book book3 = new Book( "鬼吹灯" , "天下霸唱" );
list.add(book1);
list.add(book2);
list.add(book3);
System.out.println( "Books:" + gson.toJson(list));
List<Book> listJsonBooks = gson.fromJson(gson.toJson(list),
new TypeToken<List<Book>>() {
}.getType());
for (Book book : listJsonBooks) {
System.out.println( "Name:" + book.getBookName() + "Author:"
+ book.getAuthor());
}
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结果如下:
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Books:[{ "BookName" : "明朝那些事" , "Author" : "当年明月" },{ "BookName" : "盗墓笔记" , "Author" : "南派三叔" },{ "BookName" : "鬼吹灯" , "Author" : "天下霸唱" }]
Name:明朝那些事Author:当年明月 Name:盗墓笔记Author:南派三叔 Name:鬼吹灯Author:天下霸唱 |
List<Map<String,String>>解析:
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Gson gson = new Gson();
List<Map<String, String>> listMaps = new ArrayList<Map<String,
String>>();
Map<String, String> map1 = new HashMap<String, String>();
map1.put( "Name" , "FlyElephant" );
map1.put( "Address" , "上地" );
Map<String, String> map2 = new HashMap<String, String>();
map2.put( "Name" , "中山郎" );
map2.put( "Address" , "北京" );
map2.put( "Age" , "25" );
listMaps.add(map1);
listMaps.add(map2);
System.out.println( "Map:" +gson.toJson(listMaps));
listMaps=gson.fromJson(gson.toJson(listMaps), new
TypeToken<List<Map<String,String>>>(){}.getType());
for (Map<String, String> map : listMaps) {
System.out.println( "Name:" +map.get( "Name" )+ "--Address:" +map.get( "Address" ));
}
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结果如下:
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Map:[{ "Address" : "上地" , "Name" : "FlyElephant" },{ "Address" : "北京" , "Age" : "25" , "Name" : "中山郎" }]
Name:FlyElephant--Address:上地 Name:中山郎--Address:北京 |
List<Book>和Map<String>一起解析:
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Gson gson = new Gson();
List<Book> list = new ArrayList<Book>();
Book book1 = new Book( "明朝那些事" , "当年明月" );
Book book2 = new Book( "盗墓笔记" , "南派三叔" );
Book book3 = new Book( "鬼吹灯" , "天下霸唱" );
list.add(book1);
list.add(book2);
list.add(book3);
System.out.println( "Books:" + gson.toJson(list));
List<Book> listJsonBooks = gson.fromJson(gson.toJson(list),
new TypeToken<List<Book>>() {
}.getType());
for (Book book : listJsonBooks) {
System.out.println( "Name:" + book.getBookName() + "Author:"
+ book.getAuthor());
}
Map<String, String> map = new HashMap<String, String>();
map.put( "List" , gson.toJson(list));
map.put( "Info" , "上地" );
System.out.println( "混合使用:" +gson.toJson(map));
map = gson.fromJson(gson.toJson(map),
new TypeToken<Map<String, String>>() {
}.getType());
System.out.println( "List:" + map.get( "List" ) + "--Info:" +map.get( "Info" ));
listJsonBooks= gson.fromJson(map.get( "List" ),
new TypeToken<List<Book>>() {
}.getType());
for (Book book : listJsonBooks) {
System.out.println( "Name:" + book.getBookName() + "Author:"
+ book.getAuthor());
}
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结果如下:
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Books:[{ "BookName" : "明朝那些事" , "Author" : "当年明月" },{ "BookName" : "盗墓笔记" , "Author" : "南派三叔" },{ "BookName" : "鬼吹灯" , "Author" : "天下霸唱" }]
Name:明朝那些事Author:当年明月 Name:盗墓笔记Author:南派三叔 Name:鬼吹灯Author:天下霸唱 混合使用:{ "List" : "[{\"BookName\":\"明朝那些事\",\"Author\":\"当年明月\"},{\"BookName\":\"盗墓笔记\",\"Author\":\"南派三叔\"},{\"BookName\":\"鬼吹灯\",\"Author\":\"天下霸唱\"}]" , "Info" : "上地" }
List:[{ "BookName" : "明朝那些事" , "Author" : "当年明月" },{ "BookName" : "盗墓笔记" , "Author" : "南派三叔" },{ "BookName" : "鬼吹灯" , "Author" : "天下霸唱" }]--Info:上地
Name:明朝那些事Author:当年明月 Name:盗墓笔记Author:南派三叔 Name:鬼吹灯Author:天下霸唱 |
本文转自Fly_Elephant博客园博客,原文链接:http://www.cnblogs.com/xiaofeixiang/p/4084476.html,如需转载请自行联系原作者