灵活组装Json的数据使用Gson的JsonParser和JsonReader解析Json详解例子

package com.app.json;  
  
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import net.sf.json.JSONArray;

import com.app.entity.duapp.Address;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

/**
 *@DEMO:napp
 *@Author:jilongliang
 *@Date:2013-7-20
 */
public class JsonParse {  
	private static Gson gson=new Gson();
    /**
	 * 通过JsonLib把数组转换成Json数据
	 * @param url
	 * @throws Exception
	 */
	private static JSONArray getArrayToJsonByJsonLib()throws Exception
	{
		JSONArray jsonArr=null;
		List<Address> lists=new ArrayList<Address>();
		for (int i = 1; i <=12; i++) {
			Address addr = new Address(); 
			addr.setProvince("第"+i+"个省份");
			addr.setCity("第"+i+"个城市");
			addr.setCityCode("130"+i);
			addr.setStreet("街道"+i);
			addr.setStreetNumber("街道号码"+i);
			lists.add(addr);
		}
		jsonArr = JSONArray.fromObject(lists);  //把对象转换成Json对象
		return jsonArr;
	}
	
	public static void main(String[] args)throws Exception{
		getJsonGson(); 
		
	}
	
	/**
	 * 利用Json-lib封装数组Json数据,Gson解析Json数据.
	 * @throws Exception
	 */
	private static void getJsonGson() throws Exception {
		//Json-lib的JSONArray数组对象
		JSONArray  JsonArray =getArrayToJsonByJsonLib();
		String jsonData=JsonArray.toString();
		/*
		 * 自己组装成一个json格式，格式必须为{,,}才能为JsonElement对象的parse方法解析不是否则
		 * 会报错com.google.gson.JsonSyntaxException: java.io.EOFException: End of input at line 1 column 1307
		 */
		String json="{status:1,address:"+jsonData+"}";

		// 创建一个JsonParser
		JsonParser parser = new JsonParser();
		JsonElement jsonEl = parser.parse(json);
		
		JsonObject jsonObj = null;
		jsonObj = jsonEl.getAsJsonObject();//转换成Json对象
		String status=jsonObj.get("status").getAsString();//status节点
		//System.out.println(status);
		
		JsonElement addressEl=jsonObj.get("address");//address节点
		if(addressEl.isJsonArray()){//判断是否为Json数组
			JsonArray jsonArray= addressEl.getAsJsonArray();//转为数组
			for(Iterator iter=jsonArray.iterator();iter.hasNext();){
				JsonObject obj=(JsonObject) iter.next();
				//String city=obj.get("city").getAsString();//方法一：根据key形势取值
				Address add=gson.fromJson(obj, Address.class);//方法二：灵活使用Gson取数据
				System.out.println(add.getProvince()+"\t"+add.getCity());
			 }
		}
	}
	 
 } 

 json数据是由运行JsonRead类可以生成

{
	"info":
	{
		"users":{"username":"liangjilong","email":"[e-mail]","tel":"12396878","age":"25"},
		"address":{"street":"棠东","province":"广东省","district":"天河区","city":"广州市"}
	}
}

 JsonRead

package com.app.json;

import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.util.HashMap;
import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.stream.JsonReader;

/**
 *@DEMO:napp
 *@Author:jilongliang
 *@Date:2013-7-20
 */
public class JsonRead {
	private static Gson gson=new Gson();
	/**
	 * @param args
	 */
	public static void main(String[] args) throws Exception{
		 getJsonData();
         
        //方法二
        //String pathname="src/config/doc/json";
 		//InputStream input = new FileInputStream(new File(pathname));
 		//readJsonData(input,null);
	}
	/**
	 * 组装Json数据
	 * @throws Exception
	 */
	private static void getJsonData() throws Exception {
		/**
		  * 组装address对象的数据
		  */
		 Map<String, String> address = new HashMap <String, String>(); 
		 address.put("province", "广东省");
		 address.put("city", "广州市");
		 address.put("district", "天河区");
		 address.put("street", "棠东"); 
		 /**
		  * 组装users对象的数据
		  */
		 Map<String, String> users = new HashMap <String, String>(); 
		 users.put("username", "liangjilong");
		 users.put("age", "25");
		 users.put("tel", "12396878");
		 users.put("email", "[e-mail]"); 
		 
		 Map<Object, Object> listsObj = new HashMap <Object, Object>(); 
		 listsObj.put("address",address);//address节点
		 listsObj.put("users",users);//users节点
		 
		 Object obj=listsObj;//转换成对象
		 
		 Map<Object, Object> info = new HashMap <Object, Object>(); 
		 info.put("info", obj);//json的根节点
		 
		 
         String json=gson.toJson(info);//转换成json数据
         System.out.println(json);//打印json数据
         readJsonData(null,json);
	}
	/**
	 * 从文件读取json数据
	 * @param in
	 * @throws Exception
	 */
	public static void readJsonData(InputStream in,String json) throws Exception {
		//JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8"));
		JsonReader reader = new JsonReader(new StringReader(json));
		try {
			reader.beginObject();
			String tagName = reader.nextName();
			if (tagName.equals("info")) {
				readInfo(reader);
			}
			reader.endObject();
		} finally {
			reader.close();
		}
	}
	/**
	 * 读取json的父(根,第一个)节点
	 * @param reader
	 * @throws Exception
	 */
	public static void readInfo(JsonReader reader) throws Exception {
		reader.beginObject();
		while (reader.hasNext()) {
			String tagName = reader.nextName();
			if (tagName.equals("address")) {
				readAddress(reader);
			} else if (tagName.equals("users")) {
				readUsers(reader);
			} 
		}
		reader.endObject();
	}
	/**
	 * 读取用户信息值
	 * @param reader
	 * @throws IOException
	 */
	public static void readUsers(JsonReader reader) throws IOException {
		reader.beginObject();
		while (reader.hasNext()) {
			String tag = reader.nextName();
			if (tag.equals("username")) {
				String username = reader.nextString();
				System.out.println("用户名:" + username);
			} else if (tag.equals("email")) {
				String email = reader.nextString();
				System.out.println("Email:" + email);
			} else if (tag.equals("tel")) {
				String tel = reader.nextString();
				System.out.println("电话:" + tel);
			}else if (tag.equals("age")) {
				String age = reader.nextString();
				System.out.println("年龄:" + age);
			} else {
				reader.skipValue();//忽略值/跳过break
			}
		}
		reader.endObject();
	}
	/**
	 * 读取地区值
	 * @param reader
	 * @throws IOException
	 */
	public static void readAddress(JsonReader reader) throws IOException {
		reader.beginObject();
		while (reader.hasNext()) {
			String tag = reader.nextName();
			if (tag.equals("province")) {
				String province = reader.nextString();
				System.out.println("省份:" + province);
			} else if (tag.equals("city")) {
				String city = reader.nextString();
				System.out.println("街道:" + city);
			} else if (tag.equals("street")) {
				String street = reader.nextString();
				System.out.println("街道:" + street);
			}else if (tag.equals("district")) {
				String district = reader.nextString();
				System.out.println("区:" + district);
			} else {
				reader.skipValue();//忽略值/跳过break
			}
		}
		reader.endObject();
	}
}

 实体类：

package com.app.entity.duapp;

import java.io.Serializable;

import com.google.gson.annotations.Expose;
/**
 * 使用 new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
 * 创建Gson对象,没有@Expose注释的属性将不会被序列化
 * serialize序列化 默认 true
 * deserialize反序列化 默认 true
 *
 */
public class Address implements Serializable{
	@Expose(serialize=false)// 序列化  /类已经序列化
	private String streetNumber;
	@Expose(deserialize=false)// 反序列化
	private String street;
	private String district;
	private String city;
	private String province;
	private String cityCode;
	public String getCityCode() {
		return cityCode;
	}
	public void setCityCode(String cityCode) {
		this.cityCode = cityCode;
	}
	public String getStreetNumber() {
		return streetNumber;
	}
	public void setStreetNumber(String streetNumber) {
		this.streetNumber = streetNumber;
	}
	public String getStreet() {
		return street;
	}
	public void setStreet(String street) {
		this.street = street;
	}
	public String getDistrict() {
		return district;
	}
	public void setDistrict(String district) {
		this.district = district;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	public String getProvince() {
		return province;
	}
	public void setProvince(String province) {
		this.province = province;
	}
	
}