使用gson处理json字符串

首先pom.xml

<dependency>
        <groupId>com.google.code.gson</groupId>
	<artifactId>gson</artifactId>
	<version>2.8.5</version>
</dependency>

也可以直接去这个网址下载jar包 https://mvnrepository.com/artifact/com.google.code.gson/gson

我们来解析下面这个json字符串，这是我工作是要用的

  JsonParser jp = new JsonParser();
    	String aa=TranUtil.Get("武汉","广州","2019-11-21");
		  //将json字符串转化成json对象 
    	  JsonObject jo = jp.parse(aa).getAsJsonObject();
    	System.out.println(jo);
	  String list =jo.get("result").getAsJsonObject().get("list").getAsJsonArray().toString();
	    //String类型变成list
	      Gson gson = new Gson();
	    List<aaa> arrList = gson.fromJson(list, new TypeToken<List<aaa>>() {}.getType());
	    //aaa是实体类
	   //循环便利
	     List<aaa> list3 =new ArrayList<aaa>();
			  for (int i = 0; i < arrList.size(); i++) {
				  System.out.println(arrList.get(i).getType());
				
				  if(type.equals(arrList.get(i).getType())) {
					  list3.add(arrList.get(i));
				  }
				          }

下面这是一个例子

import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
 
 
public class Test {
	public static void main(String[] args) {
		String resultStr = "{\"status\": 0,\"message\": \"query ok\","+
				"\"result\": {\"address\": \"北京市海淀区镜桥\","+
				"\"address_component\": {\"nation\": \"中国\",\"province\": \"北京市\","+
				"\"city\": \"北京市\",\"district\": \"海淀区\","+
			"\"street\": \"镜桥\",\"street_number\": \"镜桥\"}}}";
		
		JsonParser jp = new JsonParser();
		//将json字符串转化成json对象
            JsonObject jo = jp.parse(resultStr).getAsJsonObject();
            //获取message对应的值
            String message = jo.get("message").getAsString();
            System.out.println("message：" + message);
            //获取address对应的值
            String address = jo.get("result").getAsJsonObject().get("address").getAsString();
            System.out.println("address：" + address);
            //获取city对应的值
            String nation = jo.get("result").getAsJsonObject().get("address_component")
        						.getAsJsonObject().get("nation").getAsString();
            System.out.println("nation：" + nation);
	}
}

2，gson之将对象转化成json字符串的方法

public class GsonUtil {
    /**
     * 将object对象转成json格式字符串
     */
    public static String toJson(Object object) {
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.setPrettyPrinting();
        Gson gson = gsonBuilder.create();
        return gson.toJson(object);
    }
}