Java解析json字符串（一）

最近突然對json比較敏感，項目裏不少地方需要自己拼接json或者對json進行解析處理，來記錄一下學習經歷，這篇說說直接訪問json進行解析的方式，後續更解析成Javabean的方式~

有三種解析方式：解析的方式無大差異只是方法名不一樣需要注意

1.jsonlib解析：比較麻煩，需要引入的jar包比較多：

• commons-beanutils-xxx.jar
• commons-collections-xxx.jar
• commons-lang-xxx.jar
• commons-logging-xxx.jar
• ezmorph-xxx.jar
• json-lib-xxx.jar

2.阿里巴巴的FastJson解析：這個比較好，功能和jsonlib差不多但是隻需要引一個jar包就好：fastjson-xxx.jar

3.谷歌的gson解析：gson-xxx.jar

1.jsonlib解析

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class textJsonLib {
    public static void main(String[] args) {
        //最簡單的json格式解析：
        String hehe = "{'question':'123','answer':'456'}";
        JSONObject jsonObject = JSONObject.fromObject(hehe);
        System.out.println("question:" + jb.get("question") + "," + "answer:" +     jb.get("answer"));
        輸出格式：question:123,answer:456
        System.out.println("====================");

        //複雜一點的json格式解析,json裏帶數組的
        String hehe = "{'type':'multy','question':'愛好','options':[{'value':'籃球'},{'value':'足球'}]}";
        JSONObject jsonObject = JSONObject.fromObject(hehe);
        String type = (String) jsonObject.get("type");
	String question = (String) jsonObject.get("question");
	System.out.println(type + "," + question);
        //解析中間json數組
        JSONArray items = jsonObject.getJSONArray("options");
        JSONObject row = null;
        for (int i = 0; i < items.size(); i++) {
            row = items.getJSONObject(i);
            System.out.println(row.get("value"));
        }
        System.out.println("====================");

        String hehe = "{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球'},{'value':'足球'}]}}";
        JSONObject jsonObject = JSONObject.fromObject(hehe);
        String type = (String) jsonObject.get("type");
	String question = (String) jsonObject.get("question");
	System.out.println(type + "," + question);
        JSONArray items = jsonObject.getJSONObject("options").getJSONArray("items");
        JSONObject row = null;
        for (int i = 0; i < items.size(); i++) {
            row = items.getJSONObject(i);
            System.out.println(row.get("value"));
        }
        System.out.println("====================");

        String hehe = "{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','value':'足球'}]}}";
        JSONObject jsonObject = JSONObject.fromObject(hehe);
        String type = (String) jsonObject.get("type");
	String question = (String) jsonObject.get("question");
	System.out.println(type + "," + question);
        JSONArray items = jsonObject.getJSONObject("options").getJSONArray("items");
        JSONObject row = null;
        for (int i = 0; i < items.size(); i++) {
            row = items.getJSONObject(i);
            System.out.println(row.get("value"));  //這樣可以直接取出數組中的兩條數據
            //也可以將items對應的數組取出來再進行遍歷   ["籃球","足球"]
            JSONArray values = JSONArray.fromObject(row.get("value"));
            System.out.println(values);
	    for (int k = 0; k < values.size(); k++) {
	        System.out.println(values.get(k));   //這樣也可以取出來對應的兩條數據
	    }
        }
        System.out.println("====================");

        //再來個複雜點的，數組裏嵌套json的
        String json = "{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}}";
	JSONObject jsonObject = JSONObject.fromObject(json);
	System.out.println("type:" + jsonObject.get("type") + "," + "question:" + jsonObject.get("question"));
	JSONArray items = jsonObject.getJSONObject("options").getJSONArray("items");
	JSONObject row = null;
	for (int i = 0; i < items.size(); i++) {
	    row = items.getJSONObject(i);
	    System.out.println("value:" + row.get("value"));
            JSONObject country = row.getJSONObject("country");
	    System.out.println("privince:" + country.get("privince") + "," + "city:" + country.get("city"));
	}
        /*
         * 輸出
         * type:multy,question:愛好
         * value:籃球
         * privince:liaoning,city:shenyang		
         */
        System.out.println("====================");

        //解析json數組，說白了就是分成挨個json字符串挨個解析
        String json = "[{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}},{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}}]";
	JSONArray jsonArray = JSONArray.fromObject(json);
	for (int i = 0; i < jsonArray.size(); i++) {
	    JSONObject jsonObject = JSONObject.fromObject(jsonArray.get(i));
	    System.out.println(jsonObject.get("type") + "," + jsonObject.get("question"));
	    JSONArray items = jsonObject.getJSONObject("options").getJSONArray("items");
	    JSONObject row = null;
	    for (int j = 0; j < items.size(); j++) {
	        row = items.getJSONObject(j);
		System.out.println(row.get("value"));
		JSONObject country = row.getJSONObject("country");
		System.out.println(country.get("privince") + "," + country.get("city"));
	    }
	}

    }
}

以上全部親測有效~
2.fastjson解析：這裏只貼一個解析json數組的代碼了，基本上和jsonlib的一樣，只是方法名有點不同，注意一下就好

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class testFstJson {
    public static void main(String[] args) {
        String json = "[{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}},{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}}]";
        JSONArray jsonArray = JSONArray.parseArray(json);
	for (int i = 0; i < jsonArray.size(); i++) {
	    JSONObject jsonObject = JSONObject.parseObject(jsonArray.getString(i));
	    System.out.println(jsonObject.get("type") + "," + jsonObject.get("question"));
	    JSONArray items = jsonObject.getJSONObject("options").getJSONArray("items");
	    JSONObject row = null;
	    for (int j = 0; j < items.size(); j++) {
	        row = items.getJSONObject(j);
		System.out.println(row.get("value"));
		JSONObject country = row.getJSONObject("country");
		System.out.println(country.get("privince") + "," + country.get("city"));
	    }
	}
        /*
	 * 輸出格式
	 * multy,愛好
	 * 籃球
	 * liaoning,shenyang
	 * multy,愛好
	 * 籃球
	 * liaoning,shenyang
	 */
    }
}

3.gson方式解析：親身嘗試之後感覺不如前兩個好，不推薦使用

import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

public class testGsonJson {
    public static void main(String[] args) {
        //解析json數據
        String json = "{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}}";
	JsonObject jsonObject = (JsonObject) new JsonParser().parse(json);
        //此處可以直接輸出，如果要取出值放到別出用的話一定要用getAsString()或者toString()方法轉換一下類型，否則報錯
	String type = jsonObject.get("type").getAsString();
	String question = jsonObject.get("question").getAsString();
	System.out.println(type + "," + question);
	JsonArray jsonArray = jsonObject.get("options").getAsJsonObject().get("items").getAsJsonArray();
	JsonObject row = null;
	for (int i = 0; i < jsonArray.size(); i++) {
	    row = (JsonObject) jsonArray.get(i);
	    System.out.println(row);
	    String value = row.get("value").getAsString();
	    System.out.println("value:" + value);
            JsonObject country = row.get("country").getAsJsonObject();
	    System.out.println("privince:" + country.get("privince") + "," + "city:" + country.get("city"));
	}
        /*
         * 控制檯輸出
	 * multy,愛好
	 * value:籃球
	 * privince:"liaoning",city:"shenyang"
	 */
        System.out.println("====================");

        //解析json數組，此處有坑請注意
        String json = "[{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}},{'type':'multy','question':'愛好','options':{'items':[{'value':'籃球','country':{'privince':'liaoning','city':'shenyang'}}]}}]";
	JsonArray jsonArray = new JsonParser().parse(json).getAsJsonArray();
	for (int i = 0; i < jsonArray.size(); i++) {
            /*
	     * 此處有坑：執行new JsonParser().parse(json數組)後
	     * 得到的是一個JsonElement對象無法進行後續操作（取值或循環遍歷）
	     * 需要執行getAsString()或toString()方法將其變成字符串
	     */
	    JsonObject jsonObject = (JsonObject) new JsonParser().parse(jsonArray.get(i).toString());
	    System.out.println("type:" + jsonObject.get("type") + "," + "question:" + jsonObject.get("question"));
	    JsonArray items = jsonObject.get("options").getAsJsonObject().get("items").getAsJsonArray();
            JsonObject row = null;
	    for (int j = 0; j < items.size(); j++) {
	        row = (JsonObject) items.get(j);
		String value = row.get("value").getAsString();
		System.out.println("value:" + value);
		JsonObject country = row.get("country").getAsJsonObject();
		System.out.println("privince:" + country.get("privince") + "," + "city:" + country.get("city"));
		System.out.println("====================");
	    }
	}
        /*
	 * 控制檯輸出
	 * type:"multy",question:"愛好"
	 * value:籃球
	 * privince:"liaoning",city:"shenyang"
	 * ====================
	 * type:"multy",question:"愛好"
	 * value:籃球
	 * privince:"liaoning",city:"shenyang"
	 * ====================
	 */
    }
}

綜上是小編參考和自己摸索出來的結果，如有錯誤請指教~