Json in Java 的使用
1 json 就是一种数据的组拼形式,举个例子:
{"mine":[{"name":"name0","time":"time0"},{"name":"name1","time":"time1"},{"name":"name2","time":"time2"},{"name":"name3","time":"time3"},{"name":"name4","time":"time4"},{"name":"name5","time":"time5"},{"name":"name6","time":"time6"},{"name":"name7","time":"time7"},{"name":"name8","time":"time8"},{"name":"name9","time":"time9"}],"others":[{"name":"name0"},{"name":"name1"},{"name":"name2"},{"name":"name3"},{"name":"name4"}]}
整体结构是{"mine": xxx,"others":xxxx}, 即{jsonObject,jsonObject,...}有两个JsonObject组成。
第一个JsonObject:
"mine":[{"name":"name0","time":"time0"},{"name":"name1","time":"time1"},{"name":"name2","time":"time2"},{"name":"name3","time":"time3"},{"name":"name4","time":"time4"},{"name":"name5","time":"time5"},{"name":"name6","time":"time6"},{"name":"name7","time":"time7"},{"name":"name8","time":"time8"},{"name":"name9","time":"time9"}]
它的key是mine, 它的value是一个JsonArray,呦[]包裹,[]中间放的是一系列的jsonObject,即[jsonObject,jsonObject,.....]
JsonArray的存储形式类似于ListArray,其中存储的对象类型相同,
JsonObject的存储形式类似于Map,有一系列的Key-value组成而value的类型是多种多样的,可以是一个String对象,也可以是一个ArrayList对象
2 如何使用json来完成数据的组拼?
2.1 根据1中介绍的内容,我们完全可以自己组拼出这样一个json格式的数据,。
优点:不需要导入格外的jar包
缺点:很容易出错,标点符号,大括号等等。。
2.2 使用额外的jar包,一共需要六个jar包,分别是:
- commons-logging-1.0.4.jar
- commons-lang-2.3.jar
- commons-collections-3.2.jar
- commons-beanutils-1.7.0.jar
- json-lib-2.2.1-jdk15.jar
- ezmorph-1.0.4.jar
3 举例:
3.1 组拼出1的的那一串json数据:
public static JSONObject setData(){ JSONObject jsonObject = new JSONObject(); JSONArray jsonArray = new JSONArray(); Mine mine1 = new Mine("name1", "time1"); Mine mine2 = new Mine("name2", "time2"); List<Mine> list = new ArrayList<Mine>(); for(int i=0;i<10;i++){ Mine mine = new Mine("name"+i, "time"+i); list.add(mine); } for(int i=0;i<list.size();i++){ Mine mine = list.get(i); JSONObject jsonObject2 = new JSONObject(); jsonObject2.put("name", mine.getName()); jsonObject2.put("time", mine.getTime()); jsonArray.add(jsonObject2); } JSONArray jsonArray2 = new JSONArray(); List<Others> list2 = new ArrayList<Others>(); for(int i=0;i<5;i++){ Others others = new Others("name"+i); list2.add(others); } for(int i=0;i<list2.size();i++){ Others others = list2.get(i); JSONObject jsonObject2 = new JSONObject(); jsonObject2.put("name", others.getName()); jsonArray2.add(jsonObject2); } jsonObject.put("mine", jsonArray); jsonObject.put("others", jsonArray2); System.out.println(jsonObject.toString()); return jsonObject; }
3.2 往往json格式的数据,是用来数据存储和数据传输的,当拿到json格式的数据之后,我们需要将其解析成我们需要的对象。
public static void getData(JSONObject jsonObject){ JSONArray jsonArray = jsonObject.getJSONArray("mine"); for(int i=0;i<jsonArray.size();i++){ JSONObject jsonObject2 = jsonArray.getJSONObject(i); String name = jsonObject2.getString("name"); String time = jsonObject2.getString("time"); Mine mine = new Mine(name, time); System.out.println(mine.toString()); } }
补充例子中提到的那两个类:
class Mine{ private String name; private String time; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getTime() { return time; } public void setTime(String time) { this.time = time; } public Mine(String name, String time) { super(); this.name = name; this.time = time; } @Override public String toString() { return "Mine [name=" + name + ", time=" + time + "]"; } } class Others{ private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } public Others(String name) { super(); this.name = name; } @Override public String toString() { return "Others [name=" + name + "]"; } }
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