JSON入门学习第四节

基于json-lib.jar包Json实例程序

1.从头或者从零开始，创建一个JSONObject(Creating a JSONObject from scratch)

实例1：

JSONObject jsonObject = new JSONObject();

jsonObject.element("name", "周星星");

jsonObject.element("sex", "male");

jsonObject.element("age", 18);

jsonObject.element("job", "student");

System.out.println(jsonObject.get("name"));// 周星星

System.out.println(jsonObject.get("job"));// student

System.out.println(jsonObject.getString("sex"));// male

System.out.println(jsonObject.getInt("age"));// 18

实例2：

JSONObject jsonObject = new JSONObject().element("string", "JSON").element("integer", "1").element("double", "2.0").element("boolean", "true");

assertEquals("JSON", jsonObject.getString("string"));

assertEquals(1, jsonObject.getInt("integer"));

assertEquals(2.0d, jsonObject.getDouble("double"), 0d);

assertTrue(jsonObject.getBoolean("boolean"));

注：这是对实例1的一个简化版

2.使用一个JSON格式化字符串来创建一个JSONObject(Creating a JSONObject from a JSON formatted string)

实例1：

String json = "{name:/"周星星/",sex:/"male/",age:18,job:/"student/"}";

JSONObject jsonObject = JSONObject.fromObject(json);

//或者使用 JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(json);

System.out.println(jsonObject.get("name"));// 周星星

System.out.println(jsonObject.get("job"));// student

System.out.println(jsonObject.getString("sex"));// male

System.out.println(jsonObject.getInt("age"));// 18

实例2：

String str = "{'string':'JSON', 'integer': 1, 'double': 2.0, 'boolean': true}";

JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(str);

assertEquals("JSON", jsonObject.getString("string"));

assertEquals(1, jsonObject.getInt("integer"));

assertEquals(2.0d, jsonObject.getDouble("double"), 0d);

assertTrue(jsonObject.getBoolean("boolean"));

3.使用一个Map来创建一个JSONObject(Creating a JSONObject from a Map)

实例1：

Map map = new HashMap();

map.put( "string", "JSON" );

map.put( "integer", "1" );

map.put( "double", "2.0" );

map.put( "boolean", "true" );

JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON( map );

assertEquals( "JSON", jsonObject.getString("string") );

assertEquals( 1, jsonObject.getInt("integer") );

assertEquals( 2.0d, jsonObject.getDouble("double"), 0d );

assertTrue( jsonObject.getBoolean("boolean") );

4.使用一个JavaBean来创建一个JSONObject(Creating a JSONObject from a JavaBean)

实例1：

public class Mybean { private String string; private int integer; private double dooble; private boolean bool; // getters & setters}

Mybean bean = new Mybean();

bean.setString("JSON");

bean.setInteger(1);

bean.setDooble(2.0d);

bean.setBool(true);

JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(bean);

assertEquals("JSON", jsonObject.getString("string"));

assertEquals(1, jsonObject.getInt("integer"));

assertEquals(2.0d, jsonObject.getDouble("dooble"), 0d);

assertTrue(jsonObject.getBoolean("bool"));

由此可见，无论要转换的源是哪种类型，都可以使用(JSONObject) JSONSerializer.toJSON()或JSONObject.fromObject()来转换;