JSON学习笔记02

public String execute(){
        try {
            System.out.println("ListBean");
            List list=new ArrayList();
            list.add(new Userinfo("1","username1","password1"));
            list.add(new Userinfo("2","username2","password2"));
            list.add(new Userinfo("3","username3","password3"));
            list.add(new Userinfo("4","username4","password4"));

            String jsonString=JSONArray.fromObject(list).toString();
            HttpServletResponse response=ServletActionContext.getResponse();
            response.setCharacterEncoding("utf-8");
            PrintWriter out=response.getWriter();
            out.print(jsonString);
            out.flush();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

result:

[{"id":"1","password":"password1","username":"username1"},
     {"id":"2","password":"password2","username":"username2"},
     {"id":"3","password":"password3","username":"username3"},
     {"id":"4","password":"password4","username":"username4"}]

public String execute(){
        try {
            System.out.println("listString");
            List list=new ArrayList();
            list.add("a1");
            list.add("a2");
            list.add("a3");
            list.add("a4");
            String jsonString=JSONArray.fromObject(list).toString();
            HttpServletResponse response=ServletActionContext.getResponse();
            response.setCharacterEncoding("utf-8");
            PrintWriter out=response.getWriter();
            out.print(jsonString);
            out.flush();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

result:

["a1","a2","a3","a4"]

public String execute() {
        try {
            System.out.println("ListMap");
            Map map1=new HashMap();
            map1.put("a1", "valuea1");
            map1.put("a2", "valuea2");
            Map map2=new HashMap();
            map2.put("a3", "valuea3");
            map2.put("a4", "valuea4");
            List list = new ArrayList();
            list.add(map1);
            list.add(map2);

            String jsonString = JSONArray.fromObject(list).toString();
            HttpServletResponse response = ServletActionContext.getResponse();
            response.setCharacterEncoding("utf-8");
            PrintWriter out = response.getWriter();
            out.print(jsonString);
            out.flush();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

result:

[{"a1":"valuea1","a2":"valuea2"},{"a3":"valuea3","a4":"valuea4"}]

public String execute() {
        try {
            System.out.println("MapBean");
            Map map1 = new LinkedHashMap();
            map1.put("a1", new Userinfo("1","username1","password1"));
            map1.put("a2", new Userinfo("2","username2","password2"));

            String jsonString=JSONObject.fromObject(map1).toString();
            //String jsonString = JSONArray.fromObject(map1).toString();
            HttpServletResponse response = ServletActionContext.getResponse();
            response.setCharacterEncoding("utf-8");
            PrintWriter out = response.getWriter();
            out.print(jsonString);
            out.flush();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

{"a1":{"id":"1","password":"password1","username":"username1"},
"a2":{"id":"2","password":"password2","username":"username2"}} 

public String execute() {
        try {
            System.out.println("MapString");
            Map map1 = new LinkedHashMap();
            map1.put("a1", "valuea1");
            map1.put("a2", "valuea2");

            String jsonString=JSONObject.fromObject(map1).toString();
            //String jsonString = JSONArray.fromObject(map1).toString();
            HttpServletResponse response = ServletActionContext.getResponse();
            response.setCharacterEncoding("utf-8");
            PrintWriter out = response.getWriter();
            out.print(jsonString);
            out.flush();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

{"a1":"valuea1","a2":"valuea2"}