js_ajax简单例子_基于json的实现

忘是亡心i 2022-05-19 10:19 203阅读 0赞

@WebServlet("/ajax.do")
    public class HelloAjax extends HttpServlet {
    	private static final long serialVersionUID = 1L;
        private static Map<Integer, List<Person>> personMap=null;
        /**
         * @see HttpServlet#HttpServlet()
         */
        public HelloAjax() {
            super();
            // TODO Auto-generated constructor stub
            personMap=new HashMap<>();
            List<Person> ps=new ArrayList<>();
            ps.add(new Person(1, "1xm1", "男", 150.8));
            ps.add(new Person(2, "1xm2", "男", 150.9));
            ps.add(new Person(3, "1xm3", "男", 160.8));
            ps.add(new Person(4, "1xm4", "男", 170.8));
            personMap.put(1, ps);
            
            ps=new ArrayList<>();
            ps.add(new Person(1, "2xm1", "男", 250.8));
            ps.add(new Person(2, "2xm2", "男", 250.9));
            ps.add(new Person(3, "2xm3", "男", 260.8));
            ps.add(new Person(4, "2xm4", "男",270.8));
            personMap.put(2, ps);
            
            ps=new ArrayList<>();
            ps.add(new Person(1, "3xm1", "男", 350.8));
            ps.add(new Person(2, "3xm2", "男", 350.9));
            ps.add(new Person(3, "3xm3", "男", 360.8));
            ps.add(new Person(4, "3xm4", "男", 370.8));
            personMap.put(3, ps);
        }
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		doPost(request, response);
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		response.setContentType("text/html;charset=utf-8");
    		int depid=Integer.parseInt(request.getParameter("dep"));
    		List<Person> ps=personMap.get(depid);
    		StringBuffer xml=new StringBuffer();
    		xml.append("[");
    		int index=0;
    		for(Person p:ps) {
    			if(index==0) {
    				xml.append("{");
    			}else {
    				xml.append(",{");
    			}
    			index++;
    			xml.append("id:").append(p.getId()).append(",");
    			xml.append("name:\"").append(p.getName()).append("\",");
    			xml.append("sex:\"").append(p.getSex()).append("\",");
    			xml.append("salary:\"").append(p.getSalary()).append("\"");
    			xml.append("}");
    		}
    		xml.append("]");
    	    response.getWriter().write(xml.toString());
    	}
    
    }

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>Insert title here</title>
    <script type="text/javascript">
    window.onload=init;
    function init(){
    	var deps=document.getElementById("dep");
        deps.onchange=getdata;
    }
    function getdata(){
    	var value=this.value;
    	var xtr;
    	if (window.XMLHttpRequest) 
    	  {// code for IE7+, Firefox, Chrome, Opera, Safari 
    		xtr=new XMLHttpRequest(); 
    	  } 
    	else 
    	  {// code for IE6, IE5 
    		xtr=new ActiveXObject("Microsoft.XMLHTTP"); 
    	  }
    	xtr.open("post","ajax.do",true);
    	xtr.onreadystatechange=function(){
    		if(xtr.readyState==4&&xtr.status==200){
    			var jsonDoc=xtr.responseText;
    			var ps=eval(jsonDoc);
    			var str="";
    			for(var i=0;i<ps.length;i++){
    				str+=ps[i].id+"----"+ps[i].name+"----"+ps[i].sex+"----"+ps[i].salary+"<br>";
    			}
    			document.getElementById("display").innerHTML=str; 
    		}
    	}
    	xtr.setRequestHeader("Content-type","application/x-www-form-urlencoded"); 
    	xtr.send("dep="+value);
    	
    	
    }
    </script>
    </head>
    <body>
    <input type="button" id="btn" value="测试">
    <select id="dep">
    <option value="1">技术部1</option>
    <option value="2">技术部2</option>
    <option value="3">技术部3</option>
    </select>
    <div id="display"></div>
    </body>
    </html>

注意:(1).使用json,需要设置“text/html;charset=utf-8”

(2).json格式 \[\{,\},\{,\}\]，在引号内若想再引入引号，需要用\\"

(3).responseText返回的是json字符串，若想变为对象数组，需要使用eval()