ajax發送get、post請求

ajax可以發送post或者get請求，並且可以設置同步或者異步，這裏羅列了幾種。其中，後臺處理請求由servlet實現。

第一種方式：

var xmlhttp = new XMLHttpRequest();
//發送post請求，false表示發送同步請求
xmlhttp.open("POST","AdminLogin",false);
//設置文件的頭,UTF-8應與html編碼格式一致，告訴瀏覽器對參數編碼的格式，可以解決中文傳輸亂碼的問題
xmlhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded;charset=UTF-8");
//設置傳遞的參數
xmlhttp.send("id="+id+"&password="+password);
//顯示返回結果
alert(xmlhttp.responseText);

第二種方式（接受JSON包）：

//使用ajax方法,JS代碼
$.ajax({
    url: "GetStudentInfo",
    type: 'POST',
    async: false,
    contentType: 'application/json',
    mimeType: 'application/json',
    success: function (data) {//對返回值的處理
		$("#id").val(data.id);
		$("#name").val(data.name);
		$("#year").val(data.year);
		$("#specialty").val(data.specialty);
		$("#phone").val(data.phone);
		$("#email").val(data.email);
    },
});

//Servlet代碼
public class User {
	public String id;
	public String name;
	public String year;
	public String specialty;
	public String phone;
	public String email;
}

protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
	ObjectMapper mapper = new ObjectMapper();
        Connection con = DBTool.getConnection();
	User u = new User();
	u.id = "a";
	u.name = "b";
	u.year = "c";
	u.specialty = "d";
	u.phone = "e";
	u.email = "f";
	response.setContentType("application/json");  
}

第三種方式（接受JSON包，返回值爲集合）：

//JS代碼
$.ajax({
      url: "CheckAllStudent",
      type: 'POST',
      contentType: 'application/json',
      mimeType: 'application/json',
      success: function (data) {
          $.each(data, function (index, student) {
        	var string = "<tr>";
        	string += "<td>" + student.id+ "</td>";
        	string += "<td>" + student.name+ "</td>";
        	string += "<td>" + student.year+ "</td>";
        	string += "<td>" + student.specialty+ "</td>";
        	string += "<td>" + student.phone+ "</td>";
        	string += "<td>" + student.email+ "</td>";
        	$("tbody").append(string);
          }); 
      },
});

//Servlet代碼
protected void doPost(HttpServletRequest request, HttpServletResponse response) 
    throws ServletException, IOException {
    	ObjectMapper mapper = new ObjectMapper();
    	//把相同的對象放入List中
    	List<User>	list = new ArrayList<User>();
    	User u1,u2,u3;
    	list.add(u1);
    	list.add(u2);
    	list.add(u3);
	response.setContentType("application/json");  
	mapper.writeValue(response.getOutputStream(), list);
}

第四種方式（ajax方法，帶參數）：

$.ajax({
	url: "ShowAdvertise",
	type: 'POST',
	data: {time:time},
	success: function(data) {
		alert(data);
	},
});

參考文獻：

jQuery ajax - ajax() 方法