AJAX与后台如何互传数组

本文将介绍AJAX最为常用的应用,在阅读本文前请确保你读AJAX有所理解并知道些关于JSON的技术.

AJAX和后台传递对象或者对象数组时,本人最常用的是关于JSON技术下面本人将给出实际开发过程中用到的例子.

下面这个例子为互传数字型字符串数组("1111111111111")

function pageVerifySegment10() {
var warn = document.getElementById('warn');
warn.innerText = '';
doInitArray();//本方法为初始化指定数组
xmlHttp = createXMLHttpRequest();
var url = "/servlet/com.sino.ies.inv.maintenance.servlet.ItemVarifyServlet" ;
xmlHttp.onreadystatechange = doVerifySegment10;
xmlHttp.open('POST', url, true);
xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
xmlHttp.send(segment10Array.toJSONString());
}
function doVerifySegment10() {
if (xmlHttp.readyState == 4) {
if (xmlHttp.status == 200) {
// alert(xmlHttp.responseText)
var retSegment10Array = xmlHttp.responseText.parseJSON();
if (retSegment10Array.length > 0) {
var inputs = document.getElementsByName('segment10');
for (var i = 2; i < inputs.length; i++) {
var flag = true;
for (var j = 0; j < retSegment10Array.length; j++) {
if (retSegment10Array[j] == inputs[i].value) {
flag = false;
break;
}
}
if (flag) {
inputs[i].style.color = 'red';
var warn = document.getElementById('warn');
warn.innerText = '字体为红色的数据，在数据库不存在。';
warn.style.color = 'red';
}
}
}
}
}
}
后台代码为:

JSONArray segment10Array = null;
JSONArray retArray = new JSONArray();
JSONArray itemObjectArray = null;
JSONObject itemObject = null;
PrintWriter out = null;
String jsonString = readJSONStringFromRequestBody(req);
segment10Array = new JSONArray(jsonString);
ItemDTO itemDTO = new ItemDTO();
ItemDAO itemDAO = new ItemDAO(req, conn);
for (int i = 0; i < segment10Array.length(); i++) {
itemDTO.setSegment10(segment10Array.getString(i));
itemDAO.setParameter(itemDTO);
boolean success = itemDAO.doVerifyItem();
if (success) {
retArray.put(i, segment10Array.getString(i));
}
}
out = res.getWriter();
out.print(retArray.toString());
out.flush();
out.close();

private String readJSONStringFromRequestBody(HttpServletRequest request) {
StringBuffer json = new StringBuffer();
String line = null;
try {
BufferedReader reader = request.getReader();
while ((line = reader.readLine()) != null) {
json.append(line);
}
}
catch (Exception e) {
System.out.println("Error reading JSON string: " + e.toString());
}
return unescape(json.toString());
}

/**
* 解码 说明：本方法保证 不论参数src是否经过escape()编码，均能得到正确的“解码”结果
* @param src
* @return
*/
private static String unescape(String src) {
StringBuffer tmp = new StringBuffer();
tmp.ensureCapacity(src.length());
int lastPos = 0, pos = 0;
char ch;
while (lastPos < src.length()) {
pos = src.indexOf("%", lastPos);
if (pos == lastPos) {
if (src.charAt(pos + 1) == 'u') {
ch = (char) Integer.parseInt(src.substring(pos + 2, pos + 6), 16);
tmp.append(ch);
lastPos = pos + 6;
} else {
ch = (char) Integer.parseInt(src.substring(pos + 1, pos + 3), 16);
tmp.append(ch);
lastPos = pos + 3;
}
} else {
if (pos == -1) {
tmp.append(src.substring(lastPos));
lastPos = src.length();
} else {
tmp.append(src.substring(lastPos, pos));
lastPos = pos;
}
}
}
return tmp.toString();
}
下面本人将介绍一些在实际开发过程中使用AJAX技术会出现乱码问题的一些解决方法.

首先介绍在JSP页面传到后台时:只要在后台读取数据时,调用本人在上面给出的unescape方法应该基本上不会有太大问题,实在不行可以在XMLHttpRequest对象的send方法中调用escape方法试下如xmlHttp.send(escape(projectNameArray.toJSONString())).这样应该会得到解决.

在后台传到JSP页面时,如果有乱码情况建议读者通过调用respose.setContentType("")方法把后台的页面类型设成和页面的页面类型一样.这样乱码问题应该得到解决.