Question

Servlet怎么返回JSON值到前台，返回的是一个数组

Answer 1

1、实体类

[java] view plain copy
import java.util.ArrayList;

public class ObjectType {

private String type;
private ArrayList<SubObjectType> subObjects;
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public ArrayList<SubObjectType> getSubObjects() {
return subObjects;
}
public void setSubObjects(ArrayList<SubObjectType> subObjects) {
this.subObjects = subObjects;
}
}

[java] view plain copy
public class SubObjectType {

private String subtype;
private double fileCount;
private double bytes;
private String timeRange;
public String getSubtype() {
return subtype;
}
public void setSubtype(String subtype) {
this.subtype = subtype;
}
public double getFileCount() {
return fileCount;
}
public void setFileCount(double fileCount) {
this.fileCount = fileCount;
}
public double getBytes() {
return bytes;
}
public void setBytes(double bytes) {
this.bytes = bytes;
}
public String getTimeRange() {
return timeRange;
}
public void setTimeRange(String timeRange) {
this.timeRange = timeRange;
}

}

2、servlet：得到一个对象列表ArrayList<T>,将其转化为jsonArray

[java] view plain copy
AccountInfoDao dao = new AccountInfoDao();
ArrayList<ObjectType> objectTypes = new ArrayList<ObjectType>();
objectTypes = dao.load();

JSONObject jsonObject = new JSONObject();
jsonObject.put("categorys", objectTypes);

JSONArray jsonArray = new JSONArray();
jsonArray.add(jsonObject);
System.out.println(jsonArray);
PrintWriter out = response.getWriter();
out.write(jsonArray.toString());

3、js处理：

[javascript] view plain copy
function load(){
$.ajax({
type:"post",//请求方式
url:"servlet/AccountInfo",//发送请求地址
dataType:"json",
data:{//发送给数据库的数据
},
//请求成功后的回调函数有两个参数
success:function(data,textStatus){
var objs=eval(data); //解析json对象
var obj = objs[0];

var table = $("#table");
table.empty();
table.append('<tr><th></th><th>类别</th><th>文件个数</th><th>文件大小</th><th>时间范围</th></tr>');

if(obj==null || obj==""){
table.append('<tr><td colspan="5" style="text-align: center; color:red">暂无数据！</td></tr>')
//$("#page").hide();
return false;
}

var categorys = obj.categorys;
for(var i=0;i<categorys.length;i++){
var type = categorys[i].type;
var subObjects = categorys[i].subObjects;
var len = subObjects.length;
table.append('<tr><td rowspan="'+len+'">'+type+'</td>'+'<td>'+subObjects[0].subtype+'</td>'+'<td>'+subObjects[0].fileCount+'</td>'+'<td>'+subObjects[0].bytes+'</td>'+'<td>'+subObjects[0].timeRange+'</td></tr>')
//table.append('<td>'+subObjects[0].subtype+'</td>'+'<td>'+subObjects[0].fileCount+'</td>'+'<td>'+subObjects[0].bytes+'</td>'+'<td>'+subObjects[0].timeRange+'</td></tr>');
for(var j=1;j<len;j++){
table.append('<tr><td>'+subObjects[j].subtype+'</td>'+'<td>'+subObjects[j].fileCount+'</td>'+'<td>'+subObjects[j].bytes+'</td>'+'<td>'+subObjects[j].timeRange+'</td></tr>');
}
}

//为鼠标移动添加样式，鼠标所在行变色，鼠标离开行恢复原状
$("tr:even").addClass("even");
$("th").first().css("text-align","left");
$("th").first().css("padding-left","5px");
$("tr").mouseenter(function(){
$(this).addClass('bs');
});
$("tr").mouseleave(function(){
$(this).removeClass('bs');
});
}
});
}

4、jsp页面

[html] view plain copy
<table width="100%" border="0" cellspacing="0" cellpadding="0" class="tab" id="table">
<tr>
<th></th>
<th>类别</th>
<th>文件大小</th>
<th>文件个数</th>
<th>时间范围</th>
</tr>
</table>
望采纳，谢谢。